Thread: GTP AFR Range?

Hey guys. According to my AEM WB I am running 10.4-10.9 AFR at WOT. Ive had trouble finding a GTP AFR range so im asking you guys if this seems normal?

Mods are: 3.5 MPS, SD Headers, Shift Kit, Intake. Meth but its OFF currently.

Last I checked IIRC guys like to keep it at the 11.5 range but I'm sure others will chime in

11.4ish is "ideal" for a safe setup. more lean means it'll probably make more power, but be more apt to detonate. more rich and it'll be safer, but you'll lose power.

Correct for boost most target 11.5. But 11-12 is ok and for NA 11.5-12.5

Originally Posted by fri3dchick3n

Hey guys. According to my AEM WB I am running 10.4-10.9 AFR at WOT. Ive had trouble finding a GTP AFR range so im asking you guys if this seems normal?

Mods are: 3.5 MPS, SD Headers, Shift Kit, Intake. Meth but its OFF currently.

10.4 is very rich. 10.9 is rich, but not that far off. I like low 11s AFR for a non-charge cooled roots blower car like yours. With an intercooler, mid-high 11s are OK.

Also note that you are going to be richer still (generally by .5 AFR, but it depends on nozzle size and water/meth ratio) when the meth is flowing.

I'd take a good look at your fueling and make some changes. I don't like that your AFR fluctuates by .5 at WOT (that's way too much) and wonder if you have a mechanical fuel delivery issue (dirty filter, weak pump) or a tune issue (MAF not dialed in). Is it getting richer or leaner during a pull? Once you get AFR to not fluctuate so much I'd lean it out to the low 11 range.

At WOT it slowly works it way up to the lean side. I believe I might have a small exhaust leak at my Flex Pipe area.
Going to clean up coils and replace plugs here in a little bit.

Going to do some logs with a local friend who has HPTuner and send them towards DynoBrian at Mobiledyno.
Nobody localy knows how to tune a GTP with meth -.-

sounds like a fueling problem in the tune, like the power enrichment isn't setup properly.

and realistically. tune without the meth first, then turn it on and see where you can add timing and boost. i'd personally leave the timing alone and run more boost.

Originally Posted by Bio248

sounds like a fueling problem in the tune, like the power enrichment isn't setup properly.

and realistically. tune without the meth first, then turn it on and see where you can add timing and boost. i'd personally leave the timing alone and run more boost.

Damn, I was planning on running a 3.5 and whatever timing I can get. I do have a 3.4 in garage though, That is the only way to change our boost is to swap pulleys right?

My car ran great, decided to get meth, Got a local retune, Was complete garbage, had him return back to the tune I had before, and now its running like this.
Had the local tuner send the file to Brian at Mobiledyno and he compared them and they are the same. So Im in a pickle.

yeah, pulley swap for more of less boost.

you can do whatever you'd like with your car, but i prefer the more boost method to more timing method on my cars. if you want timing then go for it.

Originally Posted by Bio248

yeah, pulley swap for more of less boost.

you can do whatever you'd like with your car, but i prefer the more boost method to more timing method on my cars. if you want timing then go for it.

Ive just understood that you will benefit off more timing than boost for us. But I think I heard its more stress on the engine itself, is that true?

a lot of timing and you'll blow the head gaskets, but it's pretty uncommon. more timing just leaves you more prone to detonation when under heavy load.

Originally Posted by Bio248

a lot of timing and you'll blow the head gaskets, but it's pretty uncommon. more timing just leaves you more prone to detonation when under heavy load.

I see, I'll just stick with the 3.5, my car seems to like it better I guess. Thanks for you input.

Originally Posted by Bio248

a lot of timing and you'll blow the head gaskets, but it's pretty uncommon. more timing just leaves you more prone to detonation when under heavy load.

Exactly how much timing is A LOT? I have heard of guys running 28* long term...

Originally Posted by Iceman6669

Exactly how much timing is A LOT? I have heard of guys running 28* long term...

most likely not an issue with him because i bet he runs MLS gaskets, right?

if you blow a metal gasket then something went wrong.

Originally Posted by Bio248

most likely not an issue with him because i bet he runs MLS gaskets, right?

if you blow a metal gasket then something went wrong.

No actually he was running FelPros... He said that way the head gaskets would go before the motor got hurt..

I run 10.8 to 11, I like moar fuel.


Stock PE is near 11 anyway, on a wideband.