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320-E2G sump question

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jmpcrftr(at)teleport.com
Guest

Posted: Sat Feb 11, 2006 6:25 pm Post subject: 320-E2G sump question

Has anyone successfully made a carbureted O-320 have 100 or less EGT

spread through the full range of the throttle?  If so what model

engine and what sump is on the engine?



Carbureted engine, I'm trying to sort out an annoying mixture

distribution (I know.. buy fuel injection).  Full throttle is nice

and even, typical 75-100 EGT spread.  Just off of full throttle #3 &

4 leans out and #1 & 2 goes rich, typically 275 deg F EGT spread.

Back to 2/3 throttle and on down they even back out again.



Carb is a 10-5009 with the nozzle kit to make it a 10-5217.  The kit

was supposed to improve mixture distribution.  It didn't.



 From the symptoms I can say it's not an induction leak.  I'm

wondering if this particular engine with its particular sump and

induction tubes has something to do with it.



The O-320-E2G is listed as having an A sump.  I see some references

to a straight riser sump ( -A1B for instance).  My O-320-E2G

induction tubes on cylinders 3 & 4 come out from the narrow part of

the sump in the back directly under the lower engine mount.  The

four induction tubes don't point directly to the riser where the

carb bolts on.



Thanks in advance for any help or suggestions.

(I know .. get rid of the engine monitor)

Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR

13B in gestation mode, RD-1C, EC-2

Fred Stucklen

Joined: 10 Jan 2006
Posts: 10
Location: East Windsor, CT

Posted: Mon Feb 13, 2006 5:18 am Post subject: 320-E2G sump question

Michael,



   I've been having exactly the same problem with an O-320-D1A that had 9:1

pistons. I've tried rejetting it, even sent the Carb back to Aero Sport

Power. Nothing seems to correct the situation. I did read on the Lycoming

web site last week that this is a common occurrence with Carb'ed engines.

  Iv I run the engine at different power settings, I get different EGT's &

CHT's. At 2350 RPM (fixed pitch prop) in cold air (less than 25*F) # 4 CHT

goes so low it will start skipping, especially if I have leaned at all. All

temps are fine at full throttle and at something like 2150 RPM. In warm air

the situation is much less pronounced....

  So I've gotten to the point where I ether fly slow in cold air,

(especially down low) or at full throttle, leaned, at high altitudes

(11,000' or more). Sure makes me want to reconsider a fuel injection

system....

  I do have all EGT's and CHT's, and have talked to Bart at Aero Sport Power

extensively about this situation. He doesn't have too much to add....

Fred Stucklen

RV-6A  N926RV

South Windsor, Ct 06074

phone: (860)727-2393

email: fred.stucklen(at)utcfuelcells.com

Time: 06:25:18 PM PST US

From: Michael McGee <jmpcrftr(at)teleport.com>

Subject: 320-E2G sump question




Has anyone successfully made a carbureted O-320 have 100 or less EGT

spread through the full range of the throttle?  If so what model

engine and what sump is on the engine?



Carbureted engine, I'm trying to sort out an annoying mixture

distribution (I know.. buy fuel injection).  Full throttle is nice

and even, typical 75-100 EGT spread.  Just off of full throttle #3 &

4 leans out and #1 & 2 goes rich, typically 275 deg F EGT spread.

Back to 2/3 throttle and on down they even back out again.



Carb is a 10-5009 with the nozzle kit to make it a 10-5217.  The kit

was supposed to improve mixture distribution.  It didn't.



 From the symptoms I can say it's not an induction leak.  I'm

wondering if this particular engine with its particular sump and

induction tubes has something to do with it.



The O-320-E2G is listed as having an A sump.  I see some references

to a straight riser sump ( -A1B for instance).  My O-320-E2G

induction tubes on cylinders 3 & 4 come out from the narrow part of

the sump in the back directly under the lower engine mount.  The

four induction tubes don't point directly to the riser where the

carb bolts on.



Thanks in advance for any help or suggestions.

(I know .. get rid of the engine monitor)

Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR

13B in gestation mode, RD-1C, EC-2

jlbaker(at)telepath.com
Guest

Posted: Mon Feb 13, 2006 9:01 am Post subject: 320-E2G sump question

 	  Quote: 	
		   I've tried rejetting it, even sent the Carb back to Aero

 Sport Power. Nothing seems to correct the situation. I did read on 

the
	


 	  Quote: 	
		   Lycoming web site last week that this is a common occurrence 

with
	


 	  Quote: 	
		   Carb'ed engines.


