Today's Message Index:
----------------------
1. 12:00 AM - Archie, questions on Exhaust Temps (TeamGrumman@aol.com)
2. 12:01 AM - Re: Tiger Annual update. (TeamGrumman@aol.com)
3. 03:07 AM - Re: Tiger Annual update. (cgalley)
4. 04:57 AM - Re: Archie, questions on Exhaust Temps (Archie)
5. 06:58 AM - Re: Archie, questions on Exhaust Temps (Vic Jacko)
6. 07:10 AM - Fw: Archie, questions on Exhaust Temps (Vic Jacko)
7. 09:37 AM - Re: Archie, questions on Exhaust Temps (TeamGrumman@aol.com)
8. 03:26 PM - Re: Archie, questions on Exhaust Temps (Archie)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Archie, questions on Exhaust Temps |
--> Engines-List message posted by: TeamGrumman@aol.com
Hi Archie,
I've been reading your posts for a while now. Sounds like you know your
way around Lycoming engines. A few questions. I hope you can answer these.
First, I have a Grumman Tiger with a ported and polished LyCon engine. It
dynoed at over 205 HP at 2700 rpm. I have no trouble turning redline at
12,000 feet. I also restore, modify, repair, and maintain Grumman Tigers and
Cheetahs.
I have experienced high CHTs (Over 450 degrees with a JPI 700/800) during
take-off and climb. Over the last 10 years, I have tried a lottle of this and
a
little of that in order to get the CHTs down. Good baffling helps but it's
not a panacea. I've had the best luck with removing the flashing from
between the fins on the fins under the plugs (between the intake/exhaust ports)
and
cutting back the baffle strap that wraps around the cylinder head on #3 and
#4. I have tried various static mag timings from 20 BTDC to 30 BTDC. I have
installed a water manometer to measure the pressure drop across the cylinders.
In general, I can get about 4 inches of water pressure drop across the cyls
during climb and 7 inches during cruise.
A couple of months ago, during the peak heat season (I live on the Mojave
desert), I started pulling on the carb heat instead of reducing power during
climbout in rder to keep CHTs down. It works, I just lose a lot of power.
A couple of weeks ago, climbing out of Bakersfield CA with an OAT of 80, 85%
power, instead of pulling the carb heat, I intentionally lean the mixture to
the point the engine stumbled and then enrichened it about 1/2 turn. EGTs
went high (1450+) but the CHT started to come down from 450 to 417. What was
interesting was taht the CHT was 417 for all four cyls. There wasn't 1 degree
spread. EGTs were also within 20 degrees of each other. (JPI 800). Once
I leveled off at 7500 feet, the CHTs went down to 402 to 405. EGTs stayed
pretty high, higher than I've seen.
Questions:
1) Have you measured the exhaust valve guide temperature? And, if yes,
did you measure it as a function of either CHT or EGT? What were the results.
2) In your experience, is it better to run very high EGTs (lean), i.e.,
near peak EGT, and take advantage of the lower CHTs, or to run on the rich side,
say 100-150 degrees rich?
3) What operating condition is the worst for valve seat wear?
4) What operating condition is the worst for valve guide wear?
5) What EGT would you consider maximum? I understand that placement in
the exhaust pipe has an effect. My probes are about 2 1/2 inches from the cyl
head.
Thanks for any insight you can provide.
Gary
www.AuCountry.com
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Tiger Annual update. |
--> Engines-List message posted by: TeamGrumman@aol.com
In a message dated 10/30/04 11:48:58 AM, cgalley@qcbc.org writes:
> Cy Galley - Chair,
> AirVenture Emergency Aircraft Repair
> A Service Project of Chapter 75
> EAA Safety Programs Editor - TC
> EAA Sport Pilot
>
What city, State?
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Tiger Annual update. |
--> Engines-List message posted by: "cgalley" <cgalley@qcbc.org>
AirVenture at Oshkosh.
----- Original Message -----
From: <TeamGrumman@aol.com>
Subject: Re: Engines-List: Tiger Annual update.
> --> Engines-List message posted by: TeamGrumman@aol.com
>
>
> In a message dated 10/30/04 11:48:58 AM, cgalley@qcbc.org writes:
>
>
> > Cy Galley - Chair,
> > AirVenture Emergency Aircraft Repair
> > A Service Project of Chapter 75
> > EAA Safety Programs Editor - TC
> > EAA Sport Pilot
> >
>
> What city, State?
