just a quick question for you engine guys, do you think a 383 with 11.25 comp could run on pump gas 93 oct? planning my new motor and this came up as a possibility

 

With aluminum heads and the right cam, yes it could.

 

there would be aluminum heads, the cam would be hydrolic roller with230/234 dur at .050 lift .528/.539 110 lobe seperation. so do you think it has a fighting chance?

 

Its a little high for a true pump gas motor.

If I was going to build that combo I'd build it with not more than 10.5:1. more like 10:1. A strip only car that runs for 12sec's at WOT at a time then cools down can/may get away with it but a street driven car has to operate under much less than optimum conditions. First thing to do is to measure and calculate the actual true compression ratio, then deside how best to adjust it. A motor that has say 10.3:1 compression that will run at optimim timing and AFR will make more power everyday than one that has toomuch compression requiring compromized tune (less timing, over rich AFR) to keep it from knocking @ WOT. At any rate you'd want to optimize the cylinder quench clearance.

Is this a motor that is already built or one that you're planning on building?

 

its in the planning stages

 

If its still in the planning stanges, then I'd suggest dropping it to around 10.5:1 as well. It will be much less of a PITA to get it to run properly and not ping with hot weather. I run 11:1 with iron heads, but it can be a pain getting it tuned so perfectly that it doesn't ping on 91 octane on a hot day. I'd have been better off to keep it around 10.5 or so.

 

I agree if you want to use that cam go with around 10-10.25 compression. If you are open to using a larger cam you could go with 11:1. I use 93 octane pump gas in my 11.1:1 383 but my cam has 256/260dur @ .05. I've never had any spark knock issues.