---------------------------------------------------------- TeamGrumman-List Digest Archive --- Total Messages Posted Wed 02/25/09: 13 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:47 AM - Re: Intake runner length and balancing intake charge (flyv35b) 2. 07:50 AM - Re: Intake runner length and balancing intake charge (James Courtney) 3. 09:06 AM - Re: Intake runner length and balancing intake charge (923te) 4. 09:15 AM - Re: Intake runner length and balancing intake charge (923te) 5. 10:26 AM - Re: Intake runner length and balancing intake charge (flyv35b) 6. 04:16 PM - Re: Cranking pressure (was Connecting rod length) (923te) 7. 04:18 PM - Re: Cranking pressure (was Connecting rod length) (923te) 8. 04:25 PM - Re: Intake runner length and balancing intake charge (923te) 9. 04:42 PM - Re: Cranking pressure (was Connecting rod length) (teamgrumman@aol.com) 10. 04:43 PM - Re: Cranking pressure (was Connecting rod length) (teamgrumman@AOL.COM) 11. 07:38 PM - Re: Cranking pressure (was Connecting rod length) (923te) 12. 11:09 PM - Re: Cranking pressure (was Connecting rod length) (teamgrumman@AOL.COM) 13. 11:33 PM - Re: Cranking pressure (was Connecting rod length) (teamgrumman@aol.com) ________________________________ Message 1 _____________________________________ Time: 06:47:27 AM PST US From: "flyv35b" Subject: Re: TeamGrumman-List: Intake runner length and balancing intake charge I remember talking to Ken at Lycon once and he told me he had spent some ti me trying to do this. Apparently the charge almost hits a brick wall (so t o speak) when it enters the HA-6 carb sump and doesn't divide equally from one side to the other, let alone the unequal length induction tubes. Gary is right, the best Lycoming engine induction system is the cold air system with forward facing fuel injector that many of the RV builders are using. The air is fed from the baffle plate in front of the #2 cylinder, through a filter and nice fiberglass duct to the injector. It never ceases to amaze me how much people like to talk about modifying a Grumman or it's engine installation to improve it in some way and gain bett er performance (I guess it's fun to dream). But very few people actually u ndertake even getting minor changes approved, Gary, Gene, Fred, Maynard, Ke n, etc. excepted. It's easy to dream and talk but doing it is something el se. I'd rather work on getting an STC for a FI engine that would fit in Ga ry's cowling and utilize a CS prop and different exhaust system than trying to band-aid the -A4K. But if you like to try all sorts of ideas and want the freedom to do so, why not just build an RV or Lancair and do what your want. Even those planes are pretty well engineered and somewhat =22fixed=22 in what you can do from a practical standpoint. In response to Jamey's comments, I don't think that it matters whether you are LOP or ROP as far as needing to have a balanced air flow to each cylind er. If you look at the power developed vs. EGT you see that the power cont inues to fall even faster on the lean side of peak the leaner yet get. So a cylinder running 10* LOP is developing more HP than one running 50* LOP a s I understand it. GAMI's whole intent was to get all cylinders to peak at the same time by adjusting the fuel flow thereby keeping one or more cylin ders from falling off in power on the lean side while the others are still remaining relatively constant on the rich side as the mixture is leaned. B ut they did nothing to change or improve the less than optimum air flow dis tribution of the Continental log manifold. With this induction system you can still have noticeable power differences from one cylinder to another ev en if they all peak at exactly the same time. The IO-550 used by Cirrus, e tc. attempts to further balance the air flow. I'm sure that the cross flow cylinder head (intake in one side, exhaust out the other) doesn't hurt eit her. Once the air flows are equal then you can use the same fuel injector on each cylinder and the power should be very nearly identical, resulting i n a very smooth running engine. Cliff ----- Original Message ----- From: James Courtney To: teamgrumman-list@matronics.com Sent: Tuesday, February 24, 2009 11:24 PM Subject: RE: TeamGrumman-List: Intake runner length and balancing intake charge The short answer is no and I don=99t know much about the Continentals. T he new IO-550Rs or whatever they are putting in the new Cirrus and Cessna a ircraft claim 10 more HP and a 2000 hr. TBO up from 1700. I suspect the TB O increase has more to do with the metallurgy and manufacturing processes a vailable during certification of this slightly more modern line of engines than the tuned induction but that=99s pure conjecture on my part. I=99m as suming most of the power balancing still comes by regulating fuel flow to e ach cylinder using balanced injectors. Once LOP where many folks run the b ig Continentals you have a surplus of air so minor differences in the induc tion shouldn=99t matter much. ROP maybe the tuned engines are a little smo other=3F Jamey From: owner-teamgrumman-list-server@matronics.com [mailto:owner-teamgrumm an-list-server@matronics.com] On Behalf Of 923te Sent: Tuesday, February 24, 2009 7:20 AM To: teamgrumman-list@matronics.com Subject: TeamGrumman-List: Intake runner length and balancing intake char ge Anyone here ever experiment with trying to balance power output between c ylinders by adjusting the intake runners on an A4K Lycoiming=3F Any thoughts=3F I'm wondering if the aft tubes were effectively lengthened would that mak e a difference=3F Lengthened so that the distance from the carb to the cylind er head would be the same for all 4 cylinders. Or would a change in the shape of the pathways in the sump be more effect ive=3F Or both required to get a good balance of power=3F Does the tuned induction on the Continentals work to balance power=3F If so why=3F Thanks, Ned http://www.matronics.com/Navigator=3FTeamGrumman-Listhttp://forums.matronic s.comhttp://www.matronics.com/contribution No virus found in this incoming message. 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The Professional version does not have this message ________________________________ Message 2 _____________________________________ Time: 07:50:27 AM PST US From: "James Courtney" Subject: RE: TeamGrumman-List: Intake runner length and balancing intake charge Hey Cliff, No great disagreement with you and I certainly agree that 10 LOP is more HP than 50 but my point was WRT GAMIs theory that engine roughness when LOP is due to uneven power production across the cylinders. This is happening because, just like ROP where minor fuel flow deltas between the cylinders don=99t affect engine smoothness as long as all cylinders have a surplus of fuel for the combustion event, I would conjecture that LOP minor differences in induction air flow to each cylinder don=99t have as major an effect because the combustion event is throttled by the amount of fuel available. I do see your point about being leaner or richer having a greater effect on HP produced LOP but I think this is the lesser effect to getting the fuel distribution consistent because the differences in induction air flow are comparatively minor. To clarify: I start with the assumption that a smooth running engine is producing a relatively consistent amount of HP across all cylinders. This seems to be widely held and agreed upon. If this is the case then, when ROP the, since the combustion event is controlled by available air then I think the conclusion follows that the air induction system is reasonably well balance even on the older engine designs. LOP ops depend on this even distribution and are simply fine-tuned with balanced injectors to account for minor inconsistencies in the induction system and presumably the fuel delivery system and even the cylinders themselves. This (fuel distribution) is the harder nut to crack since the quantities of fuel being delivered are rather small compared to the volume of air and thus, for proper combustion, the metering of the fuel to each cylinder is the more sensitive adjustment. With truly poor air distribution then smooth LOP (or ROP) operations would be difficult. That was my point. I=99m sure there are IO-550s that run well LOP down to 14 GPH at 75% where as mine starts getting rough at about 