>
>
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Archie, questions on Exhaust Temps |
--> Engines-List message posted by: "Archie" <archie97@earthlink.net>
> --> Engines-List message posted by: TeamGrumman@aol.com
>
> Hi Archie,
>
> I've been reading your posts for a while now. Sounds like you know your
> way around Lycoming engines. A few questions. I hope you can answer
> these.
>
> First, I have a Grumman Tiger with a ported and polished LyCon engine.
> It
> dynoed at over 205 HP at 2700 rpm. I have no trouble turning redline at
> 12,000 feet. I also restore, modify, repair, and maintain Grumman Tigers
> and
> Cheetahs.
>
> I have experienced high CHTs (Over 450 degrees with a JPI 700/800) during
> take-off and climb. Over the last 10 years, I have tried a lottle of
> this and a
> little of that in order to get the CHTs down. Good baffling helps but
> it's
> not a panacea. I've had the best luck with removing the flashing from
> between the fins on the fins under the plugs (between the intake/exhaust
> ports) and
> cutting back the baffle strap that wraps around the cylinder head on #3
> and
> #4. I have tried various static mag timings from 20 BTDC to 30 BTDC. I
> have
> installed a water manometer to measure the pressure drop across the
> cylinders.
> In general, I can get about 4 inches of water pressure drop across the
> cyls
> during climb and 7 inches during cruise.
>
> A couple of months ago, during the peak heat season (I live on the Mojave
> desert), I started pulling on the carb heat instead of reducing power
> during
> climbout in rder to keep CHTs down. It works, I just lose a lot of
> power.
>
> A couple of weeks ago, climbing out of Bakersfield CA with an OAT of 80,
> 85%
> power, instead of pulling the carb heat, I intentionally lean the mixture
> to
> the point the engine stumbled and then enrichened it about 1/2 turn.
> EGTs
> went high (1450+) but the CHT started to come down from 450 to 417. What
> was
> interesting was taht the CHT was 417 for all four cyls. There wasn't 1
> degree
> spread. EGTs were also within 20 degrees of each other. (JPI 800).
> Once
> I leveled off at 7500 feet, the CHTs went down to 402 to 405. EGTs
> stayed
> pretty high, higher than I've seen.
>
> Questions:
>
> 1) Have you measured the exhaust valve guide temperature? And, if yes,
> did you measure it as a function of either CHT or EGT? What were the
> results.
No, I have not measured VGT. Obviously, EGT affects the guide most insamuch
as it
is in direct contact with the flame, and the one of greater concern.
The intake, if incorporating reccommended clearances, draws oil mist during
the
intake cycle, and unless overheated, does not seem to be much of a problem.
> 2) In your experience, is it better to run very high EGTs (lean), i.e.,
> near peak EGT, and take advantage of the lower CHTs, or to run on the rich
> side,
> say 100-150 degrees rich?
From a personal standpoint, I prefer to run lean of peak, but in your case,
may need to improve cooling air flow. In experimentals, this is not a
problem inasmuch
as reworks can be conducted until it is correct. IE: prop cuffs, ala Tracy
Crook,
relocating and sizing intake openings, etc.
If you are running with higher static compression ratios, such as 9-10:1,
leaning may be a bit more sensitive.
BTW, many seem to be concerned with the baffling an the lower part
of the induction openings, and neglect the upper.
Perhaps worth looking into.
> 3) What operating condition is the worst for valve seat wear?
Weak valve springs at high RPM.
> 4) What operating condition is the worst for valve guide wear?
Rocker arm geometry incorrect from the factory, and "gas station" type
valve work. If the valves and seats had to be lapped to achieve a good mate,
chances are that there will be a slight drag on one side of the guide.
> 5) What EGT would you consider maximum? I understand that placement in
> the exhaust pipe has an effect. My probes are about 2 1/2 inches from
> the cyl
> head.
This is arbitrary, and you will get a number of responses citing various
reasons,
but depending on the application, I would say anything over 1600.
