AFR Range.

Q&A regarding engines, turbos, and intercoolers and power upgrades

AFR Range.

Postby MrMcQuacker » Sun Oct 20, 2013 6:47 am

Hello guys. I just wanted to ask you 3sgte gurus or what is considered a good zone for our cars. I was asking my brother and cousin and they said usually you don't want to go any higher than 12.5. Just wanted to know where I can be. If needed this is where I am at with motor wise. I have a st205 swapped into a st165. Full 3" exhaust, upgraded inter cooler core/pump and On its way are ARP head studs.Thank You.
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Re: AFR Range.

Postby warracer » Sun Oct 20, 2013 4:02 pm

12.5-13.5 for cold engine idle and load
14.5-15.5 for idle, which ever is smoother on your set up(and more rich is a waste of gas)
14.5-15.5 cruise, any leaner and your heating up the engine and will be lacking torque
>10.5 in boost, up to 11.5 - 12 max to be safe.
____________
ST185H A-Spec:
-IHI VF28 -BC Racing coilover
-Yonaka FMIC -Swift Spring
-ARP head stud -St205 rear end
-Cometic Metal HG -Supra TT Fuel Pump
-3'' SS straight pipe -Poly bushing
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Re: AFR Range.

Postby MrMcQuacker » Sun Oct 20, 2013 4:44 pm

With max boost 10.5 to 12 is safe? So if I hit 12.3 or 12.6 for a split sec or so and then It drops back to 11.9-12.2 ish is that ok? At WOT I'm around 11.9-12.5 is that ok?
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Re: AFR Range.

Postby klue » Sun Oct 20, 2013 6:31 pm

IMO, stock piston anything over 11s is to lean for me.

keep it cool, keep it fueled.
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Re: AFR Range.

Postby MrMcQuacker » Sun Oct 20, 2013 10:18 pm

I guess I'll leave it where it stands like I hear from a lot of people. St205 17psi is good and that's it. Of course with some supporting mods.
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Re: AFR Range.

Postby klue » Sun Oct 20, 2013 10:54 pm

MrMcQuacker wrote:I guess I'll leave it where it stands like I hear from a lot of people. St205 17psi is good and that's it. Of course with some supporting mods.



if you hear something rattling in your exhaust, and the turbo doesn't make pressure anymore; that's your turbine wheel :P
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Re: AFR Range.

Postby MrMcQuacker » Mon Oct 21, 2013 12:24 am

Good thing my turbo is upgraded with a steel wheel! Woot woot thx for the heads up! Also soon I'll have arp head studs. Once that done I guess I'll try and pump it up maybe 1-2 psi more :) as long as I don't pass 12.5 afr's right?
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Re: AFR Range.

Postby warracer » Mon Oct 21, 2013 1:32 am

your limitation are your pistons not your head stud, get forged internals if you want to go leaner :P
____________
ST185H A-Spec:
-IHI VF28 -BC Racing coilover
-Yonaka FMIC -Swift Spring
-ARP head stud -St205 rear end
-Cometic Metal HG -Supra TT Fuel Pump
-3'' SS straight pipe -Poly bushing
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Re: AFR Range.

Postby klue » Mon Oct 21, 2013 10:28 pm

MrMcQuacker wrote:Good thing my turbo is upgraded with a steel wheel! Woot woot thx for the heads up! Also soon I'll have arp head studs. Once that done I guess I'll try and pump it up maybe 1-2 psi more :) as long as I don't pass 12.5 afr's right?



Realistically, you'll blow a ring land, or melt a piston before the turbine lets go

keep it cool keep it fueled, stock pistons like 11s or less
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