15.5 even with well tuned injectors and this may well be reflective of how well balanced the induction system is but in general I think the air induction systems must be reasonably well balanced. Anyway, that=99s my theory so poke away at itJ Jamey From: owner-teamgrumman-list-server@matronics.com [mailto:owner-teamgrumman-list-server@matronics.com] On Behalf Of flyv35b Sent: Wednesday, February 25, 2009 6:46 AM Subject: Re: TeamGrumman-List: Intake runner length and balancing intake charge I remember talking to Ken at Lycon once and he told me he had spent some time trying to do this. Apparently the charge almost hits a brick wall (so to speak) when it enters the HA-6 carb sump and doesn't divide equally from one side to the other, let alone the unequal length induction tubes. Gary is right, the best Lycoming engine induction system is the cold air system with forward facing fuel injector that many of the RV builders are using. The air is fed from the baffle plate in front of the #2 cylinder, through a filter and nice fiberglass duct to the injector. It never ceases to amaze me how much people like to talk about modifying a Grumman or it's engine installation to improve it in some way and gain better performance (I guess it's fun to dream). But very few people actually undertake even getting minor changes approved, Gary, Gene, Fred, Maynard, Ken, etc. excepted. It's easy to dream and talk but doing it is something else. I'd rather work on getting an STC for a FI engine that would fit in Gary's cowling and utilize a CS prop and different exhaust system than trying to band-aid the -A4K. But if you like to try all sorts of ideas and want the freedom to do so, why not just build an RV or Lancair and do what your want. Even those planes are pretty well engineered and somewhat "fixed" in what you can do from a practical standpoint. In response to Jamey's comments, I don't think that it matters whether you are LOP or ROP as far as needing to have a balanced air flow to each cylinder. If you look at the power developed vs. EGT you see that the power continues to fall even faster on the lean side of peak the leaner yet get. So a cylinder running 10* LOP is developing more HP than one running 50* LOP as I understand it. GAMI's whole intent was to get all cylinders to peak at the same time by adjusting the fuel flow thereby keeping one or more cylinders from falling off in power on the lean side while the others are still remaining relatively constant on the rich side as the mixture is leaned. But they did nothing to change or improve the less than optimum air flow distribution of the Continental log manifold. With this induction system you can still have noticeable power differences from one cylinder to another even if they all peak at exactly the same time. The IO-550 used by Cirrus, etc. attempts to further balance the air flow. I'm sure that the cross flow cylinder head (intake in one side, exhaust out the other) doesn't hurt either. Once the air flows are equal then you can use the same fuel injector on each cylinder and the power should be very nearly identical, resulting in a very smooth running engine. Cliff ----- Original Message ----- From: James Courtney Sent: Tuesday, February 24, 2009 11:24 PM Subject: RE: TeamGrumman-List: Intake runner length and balancing intake charge The short answer is no and I don=99t know much about the Continentals. The new IO-550Rs or whatever they are putting in the new Cirrus and Cessna aircraft claim 10 more HP and a 2000 hr. TBO up from 1700. I suspect the TBO increase has more to do with the metallurgy and manufacturing processes available during certification of this slightly more modern line of engines than the tuned induction but that=99s pure conjecture on my part. I=99m assuming most of the power balancing still comes by regulating fuel flow to each cylinder using balanced injectors. Once LOP where many folks run the big Continentals you have a surplus of air so minor differences in the induction shouldn=99t matter much. ROP maybe the tuned engines are a little smoother? Jamey From: owner-teamgrumman-list-server@matronics.com [mailto:owner-teamgrumman-list-server@matronics.com] On Behalf Of 923te Sent: Tuesday, February 24, 2009 7:20 AM Subject: TeamGrumman-List: Intake runner length and balancing intake charge Anyone here ever experiment with trying to balance power output between cylinders by adjusting the intake runners on an A4K Lycoiming? Any thoughts? I'm wondering if the aft tubes were effectively lengthened would that make a difference? Lengthened so that the distance from the carb to the cylinder head would be the same for all 4 cylinders. Or would a change in the shape of the pathways in the sump be more effective? Or both required to get a good balance of power? Does the tuned induction on the Continentals work to balance power? If so why? Thanks, Ned http://www.matronics.com/Navigator?TeamGrumman-List http://forums.matronics.com http://www.matronics.com/contribution Checked by AVG - www.avg.com 02/24/09 06:43:00 _____ /2009 6:43 AM _____ . We are a community of 6 million users fighting spam. SPAMfighton does not have this message. Checked by AVG - www.avg.com 02/24/09 13:35:00 ________________________________ Message 3 _____________________________________ Time: 09:06:44 AM PST US From: "923te" <923te@att.net> Subject: Re: TeamGrumman-List: Intake runner length and balancing intake charge I did not say I was going to modify my grumman A4K. I just ask a question about it. I do have an RV with an O320 and I could modify it without much certification issues. My previous RV 6 had a 4.3liter GM marine engine in it. I had a lot of fun experimenting with it too. I don't understand why that torques some people so much??? Let me ask, if one cylinder has an intake leak causing EGT to be a bit higher than the other cylinders but otherwise functions well why couldn't one put a orfice on an overly rich cylinder intake to make it run leaner at best power? ned ----- Original Message ----- From: flyv35b To: teamgrumman-list@matronics.com Sent: Wednesday, February 25, 2009 8:46 AM Subject: Re: TeamGrumman-List: Intake runner length and balancing intake charge I remember talking to Ken at Lycon once and he told me he had spent some time trying to do this. Apparently the charge almost hits a brick wall (so to speak) when it enters the HA-6 carb sump and doesn't divide equally from one side to the other, let alone the unequal length induction tubes. Gary is right, the best Lycoming engine induction system is the cold air system with forward facing fuel injector that many of the RV builders are using. The air is fed from the baffle plate in front of the #2 cylinder, through a filter and nice fiberglass duct to the injector. It never ceases to amaze me how much people like to talk about modifying a Grumman or it's engine installation to improve it in some way and gain better performance (I guess it's fun to dream). But very few people actually undertake even getting minor changes approved, Gary, Gene, Fred, Maynard, Ken, etc. excepted. It's easy to dream and talk but doing it is something else. I'd rather work on getting an STC for a FI engine that would fit in Gary's cowling and utilize a CS prop and different exhaust system than trying to band-aid the -A4K. But if you like to try all sorts of ideas and want the freedom to do so, why not just build an RV or Lancair and do what your want. Even those planes are pretty well engineered and somewhat "fixed" in what you can do from a practical standpoint. In response to Jamey's comments, I don't think that it matters whether you are LOP or ROP as far as needing to have a balanced air flow to each cylinder. If you look at the power developed vs. EGT you see that the power continues to fall even faster on the lean side of peak the leaner yet get. So a cylinder running 10* LOP is developing more HP than one running 50* LOP as I understand it. GAMI's whole intent was to get all cylinders to peak at the same time by adjusting the fuel flow thereby keeping one or more cylinders from falling off in power on the lean side while the others are still remaining relatively constant on the rich side as the mixture is leaned. But they did nothing to change or improve the less than optimum air flow distribution of the Continental log manifold. With