I've probably done hours of research just on fuel management choices for my 420a turbo setup...I've put off starting a thread somewhere just because I know there's so many out there already! But I am now at a loss and need some specific help :(

So here's what I'll be running- rebuilt 14b turbo, walbro 255lph fuel pump, 1g bov, 1g side mount IC, and probably some upgraded injectors when I get to that point. Will likely be running 8psi.

I was originally planning on running just a plain old 12:1 Vortech FMU with the Walbro. Initially I was under the impression this would be enough. Now I have been told differently. Next I was told the FMU paired with a SAFC II...I came across an SAFC II for only $90 that I'm contemplating picking up. However, I've been reading how SAFC II's are a pain or not required for a 420a turbo build.

Can someone please point me in the right direction? I am trying to keep the budget down as much as possible, but if I need to spend more to do it right then I will do that. What is the most logical option(s) for me? Thanks for any replies!

if you wanna keep costs down, just get a 12:1 fmu. You don't need an AFC, but if you wanna run higher than 6psi, i'd recommend it. Its just for tuning your setup.

Awesome, thanks for the reply. I think I'll pick up the safc just because it's such a good deal...but not sure I'll use it yet :)

Originally posted by tec_41
I've probably done hours of research just on fuel management choices for my 420a turbo setup...I've put off starting a thread somewhere just because I know there's so many out there already! But I am now at a loss and need some specific help

+1 for the work. That's exactly the way this should be done. Research, get information, process and then generate specific questions.

:thumbsup

Thumbs down on tuning fuel with the SAFC. Take the money and invest in MSnS. It is WAY better. You really get almost no real tuning ability with the SAFC. Take it from me, I have one. I hate it. Get MSnS, I wish I did already...

Originally posted by bzoss
Thumbs down on tuning fuel with the SAFC. Take the money and invest in MSnS. It is WAY better. You really get almost no real tuning ability with the SAFC. Take it from me, I have one. I hate it. Get MSnS, I wish I did already...

i'm sorry, whereever you're getting your $90 MSnS, please, share with everyone. he stated cost was an issue. The safc will do fine for him as he, if he wants to, will be able to lean out the fuel w/ it. You obviously hate it because you don't know WTF you're doing. If you have the extra $300+ he'll need to get MSnS, paypal it to him.

http://www.2gnt.com/?d=SAFC_Installation_and_Tuning_(By_RS_Guy) start readin bzossssssssss

Originally posted by 420agreenvilleSC
blah blah

Where the fuck did he say $90 for an MSNS?? The SAFC does suck for tuning on the 420A. Proven fact. Yes it will lean out the fuel but that is all and there have been proven instances where using the SAFC to tune on a turbo car can actually affect the ignition curve. Not exactly what you want.

Lose the know it all attitude when obviously you don't!

Originally posted by djtrickee

Originally posted by 420agreenvilleSC blah blah

Where the fuck did he say $90 for an MSNS?? The SAFC does suck for tuning on the 420A. Proven fact. Yes it will lean out the fuel but that is all and there have been proven instances where using the SAFC to tune on a turbo car can actually affect the ignition curve. Not exactly what you want. Lose the know it all attitude when obviously you don't!

I HATE YOUYUUUUUUUUUUU lolllllllll

Aaaaaand it begins again. I started a thread HERE, 2GFRICKIN-NT because everywhere else there are 2 sides- "Yea use it" and "it doesn't work, don't use it".

If there are people out there saying it works...and I've seen youtube videos of it working...I'm probably going to try it for $90.

MSNS? Yeah, that'd be great and I'm sure it would work better. But that would cost more than I've spent on every part I've got so far combined. My goal is a reliable setup for well under $1k, which I am on my way to doing. So please, will the SAFC paired with a 12:1 FMU be a decent setup?

i dont know, ask deej. he can tell you. I dont know shit. :shrug sorry. quit calln me out deej, it gets old. no matter what you fuckn say to me, i still love you so GET OVER IT :)

At 8 psi you do not need the SAFC, just the 12:1 with stock injectors. It'll run a safe AFR up to redline, assuming it's pretty much a stock engine. Don't waste the money, save up for MS, that'll give you plenty of time to read up on it and how to tune it so you'll be armed when you can get it.

