quote Originally posted by gtoformula: There are multitude of threads regarding KR, but I haven't found one yet that indicates how much is acceptable. Assuming that zero is ideal, what is an acceptable range? 2, 3, 4 ...?

Ten different people will give you 10 different answers. IMO, more than a couple of degrees anywhere in the RPM range is cause for concern. The PCM will sense knock and cut the timing back and report the KR's but that's just a reaction to the problem. I prefer to tune or build to avoid the problem before it happens. I am running 11 psi of boost and no matter how we tuned some KR's were still there. After installing the intercooler my KR's are now zero. I advise all those that wish to run a 3.4" pulley on the series V superchargers that an IC is a must.
What does your setup look like?

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "