alittle new to all this FI stuff. i wanted to ask you guys your opinion. i was wondering what would result in more power. more boost and less timing. or more timing and less boost. alittle info on my car might help so here it is.
2000 ss 383 forged 8.5 comp. afr stage 2 heads. 03 z06 cam and intake. custom headers to the turbo. right now i am running 12#'s boost and 14* of timing. no numbers on this setup yet. when it was s/c'ed i had 8* timing and 17#'s all on 93 oct pump gas and made 684rwhp. the car is wanting to detonate alittle and pulled some timing at 14#'s and 16* of timing. i was thinking of dropping the timing back to 8* and add some boost. what do you guys think. thanks!

randy

 

More boost.

Rich

 

all i needed to know....thank you

 

we are putting a meth kit in a week or two. i was just unsure what was best with timing and boost. my old tuner speedinc had 8*timing and ran the boost up to 17# and it pulled hard. 684/649. my new tuner for the turbo wants to do low boost 12-14# and more timing like 14+. this is all with pump gas though 93 max. so i was just lost with two pro's on completely different sides of the tune. even with the meth he wants to run 14#'s boost and around 20* of timing.

randy

 

Just out of curiousity, what gap are you running on your plugs?

 

i would have to look to be positive but i believe .46

 

If you take a look at Turbobuick.com and do a search on this same subject you will see the more boost and less timing or less boost and more timing question has been talked about many times. My opinion with a good tuner both ways can end up with the same result (more than one way to skin a cat....no offence meant to the P.E.T.A group).

I personally went with the more timing and less boost. Boosting up the air makes more heat for the I/C to take care of.

As for plug gap you will find with higher boost levels the gap of the plug usually has to be tightened up. The boost will blow the spark out. I would run the NGK 4554 plugs gapped at .035 running 25# of boost.

At this time the motor builder for the z28's motor told me .035 was best. It's a N/A motor at this time. The plan is to stick a 8-71 on it some time this summer. I know a turbo will make more power but I do like the looks of a fuel injected 8-71 sticking out of the hood

Good Luck

 

This shouldn't even be a debate among people who actually use a dyno and experiement with this stuff. It's really not either/or. There are too many variables for experssing it that way. But if you have to answer one way or another, pick boost. Excessively retarded timing and excessivelty rich fuel mixtures are both "bandaids" for fuel that is of too low an actane for the application. The right answer is "more octane", but that's not haw the question was phrased. I could write an essay, but I am not in the mood. The most practical answer is get the car or engine on a dyno and find out what works best.

Rich

 

Depending on what fuel you are going to use and the intent for the car here is a link to show you a chart. This chart shows or compairs boost VS compression.

http://www.blowerdriveservice.com/techcharts.php

This does not only apply to blowers but turbo chargers I found with race gas (118 octane) 9:1 was about the best for me. I did try 10:1 on one motor but kept the max boost under 25# If you go lower compression ratio you can go higher boost. I am only talking about race gas. If you change fuels and go with something like alkey you can start with 14:1 compression ratio. I have not ever tried a fuel like nitro.

To get the max performance out of a forced induction motor over a N/A motor the cam also should be changed. Forced induction cam like lift but not duration with lobe seperations of 110 to 112 deg. Yes other combinations will work.

This is just some highlights to point out. I hope that helps some.