EGT probe placement does have an effect, and they should be place in the
same
location in all pipes. (arc and distance), then if possible, checked for
accuracy/
calibration. I have seen frustration encountered by improper reading
instruments.
Probably not the specific answers you sought, and I tend to become a bit
long winded,
but we keep plugging away..................
Archie Frangoudis
Archie's Racing Service
> Thanks for any insight you can provide.
>
> Gary
> www.AuCountry.com
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Archie, questions on Exhaust Temps |
--> Engines-List message posted by: "Vic Jacko" <vicwj@earthlink.net>
Archie, would appreciate your feelings on reducing pumping losses by
fooling the engine in believing that it is at a higher altitude than it
really is.
If we can make the engine think it is at 8,000 to 10,000 feet one can run
full throttle without exceeding 100 percent power. I am aware this happens
at a lower altitude depending on outside temperature.
Full throttle reduces pumping losses rather than pulling the throttle back
to reduce power for cruise efficiency. Sooo this is what I suggest:
Please fell free to flame me! We will enjoy your remarks!
My suggestion is to heat the incoming air charge above the cold side of the
ram air intake by using carb heat in the right proportion to cause the
engine to think it is in a higher density altitude once cruise flight
begins. One could use a fuel flow device to determine the most efficient
engine operation at altitude.
I am fully aware that one will lose power by applying carb heat. Power is
not the point, pumping losses are what we want to reduce to increase
efficiency.
Also, correct me if I am wrong but will a warm intake charge increase the
effective cylinder pressures than a cold charge at a given power output?
If this is true then will we not have an increase in the effective
compression ratio in the above question at the same power output.?
I hope you have time to give us you view on these ideas. Maybe if I am
correct in my thesis we can save some fuel!
Vic,
Roswell, NM
----- Original Message -----
From: "Archie" <archie97@earthlink.net>
Subject: Re: Engines-List: Archie, questions on Exhaust Temps
> --> Engines-List message posted by: "Archie" <archie97@earthlink.net>
>
>
> > --> Engines-List message posted by: TeamGrumman@aol.com
> >
> > Hi Archie,
> >
> > I've been reading your posts for a while now. Sounds like you know
your
> > way around Lycoming engines. A few questions. I hope you can answer
> > these.
> >
> > First, I have a Grumman Tiger with a ported and polished LyCon engine.
> > It
> > dynoed at over 205 HP at 2700 rpm. I have no trouble turning redline
at
> > 12,000 feet. I also restore, modify, repair, and maintain Grumman
Tigers
> > and
> > Cheetahs.
> >
> > I have experienced high CHTs (Over 450 degrees with a JPI 700/800)
during
> > take-off and climb. Over the last 10 years, I have tried a lottle of
> > this and a
> > little of that in order to get the CHTs down. Good baffling helps but
> > it's
> > not a panacea. I've had the best luck with removing the flashing from
> > between the fins on the fins under the plugs (between the intake/exhaust
> > ports) and
> > cutting back the baffle strap that wraps around the cylinder head on #3
> > and
> > #4. I have tried various static mag timings from 20 BTDC to 30 BTDC.
I
> > have
> > installed a water manometer to measure the pressure drop across the
> > cylinders.
> > In general, I can get about 4 inches of water pressure drop across the
> > cyls
> > during climb and 7 inches during cruise.
> >
> > A couple of months ago, during the peak heat season (I live on the
Mojave
> > desert), I started pulling on the carb heat instead of reducing power
> > during
> > climbout in rder to keep CHTs down. It works, I just lose a lot of
> > power.
> >
> > A couple of weeks ago, climbing out of Bakersfield CA with an OAT of 80,
> > 85%
> > power, instead of pulling the carb heat, I intentionally lean the
mixture
> > to
> > the point the engine stumbled and then enrichened it about 1/2 turn.
> > EGTs
> > went high (1450+) but the CHT started to come down from 450 to 417.
What
> > was
> > interesting was taht the CHT was 417 for all four cyls. There wasn't 1
> > degree
> > spread. EGTs were also within 20 degrees of each other. (JPI 800).
> > Once
> > I leveled off at 7500 feet, the CHTs went down to 402 to 405. EGTs
> > stayed
> > pretty high, higher than I've seen.
