dumb question on max compression ratio

[Harpo]

Good evening Pelican

What is the highest CR on a single plug with pump gas?


Thank you


David

[chrismorse]

Fuel octane ratings vary. here in kalifoania, 92 is about it and that is with alcohol. We cannot buy "pure" gas unless we swear a blood oath, in writing, that such criminal fuel will NEVER be used on the highway.

did someone get bought off on that one???

To a lesser extent, it depends on the cam duration, overlap and the ability of the engine to go over 100% volumetric efficiency, (dynamic compression).

Still pissed off,
chris

[racing97]

10:1

[Schmierung]

10.5:1 with carbs and, most importantly, S + cams. The overlap reduces the dynamic compression. Single plug.
In MI, you may be able to get away with milder cams. My euro 3.0 has SC equivalent cams stock and 9.8:1 stock, pump gas, single plug.

[Harpo]

I'm still on the fence weather I want carbs or ITB. I have absolutely no idea about what Cams I want other than I have no intention on racing so nothing too aggressive.

Thanks

David

[safe]

Originally Posted by Harpo

I'm still on the fence weather I want carbs or ITB. I have absolutely no idea about what Cams I want other than I have no intention on racing so nothing too aggressive.

Thanks

David

Well tuned carbs vs well tuned ITB / EFI:

https://www.youtube.com/watch?v=aj-Z33MO2Gk

Quite interesting.