	


Not that you may be able to do anything about it, but this sure 

sounds like an exhaust scavenging problem. If all the intake runners 

are approximately the same length, what is the situation with your 

exhaust systems? Is it an issue that a crossover system might cure? 

Just a thought.....

Jim Baker

580.788.2779

'71 SV,  492TC

Elmore City, OK

Dww0708(at)aol.com
Guest

Posted: Mon Feb 13, 2006 10:38 am Post subject: 320-E2G sump question

Just listening in here   All carbureted engines should have the  distinct 

slight rise in RPM just prior to fuel off at Idle RPM.  That  establishes not 

induction leaks and proper idle fuel to air ration.    That said better swap your 

probe around to establish repeatability of you  symptom. Use a remote 

pyrometer and be sure that you guages are  accurate.  The spark plugs are vital,  

play musical  sparkplug's.  Keep a numbering system and vibe ech them to keep 

them  straight.   Plugs should be examined closely for indications as to  

combustion quality.  Compressions should be with in 80 percent of each  other.  David

Fred Stucklen

Joined: 10 Jan 2006
Posts: 10
Location: East Windsor, CT

Posted: Tue Feb 14, 2006 4:40 am Post subject: 320-E2G sump question

Jim,

 

  My RV-6A does use the Vetterman crossover exhaust system.....



Fred Stucklen

RV-6A  N926RV



      

      

<mailto:jlbaker(at)telepath.com> >

      

      > I've tried rejetting it, even sent the Carb back to Aero

      > Sport Power. Nothing seems to correct the situation. I did read on 

      the

      > Lycoming web site last week that this is a common occurrence 

      with

      > Carb'ed engines.

      

      Not that you may be able to do anything about it, but this sure 

      sounds like an exhaust scavenging problem. If all the intake runners 

      are approximately the same length, what is the situation with your 

      exhaust systems? Is it an issue that a crossover system might cure? 

      Just a thought.....

      

      

      Jim Baker

      580.788.2779

      '71 SV,  492TC

      Elmore City, OK

glcasey(at)adelphia.net
Guest

Posted: Tue Feb 14, 2006 5:03 am Post subject: 320-E2G sump question

 	  Quote: 	
		  


	


 	  Quote: 	
		    Nothing seems to correct the situation. I did read on the Lycoming

 web site last week that this is a common occurrence with Carb'ed  

 engines.

   Iv I run the engine at different power settings, I get different  

 EGT's &

 CHT's. At 2350 RPM (fixed pitch prop) in cold air (less than 25*F)  

 # 4 CHT

 goes so low it will start skipping, especially if I have leaned at  

 all. All

 temps are fine at full throttle and at something like 2150 RPM. In  

 warm air

 the situation is much less pronounced....

   So I've gotten to the point where I ether fly slow in cold air,

 (especially down low) or at full throttle, leaned, at high altitudes

 (11,000' or more). Sure makes me want to reconsider a fuel injection

 system....

   I do have all EGT's and CHT's, and have talked to Bart at Aero  

 Sport Power

 extensively about this situation. He doesn't have too much to add....

 Fred Stucklen


	


One thing that we learned on car engines way back when was that the  

carb inlet condition makes a big difference.  I've seen some aircraft  

installations that were well done except for the carb inlet.  Ideally  

the inlet should be a bell-mouth (elliptical is a good approximation)  

or at least radiused with equal air flow from all directions.  Not  

easy to do with the tight space constraints that usually exist.  One  

way to do it that I have looked at (not done as I don't have a carb'd  

engine) is to bolt a radius - no duct - to the carb inlet and then  

surround the carb with inlet air by building a dam well above the  

inlet that extends outward from the carb to the lower cowl.  Air can  

then flow past the carb and enter the inlet from the rear, balancing  

the flow that comes from the front.  The lower restriction will give  

more power as well.  Remember, a sharp-edge inlet will have a Cd of  

about 0.6 compared to a radiused inlet that will have a Cd of almost  

1.0, meaning the pressure drop at the inlet will be 60% of what it is  

with a sharp edge.  Might be worth a try.