this induction system you can still have noticeable power differences from one cylinder to another even if they all peak at exactly the same time. The IO-550 used by Cirrus, etc. attempts to further balance the air flow. I'm sure that the cross flow cylinder head (intake in one side, exhaust out the other) doesn't hurt either. Once the air flows are equal then you can use the same fuel injector on each cylinder and the power should be very nearly identical, resulting in a very smooth running engine. Cliff ----- Original Message ----- From: James Courtney To: teamgrumman-list@matronics.com Sent: Tuesday, February 24, 2009 11:24 PM Subject: RE: TeamGrumman-List: Intake runner length and balancing intake charge The short answer is no and I don=99t know much about the Continentals. The new IO-550Rs or whatever they are putting in the new Cirrus and Cessna aircraft claim 10 more HP and a 2000 hr. TBO up from 1700. I suspect the TBO increase has more to do with the metallurgy and manufacturing processes available during certification of this slightly more modern line of engines than the tuned induction but that=99s pure conjecture on my part. I=99m assuming most of the power balancing still comes by regulating fuel flow to each cylinder using balanced injectors. Once LOP where many folks run the big Continentals you have a surplus of air so minor differences in the induction shouldn=99t matter much. ROP maybe the tuned engines are a little smoother? Jamey From: owner-teamgrumman-list-server@matronics.com [mailto:owner-teamgrumman-list-server@matronics.com] On Behalf Of 923te Sent: Tuesday, February 24, 2009 7:20 AM To: teamgrumman-list@matronics.com Subject: TeamGrumman-List: Intake runner length and balancing intake charge Anyone here ever experiment with trying to balance power output between cylinders by adjusting the intake runners on an A4K Lycoiming? Any thoughts? I'm wondering if the aft tubes were effectively lengthened would that make a difference? Lengthened so that the distance from the carb to the cylinder head would be the same for all 4 cylinders. Or would a change in the shape of the pathways in the sump be more effective? Or both required to get a good balance of power? Does the tuned induction on the Continentals work to balance power? If so why? Thanks, Ned http://www.matronics.com/Navigator?TeamGrumman-Listhttp://forums.matronic s.comhttp://www.matronics.com/contribution No virus found in this incoming message. Checked by AVG - www.avg.com 02/24/09 06:43:00 ------------------------------------------------------------------------- --- /2009 6:43 AM ------------------------------------------------------------------------- ----- We are a community of 6 million users fighting spam. SPAMfighton does not have this message. ________________________________ Message 4 _____________________________________ Time: 09:15:01 AM PST US From: "923te" <923te@att.net> Subject: Re: TeamGrumman-List: Intake runner length and balancing intake charge Very interesting Gary. I did not know how complicated it was. Sounds like very small changes could have very large effects. On the TIger it would be much better to slip in a B1E and then start the fuel mix in the intake part of the cylinder ----- Original Message ----- From: teamgrumman@aol.com To: teamgrumman-list@matronics.com Sent: Wednesday, February 25, 2009 12:25 AM Subject: Re: TeamGrumman-List: Intake runner length and balancing intake charge Wouldn't it be nice if air flow was one-dimensional? Then, a simple restrictor would have no effect on turbulence in the intake, the fuel wouldn't separate (i.e., fall out of the air flow) due to the pressure change, and the flow velocity profile wouldn't be affected. For what it's worth, the length of the intake affects the amount of kinetic energy in the intake charge. Short runners are good for high rpm horsepower. Long ones for low rpm torque. A difference of a few centimeters can be corrected by porting and polishing, taking the entire assembly into consideration. Here is something to ponder, regarding flow in a port: consider a solid propellent rocket motor. The solid propellent is a cylindrical cross section, let's say, with a cross-section thickness of 1 inch, an outside diameter of 3 inches and internal diameter of 1 inch. One end is closed. The other end has a converging/diverging nozzle. Now, uniformly light the propellent surface. Question(s): (1) What do you expect the velocity profile to look like going down the port? (2) What would you expect the profile to look like going through the nozzle? (picture the booster engines on the space shuttle) If your answer to (1) was uniform flow going down the port, what would you think if I told you there are, at times, 4 to to 7 highly rotational flows, rotating as a mass clockwise, then count er-clockwise, then clockwise, etc. The classical one-dimensional profile you learned when creating a whistle by blowing across the top of a pop bottle, doesn't exist in the real world. If your answer to (2) is the type of flow you hope is happening in the venturi of your carburetor, you'd be wrong again. There is, in the highly rotational flow trying to exit the nozzle, a core which is not in the center of the flow, but which rotates around the nozzle like the core of a hurricane trying to get out. Within the intake tubes, every bend and every shape change, changes the fuel density distribution. Equal length tubes cannot prevent that. Equal length tubes only affect the amount of energy being stored in the intake charge between each intake valve opening cycle. Clever manipulation of the rocker arm geometry or cam profile can correct that. -----Original Message----- From: Andy Thomas To: teamgrumman-list@matronics.com Sent: Tue, 24 Feb 2009 5:34 pm Subject: Re: TeamGrumman-List: Intake runner length and balancing intake charge why couldn't you take a plain old O360 and put restrictors in the rich cylinder intakes to balance all cylinders at say 2500 rpm. Maybe a restrictor like the aperture of a camera with an adjustment screw that could be mount ed in the rubber boot that connects the intake pieces. The amount of air coming in should be the same so you are just redistributing it (and fuel) so power should stay the same, but balanced. No? seems like it should work.... Andy Thomas ----- Original Message ----- From: 923te To: teamgrumman-list@matronics.com Sent: Tuesday, February 24, 2009 2:48 PM Subject: Re: TeamGrumman-List: Intake runner length and balancing intake charge From SSP204 IO-360-M1A 180/ 2700/ 100/100LL 8.50:1 Same as =93B1E except has a front mounted propeller -51 160 2400 governor pad and a front mounted fuel injector IO-360-M1B 180 2700 100/100LL 8.50:1 Same as =93M1A except propeller governor located in -51 the rear, relocated flow divider and impulse Magneto So the M1B has a front facing fuel injector....why couldn't it fit on a Tiger? Put a ram air induction on it and have the filtered air come in from elsewhere. Have an intake like a Cheetah but instead of a NACA put a round pipe extending to the prop... I'm thining of doing the Sabertooth that way... ----- Original Message ----- From: teamgrumman@aol.com To: teamgrumman-list@matronics.com Sent: Tuesday, February 24, 2009 2:34 PM Subject: Re: TeamGrumman-List: Intake runner length and balancing intake charge The IO360M1B is the engine to get for perfect intakes. It just won't fit in a Tiger -----Original Message----- From: 923te <923te@att.net> To: teamgrumman-list@matronics.com Sent: Tue, 24 Feb 2009 7:20 am Subject: TeamGrumman-List: Intake runner length and balancing intake charge Anyone here ever experiment with trying to balance power output between cylinders by adjusting the intake runners on an A4K Lycoiming? Any thoughts? I'm wondering if the aft tubes were effectively lengthened would that make a difference? Lengthened so that the distance from the carb to the cylinder head would be the same for all 4 cylinders. Or would a change in the shape of the pathways in the sump be more effective? Or both required to get a good balance of power? Does the tuned induction on the Continentals work to balance power? If so why? Thanks, Ned or?TeamGrumman-List">http://www.matronics.com/Navigator?TeamGrumman-List p://forums.matronics.com ution">http://www.matronics.com/contribution ------------------------------------------------------------------------- - A Good Credit Score is 700 or Above. 