well yes I know I can run higher timming with 93 now, but the question is will it run better with 89 or 93 as the tune stands.

remember this is the same tune I ran the 12.51 with, nothing has changed except for the octane rating.

I'm running a 226 226 585 585 112 cam in the truck.

 

Apparently there is no gain from runing a higher octane from what you have said..... Given there are alot of variables....... If you want to run faster I would say bump up the timing a little bit and she what happens. I was just trying to apply what I learned in college, in theroy since your not experiencing any knock (I.E. at 89 then adding more timing @93 should yeild higher HP, given everything else is constant..... i

 

well damn, when i get back home i'll have to try some 89 and 87 and do some logs since i run 93 all the time with 28* i think i could get away with it.

 

There's another guy that I know of that has done the same thing. He has heads/cam on his 5.3 and actually ran his best time at the track on 89.

 

well not every truck will act the same. So be very carefull on the gas you run. Do plenty of logging to check everything, my checks have been from morning to late evening temps from 73 degrees to 93 degrees.

 

I agree. Outside temp will have a big affect on it. At 65 degrees, it could be fine, but at 90 degrees it could start knocking.

 

With the same exact tune I am going to go ahead and say that the 89 octane will perofrm better if the conditions are right. As bluecajun stated, more octane burns slower. If you are having to detonation or knock with the 89 you are having a cleaner and faster burn than the 93octane. These are just my thoughts on the subject, I could be completely off.

 

thanks 02, thats my thoughts, but time will tell. Damn rain wont stop down here in houston.

 

I have a fairly large cam in the ol 4.8L
224 on a 112..
cant run 89 with that cam

 

welp only could muster a 12.81@104.27 with the 89 octane gas. going back to 93 in the morning. Just to be safe with the tune.