> >
> > Questions:
> >
> > 1) Have you measured the exhaust valve guide temperature? And, if
yes,
> > did you measure it as a function of either CHT or EGT? What were the
> > results.
> No, I have not measured VGT. Obviously, EGT affects the guide most
insamuch
> as it
> is in direct contact with the flame, and the one of greater concern.
> The intake, if incorporating reccommended clearances, draws oil mist
during
> the
> intake cycle, and unless overheated, does not seem to be much of a
problem.
>
> > 2) In your experience, is it better to run very high EGTs (lean),
i.e.,
> > near peak EGT, and take advantage of the lower CHTs, or to run on the
rich
> > side,
> > say 100-150 degrees rich?
> From a personal standpoint, I prefer to run lean of peak, but in your
case,
> may need to improve cooling air flow. In experimentals, this is not a
> problem inasmuch
> as reworks can be conducted until it is correct. IE: prop cuffs, ala Tracy
> Crook,
> relocating and sizing intake openings, etc.
> If you are running with higher static compression ratios, such as 9-10:1,
> leaning may be a bit more sensitive.
> BTW, many seem to be concerned with the baffling an the lower part
> of the induction openings, and neglect the upper.
> Perhaps worth looking into.
>
> > 3) What operating condition is the worst for valve seat wear?
> Weak valve springs at high RPM.
>
> > 4) What operating condition is the worst for valve guide wear?
> Rocker arm geometry incorrect from the factory, and "gas station" type
> valve work. If the valves and seats had to be lapped to achieve a good
mate,
> chances are that there will be a slight drag on one side of the guide.
>
> > 5) What EGT would you consider maximum? I understand that placement
in
> > the exhaust pipe has an effect. My probes are about 2 1/2 inches from
> > the cyl
> > head.
> This is arbitrary, and you will get a number of responses citing various
> reasons,
> but depending on the application, I would say anything over 1600.
> EGT probe placement does have an effect, and they should be place in the
> same
> location in all pipes. (arc and distance), then if possible, checked for
> accuracy/
> calibration. I have seen frustration encountered by improper reading
> instruments.
> Probably not the specific answers you sought, and I tend to become a bit
> long winded,
> but we keep plugging away..................
> Archie Frangoudis
> Archie's Racing Service
>
> > Thanks for any insight you can provide.
> >
> > Gary
> > www.AuCountry.com
>
>
Message 6
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Archie, questions on Exhaust Temps |
--> Engines-List message posted by: "Vic Jacko" <vicwj@earthlink.net>
Archie,
I almost forgot, no, I did forget to mention that we would lean the
mixture to LOP once we are at altitude cruise with carb heat at full
throttle!
Vic
----- Original Message -----
From: "Vic Jacko" <vicwj@earthlink.net>
Subject: Re: Engines-List: Archie, questions on Exhaust Temps
> Archie, would appreciate your feelings on reducing pumping losses by
> fooling the engine in believing that it is at a higher altitude than it
> really is.
>
> If we can make the engine think it is at 8,000 to 10,000 feet one can run
> full throttle without exceeding 100 percent power. I am aware this
happens
> at a lower altitude depending on outside temperature.
>
> Full throttle reduces pumping losses rather than pulling the throttle back
> to reduce power for cruise efficiency. Sooo this is what I suggest:
>
> Please fell free to flame me! We will enjoy your remarks!
>
> My suggestion is to heat the incoming air charge above the cold side of
the
> ram air intake by using carb heat in the right proportion to cause the
> engine to think it is in a higher density altitude once cruise flight
> begins. One could use a fuel flow device to determine the most efficient
> engine operation at altitude.
>
> I am fully aware that one will lose power by applying carb heat. Power is
> not the point, pumping losses are what we want to reduce to increase
> efficiency.
>
> Also, correct me if I am wrong but will a warm intake charge increase the
> effective cylinder pressures than a cold charge at a given power output?
>
> If this is true then will we not have an increase in the effective
> compression ratio in the above question at the same power output.?
>
> I hope you have time to give us you view on these ideas. Maybe if I am
> correct in my thesis we can save some fuel!
