Aerovee one EGT high

[Bryan Cotton]

Test flight - 1415 in climb until I got to 3000' MSL or so. Awesome RPM, over 3200. At 90kts was almost 3300, but the EGT went to 1430. Way better than before. I'm not done but on the right track I think.

[Bryan Cotton]

So I'm making another flow straightener. Here are the parts. I prototyped in flashing.

This is made from 0.016 2024-T3 and AN470AD3-3 rivets.

It slips in like this:

Here it is all the way in. The ends are bent to put some swirl in the flow, hopefully sending more fuel to the left side.

Next up is test, re-bend, and repeat until I'm happy.

[Bryan Cotton]

So, some results to report. I ran out of time to test it last night due to thunderstorms. Got up early for a test flight, in the configuration pictured above. In that picture the flow is going clockwise a little from the perspective of looking into the elbow. The top tab in the picture is bent to the right, the bottom to the left, and so on. On the first flight the EGT was higher than the last iteration, about 1460 in takeoff climb. I had chosen the clockwise rotation based on my guess of what the airflow needed to do. Since that seemed to make it worse, I bent the tabs the other way, and put a little more bend on them. I was able to keep the high EGT under 1400 in climb. Not quite in balance yet, but about the same as before I added the fresh air inlet. And I'm climbing out at 3250 RPM, rather than around 3050 or so. Definite gains. More tweaking to come but this seems really encouraging. I safetied up the hose clamp and left it in that configuration so Adam could take his buddy for a ride as posted in my photos thread.

[WaiexB22]

That sounds promising and seems like you have figured out what is going on.

FWIW I designed industrial piping for a few years right out of college. Sometimes we would use to use something called a "flow straightener" upstream of a measuring device or process in order to redistribute the flow evenly across the cross section. There were fin type, which looked very much like yours. There were also tube type, which was a series of small tubes within the larger pipe. They both did the same thing. Generally, there was lower pressure drop across vanes, but the tubes seemed to straighten the flow more reliably. It would be more difficult to fabricate a tube style without risking ingesting one in the engine. It looks like you have the vanes working well, but could be a consideration for someone in the future.

[Jester504]

Do all the cylinders hit peak EGT around the same time when you pull it back from full rich?

[Bryan Cotton]

Robert,
I had considered getting some hex shaped flow straightener material and CNCing a circle out of it. I'm not sure if straight is the answer, or just crooked enough to steer the fuel.

Do all the cylinders hit peak EGT around the same time when you pull it back from full rich?

Definitely not. The hot one peaks first.

[Bryan Cotton]

In the picture above, the tabs were bent the wrong way - temps got worse. Here is the iteration where they were about as good as before I added fresh air induction.

Screenshot_20240508-215708.png (2.01 MiB) Viewed 2255 times

Here is my next iteration - more swirl in the same direction, to see if there is an improvement.