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What would you do with this?

Dbro172

Well Known Member
My throttle produces severely offset CHTs and EGTs at about a 75% position. If I dump in full throttle or pull back to 65% or less all the numbers even out nicely though. I've verified I can get a good EGT rise at altitude by leaning. But this spot around 75% has some wicked offsets. Aerosprort was of little help.


bdoz9d.jpg
 
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I'd lean the engine out. 11.7 GPH on an O320 is a ton of fuel at 72% power on an O320. It's enough to support almost 170 HP, and you're producing about 115.

Does it clean up when you drop to 10-ish GPH, which is much more in line with a ROP mixture at that power?

What do your fuel flows look like at WOT and 65% power?

--Ian
Dynon Avionics
 
I will have to lean it out and check to respond to your question but I think it has more to do with the butterfly valve setting. I can check fuel flow at wot and 65% power but that will pry mean climbing to 12500 da or so?

I think I'm realizing some significant ram air horsepower or some significant horsepower increase from the ASA vacuum valve because whereas I only get 2150 rpm static at 1500 msl, I can still wind it up to 2750 at 10,000 DA.
 
Agree with the leaning recommendation

I have likely the same engine in a 9A - Superior IO-320 - furnished by Aerosport Power. At that altitude and at 72% power I'd be leaned w-a-y back and burning 6.5gph or less. Even at <4000 ft running 75% and 100 ROP my fuel burn is ~ 9 to 9.3gph. That 11.7 - as others have observed - is WAY high.
 
RPM 2690

I take it that you have a fixed pitch propeller. A sweet spot at nearly 2700 RPM?
If you had a constant speed prop, you could set around 23/23, lean to around 6-7 GPH and watch things quiet down and cool off.
 
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Here is a photo and my sump riser (spacer) that was asked about previously. Perhaps it should be above the throttle bracket?

jt8e82.jpg
 
Here is a photo and my sump riser (spacer) that was asked about previously. Perhaps it should be above the throttle bracket?

jt8e82.jpg

Yes... and mounted inside the bottom of the sump. You have a Superior Engine, not going to be your issue. :)
 
Reiley - can you clarify your response? are you saying the brown spacer should be above the white throttle bracket?
 
The insert referred to in the SB mounts inside the sump. Google SB-258 and you can find the drawing. It pertains to OLD lycomings only.
 
from 9-12-13

I had a local guy at HAO make a sump riser (SB258) for my Superior O-320 because I had a rough engine and high rear cylinder head temps (400F) on my two flights that I was not satisfied with. My front cylinders were 325F. I added a lip to the sump riser insert to account for the throttle bracket and gasket offset to minimize abrupt steps in the riser from the carb. I also polished some flash from the carb vanes. I will have MT prop gov SB (prop surging issue), gear fairings and wheel pants and D100 software update, and sump riser for the next flight. I'll report on engine response. I have a copy of SB258 I can send you. Note: I followed Bob's idea and purchased the thick walled alum tubing from England to make the riser.

http://www.vansairforce.com/community/showthread.php?t=64910&highlight=sump+riser+insert&page=2

Superior uses the same sump for both 320 and 360. This sump has a taper at the opening that creates a step at the 320 carb that causes the rear cylinders fuel distribution issue. Superior will tell you that it doesn't matter, but it does. You need the sump riser insert. I pro-sealed my custom insert in place rather than drilling an anti-rotation pin into the sump wall. After a year upon inspection (200 hrs) it is solid. CHT and EGT are even across all cylinders with the sump riser.

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I will have to lean it out and check to respond to your question but I think it has more to do with the butterfly valve setting. I can check fuel flow at wot and 65% power but that will pry mean climbing to 12500 da or so?

I think if you look at the charts 75% (or less) would be reached with WOT - and leaned to Rupsters range of fuel flow. esp at 9500 ft. This way you avoid that throttle position.

I think I'm realizing some significant ram air horsepower or some significant horsepower increase from the ASA vacuum valve because whereas I only get 2150 rpm static at 1500 msl, I can still wind it up to 2750 at 10,000 DA.

Neither is affecting your RPM. You have a fixed pitch, so with the incoming airspeed the balance RPM match of prop demand and engine power increases. Like full power and going into a dive, RPM will increase.

I added the colored responses above.
 
throttle bolt

Yes... and mounted inside the bottom of the sump. You have a Superior Engine, not going to be your issue. :)

side issue: you may think about reversing the orientation of the throttle cable bolt to reduce fatigue in the threads.
 
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sump riser

Does anybody have a photo of the insert before installation?

Don Broussard

RV 9 Rebuild in Progress
 
sketch

I made mine to this sketch because I wanted no gaps between the riser and carb. I let it cure in place with proseal. Also, I think you can still buy the Lycoming sump riser insert listed in SB258. I still have about of foot of tubing from England that is the correct ID.

sump%2Briser.bmp
 
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Per Aerosport my superior O-320 has an 0-320 sump and therefore i dont believe this spacer will help me any.

Edit: this proved to be wrong later down the road when I researched further and removed the carb... Deffinately a difference in diameter from my ma4spa carb to the opening in the bottom of the sump. About a 3/16" step wider from carb to sump
 
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Follow up to this issue - solved

I finally made major breakthrough in my issue with split EGTs and uneven fuel distribution between the front and rear cylinders. Aerosport fabricated me an insert, similar to applicable service bulletin, SB 258 dating back to the 50's, that smoothes out the transition from my ma4spa carb to the O-360 sump. First test flight showed way more even EGTs leaned out in cruise as well as smoother operation at higher power and ability to lean better. Can't wait to get up high and stretch the legs on it now. This eliminates the step in varying diameters from the carb to the sump, which must have been disturbing the airflow.

b6vj1v.jpg


33lyys8.jpg
 
I finally made major breakthrough in my issue with split EGTs and uneven fuel distribution between the front and rear cylinders. Aerosport fabricated me an insert, similar to applicable service bulletin, SB 258 dating back to the 50's, that smoothes out the transition from my ma4spa carb to the O-360 sump. First test flight showed way more even EGTs leaned out in cruise as well as smoother operation at higher power and ability to lean better. Can't wait to get up high and stretch the legs on it now. This eliminates the step in varying diameters from the carb to the sump, which must have been disturbing the airflow.

b6vj1v.jpg


33lyys8.jpg
Thanks for posting this Derek. This is exciting! I have an aerosport 0-320 that has very dramatic differences in front vs rear CHTS depending on whether I'm WOT or pulled back a bit. Does this sound like you? Any suggestions about how to approach aerosport with this (e.g. Any specific tests/numbers they wanted?).

Also, given the thickness of the riser, did it mess with your snorkel/FAB alignment?
 
Exactly

That is exactly the issue I had... Call Scott at Aerosport. He listened and helped. Based on my dealings there, he will know what you need. He will need to look up your engine though, to know the exact carb and sump.

My initial setup had a 1/4" phenolic spacer to begin with, thus the thick spacer that is integral to my tapered insert. Otherwise, yes it would alter the alignment from The lower cowl snout intake to the filtered air box.
 
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Yeah, that sump step is a bad deal. I got the lycoming one, but finding the kit is hard these days.
 
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