In general, you want to add boost over timing. An old rule of thumb is that two degrees of timing is worth one pound of boost, in terms of deto or KR. One pound of boost gives us roughly 7 to 8 whp, and two degrees of timing gives us about 5 to 6 whp. So boost wins over. Not only that, but we've found out that excessive timing will take out head gaskets much faster than excessive boost, within reasonable limits of course.
Ya, added PSI means you can add more fuel. HP comes with it. But on gen3 M90 most start to see KR around 10-11 PSI. (no IC,WI stuff like that) So I think thats were about were the trade off. So at the track with race gas, timming contraol, and a gen3 (even ported) I think should run X pulley for 11-13 PSI than add timming untill KR.
And on the street don't run alot of timming. If you get bad gas, or you IC pump dies and your running a 2.6 20*+......... thats how you chip stock pistons. they don't like KR with timing that hi. And I don't see a resone to drive around with lots of timming, (IC) people that can run 23+ on 93. Your cars fast as is. No hige ass dyno differnce runing a lower 17ish advace. Your just looking for troble w/ the lots of timing.
Raising the timing adds little room for error. The higher the timing is the less the motor is able to deal with knock amicably. knock on 22+ degrees of timing has the potential to give you a cast iron paper weight.
I agree fully and that is a big reason why I have not dropped down in pulley size on my car. My INTENSE PCM commands around 21 that I see as full timing, sometimes 22. I keep my boost at 9lbs with my 3.25 pulley and have yet to see a single degree of knock on this setup no matter what the weather is like. If I had as little as two degrees I would run a larger pulley. I do have the luxury of 94 octane out here too so that helps.
As far as which is better, I find it easier to obtain higher timing on less boost that more boost on less timing when battling KR.. but that's just my setup... others may vary.
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