Cylinder check

[Jay Honeck]

Why are you using any leaded gas at all? use unleaded, get lean, and the engine will stay clean. Since you're experimental, why not switch to EFI and really save money on fuel and maintenance?

Skip the MMO in the oil, won't do anything positive. If you want to get rid of the carbon, flood the cylinders with Berryman's for a while then change the oil and go run it hard for 15 minutes.

I've been a bit worried about detonation, using a lower octane fuel in our intense South Texas heat. It was still 85 at 5500' on Sunday.

So, we are trying to keep about 75/25 av-to-mogas, just to give us a little margin. In real life, with mogas unavailable at airports, we end up running about that mix naturally.

 

[Henning]

I've been a bit worried about detonation, using a lower octane fuel in our intense South Texas heat. It was still 85 at 5500' on Sunday.

So, we are trying to keep about 75/25 av-to-mogas, just to give us a little margin. In real life, with mogas unavailable at airports, we end up running about that mix naturally.

What compression ratio is your engine? What do your CHTs run at? Detonation is not likely your worry, vapor lock is.

 

[Jay Honeck]

What compression ratio is your engine? What do your CHTs run at? Detonation is not likely your worry, vapor lock is.

I don't know the compression off the top of my head, but CHTs will push 400 in the climb, settling into the 340 range in cruise.

We level off if we hit 400, and it immediately drops. Interestingly, after that first spike, once it drops below 400 we can climb basically forever, up to 15000', without it spiking again.

 

[Tom-D]

It is no problem if the differential is being lost at the rings. If it is hissing in the exhaust pipe, I would park the plane under a shade tree, pull the rocker cover and valve gear down to the bare stem and attach my drill motor to it, then pull the exhaust and reach up through with some lapping compound and proceed to lap the valve in place, saving me from a burned valve shortly down the road. But that's just shade tree mechanic me. I'll likely kill myself soon doing this kind of maintenance to keep my costs down.

I see by that statement, you do not under stand dynamic compression.