>
> Vic,
>
> Roswell, NM
>
>
> ----- Original Message -----
> From: "Archie" <archie97@earthlink.net>
> To: <engines-list@matronics.com>
> Sent: Sunday, October 31, 2004 5:56 AM
> Subject: Re: Engines-List: Archie, questions on Exhaust Temps
>
>
> > --> Engines-List message posted by: "Archie" <archie97@earthlink.net>
> >
> >
> > > --> Engines-List message posted by: TeamGrumman@aol.com
> > >
> > > Hi Archie,
> > >
> > > I've been reading your posts for a while now. Sounds like you know
> your
> > > way around Lycoming engines. A few questions. I hope you can
answer
> > > these.
> > >
> > > First, I have a Grumman Tiger with a ported and polished LyCon engine.
> > > It
> > > dynoed at over 205 HP at 2700 rpm. I have no trouble turning redline
> at
> > > 12,000 feet. I also restore, modify, repair, and maintain Grumman
> Tigers
> > > and
> > > Cheetahs.
> > >
> > > I have experienced high CHTs (Over 450 degrees with a JPI 700/800)
> during
> > > take-off and climb. Over the last 10 years, I have tried a lottle of
> > > this and a
> > > little of that in order to get the CHTs down. Good baffling helps
but
> > > it's
> > > not a panacea. I've had the best luck with removing the flashing
from
> > > between the fins on the fins under the plugs (between the
intake/exhaust
> > > ports) and
> > > cutting back the baffle strap that wraps around the cylinder head on
#3
> > > and
> > > #4. I have tried various static mag timings from 20 BTDC to 30 BTDC.
> I
> > > have
> > > installed a water manometer to measure the pressure drop across the
> > > cylinders.
> > > In general, I can get about 4 inches of water pressure drop across
the
> > > cyls
> > > during climb and 7 inches during cruise.
> > >
> > > A couple of months ago, during the peak heat season (I live on the
> Mojave
> > > desert), I started pulling on the carb heat instead of reducing power
> > > during
> > > climbout in rder to keep CHTs down. It works, I just lose a lot of
> > > power.
> > >
> > > A couple of weeks ago, climbing out of Bakersfield CA with an OAT of
80,
> > > 85%
> > > power, instead of pulling the carb heat, I intentionally lean the
> mixture
> > > to
> > > the point the engine stumbled and then enrichened it about 1/2 turn.
> > > EGTs
> > > went high (1450+) but the CHT started to come down from 450 to 417.
> What
> > > was
> > > interesting was taht the CHT was 417 for all four cyls. There wasn't
1
> > > degree
> > > spread. EGTs were also within 20 degrees of each other. (JPI 800).
> > > Once
> > > I leveled off at 7500 feet, the CHTs went down to 402 to 405. EGTs
> > > stayed
> > > pretty high, higher than I've seen.
> > >
> > > Questions:
> > >
> > > 1) Have you measured the exhaust valve guide temperature? And, if
> yes,
> > > did you measure it as a function of either CHT or EGT? What were the
> > > results.
> > No, I have not measured VGT. Obviously, EGT affects the guide most
> insamuch
> > as it
> > is in direct contact with the flame, and the one of greater concern.
> > The intake, if incorporating reccommended clearances, draws oil mist
> during
> > the
> > intake cycle, and unless overheated, does not seem to be much of a
> problem.
> >
> > > 2) In your experience, is it better to run very high EGTs (lean),
> i.e.,
> > > near peak EGT, and take advantage of the lower CHTs, or to run on the
> rich
> > > side,
> > > say 100-150 degrees rich?
> > From a personal standpoint, I prefer to run lean of peak, but in your
> case,
> > may need to improve cooling air flow. In experimentals, this is not a
> > problem inasmuch
> > as reworks can be conducted until it is correct. IE: prop cuffs, ala
Tracy
> > Crook,
> > relocating and sizing intake openings, etc.
> > If you are running with higher static compression ratios, such as
9-10:1,
> > leaning may be a bit more sensitive.
> > BTW, many seem to be concerned with the baffling an the lower part
> > of the induction openings, and neglect the upper.
> > Perhaps worth looking into.
> >
> > > 3) What operating condition is the worst for valve seat wear?
> > Weak valve springs at high RPM.
> >
> > > 4) What operating condition is the worst for valve guide wear?
