| with stock size turbos and while it worked OK and was a major improvement over NA, detonation on 91 was a major issue. Like Harry pointed out it required a major decrease in timing at high load/rpm to prevent detonation. Richer fuel mixtures helped some but with the retarded timing I was worried about the heat from the fuel still burning as it left the cylinder. I did get to tune it on some 93 octane and that was a definite improvement but it's not available in my area so I was stuck with 91. This was all at a max of 10 psi of boost. A month ago I put stock TT pistons in my spare engine and dropped it in the Z. Wow what an improvement. I'm running a stock TT timing map and at 10 psi it's much faster than the high compression engine. No detonation on 91 and I can add more boost now if I feel the need. The reason I went HC in the first place was to retain throttle response but with the need to retard the timing the LC engine is just as responsive and has more peak power.
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