Originally Posted by Chiburbian (Post 1161995)

darn it. :)

BTW- my assumption is a tank or two every year. The trip I have in mind is from Chicago to Colorado. In Illinois, Iowa, and Nebraska I have found either 93 octane or e85 everywhere. Colorado has a max of 91 octane with occasional e85. I am just worried what would happen if I was running say, 11:1 and had no choice but to put a partial or full tank of 91 in.

I am half willing to risk it because I am sure I will get good at finding e85 stations around my local area before I go on a trip and have to worry about learning that habit.

Originally Posted by sixshooter (Post 1162115)

To put it in perspective, the difference on a dyno on a 7.6 liter gasoline v8 between 8.5 and 9.5 compression is about 20ft lbs of torque on a ~500ft lbs engine. If you rationalize that down using napkinscratch guestimating it won't be but about 4.75 ft lbs on a 1.8 liter. But the extra couple of lbs of boost you could run without detonation will be worth far more power than that. YMMV.

Originally Posted by sixshooter (Post 1162115)

To put it in perspective, the difference on a dyno on a 7.6 liter gasoline v8 between 8.5 and 9.5 compression is about 20ft lbs of torque on a ~500ft lbs engine. If you rationalize that down using napkinscratch guestimating it won't be but about 4.75 ft lbs on a 1.8 liter. But the extra couple of lbs of boost you could run without detonation will be worth far more power than that. YMMV.