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See yours in just 2 easy steps! ________________________________ Message 5 _____________________________________ Time: 10:26:18 AM PST US From: "flyv35b" Subject: Re: TeamGrumman-List: Intake runner length and balancing intake charge I wasn't referring to you, Ned, just making a general statement. Nothing wrong with experimenting and it doesn't bother me at all. That's what experimentals are all about, but the FAA has seen fit to make sure it doesn't happen with certified aircraft, unless you follow their rules (STC process). Actually you could surrender your airworthiness certificate and get an experimental one and do most anything you want (for a short time) to evaluate a theory, etc. and then convert it back to a standard airworthiness certificate. You probably could throttle the intake for an overly rich cylinder to make it develop less power, but it might not be leaner. I've never heard of anyone trying to do something like that. But it seems to me that every time you change RPM or throttle setting something changes and now some other cylinder might be the richest one. Cliff ----- Original Message ----- From: 923te To: teamgrumman-list@matronics.com Sent: Wednesday, February 25, 2009 9:00 AM Subject: Re: TeamGrumman-List: Intake runner length and balancing intake charge I did not say I was going to modify my grumman A4K. I just ask a question about it. I do have an RV with an O320 and I could modify it without much certification issues. My previous RV 6 had a 4.3liter GM marine engine in it. I had a lot of fun experimenting with it too. I don't understand why that torques some people so much??? Let me ask, if one cylinder has an intake leak causing EGT to be a bit higher than the other cylinders but otherwise functions well why couldn't one put a orfice on an overly rich cylinder intake to make it run leaner at best power? ned ----- Original Message ----- From: flyv35b To: teamgrumman-list@matronics.com Sent: Wednesday, February 25, 2009 8:46 AM Subject: Re: TeamGrumman-List: Intake runner length and balancing intake charge I remember talking to Ken at Lycon once and he told me he had spent some time trying to do this. Apparently the charge almost hits a brick wall (so to speak) when it enters the HA-6 carb sump and doesn't divide equally from one side to the other, let alone the unequal length induction tubes. Gary is right, the best Lycoming engine induction system is the cold air system with forward facing fuel injector that many of the RV builders are using. The air is fed from the baffle plate in front of the #2 cylinder, through a filter and nice fiberglass duct to the injector. It never ceases to amaze me how much people like to talk about modifying a Grumman or it's engine installation to improve it in some way and gain better performance (I guess it's fun to dream). But very few people actually undertake even getting minor changes approved, Gary, Gene, Fred, Maynard, Ken, etc. excepted. It's easy to dream and talk but doing it is something else. I'd rather work on getting an STC for a FI engine that would fit in Gary's cowling and utilize a CS prop and different exhaust system than trying to band-aid the -A4K. But if you like to try all sorts of ideas and want the freedom to do so, why not just build an RV or Lancair and do what your want. Even those planes are pretty well engineered and somewhat "fixed" in what you can do from a practical standpoint. In response to Jamey's comments, I don't think that it matters whether you are LOP or ROP as far as needing to have a balanced air flow to each cylinder. If you look at the power developed vs. EGT you see that the power continues to fall even faster on the lean side of peak the leaner yet get. So a cylinder running 10* LOP is developing more HP than one running 50* LOP as I understand it. GAMI's whole intent was to get all cylinders to peak at the same time by adjusting the fuel flow thereby keeping one or more cylinders from falling off in power on the lean side while the others are still remaining relatively constant on the rich side as the mixture is leaned. But they did nothing to change or improve the less than optimum air flow distribution of the Continental log manifold. With this induction system you can still have noticeable power differences from one cylinder to another even if they all peak at exactly the same time. The IO-550 used by Cirrus, etc. attempts to further balance the air flow. I'm sure that the cross flow cylinder head (intake in one side, exhaust out the other) doesn't hurt either. Once the air flows are equal then you can use the same fuel injector on each cylinder and the power should be very nearly identical, resulting in a very smooth running engine. Cliff ----- Original Message ----- From: James Courtney To: teamgrumman-list@matronics.com Sent: Tuesday, February 24, 2009 11:24 PM Subject: RE: TeamGrumman-List: Intake runner length and balancing intake charge The short answer is no and I don=99t know much about the Continentals. The new IO-550Rs or whatever they are putting in the new Cirrus and Cessna aircraft claim 10 more HP and a 2000 hr. TBO up from 1700. I suspect the TBO increase has more to do with the metallurgy and manufacturing processes available during certification of this slightly more modern line of engines than the tuned induction but that=99s pure conjecture on my part. I=99m assuming most of the power balancing still comes by regulating fuel flow to each cylinder using balanced injectors. Once LOP where many folks run the big Continentals you have a surplus of air so minor differences in the induction shouldn=99t matter much. ROP maybe the tuned engines are a little smoother? Jamey From: owner-teamgrumman-list-server@matronics.com [mailto:owner-teamgrumman-list-server@matronics.com] On Behalf Of 923te Sent: Tuesday, February 24, 2009 7:20 AM To: teamgrumman-list@matronics.com Subject: TeamGrumman-List: Intake runner length and balancing intake charge Anyone here ever experiment with trying to balance power output between cylinders by adjusting the intake runners on an A4K Lycoiming? Any thoughts? I'm wondering if the aft tubes were effectively lengthened would that make a difference? Lengthened so that the distance from the carb to the cylinder head would be the same for all 4 cylinders. Or would a change in the shape of the pathways in the sump be more effective? Or both required to get a good balance of power? Does the tuned induction on the Continentals work to balance power? If so why? Thanks, Ned http://www.matronics.com/Navigator?TeamGrumman-Listhttp://forums.matronic s.comhttp://www.matronics.com/contribution No virus found in this incoming message. Checked by AVG - www.avg.com 02/24/09 06:43:00 href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.m atronics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c ------------------------------------------------------------------------- - /2009 6:43 AM ------------------------------------------------------------------------- --- We are a community of 6 million users fighting spam. SPAMfighton does not have this message. href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.m atronics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c ------------------------------------------------------------------------- ----- Checked by AVG. 2/24/2009 6:43 AM ________________________________ Message 6 _____________________________________ Time: 04:16:31 PM PST US From: "923te" <923te@att.net> Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length) I've been trying to find an old article about a couple of A&P's that do compression testing and keep records to compare from annual to annual. I can't find the article right now but I think it is a great idea. We used to check out car engines this way. Seems like you could expect pressures around 17 to 20 times the compression ratio. I sure would like to find what Lycoming or Continental says you should have. It is a little different than just the compression ratio times the ambient pressure because of the effect of temperature during compression and valve overlap etc. For the Tigers you tested below it is interesting to note that for 8.5:1 you could estimate a pressure of 8.5 x 