10:1 Compression ? Detonation ?

Anyone having any problems running this CR on an L98?

Its fine if you have aluminum heads, and not recommended with iron heads.

I have it with 461 iron heads, which don't exactly have the most modern combustion chambers. Even with an agressive PROM code I get very few knock counts, and I know precisely where they are coming from. Once I trim back that section of code, I expect that I may be able to advance my timing another 2* without excessive knock counts.

This question is meaningless as writen. You can run very high ratios without detonation or have it in a low compression engine.
But I think we all know what your getting at.
And you sould not have a problem.

Kevin91Z, Please inlighten me; not recommended with iron heads. Not recommended by whom???

Jim85IROC, Like your car.

Im running 10.6:1 with an ARAP spark table with aluminum heads and it has not knocked once. Remember, your cam has something to do with it also.

Originally posted by Z28SORR

Jim85IROC, Like your car. Thanks. :)

Not recommended by common knowledge. Or so I thought...

Kevin91Z,

Not trying to be a smartass here, just see a lot of stuff that doesn't always make sense to me.

Been around Hot Rods and racing since before I could drive, legally, and that was 1963. Back then there weren't to many people that could afford aluminum heads and many of those cars had 11, 12 and even 13:1 compression ratio's.

Anyway, it's all in the search for knowledge.

I am running 10.8 with AFR 190cc heads and 93 octane with a modified ERPOM

40 years ago you had leaded gas and higher octane, so compression ratios that high were easy to support. Nowadays you're lucky to get anything above 91 octane. Those of you with 93 octane are special. My car pings at WOT using 91 octane with 10.3:1 compression on Corvette heads, and only 30 degrees timing. I have to use 100 octane unleaded at the track.

Timing, cam, shape of parts in you combustion chamber, EVERything has to do with it.

I konw a guy who runs 12:1 on his old boss 302 (true boss) and he can run it on regular without any sign of detonation. He also turned back his timing a bit

You have to watch what cam is used. I had a 214/465 with no knock. I went to a 219/525 and got some knock at WOT. I had to burn another chip and adjust the timing.
The old engines had leaded gas with the high compression to help with spark knock. I have had at least 20 muscle cars from back then and I tried unleaded reg one time when it first came out. The engine knocked so bad I though it would blow up. When you turned the engine off it ran on for 15 to 20 seconds. I have never tried it again and that has been since 1972.