Other engine has went to s**t with parts costs so I am having to hold off till next winter but I won't be left out of play next summer so time to build back up 406. I am using stock rods, had them ground smooth, shot peened, and maged and new bolts, Had Stock Crank reground, chamferred, and micropolished, using stock 400 rods and Stock Crank, With aluminum 72cc heads.. Need Forged Pistons for stock rods, stock crank.. I need to know What is the highest compression I can run with 93 octane gas??? This is still a EFI vehicle, although it's a totally different intake setup. Some one help me... I thought I seen a chart somewhere, but I'm not sure.. Also this engine will be flogged with NOS every now and then.. What's the best Compression ratio without detontation?????

 

I heard that 10.5:1 Is about the highest I can do with aluminum Heads, Does this sound right to anyone else..

Please someone confirm this..

Thanks
Kevin

 

i have a frind in IL that runs at least 14 - 1 with aluminum heads. as far as i know, he doesn't do anything special to seal them, it is a drag car though

bamaz28

 

i ran 10.5 in mine w/the old iron heads. i had to sw. head gaskets when i went to alum. heads so comp. lowered to 10.3. Ive always run 93 prem. w/no knock. and I have carbed eng. so you can def. do it w/FI. I read in a mag. once that you can go to 11:1 if you have fastburn style comb. chambers. (dont know what kind your heads have) but Id be careful w/N20. I think Id stay around 10.5:1 if I were yuu. and still add a fuel additive when planning on running the juice.
chris

 

93 octane is good up to 11.5, but not over, then you have to go with a higher octane... Alum heads are better for higher comp because of heat dissipation..Also if you go that high make sure your computer is programed correctly..

93Z Will

 

there is no hard fast rule of thumb. I won't even talk about gearing, weight or chamber design and quench.