Engine compression #'s


Some years ago I did compression tests on a bunch of SE engines. We also dynoed almost all of these cars. The purpose of this wasn’t to play “gotcha,” we’re SE, that’s not our culture. The purpose was to help the community store of knowledge.

Some of the interesting lessons learned:
-The relationship between compression and hp is weak. There was no clear trend that higher compression engines had higher hp, or lower compression=lower hp. Certainly if you went to an extreme, you’d find that because the engine would be unhealthy. But for healthy engines, high compression did not necessarily = high hp.
-The relationship between overbore and anything was weak. The overbore engines did not have obviously higher compression nor obviously higher hp.
-The high hp engine in the test below was Chuck Taylor. We taped his airbox to bring his hp below the standard. Note that several engine had higher compression than his, and that his was not .020 overbore.

The compression #'s listed are the average across the 6 cylinders. Everyone’s #'s were pretty tight between cylinders. I tested cylinders 1-6, than 6-1. If the #'s for a cylinder weren’t very close, between past 1 and pass 2, I did that cylinder again a time or two until I had #'s in agreement.

Ryan Whitinger 164 020. 4 events on engine.
Aaron Whitinger 170 1 event top, 4 events bottom.
Bob Rutzky 160 1yr on engine
Chuck Taylor 176 ~15 events
Sandro Espinosa 188 020. ~10 events on enging
Walter Araya 152 New head. 180k bottom.
Chris Harkins 183 150k + 4yrs racing
Rob Eskew 180 New engine
Olivier Bellanger 191 1 event
Carlos Mendez 164 Old bottom, 2yr top,.
Christian Malone 185 2yrs
Bill Zawrotny 179
Alex Barroso 177
Laura Parkhurst 170 4yrs
Brian Edmonds 188 020. 2yrs
David Hickey 170
Davis Aikens 170
Ty Young 176 020. 2yrs.
Michael Young 165 020. 2yrs.
Joey Townsand 167
Steve Rowlands 150