im about to have some heads machined and need to figure out how much to mill off the heads. i have a set of cometic gaskets that are 40 thousandths.i spray up to 150 shot of nitrous and drive my car everyday. how much compression can i safely run. thanks guys

 

Total timing advance is going to be more critical than compression ratio here. I ran 11.2:1 CR ratio with a wet 150 shot but I had the timing backed down to 27 degrees. I also kept the octane up around 100 when on the spray. The 0.040" gasket thickness alone would bring you to around 10.4-10.5 with stock heads. If you mill around 0.030" and use those gaskets you will be around 11.2:1 static CR. If you can't run race gas everytime you run the 150 shot I'd back off on the CR ratio or make sure your timing advance is under control.

What I would do... don't mill the heads and keep the timing around 26-27 degrees if you can't run higher octane than 93/94. Detonation is going to be your biggest enemy and should be your primary concern. If you don't detonate the engine will do fine (well as fine as the stock rings can be over time with juice).
Tim

<small>[ November 07, 2002, 06:24 PM: Message edited by: TimZ28 ]</small>