Sr20 air/fuel and boost

[cpl dozier]

Good afternoon everybody. I am making this posting because I am curious about my air fuel ratios. My car is currently a stock sr20det in an s13 hatch. I have a Walbro 255 fuel pump and a boost controller. I also have a blow off valve, a front mount intercooler, full exhaust. I just installed my AEM wideband and I am curious of my air fuel ratios. I set the car on 10 PSI and I am reading full rich sometimes 10.5 on the air fuel meter at WOT. Would it be safe for me to bump the boost without any tune to maybe 11 or 12 PSI as long as my air fuel ratio does not go any leaner than 11.9?

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[cpl dozier]

Ok...here is where I'm at. Keep turning up boost to no more than 14 psi max. And that is only if my a/f ratio stays lower than 12. Is that about right????

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[Kingtal0n]

The issue I am having with this is that you are probably running a T-25 on a redtop, yes?

If so you should stop at 10psi to conserve the life of the turbo.

if this is a T-28 turbo then 12psi or even 14psi is ok, just watch the air fuels of course, you are on the right track- around 12:1 or less is ideal for a stock S14 T-28 engine at 14psi on 93 octane.

[cpl dozier]

S13 w/t25

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[Croustibat]

Ok...here is where I'm at. Keep turning up boost to no more than 14 psi max. And that is only if my a/f ratio stays lower than 12. Is that about right????

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You are doing it wrong, because you dont understand how an engine work.

My suggestion is this:
learn how it works before blowing something. Lean AFR means overheat, det and death of engines, but it does not mean going rich prevents these from happening. Have you heard about ignition timing ?

T25s can barely make 15psi on a ca18 (and then they die pretty quick), going 14psi on a bigger engine ... that just is nonsense. Get your turbo flowmap and see for yourself what you are asking it for. 15psi on a T25, with an SR20 ... the turbo is just heating air, not really compressing it.

If you want power and reliability, you need a tune. dont go over 10psi on that turbo anyway, if you want more, get a bigger one, bigger injectors, and a bigger maf. and always, a tune.

Do you just want to see 14psi on your boost gauge ? Or do you want power ? I can guarantee you a tune at 10psi setting will net you more power than just turning the boost up to 14psi without one.

[cpl dozier]

I understand this. I was posting from my phone. I didn't want to make a huge thread on bs. I have a 2871r, nismo 740's, z32 maf. I was going to buy power fc, and install everything. I did tons of research and EVERYONE says t25's lose efficiency past 14psi. So no I don't want to see it on my gauge. I simply want the most from my setup without all the unnecessary costs. I was under the impression I could run stock injectors and a walbro also. Was told as long as I don't lean out it is safe to run 14psi on stock. My wideband stayed at 11.0 at WOT this morning on a few test pulls at 14psi. Anyone else have an opinion??? There apparently is bad information on ALL the sites.

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[Croustibat]

ok boy, business 101 : you wont find the info you are looking for, because it has value. So it wont be free.

Now you can either get some books and learn how an engine works, because clearly you dont know about ignition, nor mixture, or you can pay a tuner to tune your car. These are your only valid choice.

The third one is listening to random people you dont know on the internet and praying they know what they are talking about.

Want power ? It cost money. You need to accept that. Free power does not exist.

Now dont buy a PFC, because you still dont know how to use it. Get your car to a tuner, he should be able to burn the maps he makes on a couple of chips and install them in your ECU. Its simpler, cheaper, and it works.

[cpl dozier]

Turning boost back down to 10psi. Buying enthalpy ecu and installing bigger turbo, injectors, and maf.

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[zombiewolf513]

I simply want the most from my setup without all the unnecessary costs. I was under the impression I could run stock injectors and a walbro also. Was told as long as I don't lean out it is safe to run 14psi on stock.


I +1 with Croustibat


There is no "simply" in this; you need to talk to a professional tuner and have a shit load of deployment money under your ass, or "read a whole lot" and risk destroying your engine. "Leaning out" is a matter of opinion when it comes to tuning and should be stated as an amount of risk you're willing to take with your engine and turbo.

Read dude. Efficiency, power, ultimate setup/ whatever the fuck you want to call it; is goin to take one of two things: money or experience.

You should get cams for that turbo.

[quickdiversion]

Yes it will be perfectly fine. 10 is way to rich at that pressure. I would aim for 11.2 or 11.5 at 10 psi. I hit 18psi at over 40 lbs a minute. I run about 12.5 to 12.8 depending on what gear I am in at WOT.

[OrangeVirus1]

This same thing has been talked about like 5 times just this week

Yes it will be perfectly fine. 10 is way to rich at that pressure. I would aim for 11.2 or 11.5 at 10 psi. I hit 18psi at over 40 lbs a minute. I run about 12.5 to 12.8 depending on what gear I am in at WOT.



dude 11.2 for 10psi is retard rich.

OP shoot for 12.0-12.2

[cpl dozier]

Not worried any more. ordered an enthalpy ecu. Rocker arm stoppers and other supporting accessories. Might pick up an safc also. Thanks to the ones who didn't flame me. I get tired of seeing responses from people saying search when someone has searched. it's why some people end up blowing motors because they would rather not get flammed for asking a question even though they have searched.

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[jr_ss]

If you aren't familiar with tuning, you should be looking into a tuner as an option period. If you don't know what you are doing or the effects they have or will cause you shouldn't be fucking with it.

With that said, you did the right thing. Martin is a very good Rom tuner.