Another thing we tried was a "dip tube", which is a tube that extends  

down (oops, up) into the manifold slightly past where the individual  

runners come off the manifold.  This creates a sharp edge that  

prevents the fuel and/or air from clinging to one side and not the  

other.  Made a definite improvement and carefully done didn't impede  

the air flow too much.



Gary Casey

Fred Stucklen

Joined: 10 Jan 2006
Posts: 10
Location: East Windsor, CT

Posted: Tue Feb 14, 2006 5:21 am Post subject: 320-E2G sump question

David,

 

  I've calibrated all probes (with a certified calibrations device). All are

within 1% accuracy. The idle cuttoff RPM rise is present (but this should

have no effect on the cruise RPM or cruise mixture problem). I've also tried

a new set of plugs, with exactly the same results.

  Just to recap the issue, CHT's & EGt's between cyclinders are diverging

under certainpower settings (10-5217 carbureted O-320-D1A engine with

Vetterman crossover exhaust). Running the engine at low power settings (2100

RPM and lower) and at full power setting results in CHT's & EGT's that are

very similar (CHT's within 5*-10*, EGT's within 50*). Runing the engine

between 2200 - 2440 RPMS (maybe around 90% throttle) results in diverging

CHT's & EGT's, with cylinders #3 & #4 (#4 being the coldest), especially in

cold air (< 25*F) and leaned. #4 CHT will go below 200*F and begin skipping.

  The tests I have run seem to indicate that the CHT/EGT divergence is

directly related to the throttle plate position. Try this: pick an altitude

below 8000' where the OTA is 20* or less. Run at 1900 RPM cruise, full rich,

and note all CHT's & EGT's. Be sure to allow time for thermal stabalization.

Repeat the same test at 500 RPM increments, and then at different mixture

settings (witht he 1900 RPM mixture setting as the reference point.).

Normalize the numbers by showing only the differences in temps between the

1900 RPM full rich data, and all other data. Plot out curves of divergence

Vs Throttle position for different mixture settings. (Having a normalized

CHT/EGT gauge helps emmensly in visualizing the resulting divergences...)

   What I saw was about the same CHT's/EGT's differences at 1900 RPM and

full throttle, with diverging temps at throttle positions in between those

settings. I have also noted that at higher Outside Air temps, there is a

lesser problem. This might suggest that the fuel atomization at the colder

OAT's is not as complete at is is with higher OAT's. This, coupled with the

throttle plate position, could cause more fuel to be routed into the front

cylinders, with more air going to the back cylinders. (Remember, the

throttle plate position [at less than full throttle] favors flow towards the

front cylinders.) 

  I would like to try other carburetors to see if there isn't a better

solution. I'm not sure that there are any other carbs out there that will

run OK on this engine.... Another solution might be to put a honey cone type

device between the carb and the sump. This should help straighten out the

air flow....

 

Fred Stucklen

RV-6A  N926RV

430 Hrs

 



      

      

<mailto:Dww0708(at)aol.com> 

      

      Just listening in here   All carbureted engines should have the

distinct 

      slight rise in RPM just prior to fuel off at Idle RPM.  That

establishes not 

      induction leaks and proper idle fuel to air ration.    That said

better swap your

      

      probe around to establish repeatability of you  symptom. Use a remote 

      pyrometer and be sure that you guages are  accurate.  The spark plugs

are vital,

      

      play musical  sparkplug's.  Keep a numbering system and vibe ech them

to keep 

      them  straight.   Plugs should be examined closely for indications as

to  

      combustion quality.  Compressions should be with in 80 percent of each

other.

      David

Dww0708(at)aol.com
Guest

Posted: Tue Feb 14, 2006 7:21 pm Post subject: 320-E2G sump question

vetterman? The idle cut off check is kind of an induction tube  integitidy 

check,it proofs if you have vacuum leaky pipes. Vacuum is strongest  at idle 

RPMs and a sucking leak will inhibit the proper RPM rise ( lean out ) at  Idle 

cutoff indicating lean condition. I know Lyc uses an oil  heated induction 

manifold, Helps atomization. If the carb heat is  leaking it can adversely affect 

the fuel air ratio. Any way  looks  like you have been trial and erroring it.   

