fstringham7a
Well Known Member
RE: Cowl inlet /outlet ratio
I am flying with Van's Cowl fitted with my mod for ram air induction. I have also fitted the engine with a plenum top made of metal instead of typical baffle seal to cowl top. Still @ nearly 40 hours the CHT's are right at 400 with #3 running hotter at 415, with a 12 GPH fuel flow. At the last oil change (30 hours) the plugs were also checked and the tops were clean (slight graying) and the bottoms were wet. The engine is burning about 1.5 quarts per 10 hours (TO MUCH) so the engine is either not broken in or...............
Bob Looper, who ran the engine in thinks that even though these nickle cylinder break in early mine might just be stubborn. He said that I should see the oil consumption decrease slowly between now and about 75 hours. I am also chasing down a very small leak of oil that I think is orginating from the right bottom are of the right mag.
So now the big question. The inlet area is .41 and the exit area is .68. I have the Vettermin four exhaust pipe set up. I have read some threads on this issue but couldn't find a magic inlet to exit ratio for optimum cooling effect. Colling drag is an issue but too early in the planes life to worry about that.
Any Thoughts would be appreciated.
NEW INFO ......NO I JUST DID MY DUE DILGENCE LATE!!!!!!!! This thread give the me my answer or answers!!!!!!
http://www.vansairforce.com/community/showthread.php?t=20633&highlight=cowl+inlet+exit+ratio
Frank @ 1L8 & KSGU ...RV7A... Next flight will see the end of PHASE 1 Prison.
I am flying with Van's Cowl fitted with my mod for ram air induction. I have also fitted the engine with a plenum top made of metal instead of typical baffle seal to cowl top. Still @ nearly 40 hours the CHT's are right at 400 with #3 running hotter at 415, with a 12 GPH fuel flow. At the last oil change (30 hours) the plugs were also checked and the tops were clean (slight graying) and the bottoms were wet. The engine is burning about 1.5 quarts per 10 hours (TO MUCH) so the engine is either not broken in or...............
Bob Looper, who ran the engine in thinks that even though these nickle cylinder break in early mine might just be stubborn. He said that I should see the oil consumption decrease slowly between now and about 75 hours. I am also chasing down a very small leak of oil that I think is orginating from the right bottom are of the right mag.So now the big question. The inlet area is .41 and the exit area is .68. I have the Vettermin four exhaust pipe set up. I have read some threads on this issue but couldn't find a magic inlet to exit ratio for optimum cooling effect. Colling drag is an issue but too early in the planes life to worry about that.
Any Thoughts would be appreciated.
NEW INFO ......NO I JUST DID MY DUE DILGENCE LATE!!!!!!!! This thread give the me my answer or answers!!!!!!
http://www.vansairforce.com/community/showthread.php?t=20633&highlight=cowl+inlet+exit+ratio
Frank @ 1L8 & KSGU ...RV7A... Next flight will see the end of PHASE 1 Prison.
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