newbie..have a question.

Reply Subscribe

Thread Tools

Search this Thread

Sep 17, 2003 | 06:50 AM

02superscooby

Guest

Posts: n/a

newbie..have a question.

Hey everybody I'm new to the forum and I have a question. I've done some research on the topic but can't seem to get it exactly right. What I have is an IHI VF32, STi pink injectors, factory downpipe, aftermarket exhaust manifold & up-pipe, a 3" mandrel bent catback, and Injen cold air intake with the stock intercooler. I was just wondering how many psi to stop at without the larger downpipe and intercooler. Any help is greatly appreciated.

Sep 17, 2003 | 02:26 PM

Kevin M

Registered User

iTrader: (12)

Joined: Nov 2002

Posts: 18,369

From: Reno, NV

Car Info: 1993/2000/2001 GF4 mostly red

What engine management do you have?

Sep 17, 2003 | 02:42 PM

02superscooby

Guest

Posts: n/a

s-afc 2. i have a wide band hooked up in it right now for some tuning but i ran into the problem of it spiking @ 20psi and fluxuating between 15-20 psi while it's in boost.

Sep 18, 2003 | 08:07 PM

Kevin M

Registered User

iTrader: (12)

Joined: Nov 2002

Posts: 18,369

From: Reno, NV

Car Info: 1993/2000/2001 GF4 mostly red

With that much in mods, you really need to get better engine management to control your boost and ignition timing. The car will run much better and be noticeably faster. As it sits, I would not allow it to be leaner than 12 to 1 under boost, less if you can.

Sep 19, 2003 | 08:37 AM

impreza7

Guest

Posts: n/a

12:1?

Well, that's so rich that you'll almost be blowing out the spark on your stock spark system. Watch that S-AFC, the Sub. computer starts to slowly recalibrate itself until the S-AFC does absolutely nothing positive. If you see your A:F gauge consistently at about 14.1:1, then you know the computer took over. It took about 3 weeks until mine ignored me. I'm ditching it in favor of a RRFPR until I can afford real engine management.

7

Sep 19, 2003 | 09:10 AM

02superscooby

Guest

Posts: n/a

well, i think next im going to get a front mount intercooler and a downpipe. what engine management has everyone had luck with? i know that the aem is hard to tune and i haven't really heard anything about the greddy e-manage. thanks alot for all your help.

Sep 19, 2003 | 09:14 AM

02superscooby

Guest

Posts: n/a

i guess i'm pretty confident with the s-afc 2 i was just unsure how much boost i could run before detonation on that turbo and the factory intercooler.

Sep 19, 2003 | 01:49 PM

Kevin M

Registered User

iTrader: (12)

Joined: Nov 2002

Posts: 18,369

From: Reno, NV

Car Info: 1993/2000/2001 GF4 mostly red

Quote:

Originally posted by impreza7
12:1?

Well, that's so rich that you'll almost be blowing out the spark on your stock spark system. Watch that S-AFC, the Sub. computer starts to slowly recalibrate itself until the S-AFC does absolutely nothing positive. If you see your A:F gauge consistently at about 14.1:1, then you know the computer took over. It took about 3 weeks until mine ignored me. I'm ditching it in favor of a RRFPR until I can afford real engine management.

7

You show me a modded WRX making good power, and I'll show you 11.5:1 AFR- max. You cannot, repeat NOT, run stoich on a turbocharged small engine.

Sep 19, 2003 | 03:34 PM

EvoHunter

Guest

Posts: n/a

Quote:

Originally posted by BAN SUVS
You show me a modded WRX making good power, and I'll show you 11.5:1 AFR- max. You cannot, repeat NOT, run stoich on a turbocharged small engine.

why not ?

Sep 19, 2003 | 03:53 PM

#10

Kevin M

Registered User

iTrader: (12)

Joined: Nov 2002

Posts: 18,369

From: Reno, NV

Car Info: 1993/2000/2001 GF4 mostly red

Quote:

Originally posted by EvoHunter
why not ?

When you run lean, you have to retard timing to prevent detonation. When you retard timing, you lose power. If you don't retard timing, you're going to hole a piston or bust a ring land. tuning is a matter of balancing how much power you make with how much risk you take of breaking something. Running richer enables you to maximize both, up to a point. For reference, a rotary engine making big power can run as rich as 9:1. Hondas on Vtec are around 13.5:1, normally aspirated.

Sep 22, 2003 | 01:42 PM

#11

impreza7

Guest

Posts: n/a

So how does a RRFPR help to combat this problem. Doesn't the ECU overrule it and send the same amount of fuel anyway?

Sep 24, 2003 | 08:14 AM

#12

jid2

Guest

Posts: n/a

A RRFPR mechanically raises the pressure of the fuel in your system by physically blocking the fuel return line. This blockage is caused by a diapgragm that uses boost pressure to deflect and "block" the return line. Fuel pressure on a subby is all mechanical, your ECU doesn't controll any of it.

Sep 24, 2003 | 05:43 PM

#13

Jgrahn555

Sarcastic Jackass

Joined: Dec 2002

Posts: 622

From: Western Washington

Car Info: i drive a beater

Quote:

Originally posted by BAN SUVS
You cannot, repeat NOT, run stoich on a turbocharged small engine.

Yes you can. Here's one: http://turbocelica.com/Autos/WhiteAl...eb/default.htm; DSMs have been doing it for quite a while as well.

It's really easy at cruise and at idle if you know what you're doing (by the way a RRFPR is not included in the "know what you're doing" statement)