The industry is like  that.  I am curious,  Lyc operators manual?  I have  

one,   the thing that comes to me is what is the manifold pressure  doing?  Is 

there a curve trend that should/would mirror you other  parameters?  Manifold 

pressure at pressure altitude and OAT. Manifold  pressure is the power 

indicator. Then there is the basic push rod clearance  with dry tap it.   Very 

important to brake horses and volumetric  effeciency.Selection of push rod lengths 

are how to adjust dry tappet  clearance. Some might say that that valve timing 

issue would lead to engine  roughness and it should but needs confirmed. Very 

basic. If I was  a Lyc tech rep I would verify all this before before 

experimenting away from the  basic engine design. Have read about the intake and 

exhaust rocker arm  movements and making sure consistent to other cylinders.  Are 

all the  correct part number items include in proper engine build up.   David

Fred Stucklen

Joined: 10 Jan 2006
Posts: 10
Location: East Windsor, CT

Posted: Wed Feb 15, 2006 5:47 am Post subject: 320-E2G sump question

David, Gary,

 

  Veternman crossover exhaust: I think his company name is High Mountain

Exhaust. 

Standard system for most RV's.....

  The idle cutoff test worked fine, with a 100 RPM rise, so I'm sure there

aren't any

intake leaks. I've looked very carefully at all intake components and can't

find any

leaks. I've even performed checks to find cracks (exterior surface powder &

carb 

cleaner into intakes/exhaust ports, compression checks, visual checks)....

  Trial & Error approach: I'd like to think that I've taken a lot of data

that characterizes

just how the engine is operating. I have documented everything: fuel flow,

manifold 

pressure, OAT, EGT, CHT, throttle position, mixture position, RPM, oil temp

& 

pressure, etc....  The ONLY relationship to the poor EGT's & CHT's seems to

be 

throttle position.

  By the way, Bart Lablond (Aero Sport Power) has also looked at this engine

and can't seem to find why it's behaving the way it is..... He ran it in a

test cell, I've

run it in the plane, so the induction system (major difference) might still

be the

culprit.

  I have checked the dry tappet clearances and they are within the Lycoming

specs...

 

  Induction System: I'm using Van's standard FAB320 Air box. This is a

snorkel type

airbox that utilizes the lower cowl shape (snorkel) to feed air into a short

snorkel,

then into a larger chamber (much like a car airbox). The air filter is

mounted to

the bottom of the carb (Oval shaped with top/bottom plates).   I have tried

to 

modify the airflow into the filter box area by placing a wedge in front of

the filter

to divert some of the ram air flow. This didn't seem to help at all.

  Since this is the second RV-6A that I've built (the first didn't have

these problems)

I've had a chance to compare the two induction systems. The first RV did

have

a larger volume area around the filter. This probably allowed better

distribution of 

the air around the filter. I've ordered a new fiberglass air box part, and

plan on 

installing it with modifications that will increase the airbox volume.

(Unfortunately,

Van has made some cowl, and engine mount changes that don't allow for the

use of his original airbox.) The air filter is the same....

  I have experimented with the current air box. Putting a hole 

in the bottom of the box (allowing air to enter/exit into the lower cowl)

did show

a significant change in the EGT/CHT patterns. The basic problem didn't go

away,

just changed how the engine breaths. 

  So that is the path that I'm going down next........ A modified airbox to

increase

the volume. I'd also like to run the engine without a filter to see what

happens to 

the EGT/CHT patterns at various throttle settings. The filter should

actually result

in better airflows into the carb, but I need to know what it does without

it.

 

Fred Stucklen

RV-6A  N926RV

 

 

      vetterman? The idle cut off check is kind of an induction tube

integitidy 

      check,it proofs if you have vacuum leaky pipes. Vacuum is strongest

at idle 

      RPMs and a sucking leak will inhibit the proper RPM rise ( lean out )

at  Idle

      

      cutoff indicating lean condition. I know Lyc uses an oil  heated

induction 

      manifold, Helps atomization. If the carb heat is  leaking it can

adversely affect

      

      the fuel air ratio. Any way  looks  like you have been trial and

erroring it. 

      

      The industry is like  that.  I am curious,  Lyc operators manual?  I

have  

      one,   the thing that comes to me is what is the manifold pressure

doing?  Is

      

      there a curve trend that should/would mirror you other  parameters?

