Quote:
Originally Posted by Vettezuki
So, if they make E85 more readily available in CA, I'm tempted to make my lil' ole 346 a forged 383, bump the cam one size up and crank up the CR as far as I dare.
E85 seems to vary in Octane rating between 100-105. It also has wonderful cooling effects being 85% alcohol and all.
So, who can calculate a highest safe potential CR. I was thinking at least 13:1, but maybe 14:1.  |
You won't be able to predict the exact compression ratio that you can use. There are a lot of other things to consider such as cam specs, combustion chamber design, timing, etc. I can tell you that with 100 octane race fuel I’m able to run 12.25:1 compression on the Chevelle with 40° total timing with a cam that has a .623 lift, 242° @ .050 on a 110° lobe separation with an aluminum head without detonation. I also know that I’m right at the edge from detonating because I’ve tried mixing pump gas and race fuel for less octane and the car detonated. If I were to run E85 I think I could get away with a little more compression (12.5:1 or so) with a 112 lobe separation and still not detonate. However, I do think I would be right at the edge but that’s just my opinion I do not know for sure.
I'm not sure what design the heads you have are but I've heard that the LS6 combustion chamber design is great so you might be able to get away with 13:1 if your heads have the same design.