30.2 X 0.4912 psi/inHG = 126 psi (where 30.2 was the barometric pressure around 3pm yesterday http://www.wunderground.com/weatherstation/WXDailyHistory.asp?ID=KCAAUB UR7&month=2&day=24&year 09) On Tiger 1 did you do a leak down test to see if it could help tell where the wear was? Seems like we could tell whether the rings were worn with a compression test by doing it wet after the dry run. Wet meant addding a teaspoon or 2 of oil in the spark plug hole and doing another test. If the low cylinder psi went up then it was thought that the rings were the source of the leak instead of the valves or a worn cam. But I haven't done a compression test in a long time... Do you have any data or rules of thumb as to what the pressures should be in a Lycoming? ned ----- Original Message ----- From: teamgrumman@aol.com To: teamgrumman-list@matronics.com Sent: Tuesday, February 24, 2009 12:22 AM Subject: TeamGrumman-List: Cranking pressure (was Connecting rod length) I could open this one. Thanks Ned. I have that manual. I didn't think to check it. I've become too dependent on the internet. I checked the cranking pressure vs the leak-down pressure on two separate Tigers today Tiger 1 (1600 TTSMOH) 72/110 75/110 76/112 75/125 Tiger 2 (140 SFNEW) 79/130 78/130 79/130 79/130 Compare this to a Lycon O320 and 140 to 145 pounds. This Lycon dynoed at 188 hp at 2725 rpm. -----Original Message----- From: 923te <923te@att.net> To: teamgrumman-list@matronics.com Sent: Mon, 23 Feb 2009 6:15 am Subject: Re: TeamGrumman-List: Connecting rod length Gary I attached the length from the table of linits from the OH manual. ned ----- Original Message ----- From: teamgrumman@aol.com To: teamgrumman-list@matronics.com ; engines-list@matronics.com Sent: Monday, February 23, 2009 1:39 AM Subject: TeamGrumman-List: Connecting rod length I can't find the connecting rod length of either the O320 or O360. Can anyone help? ------------------------------------------------------------------------- --- A Good Credit Score is 700 or Above. See yours in just 2 easy steps! href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.m atronics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c ________________________________ Message 7 _____________________________________ Time: 04:18:34 PM PST US From: "923te" <923te@att.net> Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length) Would running a compression test with the throttle closed be a good way to find the cylinder that might have an induction leak? ----- Original Message ----- From: teamgrumman@aol.com To: teamgrumman-list@matronics.com Sent: Tuesday, February 24, 2009 12:22 AM Subject: TeamGrumman-List: Cranking pressure (was Connecting rod length) I could open this one. Thanks Ned. I have that manual. I didn't think to check it. I've become too dependent on the internet. I checked the cranking pressure vs the leak-down pressure on two separate Tigers today Tiger 1 (1600 TTSMOH) 72/110 75/110 76/112 75/125 Tiger 2 (140 SFNEW) 79/130 78/130 79/130 79/130 Compare this to a Lycon O320 and 140 to 145 pounds. This Lycon dynoed at 188 hp at 2725 rpm. -----Original Message----- From: 923te <923te@att.net> To: teamgrumman-list@matronics.com Sent: Mon, 23 Feb 2009 6:15 am Subject: Re: TeamGrumman-List: Connecting rod length Gary I attached the length from the table of linits from the OH manual. ned ----- Original Message ----- From: teamgrumman@aol.com To: teamgrumman-list@matronics.com ; engines-list@matronics.com Sent: Monday, February 23, 2009 1:39 AM Subject: TeamGrumman-List: Connecting rod length I can't find the connecting rod length of either the O320 or O360. Can anyone help? ------------------------------------------------------------------------- --- A Good Credit Score is 700 or Above. See yours in just 2 easy steps! href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.m atronics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c ________________________________ Message 8 _____________________________________ Time: 04:25:07 PM PST US From: "923te" <923te@att.net> Subject: Re: TeamGrumman-List: Intake runner length and balancing intake charge Okay thanks Cliff. I agree it would all change with every RPM change... I'm just thinking about racing where the throttle is Wide Open all the time anyway....come to think of it that's pretty much how my piston plane flies all the time anyway;) ned ----- Original Message ----- From: flyv35b To: teamgrumman-list@matronics.com Sent: Wednesday, February 25, 2009 12:25 PM Subject: Re: TeamGrumman-List: Intake runner length and balancing intake charge I wasn't referring to you, Ned, just making a general statement. Nothing wrong with experimenting and it doesn't bother me at all. That's what experimentals are all about, but the FAA has seen fit to make sure it doesn't happen with certified aircraft, unless you follow their rules (STC process). Actually you could surrender your airworthiness certificate and get an experimental one and do most anything you want (for a short time) to evaluate a theory, etc. and then convert it back to a standard airworthiness certificate. You probably could throttle the intake for an overly rich cylinder to make it develop less power, but it might not be leaner. I've never heard of anyone trying to do something like that. But it seems to me that every time you change RPM or throttle setting something changes and now some other cylinder might be the richest one. Cliff ----- Original Message ----- From: 923te To: teamgrumman-list@matronics.com Sent: Wednesday, February 25, 2009 9:00 AM Subject: Re: TeamGrumman-List: Intake runner length and balancing intake charge I did not say I was going to modify my grumman A4K. I just ask a question about it. I do have an RV with an O320 and I could modify it without much certification issues. My previous RV 6 had a 4.3liter GM marine engine in it. I had a lot of fun experimenting with it too. I don't understand why that torques some people so much??? Let me ask, if one cylinder has an intake leak causing EGT to be a bit higher than the other cylinders but otherwise functions well why couldn't one put a orfice on an overly rich cylinder intake to make it run leaner at best power? ned ----- Original Message ----- From: flyv35b To: teamgrumman-list@matronics.com Sent: Wednesday, February 25, 2009 8:46 AM Subject: Re: TeamGrumman-List: Intake runner length and balancing intake charge I remember talking to Ken at Lycon once and he told me he had spent some time trying to do this. Apparently the charge almost hits a brick wall (so to speak) when it enters the HA-6 carb sump and doesn't divide equally from one side to the other, let alone the unequal length induction tubes. Gary is right, the best Lycoming engine induction system is the cold air system with forward facing fuel injector that many of the RV builders are using. The air is fed from the baffle plate in front of the #2 cylinder, through a filter and nice fiberglass duct to the injector. It never ceases to amaze me how much people like to talk about modifying a Grumman or it's engine installation to improve it in some way and gain better performance (I guess it's fun to dream). But very few people actually undertake even getting minor changes approved, Gary, Gene, Fred, Maynard, Ken, etc. excepted. It's easy to dream and talk but doing it is something else. I'd rather work on getting an STC for a FI engine that would fit in Gary's cowling and utilize a CS prop and different exhaust system than trying to band-aid the -A4K. But if you like to try all sorts of ideas and want the freedom to do so, why not just build an RV or Lancair and do what your want. Even those planes are pretty well engineered and somewhat "fixed" in what you can do from a practical standpoint. In response to Jamey's comments, I don't think that it matters whether you are LOP or ROP as far as needing to have a balanced air flow to each cylinder. If you look at the power developed vs. EGT you see that the power continues to fall even faster on the lean side of peak the leaner yet get. So a cylinder running 10* LOP is developing more HP than one running 50* LOP as I understand it. GAMI's whole intent was to get all cylinders to peak at the same time by adjusting the fuel flow thereby keeping one or more cylinders from falling off in power on the lean side while the