Manifold 

      pressure at pressure altitude and OAT. Manifold  pressure is the power



      indicator. Then there is the basic push rod clearance  with dry tap

it.   Very

      

      important to brake horses and volumetric  effeciency.Selection of push

rod lengths

      

      are how to adjust dry tappet  clearance. Some might say that that

valve timing

      

      issue would lead to engine  roughness and it should but needs

confirmed. Very 

      basic. If I was  a Lyc tech rep I would verify all this before before 

      experimenting away from the  basic engine design. Have read about the

intake and

      

      exhaust rocker arm  movements and making sure consistent to other

cylinders.  Are

      

      all the  correct part number items include in proper engine build up.

David

glcasey(at)adelphia.net
Guest

Posted: Wed Feb 15, 2006 6:58 am Post subject: 320-E2G sump question

A couple more comments:



It looks like you correctly found out that throttle position makes a  

difference.  Sometimes it is better for the throttle to be full open  

and other times it is better with the throttle partly closed or even  

past fully open, deflecting the flow the other way.  There is nothing  

wrong with running with a partially closed throttle as the last maybe  

20 degrees of rotation won't give any more air flow anyway.



Another observation - these engines are running in certified aircraft  

and from you description I'm sure they don't have the problem - or at  

least not so serious as to cause a problem.  Since the engine itself  

(sump, runners, carb) is of a standard configuration, what else is  

different.  The engine configuration probably doesn't need fixing.   

Some have argued that the exhaust system could play a role, but I  

reject that notion as at the rpm you are running there isn't much in  

the way of tuning or pulsation effects that will be noticeable.   

Also, any cam wear or valve clearance issues will only result in  

slight power differences between cylinders, not large mixture  

variations.



I still strongly suspect the carb inlet configuration.  What is it like?



Gary

James Baldwin

Joined: 16 Jan 2006
Posts: 23

Posted: Wed Feb 15, 2006 9:05 am Post subject: 320-E2G sump question

Fred -

Sounds like you've zeroed in on your engine's performance pretty 

accurately.  Before you get your knickers in a real knot, realize you 

are collecting data at a level few people do with what production 

aircraft your engine is in.  My friend and I both had Grumman Cheetahs 

with the carburated O320s.  He installed the four cyl JPI EGT/CHT probe 

system very accurately i.e. all the CHT probes were screw-in and the EGT 

probes were positioned as close as possible to be in the same position 

relative to the exhaust outlet per JPI install instructions.  As an 

engineer I was very interested because we were going to really get some 

improved BSFC out of these engines.  (we thought).  Long story short, we 

experienced exactly what you are seeing and in my humble opinion, you 

will not be able to tighten the observed spread in EGT performance with 

respect to throttle position in all cases.  That's one reason why the 

manufacturers eventually went to the mechanical fuel injection systems 

in use today.  They can tune each cylinder as if it were an individual 

engine and not worry about how the fuel is distributed.  Wide open 

throttle is what we settled for and used altitude as the variable for 

desired percent power.  Don't waste any more time, go get some fuel 

injection for it and spend your time tuning the injection nozzles to 

tighten your EGT spread.  Then you can go after fine tuning of the 

cooling baffles to even out the CHT spread.  JBB



Stucklen, Frederic W UTPWR wrote:



 	  Quote: 	
		  



David, Gary,

 

  Veternman crossover exhaust: I think his company name is High Mountain

Exhaust. 

Standard system for most RV's.....

  The idle cutoff test worked fine, with a 100 RPM rise, so I'm sure there

aren't any

intake leaks. I've looked very carefully at all intake components and can't

find any

leaks. I've even performed checks to find cracks (exterior surface powder &

carb 

cleaner into intakes/exhaust ports, compression checks, visual checks)....

  Trial & Error approach: I'd like to think that I've taken a lot of data

that characterizes

just how the engine is operating. I have documented everything: fuel flow,

manifold 

pressure, OAT, EGT, CHT, throttle position, mixture position, RPM, oil temp

& 

pressure, etc....  The ONLY relationship to the poor EGT's & CHT's seems to

be 

throttle position.

  By the way, Bart Lablond (Aero Sport Power) has also looked at this engine

and can't seem to find why it's behaving the way it is..... He ran it in a

test cell, I've

run it in the plane, so the induction system (major difference) might still

be the

culprit.

