supercharging · FF-0388

What compression ratio did Steve's ARDUN engine end up with, and why does it matter for the blower?

Steve had the heads flow tested and measured the chamber volume. Compression came out at 9.9 to 1, higher than the roughly 9 to 1 he had expected. That is fine naturally aspirated, but it limits how much boost the supercharger can add, because cylinder pressure is already high before the blower packs in more air and fuel.

Expert

Steve Coppock

Evidence

expert attributed

Component

compression ratio and boost

Applicable scope

Steve Coppock's supercharged ARDUN overhead valve Flathead, mocked up before its dyno test