Boost and Fuel Correction Question.

[Suicide.Veteran]

I've searched and I can't find the answer, but if you raise the boost with an MBC, do you have to retune the Afr's?

[Florida240sx]

Yes. Everything will change. Car will be driveable but power will be gained from re-tune. If it's just a coupel psi no big deal, so how much are you increasing??

[Suicide.Veteran]

just from 6.5 to 10 psi, but it runs a little richer than optimum right now.

What if I change turbos to one that spools later, like starting at 3,000 instead of 2500 but doesnt run out of breath as much at top end? Sorry for all the questions.

[Florida240sx]

What you got for tuning? Whenever one part of the system changes, Turbo, mani, exhaust, FMIC, ignition. You need a re-tune. Your driveable but not to full potential. Go run at the track and then get tuned and see what you improve But would be best to tune first in case your car gets lean in the top end, don't want to pop the motor

[Suicide.Veteran]

Safc 2 and an LC-1 that finally works (i beleve cuz of your input lol). as for ignition, stock ignition can handle 10psi on 93 octane, but i got an msd unit on the way.

thx a bunch!

[Edub1]

No, once you have your A/F ratio right the ECU will read from the MAF and do what needs to be done. I have went from 5lbs to 17lbs on the same tune with no change in A/F ratio.

[Florida240sx]

Everyone's set-up is different. I go from 10psi to 17psi and my a/f is different. Your lucky.

[WDRacing]

Everyone needs to step away from the crack rock...if you increase the boost anymore then 2-3 psi on any set of injectors, unless you were ugly rich before...you'll start popping pistons. Retune is ALWAYS better. Anyone who says different will simply lose to me on any argument, because I'm the MAN.

Been there done that.

You have a wideband so you can answer your own questions. Keep your AFR's below 12.5 and the timing retarded above 8 psi by 1 degree per psi over 8.

Thats WD's combo for success baby. I ran that all the way to 20 psi till I tossed a rod. Nothing to do with mixture.

WD

[KATwo40]

^^^ Agreed.

[S13FX]

Yes especially with something like the SAFC if you raise the boost you have to re tune, you also have to realize you have to do something for timing which is very important too especially when raising boost level.
Modified by S13FX at 7:41 AM 1/12/2007

[Edub1]

That might be true with the SAFCII. That is why you tune your ECU. Once fueling is corrected in the ECU it will hold that A/F ratio regardless of boost. At least mine does.