  I have checked the dry tappet clearances and they are within the Lycoming

specs...

 

  Induction System: I'm using Van's standard FAB320 Air box. This is a

snorkel type

airbox that utilizes the lower cowl shape (snorkel) to feed air into a short

snorkel,

then into a larger chamber (much like a car airbox). The air filter is

mounted to

the bottom of the carb (Oval shaped with top/bottom plates).   I have tried

to 

modify the airflow into the filter box area by placing a wedge in front of

the filter

to divert some of the ram air flow. This didn't seem to help at all.

  Since this is the second RV-6A that I've built (the first didn't have

these problems)

I've had a chance to compare the two induction systems. The first RV did

have

a larger volume area around the filter. This probably allowed better

distribution of 

the air around the filter. I've ordered a new fiberglass air box part, and

plan on 

installing it with modifications that will increase the airbox volume.

(Unfortunately,

Van has made some cowl, and engine mount changes that don't allow for the

use of his original airbox.) The air filter is the same....

  I have experimented with the current air box. Putting a hole 

in the bottom of the box (allowing air to enter/exit into the lower cowl)

did show

a significant change in the EGT/CHT patterns. The basic problem didn't go

away,

just changed how the engine breaths. 

  So that is the path that I'm going down next........ A modified airbox to

increase

the volume. I'd also like to run the engine without a filter to see what

happens to 

the EGT/CHT patterns at various throttle settings. The filter should

actually result

in better airflows into the carb, but I need to know what it does without

it.

 

Fred Stucklen

RV-6A  N926RV

 

 

      vetterman? The idle cut off check is kind of an induction tube

integitidy 

      check,it proofs if you have vacuum leaky pipes. Vacuum is strongest

at idle 

      RPMs and a sucking leak will inhibit the proper RPM rise ( lean out )

at  Idle

      

      cutoff indicating lean condition. I know Lyc uses an oil  heated

induction 

      manifold, Helps atomization. If the carb heat is  leaking it can

adversely affect

      

      the fuel air ratio. Any way  looks  like you have been trial and

erroring it. 

      

      The industry is like  that.  I am curious,  Lyc operators manual?  I

have  

      one,   the thing that comes to me is what is the manifold pressure

doing?  Is

      

      there a curve trend that should/would mirror you other  parameters?

Manifold 

      pressure at pressure altitude and OAT. Manifold  pressure is the power



      indicator. Then there is the basic push rod clearance  with dry tap

it.   Very

      

      important to brake horses and volumetric  effeciency.Selection of push

rod lengths

      

      are how to adjust dry tappet  clearance. Some might say that that

valve timing

      

      issue would lead to engine  roughness and it should but needs

confirmed. Very 

      basic. If I was  a Lyc tech rep I would verify all this before before 

      experimenting away from the  basic engine design. Have read about the

intake and

      

      exhaust rocker arm  movements and making sure consistent to other

cylinders.  Are

      

      all the  correct part number items include in proper engine build up.

David

GrummanDude

Joined: 15 Jan 2006
Posts: 926
Location: Auburn, CA

Posted: Wed Feb 15, 2006 10:28 am Post subject: 320-E2G sump question

In a message dated 2/15/06 7:00:44 AM, glcasey(at)adelphia.net writes:

 	  Quote: 	
		   There is nothing=A0

 wrong with running with a partially closed throttle as the last maybe=A0

 20 degrees of rotation won't give any more air flow anyway.




	


Not sure if you've tried this, (I haven't read all of the emails) but, try a

little carb heat at different throttle positions.   I have an O360 with the

JPI 800.   Carb heat has shown to move the EGT spread around at different

throttle settings.

_________________
Gary
AuCountry Aviation
Home of Team Grumman

jlbaker(at)telepath.com
Guest

Posted: Wed Feb 15, 2006 4:26 pm Post subject: 320-E2G sump question

 	  Quote: 	
		   That's one reason why the manufacturers eventually went to the

 mechanical fuel injection systems in use today.  They can tune 

each
	


 	  Quote: 	
		   cylinder as if it were an individual engine and not worry about how

 the fuel is distributed. > 


	




Well, that's partly true. FI is a whole lot better than carburetion in 

terms of getting the right amount to each port.....avoiding having it 

robbed from one port to someplace in the induction runner or to 

another intake port is still a problem. I see about 125F difference 

from top to bottom on my IO520. Unless you can do direct injection, 

there's always some interference in the process at some given 

RPM(s).