others are still remaining relatively constant on the rich side as the mixture is leaned. But they did nothing to change or improve the less than optimum air flow distribution of the Continental log manifold. With this induction system you can still have noticeable power differences from one cylinder to another even if they all peak at exactly the same time. The IO-550 used by Cirrus, etc. attempts to further balance the air flow. I'm sure that the cross flow cylinder head (intake in one side, exhaust out the other) doesn't hurt either. Once the air flows are equal then you can use the same fuel injector on each cylinder and the power should be very nearly identical, resulting in a very smooth running engine. Cliff ----- Original Message ----- From: James Courtney To: teamgrumman-list@matronics.com Sent: Tuesday, February 24, 2009 11:24 PM Subject: RE: TeamGrumman-List: Intake runner length and balancing intake charge The short answer is no and I don=99t know much about the Continentals. The new IO-550Rs or whatever they are putting in the new Cirrus and Cessna aircraft claim 10 more HP and a 2000 hr. TBO up from 1700. I suspect the TBO increase has more to do with the metallurgy and manufacturing processes available during certification of this slightly more modern line of engines than the tuned induction but that=99s pure conjecture on my part. I=99m assuming most of the power balancing still comes by regulating fuel flow to each cylinder using balanced injectors. Once LOP where many folks run the big Continentals you have a surplus of air so minor differences in the induction shouldn=99t matter much. ROP maybe the tuned engines are a little smoother? Jamey From: owner-teamgrumman-list-server@matronics.com [mailto:owner-teamgrumman-list-server@matronics.com] On Behalf Of 923te Sent: Tuesday, February 24, 2009 7:20 AM To: teamgrumman-list@matronics.com Subject: TeamGrumman-List: Intake runner length and balancing intake charge Anyone here ever experiment with trying to balance power output between cylinders by adjusting the intake runners on an A4K Lycoiming? Any thoughts? I'm wondering if the aft tubes were effectively lengthened would that make a difference? Lengthened so that the distance from the carb to the cylinder head would be the same for all 4 cylinders. Or would a change in the shape of the pathways in the sump be more effective? Or both required to get a good balance of power? Does the tuned induction on the Continentals work to balance power? If so why? Thanks, Ned http://www.matronics.com/Navigator?TeamGrumman-Listhttp://forums.matronic s.comhttp://www.matronics.com/contribution No virus found in this incoming message. Checked by AVG - www.avg.com 02/24/09 06:43:00 href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.m atronics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c ------------------------------------------------------------------------ /2009 6:43 AM ------------------------------------------------------------------------- - We are a community of 6 million users fighting spam. SPAMfighton does not have this message. href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.m atronics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.m atronics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c ------------------------------------------------------------------------- --- 2/24/2009 6:43 AM ________________________________ Message 9 _____________________________________ Time: 04:42:40 PM PST US Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length) From: teamgrumman@aol.com there are a lot of equations and supposition regarding computing the crankin g pressure vs compression, but, if I use any of them, they don't correspond to what I've been measuring. =C2- I did the leak down and cranking pressure tests as part of an annual. =C2 - -----Original Message----- From: 923te <923te@att.net> Sent: Wed, 25 Feb 2009 4:15 pm Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length ) I've been trying to find an old article about a couple of A&P's that do compression testing and keep records to compare from annual to annual. I can't find the article right now but I t hink it is a great idea. =C2- We used to check out car engines this way. Seems like you could expect=C2-pressures around 17 to 20 times t he compression ratio. I sure would like to find what Lycoming or=C2-Continent al says you should have. It is a little different than just the compression rat io times the ambient pressure because of the effect of temperature=C2-during compression and valve overlap etc. =C2- For the Tigers you tested below it is interesting to note that for 8.5:1 you could estimate a=C2-pressure of 8.5 x 30.2 X 0.4912 psi/inHG = =C2-126 psi =C2- (where 30.2 was the barometric pressure around 3pm yesterday http://www.wunderground.com/weatherstation/WXD ailyHistory.asp?ID=KCAAUBUR7&month=2&day=24&year 09) =C2- On Tiger 1 did you do a leak down test to=2 0see if it could help tell where the wear was? =C2- Seems like we could tell whether the rings were worn with a compression test by doing it wet after the dry run. Wet=C2-meant addding a teaspoon or 2 of oil in the spark plug hole and doi ng another test.=C2-If the low cylinder psi went up then it was thought that the rings were the source of the leak instead of the valves or a worn cam. But=C2-I haven't done a compression test in a=C2-long time... =C2- Do you have any data or rules of thumb as to what the pressures should be in a Lycoming? ned ----- Original Message ----- From: teamgrumman@aol.com Sent: Tuesday, February 24, 2009 12:22 AM Subject: TeamGrumman-List: Cranking pressure (was Connecting rod length) I could open this one. =C2-Thanks Ned. =C2-I have that manual. =C2-I didn't think to check it. =C2-I've become too dependent on the internet. I checked the cranking pressure vs the leak-down pressure on two separate Tigers today Tiger 1 =C2-(1600 TTSMOH) 72/110 75/110 76/112 75/125 Tiger 2 (140 SFNEW) 79/130 78/130 79/130 79/130 Compare this to a Lycon O320 and 140 to 145 pounds. =C2-This Lycon dynoed at 188 hp at=2 02725 rpm. -----Original Message----- From: 923te <923te@att.net> Sent: Mon, 23 Feb 2009 6:15 am Subject: Re: TeamGrumman-List: Connecting rod length Gary I attached the length from the table of linits from the OH manual. ned ----- Original Message ----- From: teamgrumman@aol.com engines-list@matronics.com Sent: Monday, February 23, 2009 1:39 AM Subject: TeamGrumman-List: Connecting rod length I can't find the connecting rod length of either the O320 or O360. =C2-Can anyone help? A Good Credit Score is 700 or Above. See yours in just 2 easy steps! href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.matr onics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.matr onics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c _ -= Use the Matronics List Features Navigator to browse ________________________________ Message 10 ____________________________________ Time: 04:43:46 PM PST US Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length) From: teamgrumman@AOL.COM I've done it both ways, there is no significant change. =C2-THere is too m uch volume in the induction system to have any significant effect. -----Original Message----- From: 923te <923te@att.net> Sent: Wed, 25 Feb 2009 4:19 pm Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length ) Would=C2-running a compression test with the throttle closed be a good way to find the cylinder that might have an induct ion leak? ----- Original Message ----- From: teamgrumman@aol.com Sent: Tuesday, February 24, 2009 12:22 AM Subject: TeamGrumman-List: Cranking pressure (was Connecting rod length) I could open this one. =C2-Thanks Ned. =C2-I have that manual. =C2-I didn't think to check it. =C2-I've become too dependent on the internet. I checked the cranking pressure vs the leak-down pressure on two separate Tigers today Tiger 1 =C2-(1600 TTSMOH) 72/110 75/110 76/112 75/125 Tiger 2 (140 SFNEW) 79/130 78/130 79/130 79/130 Compare this to a Lycon O320 and 140 to 145 pounds. =C2-This Lycon dynoed at 188 hp at 2725 rpm. -----Original Message----- From: 923te <923te@att.net> Sen t: Mon, 23 Feb 2009 6:15 am Subject: Re: TeamGrumman-List: Connecting rod length Gary I attached the length from the table of linits from the OH manual. ned ----- Original Message ----- From: