Good Quench Article

That’s a pretty good article, but I skimmed through it real quick. I’ll sit down and read it all tonight.

One thing I didn’t see addressed in the article (could have missed it because I was doing my best Evelyn Wood speed) was how fuel affects quench. The burn rate of different fuels can change quench requirements.

Pump gas and/or high RPM race fuels have a much quicker burn rate than low RPM fuels.

Pump gas has a pretty quick burn rate because the RPM is usually low and you are trying to burn all the fuel you can, in the least amount.

High RPM fuels need a real quick burn rate (in most cases) because there is less time to burn the fuel, and if you use a “slow” fuel, you end up with a bunch of timing in it, which increases negative work, which kills power.

That’s why quench needs to be a thought out part of an engine build and not just get the piston as close to the head as possible. Just like raising the compression ratio, which increases the burn rate, quench does the same...so a relatively high CR on pump gas and right quench may require a reduction in timing so far that the EGT is through the roof.

It’s a balance and not a one size fits all detail.