Itinerant Air-Cooled

Ah! Compression RATIO. My mind played a trick on me when I first read that. Went back through spread sheet and did not see it. Thanks guys.

Kevin, the engine has more than 2,000 miles on the rebuild, probably more like 20,000...did you mistype a zero there?

I haven't documented the compression in a while, but it's remained around 140 on each cylinder since the rebuild. My fuel mileage was comparable to what Kevin reported for freeway drives. Also the CHTs were on par with Colins during typical freeway ruins as well.

Andrew. I copied at paste compression test from an old post of yours. FYI I found another compression test you did and it was 145 on all 4 cyl 10,000 miles ago.

I misread the question. They want to know compression ratio. Any ideas. Could it be in that folder you gave me?

If the documentation lists the bore, stroke, deck height, and cylinder head chamber volume, we can compute the compression ratio. Those are always measured during an engine build, so it's just a matter if Andrew wrote them down on the papers he gave you.

Robbie

Rusty Sub wrote:Andrew. I copied at paste compression test from an old post of yours. FYI I found another compression test you did and it was 145 on all 4 cyl 10,000 miles ago.

I misread the question. They want to know compression ratio. Any ideas. Could it be in that folder you gave me?

I should have documented it during the engine rebuild. If I did, it would be in that spreadsheet I gave you. It's sounding like I didn't.

I can say with confidence that it's the stock crankshaft and piston sizes so bore and stroke are known. It's the rest that I don't recall.