13sectransam

I have a few questions, not really Fbody specific. I'm looking for some sort of custom tuning for my 99 Jeep Grand Cherokee. I can't find any nitrous info on any Jeep forums for the 4.7 motor so I'm trying to get general info here, I always had good info for my LT1 on spray here.

Anyway, here goes. I'm running a 100 shot of nitrous on the stock tune right now with 1 range colder plugs and its awesome, but I'm ready to step up to a 150. I just ordered the jets for it tonight and a FPSS. Like I said before, I can't find anyone that does custom tuning so I could pull a few degrees of timing. Should I hold off for the timing retard? Or would I be ok just running a bigger fuel jet to richen the mixture and running 93 octane and maybe another step colder plugs. (Stock tune calls for 87 octane). Thanks guys.

Joe B

At that HP level I would run a MSD or a mallory ignition box with an adjustable retard, or at the very least, a plain MSD retard box "if" it can be integrated into your stock ignition......To be safe you will want to pull about 6-7 degree's with the 150 shot......And (like you mentioned) I would also go down one more step on the plugs from where you are now(two steps colder)......Making the fuel jetting overly rich is addressing the problem in the wrong way.....It can help reduce the chance of detonation (to a point) but pulling timing is the right way to do it....I would also "always" run the 93 octane while spraying, there's really no reason not to, ya know.........good luck with it...........Joe