EGT balance issues

[petep]

My 2.1 normally asperated AeroVee has EGT issues that are giving me a fit. The front two cylinders (4 and 2) run a hundred degrees plus lower EGT that the back two culinders (1 and 3). I have the AeroInjector tuned as rich as is possible on the front two cylinders but the back two can bearly be maintained below 1400 at cruse power and the back two cylinders can not be kept below 1400 at full throttle. I have checked valve lashing, EGT probe location and ignition timing and they are exsctly as called for in the engine manual. I have swapped the front and rear EGT probe inputs and the issue follows the rear cylinders. I bought a pair of Great plains intake elbows and tested them and have the same issues I have with the Sonex intake elbows. I also ran the engine with the air filter off with no change in EGT issues. I am thinking that the problem is that the fuel air mixture comes straight in from the rear of the intake elbow and piles up on the front of the elbow causing a much richer mixture in the front two cylinders. I also suspect the fuel dropplet size with the AeroInjector is fairly large and adds to the imbalance. Has anyone experimented with a turbulator or a flow divider in the intake eklbow to balance the fuel air charge equally between the front and rear cylinders? Also wonder if going to a turbo might help but suspect it probably will not resolve the inbalance. Any thought on a possible resolution will be appreciated.

[Bryan Cotton]

Some light reading:
viewtopic.php?f=7&t=7674

Also check near the bottom of this page.
viewtopic.php?f=7&t=3232&start=130

[Bryan Cotton]

Regarding the WOT issues, read this thread:
viewtopic.php?f=7&t=7964

I'm soon going to modify my #2 needle to admit more fuel at WOT.

[Prince]

There is a Onex in Australia owned by Dr Peter Lovell powered by a VW conversion with direct fuel injection. When I last spoke to him, maybe 5 or 6 years ago, he was exceedingly impressed with the performance and smoothness of his engine. Not sure if he’s on this forum but he’d be easy enough to track down.

[Bryan Cotton]

Sounds like the VeeCU may be an option. I think the slot in the manifold, like the stock VW slot, is the key for the AeroInjector. Would be interesting to see if someone could duplicate my results with either the stock Aeroconversions manifold or the GPAS one.

[petep]

Bryan - I have both the GP and Sonex intake elbows. I will try putting a slot in the GP elbows and run them for a test, Will let you know what I find.
Thanks,
Pete

[Bryan Cotton]

Bryan - I have both the GP and Sonex intake elbows. I will try putting a slot in the GP elbows and run them for a test, Will let you know what I find.
Thanks,
Pete

Cool. I also slotted the spacer as shown in the pictures.

[mike.smith]

What are the CHTs? That's what counts. EGTs are good for seeing trends, but not really much else. If the EGTs are 2,000 deg and the EGTs are within limits, then that's what is meaningful. One or two hundred degrees difference on EGTs on a VW is perfectly fine. It's not a fuel injected engine, and will NEVER have matching EGTs. Never. If the CHTs are good, and you are getting full power, you are good to go.

Also, you did not note if this was an engine that is still being broken in, or if it has a bunch of hours on it already. If it's still being broken in, then it really is all about the CHTs staying within limits, and that takes time, and climb management.

More info on your CHT/EGT numbers would be helpful.

[BRS]

Even on Injected engines the EGT's don't always match up and that's just fine. Intake & exhaust geometry as well as probe placement can't all be made identical. What's more important is where they peak, that they do that at the same time. On a carburated engine I care most about keeping within limits (1400 degF on Revmaster). My Sportsman, on the other hand, with the SDSEFI on a lyc IO-360, each injector can be adjusted independantly. This is done using what we call a Gami test which measures what fuel flow each cylinder reaches peak EGT. They are then adjusted to peak at the same fuel flow. Once this is done, the engine runs like butter and those four cylinders are working at equal effort. Though the EGT's don't read the same.

[Bryan Cotton]

Mike,
I agree CHT is the #1 concern. But don't you worry about going over the 1400F EGT redline? I assume it's there for the health of the exhaust valve and seat.