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)
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| Subject: | Re: 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
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| Subject: | 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 <mailto:jamey@jamescourtney.net>
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
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02/24/09 06:43:00
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/2009 6:43 AM
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02/24/09 13:35:00
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| Subject: | Re: 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
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| Subject: | Re: 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 <andy747@charter.net>
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
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| Subject: | Re: 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
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/2009 6:43 AM
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Message 6
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| Subject: | Re: 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?
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Message 7
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| Subject: | Re: 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?
-------------------------------------------------------------------------
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Message 8
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| Subject: | Re: 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
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/2009 6:43 AM
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Message 9
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| Subject: | Re: Cranking pressure (was Connecting rod length) |
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!
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Message 10
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| Subject: | Re: Cranking pressure (was Connecting rod length) |
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!
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Message 11
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| Subject: | Re: 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?
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Message 12
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| Subject: | Re: 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
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!
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onics.com/Navigator?TeamGrumman-List
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======================
Message 13
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| Subject: | Re: Cranking pressure (was Connecting rod length) |
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!
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onics.com/Navigator?TeamGrumman-List
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