> > Rocker arm geometry incorrect from the factory, and "gas station" type
> > valve work. If the valves and seats had to be lapped to achieve a good
> mate,
> > chances are that there will be a slight drag on one side of the guide.
> >
> > > 5) What EGT would you consider maximum? I understand that
placement
> in
> > > the exhaust pipe has an effect. My probes are about 2 1/2 inches
from
> > > the cyl
> > > head.
> > This is arbitrary, and you will get a number of responses citing various
> > reasons,
> > but depending on the application, I would say anything over 1600.
> > EGT probe placement does have an effect, and they should be place in the
> > same
> > location in all pipes. (arc and distance), then if possible, checked for
> > accuracy/
> > calibration. I have seen frustration encountered by improper reading
> > instruments.
> > Probably not the specific answers you sought, and I tend to become a bit
> > long winded,
> > but we keep plugging away..................
> > Archie Frangoudis
> > Archie's Racing Service
> >
> > > Thanks for any insight you can provide.
> > >
> > > Gary
> > > www.AuCountry.com
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
Message 7
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Archie, questions on Exhaust Temps |
--> Engines-List message posted by: TeamGrumman@aol.com
In a message dated 10/31/04 4:57:53 AM, archie97@earthlink.net writes:
> From a personal standpoint, I prefer to run lean of peak, but in your case,
> may need to improve cooling air flow. In experimentals, this is not a
> problem inasmuchas reworks can be conducted until it is correct. IE: prop
> cuffs, ala Tracy
> Crook,
>
I'm also making my own cowling. Pics on my web site. I have gone to
diverging inlets in an attempt to recover pressure loss. So far, I get about
an
additional inch of pressure drop across the cyls. I've sealed everything on
top. I'll let you know what the tepms look like in a week or so.
Message 8
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Archie, questions on Exhaust Temps |
--> Engines-List message posted by: "Archie" <archie97@earthlink.net>
Subject: Re: Engines-List: Archie, questions on Exhaust Temps
> --> Engines-List message posted by: "Vic Jacko" <vicwj@earthlink.net>
>
> Archie, would appreciate your feelings on reducing pumping losses by
> fooling the engine in believing that it is at a higher altitude than it
> really is.
>
> If we can make the engine think it is at 8,000 to 10,000 feet one can run
> full throttle without exceeding 100 percent power. I am aware this
> happens
> at a lower altitude depending on outside temperature.
>
> Full throttle reduces pumping losses rather than pulling the throttle back
> to reduce power for cruise efficiency. Sooo this is what I suggest:
>
> Please fell free to flame me! We will enjoy your remarks!
>
> My suggestion is to heat the incoming air charge above the cold side of
> the
> ram air intake by using carb heat in the right proportion to cause the
> engine to think it is in a higher density altitude once cruise flight
> begins. One could use a fuel flow device to determine the most efficient
> engine operation at altitude.
>
> I am fully aware that one will lose power by applying carb heat. Power is
> not the point, pumping losses are what we want to reduce to increase
> efficiency.
>
> Also, correct me if I am wrong but will a warm intake charge increase the
> effective cylinder pressures than a cold charge at a given power output?
>
> If this is true then will we not have an increase in the effective
> compression ratio in the above question at the same power output.?
>
> I hope you have time to give us you view on these ideas. Maybe if I am
> correct in my thesis we can save some fuel!
>
> Vic,
>
> Roswell, NM
Vic, Good to see that you are thinking, but I do not feel it will
produce the results you are seeking.
A cold intake charge, when the engine is running, is more dense,
and will expand to a greater degree when heated, than a warm.
Cooling the sump, or just eliminating the induction through it,
would produce positive results in this regard.
If you are able to dump the mags, and incorporate full electronics
with a crank trigger device, you will be able to run plug gaps as much
as .100 and it will run. I would recommend a running gap of around .060
(Mags, even with impulse, fire around .016/.017 gaps).
Better yet, if you can incorporate a pulsed injection system, such
as the Aerosance, (Continental), the results will be impressive.
Is your aircraft experimental?
If so, you will have it made, inasmuch as automotive injection
systems are able to be retrofitted and mapped to your desire.
If this is executed properly, I am confident you can achieve about
10 hp increase, and perhaps 1/2 gal less fuel burn.
This method would most certainly equate to more efficiency.
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|