Jim Baker

580.788.2779

'71 SV,  492TC

Elmore City, OK

James Baldwin

Joined: 16 Jan 2006
Posts: 23

Posted: Wed Feb 15, 2006 4:59 pm Post subject: 320-E2G sump question

Jim -

The Cont 520 series is well known for its air/fuel mixture distribution 

problem.  That of course is what the calibrated injector nozzles from 

George Braly  at GAMI are all about.  Are you using the GAMI nozzles in 

your airplane?   The A36 with the Tornado Alley Turbo normalizer I fly 

has them and the spread is minimal and lean of peak cruise is very 

smooth and economical.  I don't have the spread at my fingertips here 

because I actually only monitor TIT during operation.  JBB

Jim Baker wrote:

 	  Quote: 	

>That's one reason why the manufacturers eventually went to the

>mechanical fuel injection systems in use today.  They can tune 

>    

>

each

>cylinder as if it were an individual engine and not worry about how

>the fuel is distributed. > 

>    

>

Well, that's partly true. FI is a whole lot better than carburetion in 

terms of getting the right amount to each port.....avoiding having it 

robbed from one port to someplace in the induction runner or to 

another intake port is still a problem. I see about 125F difference 

from top to bottom on my IO520. Unless you can do direct injection, 

there's always some interference in the process at some given 

RPM(s).

Jim Baker

580.788.2779

'71 SV,  492TC

Elmore City, OK

flyv35b(at)ashcreekwirele
Guest

Posted: Wed Feb 15, 2006 6:09 pm Post subject: 320-E2G sump question

It's not the absolute EGT or even the difference from one cylinder to 

another that is the most important, but whether or not all cylinders reach 

peak EGT at close to the same time and mixture control position.  Granted, 

this will change with throttle position and rpm and maybe other things but 

if the spread in fuel flow from the first cylinder to reach peak to the last 

is about .25 gph  (on an IO-520 say) then you have a pretty even mixture 

distribution and the engine will run smooth on the lean side of peak EGT. 

You can have 2 different cylinders that are 50F or more apart temperature 

wise but reach peak EGT at the very same time.  The GAMI injectors taylor 

the fuel flow to match the uneven airflow distribution and thereby hopefully 

have all cylinders reach peak EGT at close to the same time.



Cliff

---

James Baldwin

Joined: 16 Jan 2006
Posts: 23

Posted: Wed Feb 15, 2006 6:24 pm Post subject: 320-E2G sump question

Yes.

flyv35b wrote:



[quote]



It's not the absolute EGT or even the difference from one cylinder to 

another that is the most important, but whether or not all cylinders reach 

peak EGT at close to the same time and mixture control position.  Granted, 

this will change with throttle position and rpm and maybe other things but 

if the spread in fuel flow from the first cylinder to reach peak to the last 

is about .25 gph  (on an IO-520 say) then you have a pretty even mixture 

distribution and the engine will run smooth on the lean side of peak EGT. 

You can have 2 different cylinders that are 50F or more apart temperature 

wise but reach peak EGT at the very same time.  The GAMI injectors taylor 

the fuel flow to match the uneven airflow distribution and thereby hopefully 

have all cylinders reach peak EGT at close to the same time.



Cliff

---

Dww0708(at)aol.com
Guest

Posted: Wed Feb 15, 2006 8:09 pm Post subject: 320-E2G sump question

sounds like pretty good scoop.... no irregularity intended David

jlbaker(at)telepath.com
Guest

Posted: Wed Feb 15, 2006 9:14 pm Post subject: 320-E2G sump question

 	  Quote: 	
		   That of course is what the calibrated injector

 nozzles from George Braly  at GAMI are all about.  Are you using 

the
	


 	  Quote: 	
		   GAMI nozzles in your airplane?   


	


Well, that's the sad part. I live about 30 miles from Ada, OK and the 

GAMI folks, have been over there several times watching installs 

and test cell runs, but no, I don't because the cost/benefit for me 

would be marginal.....except I really like the idea of LOP operation. A 

GAMI install would first necessitate a JPI install as well. $$$$$



Sigh.....



Jim Baker

580.788.2779

'71 SV,  492TC

Elmore City, OK

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