teamgrumman@aol.com engines-list@matronics.com Sent: Monday, February 23, 2009 1:39 AM Subject: TeamGrumman-List: Connecting rod length I can't find the connecting rod length of either the O320 or O360. =C2-Can anyone help? A Good Credit Score is 700 or Above. See yours in just 2 easy steps! href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.matr onics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.matr onics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c ________________________________ Message 11 ____________________________________ Time: 07:38:14 PM PST US From: "923te" <923te@att.net> Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length) I found some stuff on the net: Direct readings should be proportional to compression ratios. Expect high compression engines to be 140-170 PSI, 80 Octane engines 120-140 PSI and Turbo-charged engines 100-130 PSI. Engines with equal direct readings tend to run smooth. A 20% spread between low and high cylinders is considered normal http://www.littleflyers.com/engcomp.htm ----- Original Message ----- From: teamgrumman@aol.com To: teamgrumman-list@matronics.com Sent: Wednesday, February 25, 2009 6:41 PM Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length) there are a lot of equations and supposition regarding computing the cranking pressure vs compression, but, if I use any of them, they don't correspond to what I've been measuring. I did the leak down and cranking pressure tests as part of an annual. -----Original Message----- From: 923te <923te@att.net> To: teamgrumman-list@matronics.com Sent: Wed, 25 Feb 2009 4:15 pm Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length) I've been trying to find an old article about a couple of A&P's that do compression testing and keep records to compare from annual to annual. I can't find the article right now but I think it is a great idea. We used to check out car engines this way. Seems like you could expect pressures around 17 to 20 times the compression ratio. I sure would like to find what Lycoming or Continental says you should have. It is a little different than just the compression ratio times the ambient pressure because of the effect of temperature during compression and valve overlap etc. For the Tigers you tested below it is interesting to note that for 8.5:1 you could estimate a pressure of 8.5 x 30.2 X 0.4912 psi/inHG = 126 psi (where 30.2 was the barometric pressure around 3pm yesterday http://www.wunderground.com/weatherstation/WXDailyHistory.asp?ID=KCAAUB UR7&month=2&day=24&year 09) On Tiger 1 did you do a leak down test to see if it could help tell where the wear was? Seems like we could tell whether the rings were worn with a compression test by doing it wet after the dry run. Wet meant addding a teaspoon or 2 of oil in the spark plug hole and doing another test. If the low cylinder psi went up then it was thought that the rings were the source of the leak instead of the valves or a worn cam. But I haven't done a compression test in a long time... Do you have any data or rules of thumb as to what the pressures should be in a Lycoming? ned ----- Original Message ----- From: teamgrumman@aol.com To: teamgrumman-list@matronics.com Sent: Tuesday, February 24, 2009 12:22 AM Subject: TeamGrumman-List: Cranking pressure (was Connecting rod length) I could open this one. Thanks Ned. I have that manual. I didn't think to check it. I've become too dependent on the internet. I checked the cranking pressure vs the leak-down pressure on two separate Tigers today Tiger 1 (1600 TTSMOH) 72/110 75/110 76/112 7 5/125 Tiger 2 (140 SFNEW) 79/130 78/130 79/130 79/130 Compare this to a Lycon O320 and 140 to 145 pounds. This Lycon dynoed at 188 hp at 2725 rpm. -----Original Message----- From: 923te <923te@att.net> To: teamgrumman-list@matronics.com Sent: Mon, 23 Feb 2009 6:15 am Subject: Re: TeamGrumman-List: Connecting rod length Gary I attached the length from the table of linits from the OH manual. ned ----- Original Message ----- From: teamgrumman@aol.com To: teamgrumman-list@matronics.com ; engines-list@mat ronics.com Sent: Monday, February 23, 2009 1:39 AM Subject: TeamGrumman-List: Connecting rod length I can't find the connecting rod length of either the O320 or O360. Can anyone help? ------------------------------------------------------------------------- - A Good Credit Score is 700 or Above. See yours in just 2 easy steps! href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.m atronics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c href="http://www.matronics.com/Navigator?TeamGrumman-List">< a href="http://www.matronics.com/Navigator?TeamGrumman-List" target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c or?TeamGrumman-List">http://www.matronics.com/Navigator?TeamGrumman-List p://forums.matronics.com ution">http://www.matronics.com/contribution ------------------------------------------------------------------------- ----- A Good Credit Score is 700 or Above. See yours in just 2 easy steps! ________________________________ Message 12 ____________________________________ Time: 11:09:04 PM PST US Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length) From: teamgrumman@AOL.COM Once again, I'll reiterate: =C2-These formulas don't work. =C2-What is H igh Compression? =C2-Turbo charged engines, by design, are low compression engines (does not apply to standard engines that are turbo normalized). Like I said before, I've seen an O320 with 8.5:1 pistons with 145 psi. =C2 -And an O360 with 8.5:1 pistons with 130 psi. =C2- I've seen 7.5:1 O320s with 100 psi and 8.5:1 O360s with 120 psi There are too many variables involved to make blanket statements regarding t he relationship between compression and cranking pressure. =C2-The biggest affect on cranking pressure is lobe separation angle and the closing time o f the intake and opening time of the exhaust. I'm in the process of building a database and determining what I should expe ct with a given engine. =C2- -----Original Message----- From: 923te <923te@att.net> Sent: Wed, 25 Feb 2009 7:33 pm Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length ) I found some stuff on the net: =C2- =C2- Direct readings should be proportional to compression ratios.=C2- Expect h igh compression engines to be 140-170 PSI, 80 Octane engines 120-140 PSI and Turbo-charged engines 100-130 PSI.=C2- Engines with equal direct readings tend to run smooth. A 20% spread between low and high cylinders is considered normal =C2- http://www.littleflyers.com/engcomp.htm =C2- =C2- ----- Original Messa ge ----- From: teamgrumman@aol.com Sent: Wednesday, February 25, 2009 6:41 PM Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length) there are a lot of equations and supposition regarding computing the cranking pressure vs compression, but, if I use any of them, they don't correspond to what I've been measuring. =C2- I did the leak down and cranking pressure tests as part of an annual. =C2- -----Original Message----- From: 923te <923te@att.net> Sent: Wed, 25 Feb 2009 4:15 pm Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length) I've been trying to find an old article about a couple of A&P's that do compression testing and keep records to compare from annual to annual. I can't find the article right n ow but I think it is a great idea. =C2- We used to check out car engines this way. Seems like you could expect=C2-pressures around 17 to 20 times the compression ratio. I sure would like to find what Lycoming or=C2-Continental says you should have. It is a little different than ju st the compression ratio times the ambient pressure because of the effect of temperature=C2-during compression and valve overlap etc. =C2- For the Tigers you tested below it is=2 0interesting to note that for 8.5:1 you could estimate a=C2-pressure of 8.5 x 30.2 X 0.4912 psi/inHG = =C2-126 psi =C2- (where 30.2 was the barometric pressure around 3pm yesterday http://www.wunderground.com/weatherstation/W XDailyHistory.asp?ID=KCAAUBUR7&month=2&day=24&year 09) =C2- On Tiger 1 did you do a leak down test to see if it could help tell where the wear was? =C2- Seems like we could tell whether the rings were worn with a compression test by doing it wet after the dry run. Wet=C2-meant addding a teaspoon or 2 of oil in the spark plug hole and d oing another test.