Alright, that sounds like a plan...thanks Justin.

Originally posted by 420agreenvilleSC
i dont know, ask deej. he can tell you. I dont know shit. :shrug sorry. quit calln me out deej, it gets old. no matter what you fuckn say to me, i still love you so GET OVER IT :)

That's because I rule the school. Or not. Not sure. Kids these days...

+1 for that.
I don't care what anyone says about SAFC tuning their car. It only "tricks" the stock ECU into seeing different MAP signals, therefor different manifold pressures. Based on that, the ECU will send more or less fuel. That is it in a nutshell. Under WOT conditions, the ECU doesn't really give a shit what the MAP signal is because it goes into that open-loop mode. Sure, you can lean it out or richen it up when just cruizing around, but under WOT it doesn't have a roll in diddly. That is just pure logic to explain in simple terms that SAFC is worthless.
Obviously MSnS is more costly, but it is considerably cheaper than anything else out there that will do the same thing.

I have been down this road with the FMU & SAFC as well.

My personal opinion, the SAFC is worthless. The only reason I had used it to begin with is beacause I larger than stock injectors and I wanted to lean out the idle mixture. It did do that, but that was it really. It was a waste of money for me, and I ended up selling it on ebay and just purchasing a SFMU back a couple years ago. If you want to spend your money on something worth the bucks, just get the Vortech SFMU and call it a day.

Originally posted by eclipse982nrRST
I have been down this road with the FMU & SAFC as well. My personal opinion, the SAFC is worthless. The only reason I had used it to begin with is beacause I larger than stock injectors and I wanted to lean out the idle mixture. It did do that, but that was it really. It was a waste of money for me, and I ended up selling it on ebay and just purchasing a SFMU back a couple years ago. If you want to spend your money on something worth the bucks, just get the Vortech SFMU and call it a day.

Good post. OP, Mike is right here, pretty much a waste of money Especially if you're sticking with low boost and stock injectors.


Mark dropped the ball on this one though, moving to turbo/nitrous tech :P

I run 12:1 FMU @ 8psi (T3/T4 super 60) and it does just fine

Thanks for all the replies! One more quick and kinda dumb question, but I never really gave it any thought...

It'd be okay to install my 12:1 fmu and walbro fuel pump without turbo mods or anything, correct?

Originally posted by tec_41
Thanks for all the replies! One more quick and kinda dumb question, but I never really gave it any thought... It'd be okay to install my 12:1 fmu and walbro fuel pump without turbo mods or anything, correct?

Yees,It will run as though factory...The fmu will only raise the pressure under boost and the 255lph can be installed as well and fuel pressure will remain the same,I did it for like 3 months,As for the setup I strongly encourage that you get vortech sfmu/w biggest disc 2.72 ring/spring combo and slide in some 315cc injectors,The reason I stress this is because running around 8 psi is gonna make your stock injectors run almost %100 duty cycle which will ruin your injector causing a lean mixture on that cylinder,If yo
ur running a wideband you wont tell 1 cylinder is lean untill you wind up with a blown ring land unless you get it scanned and detect it in time.this is exactly what happened to me and my injector went out and my setup was 255lph walbro/safc2 with minor tune/stock injectors and 12-1 fmu and wideband running 7psi on t3t4 super 60-1 trim.I'm now in the process of the motor swap but this time im gonna run vortech sfmu with bleed option and calibration kit/315cc injectors/keeping safc2 for idle fuel pressure and 255lph fuel pump.Not trying to scare you im just saying this is what happened to me and dont want anyone going threw the hasstle,...good luck.

Originally posted by cs82685
Mark dropped the ball on this one though, moving to turbo/nitrous tech :P

'Tis true, 'tis true.....

