Originally posted by OhSigmaChi:
Your engine is still probably having trouble breathing, I know you have the CTA, but it may not be enough for 11.5:1 (jeeeez 
that's high), you reallt need to open up youe exhaust and intake some more. How many miles are on the car?I don't know if it's as high as 11.5, it might only be 11.2 or so... but if you can sometimes run 89 octane with that 11.5 Z, maybe that's how high I am.
I don't know why you think it would have more trouble breathing with this compression than with normal compression. I wouldn't think these are related. It doesn't draw any more air than before. I don't think I can do much more with the intake than I am doing, except with a hypothetical new manifold. Exhaust will be dealt with at some point, I suppose, but I don't plan on doing anything drastic with it.
One question that occurs to me is whether high compression calls for any different spark timing. Would a chip's 91 octane tuning work better with this compression? Or would that just push its octane requirements up to 93?
It has around 57K, mostly not mine (it was once a fleet vehicle).