=C2-If the low cylinder psi went up then it was thought tha t the rings were the source of the leak instead of the valves or a worn cam. But=C2-I haven't done a compression test in a=C2-long time... =C2- Do you have any data or rules of thumb as to what the pressures should be in a Lycoming? ned ----- Original Message ----- From: teamgrumman@aol.com Sent: Tuesday, February 24, 2009 12:22 AM Subject: TeamGrumman-List: Cranking pressure (was Connecting rod length) I could open this one. =C2-Thanks Ned. =C2-I have that manual. =C2-I didn't think to chec k it. =C2-I've become too dependen t on the internet. I checked the cranking pressure vs the leak-down pressure on two separate Tigers today Tiger 1 =C2-(1600 TTSMOH) 72/110 75/110 76/112 7 5/125 Tiger 2 (140 SFNEW) 79/130 78/130 79/130 79/130 Compare this to a Lycon O320 and 140 to 145 pounds. =C2-This Lycon dynoed at 188 hp at 2725 rpm. -----Original Message----- From: 923te <923te@att.net> Sent: Mon, 23 Feb 2009 6:15 am Subject: Re: TeamGrumman-List: Connecting rod length Gary I attached the length from the table of linits from the OH manual. ned ----- Original Message ----- From: teamgrumman@aol.com ; engines-list@mat ronics.com Sent: Monday, February 23, 2009 1:39 AM Subject: TeamGrumman-List: Connecting rod length I can't find the connecting rod length of either the O320 or O360. =C2-Can anyone help? A Good Credit Score is 700 or Above. See20yours in just 2 easy steps! href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.matr onics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c href="http://www.matronics.com/Navigator?TeamGrumman-List">< a href="ht tp://www.matronics.com/Navigator?TeamGrumman-List" target="_blank">http:// www.matronics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c or?TeamGrumman-List">http://www.matronics.com/Navigator?TeamGrumman-List p://forums.matronics.com ution">http://www.matronics.com/contribution A Good Credit Score is 700 or Above. See yours in just 2 easy steps! href="http://www.matronics.com/Navigator?TeamGrumman-List"http://www.m atronics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com "http://forums.matronics.com href="http://www.matronics.com/contribution" http://www.matronics.com/c D======================== ====================== ________________________________ Message 13 ____________________________________ Time: 11:33:11 PM PST US Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length) From: teamgrumman@aol.com 8.5:1 SOHC 8 valve 4 cylinder engine: =C2-Desired 178 psi. =C2-Service l imit: 125 psi. 7.8:1 turbo engine, DOHC: =C2-Desired 164 psi. =C2-Service limit 114 psi 9:1 =C2- =C2- =C2-2 ltr 4 cyl: =C2-Desired 192 psi. =C2-Service li mit 145 psi 9:1 =C2- =C2- =C2- 1.8 ltr =C2-4 cyl: =C2-Desired 185 psi. =C2-S ervice limit 131 psi >From another chart. =C2-7.5:1 VW engine. =C2-Desired 139 psi. =C2-Serv ice limit 115 psi. =C2- =C2-=C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2- =C2-8:1 =C2-VW engine. =C2-Desire 152 psi. =C2-Service limit 125 psi. ======================= -----Original Message----- From: teamgrumman@aol.com Sent: Wed, 25 Feb 2009 11:08 pm Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length ) Once again, I'll reiterate: =C2-These formulas don't work. =C2-What is H igh Compression? =C2-Turbo charged engines, by design, are low compression engines (does not apply to standard engines that are turbo normalized). Like I said before, I've seen an O320 with 8.5:1 pistons with 145 psi. =C2 -And an O360 with 8.5:1 pistons with 130 psi. =C2- I've seen 7.5:1 O320s with 100 psi and 8.5:1 O360s with 120 psi There are too many variables involved to make blanket statements regarding t he relationship between compression and cranking pressure. =C2-The biggest affect20on cranking pressure is lobe separation angle and the closing time of the intake and opening time of the exhaust. I'm in the process of building a database and determining what I should expe ct with a given engine. =C2- -----Original Message----- From: 923te <923te@att.net> Sent: Wed, 25 Feb 2009 7:33 pm Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length ) I found some stuff on the net: =C2- =C2- Direct readings should be proportional to compression ratios.=C2- Expect h igh compression engines to be 140-170 PSI, 80 Octane engines 120-140 PSI and Turbo-charged engines 100-130 PSI.=C2- Engines with equal direct readings tend to run smooth. A 20% spread between low and high cylinders is considered normal =C2- http://www.littleflyers.com/engcomp.htm =C2- =C2- ----- Original Message ----- From: teamgrumman@aol.com Sent: Wednesday, February 25, 2009 6:41 PM Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length) there are a lot of equations and supposition regarding computing the cranking pressure vs compression, but, if I use any of them, they don't correspond to what I've been measuring. =C2- I did the leak down and cranking pressure tests as part of an annual. =C2- -----Original Message----- From: 923te <923te@att.net> Sent: Wed, 25 Feb 2009 4:15 pm Subject: Re: TeamGrumman-List: Cranking pressure (was Connecting rod length) I've been trying to find an old article about a couple of A&P's that do compression testing and keep records to compare from annual to annual. I can't find the article right n ow but I think it is a great idea. =0 A =C2- We used to check out car engines this way. Seems like you could expect=C2-pressures around 17 to 20 times the compression ratio. I sure would like to find what Lycoming or=C2-Continental says you should have. It is a little different than ju st the compression ratio times the ambient pressure because of the effect of temperature=C2-during compression and valve overlap etc. =C2- For the Tigers you tested below it is interesting to note that for 8.5:1 you could estimate a=C2-pressur e of 8.5 x 30.2 X 0.4912 psi/inHG = =C2-126 psi =C2- (where 30.2 was the barometric pressure around 3pm yesterday http://www.wunderground.com/weatherstation/W XDailyHistory.asp?ID=KCAAUBUR7&month=2&day=24&year 09) =C2- On Tiger 1 did you do a leak down test to see if it could h elp tell where the wear was? =C2- Seems like we could tell whether the rings were worn with a compression test by doing it wet after the dry run. Wet=C2-meant addding a teaspoon or 2 of oil in the spark plug hole and d oing another test.=C2-If the low cylinder psi went up then it was thought tha t the rings were the source of the leak instead of the valves or a worn cam. But=C2-I haven't done a compression test in a=C2-long time... =C2- Do you have any data or rules of thumb as to what the pressures should be in a Lycoming? ned ----- Original Message ----- From: teamgrumman@aol.com Sent: Tuesday, February 24, 2009 12:22 AM Subject: TeamGrumman-List: Cranking pressure (was Connecting rod length) I could open this one. =C2-Thanks Ned. =C2-I have that manual. =C2-I didn't think to chec k it. =C2-I've become too dependent on the internet. I checked the cranking pressure vs the leak-down pressure on two separate Tigers today Tiger 1 =C2-(1600 TTSMOH) 72/110 75/110 76/112 7 5/125 Tiger 2 (140 SFNEW) 79/130 78/130 79/130 79/130 Compare this to a Lycon O320 and 140 to 145 pounds. =C2-This Lycon dynoed at 188 hp at 2725 rpm. -----Original Message----- From: 923te <923te@att.net> Sent: Mon, 23 F eb 2009 6:15 am Subject: Re: TeamGrumman-List: Connecting rod length Gary I attached the length from the table of linits from the OH manual. ned ----- Original Message ----- From: teamgrumman@aol.com ; engines-list@mat ronics.com Sent: Monday, February 23, 2009 1:39 AM Subject: TeamGrumman-List: Connecting rod length I can't find the connecting rod length of either the O320 or O360. =C2-Can anyone help? A Good Credit Score is 700 or Above. See yours in just 2 easy steps! href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.matr onics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c href="http://www.matronics.com/Navigator?TeamGrumman-List">< a href="ht tp://www.matronics.com/Navigator?TeamGrumman-List" target="_blank">http:// www.matronics.com/Navigator?TeamGrumman-List href="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/c or?TeamGrumman-List">http://www.matronics.com/Navigator?TeamGrumman-List p://forums.matronics.com ution">http://www.matronics.com/contribution A Good Credit Score is 700 or Above. 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