Quote:
Originally Posted by Paul Workman
Just a point of reference, AMSL for Chicago & most of the surrounding area is 600 feet - but the 93 octane is commonly available- even higher near the drag strip. So, if knock with 91 was present in your case, the altitude doesn't strike me as a contributor- might just be the octane?? (Cam timing comes to mind as well...)
No point, just musing out loud!  |
I know what you are saying, but it is very expensive and inconvenient to change the octane ($8 100oct unleaded is available in the Rancho Santa Fe gas station to service the big money toys out there), but it was easier to just drop a degree or two of timing in certain load cells.
I had already seen a wideband at wot and have new Lucas injectors, so I didn't suspect mechanical issues, just simply octane/engine load mismatch.
I could try to go richer, but I feel like that is a brute force tune (although I'd like to try it if I ever get a good deal on some dyno time- but I'll probably hold off for the day I get headers or something). I'm trying to make the engine and catalysts last and we might only be talking a couple of hp under the curve here and there. It still feels fast and might even be quicker with no knock retard coming in (not to mention the smaller exhaust diameter might have picked up a little mid range tq).
Either way, the peak hp is about the same with two different chips I ran.