Originally posted by djtrickee

Originally posted by 420agreenvilleSC blah blah

Yes it will lean out the fuel but that is all and there have been proven instances where using the SAFC to tune on a turbo car can actually affect the ignition curve. Not exactly what you want

To expand on this particular statement, yeah the Apexi Super AFC does effect timing control due to the fact it's altering the map signal to the ecu, which the ecu is using to calculate the timing demand by sensing impending load between the map,tps,and O/2 sensors.

If you set the AFC to lean down your fuel mixture IT WILL ADVANCE THE IGNITION TIMING.....No if ands or buts about it. This happens on any car that will operate properly with an AFC on it, and depending on the amount of advance that the base mapping has at that given RPM point, can cause pre-ignition or detonation at the worst case scenario N/A or turbo makes no difference.

Now that I've made that point I have had AFC's for years on several of my personal cars and installed them on others and as long as your using it to fine tune your set up and not base tune it you should be ok.

The Problem you will run into with the AFC is that as you want to upgrade your fuel system to run a larger turbo or more boost, you will run out of tune-ability from the limited window (50% adjust-ability) with the factory fuel injector size and fuel delivery rate.(fuel pump delivery rate and pressure control)

If you use a larger fuel pump (walbro 255) with no other mods your
afr's will drop....couple that with rrfpr and depending if its a 2:1 or more and your afr's will drop again. These changes alone will slowly chip away at the available amount of pulse width you can change with the result being, as your injector size increases your ability to adjust pulse width on the fuel system goes down significantly.

For example, I turbocharged a 90' Mazda Miata and it had a 1.6liter engine with 165cc fuel injectors. I augmented fuel system with Venom 385cc injectors (he was on a budget)Aeromotive RRFPR with gauge and a Walbro 255lph fuel pump. At idle with the fuel injector pulse width narrow I could adjust the AFC down to down to -40% before it would start to lean down and die out, but at higher engine speeds when there was more pulse width it would not effect the fueling below around -35%.......The only savior was that I was boosting so I needed to add fuel at around 2900rpm's, although the AFC still read negative it was only at round -10%

The positive percentage increase never exceeded 20% and it was still rich off the scale on the dyno. I guess what I'm trying to say is if you go beyond a 15-20% injector size it seriously limits the ability to get the best afr on boost. The Miata still went from 98rwhp to 200rwhp and drove very smooth, but clearly there could have been another 15-20hp in there as the afr shit canned from 11.3:1 to off scale at 6500rpm to redline and that was with the fuel pressure backed down.

If your sticking with a reasonable boost level (no more than 12psi on your turbo) and a fuel injector slightly larger than stock and ignition control which can support it then the AFC should work fine, barring you will be happy with less than 210-225whp if you want more than the only choice you have is some sort of stand alone.
You should be fine with the AFC just don't get overzealous......
William

All sorts of replies with accurate info.

I will share my own.

I was running 450cc from the GS-T and a 1:1 FPR @ 25psi on idle (with the vacuum hose on)and a walbro 255hp. My idle was not like stock but I was not bad, I had no issues at wot car had AFR of 10.8 when I took it to the dyno; that was on 10 psi. I did later ran 12 psi with no prob.

And I did not use any electronics on my setup....

I did have a SAFC2 but ended up selling it cuz it wasent leaning out on idle. After I sold it I noticed I wasn't wired correctly so that's why it did not affect the idle it only let me add fuel.


But my point is that with a SAFC you could run 450cc and a 1:1 FPR and lean out the idle to almost or equal. And have the abilty to run higher boost. Yes it's true that the SAFC does affect timing curve, leaning=advance, and richening=retard. So if your crafty you could do I bit high idle pressure like 30-35 and lean it out a bit and run high boost and do so richening to retard timing at least a bit. And will have a rich AFR on WOT with a lil retard of timing. Just my 2cents.


I would try this my selft but I am going all out and will probably get an MSns. Anyways good luck with your build.