SAFC-2 tuning with stock fuel system:Pointless?

[Ski Bum]

Using a stock 1g GSX fuel system, is there any room for improvement using the SAFC-2 to tune the fuel trims? I realize most people use the SAFC when upgrading injectors, FP etc but would it do any good on the stock fuel system? Using a datalogger to monitor and the SAFC to tune, can you lean out the AFR enough to gain anything? If so is it worth it or just better to wait for larger injectors, etc?

 

[prplhz96]

Using a stock 1g GSX fuel system, is there any room for improvement using the SAFC-2 to tune the fuel trims? I realize most people use the SAFC when upgrading injectors, FP etc but would it do any good on the stock fuel system? Using a datalogger to monitor and the SAFC to tune, can you lean out the AFR enough to gain anything? If so is it worth it or just better to wait for larger injectors, etc?

If I were you, I would rather have the SAFC before I had injectors. I am assuming you are running factory boost(no fuel mods), so you wont have any real gains with tuning.

 

[droppinbottom]

I hooked my safc-II up before I got my injectors and made adjustments. There is room for improvement especially at wot. Normally the ecu will cause the car to run rich stock so that way there is a safety factor. If you have a logger right now how are the fuel trims? If they are not real close to 100% then that should answer your quetsion about being able to make improvements.

Hope that helps

 

[98evoIIIpwr]

I agree ^^^^ you can definetly lean it out a bit and make some extra power.

 

[Ski Bum]

My setup right now is basically whats in my profile. With the MBC, I have the boost dialed to 12psi and aside from phantom low rpm knock the logs are clean and safe. At WOT up to 7k rpms I rarely get 1 count of knock. The injector duty cycles however float around 94-98% and sometimes hit 100%. Also I'm at 130% at the low trim and 100% on both medium and hign trims, can that be right? I figure thats about the limit of my fuel setup.

I do have a set of FIC 650's that are waiting to go in after I get the SAFC. Would it make any sense to throw the 650's in with a SAFC using the stock fuel pump? Should that offer some more room for power? I was planning on gathering everything as I could afford it and install it all together but that bug that makes you want to squeeze out every ounce of power any way possible has a hold on me

BTW, I once came across and excell spreadsheet for tuning with a SAFC. You just plugged in your injector size, fuel pump and turbo and it gave you a rough basis for the SAFC settings. Anyone have a link to it?

 

[Quasimondo]

You're going to run into problems of going lean at the top end with those injectors and stock pump. While going with larger injectors will lower your duty cycle since they'll put more fuel into the combustion chamber, they'll also suck in more fuel than your fuel pump can send them which will lower your fuel pressure when you don't need it to be lowered. You can put the injectors and SAFC in, but don't go bananas until you get a fuel pump that can keep those injectors properly fed.

 

[Ski Bum]

You're going to run into problems of going lean at the top end with those injectors and stock pump. While going with larger injectors will lower your duty cycle since they'll put more fuel into the combustion chamber, they'll also suck in more fuel than your fuel pump can send them which will lower your fuel pressure when you don't need it to be lowered. You can put the injectors and SAFC in, but don't go bananas until you get a fuel pump that can keep those injectors properly fed.

I do plan on running a FP and FPR eventually. I figured I would put the injectors and SAFC in and play with the tune little by little.

Any idea on what a safe boost range would be with just the injectors and SAFC?

 

[droppinbottom]

Just my opinion but it is kind of pointless putting in those injectors when you dont have a pump installed that will supply the fuel to them. Seriously a 255 pump can be had brand new for right at $100 and is one of the most important things you can get.

Just by looking at your fuel trims you can see that you need to take some fuel out in the low trim. And if you are getting your stock injectors maxed out I would try to add some fuel up top.

 

[Ski Bum]

Just my opinion but it is kind of pointless putting in those injectors when you dont have a pump installed that will supply the fuel to them. Seriously a 255 pump can be had brand new for right at $100 and is one of the most important things you can get.

Just by looking at your fuel trims you can see that you need to take some fuel out in the low trim. And if you are getting your stock injectors maxed out I would try to add some fuel up top.

I do plan on getting a walbro 255 but not without a FPR.

Can you run that fuel pump setup without any sort of tuning? ie SAFC

 

[Quasimondo]

If you keep the stock injectors in and have the base pressure set to 37 psi, you should be okay.

 

[my98GST]

I thought the stock pressure was 43.5?

 

[Ski Bum]

I thought the stock pressure was 43.5?

I just read that post too and was researching the stock pressure becuase I thought the same thing. Isn't the stock fuel pump 100 liters per hour @ 43 psi @ 12V?

If that is true (from RRE) than couldnt the fuel pressure be set by a FPR when using, say a walbro 255 without any engine management or fuel controller?

I'm just trying to figure out whether I can run a 255 Fp and a FPR without any tuning.

 

[nightspeed87]

i have a 93 gst and its all stock besides 3in exhaust ran back no cat, and a knN filter, big performance spark plugwires and ngk colder plugs, and i have the non turbos fuel pressure regulator since it has more pressure than the stock turbo models , and iordered a 190 fuel pump to put in . everythin else is stock, i have a faze airfuel ratio gauge hookd up and i kno its not very accurate at all but since that all i got right now ive just been lookin at that, and it always shows im in the real rich zone. I soon hope 2 get a afc but for the mean time does anyone have any informations or opinions on my set up right now on gettin that 190 pump with stock boost? or any advice on my nxt move ( considering i already bought the 190 pump and just waiting on its arrival) would b appreciated