View Full Version : 5sfte'ers w/ safc..how much correction?

02-08-2005, 01:42 PM
hey guys, just sitting here pondering on my 5sfte setup, and im wondering how much correction you guys are useing + or - and at what rpms are you doing it at.
which injectors your using would also help.
also, how much boost are you running.
BTW..anyone else here think that damn SAFCII manual reads like rocket science? hehe been trying to decipher that thing for MONTHS :lolhittin
i think i might be finally starting to get it.. :boring:
anyway, thanks in advance for your help! :D

02-08-2005, 07:58 PM
It all depends on your car man.

i fou nd when i was tuning my friends 98 gsr-t that you could not go off of other ppl's tuned settings.

even if the car was exactly the same. things are bound to make things different.

02-08-2005, 08:07 PM
agreed , however i will say... don't be surprised if you find your self adding alot of fuel at 2000-2500 rpms ... +10 to + 25% ... i know it sounds like alot ... but i mysteriously found that to be good for my 5sfte ... and then i looked at a bpu (i/h/e) 5sfe dyno somewhere and they apparently had a lean spot in that range too... i think it comes from the factory cams, the engine stroke ...etc the engine is very effecient in that range so that gets amplified by power adders or boost ...

so don't be surprised to see that ..
then up top you'll end up leaning it out because the stock fuel curve goes progressively richer as you approach redline (farther than 10:1 on a stock car).

specific numbers depend on your fuel setup, cams, turbo, supporting mods

02-08-2005, 09:51 PM
yea im not looking to try and replicate someone elses settings, just trying to get a genral idea or what you guys are doing with them..
thanks for the tips nuke, ill keep those thoughts in mind..

02-08-2005, 11:20 PM
yeah best thing to do is tune it on a wideband...

one way to tune is to figure out where your turbo spools on your engine say 2800 rpms
Then you go in at say 2300-2800 and lean out your mixture (as much as safely possible) ... even if it is a bit leaner than stock as long as it is not dangerously lean... if you have timing control, go ahead and try and add some timing here if you like

the combination of the not so rich mixture and hte healthy timing will increase your throttle responce, help the engine breathe... this helps pre-spool the turbo .... as you get closer to your spool rpm start gradually rolling in the fuel and rolling out the timing ... this richer mixture, less timing combo makes the engine 'fall on its face' (not really) but compared to how it was with the lean + advanced setup a few hundred rpms earlier... so now your motor is slowing down, but your turbo has alot of inertia from the healthy breathing in the previous rpms... what happens is the motor bottle neck's the flow and you build boost faster than you would have with a flat timing/fuel curve ...

some people even do this deep into the spool (with bigger turbos) so they'll stay lean/advanced up to about 4psi and then roll things out so that thing take off from there.

then you run a good a/f in the mid range 12.5:1 or so ...and as you get closer to redline, you will make more power if you hold around 12.5:1 ...but it would be safer if you slowly rolled out closer to 11.5:1 in the higher rpms just to be safe....

if you feel like you've lost a bit of power from the extra mixture at high rpms, then drop in a few more degrees of timing to pick the power back up, but leaving a good rich mixture to help cool things down in case anything happens in the future and your curve leans out (bad injectors, cloggged filter, really cold night, overboost...whatever)

i know you may be hesitant to advance timing under boost...but it's all about what rpm you are at and what the VE of the engine looks like... with an engine like the 5sfe where VE peaks down low it should be ok to add quite a bit of timing in the higher rpms (Basically the timing brings cylinder pressures back to what they would be at the more effecient / lower rpms ) ... so it's not any dangerous than less timing at a more effecient rpm ...

the other things i can tell you is that
+ corrections on the SAFC = retarded timing
- corrections on the SAFC = advanced timing

If you are messing with timing, it is more important to look at weather or not your torque curve is moving rather than your hp... if you advance timing and you reach a point where your torque doesn't rise, or even worse it begins to drop that means you are over advanced ... so if you have a torque curve that rolls off in the high rpms (like most 5sfe's) you can add timing there to pick it up a bit...but once it stops rising just back out a degree or two for safety and leave it there.

One last thing (which i read somewhere else ) and was really good advice ... engines are analog like, they're not digital... everything in your engine should ramp up, ramp down, build up, build down...

you will never find your self where your corrections look like +3 +5 +20 -8 ... etc ... they should always be gradual otherwise you're probably not tuned optimally and your factory ECU is working hard to fill in the gaps.... so think about that when you're tuning too ...usually smoother transitions in fuel and timing will give you alot better area under the curve and a better wider powre band


02-09-2005, 03:45 AM
Excellent tips nuke :)

02-09-2005, 05:00 AM
chris , i don't own these tips , nor have i ever dyno tuned an engine... all the stuff that i mentioned is a collection of things i took not of from reading tuning posts on other import and domestic forums .... basically because i am interested in dyno tuning my next setup whatever it be (i have no idea at the moment)

There's one part i left out... EGT gauge.

if you're a/f is set at a good level and it's fixed (you're not adjusting it anymore) then usually the optimum timing will give you a minimum EGT ... if you retard timing from the optimal point your EGT's will rise because you are burning more the mixture on it's way out of hte cylinder... if you advance from the point of optimality your egt's will rise because the early combustion and increased cylinder pressure will start to show it's effects... so as far as timing is concerned ...the EGT vs timing looks like a V or a U with an obvious minimum and then it increases from there no matter which way you go (advance/retard)

some people use EGT's for tuning so it's really good to be aware of what side of the U/V you are on and make sure that you know what you're doing if you make a change to timing/fuel and you find an inverse effect in EGT's (ie you think you are running rich and you advance you're timing and your EGT's rise, or you lean out your mixture and your EGT's rise as well... )

Chris i know you have some personal experience with EGT's ...

I'm just a theorist at this point...


02-09-2005, 05:26 AM
took a pic easiest way :P

02-10-2005, 12:36 PM
nuke...thanks for the great tips...man, i REALLY need to learn about timing. lol
the reason for starting the thread is that i found a local dyno shop, but the guy at the controls is a mustang guy. so i may have to try and "tune" it myself...he quoted me 50$per hr, unlimited runs, w/wideband, me driving...thoughts?
lemme rundown my setup, so you guys can have a feel for what im trying to do.
3s manifold
ct-27 w/ ported wastegate
315cc injectors (gonna be upgraded at some point.)
boost, oil pressure, and EGT gauges...still shoping for a wideband
26x6x3 intercooler
2.25" piping
hks BOV
planning to go straight from the install to a muffler shop and have 2.5" done from the DP back..not 3" just cause of clearance issues and incase i pop the motor i can go back NA on the 2.5" piping.
then from there to the dyno shop..start @ 7lbs to get a check of the a/f ratio and start tuning from there..whadya guys think?
jon, we REALLY need to get together, and even more so now you got the new setup almost together!!.

02-10-2005, 04:20 PM
315s ? i think we should really start going for 390s or 440s.

50 is cheap for dyno time ...usually it's 100+ and you just watch.

good luck

08-29-2005, 07:22 AM
I've been reading a lot about the safc and how you add fuel and things like that. What exactly are you guys setting the msd-btm at on the knob? I've spent about 4 hours searching for this stuff and its just hurting my head now. :(

08-29-2005, 07:42 AM
Also would the 2jz light blue injectors work? theyre rated 330cc?

08-29-2005, 08:17 AM
Manny, I am not an expert on the 5sfte but I will share a thought based on my research about the 3sgte. You may want to consider an AFPR to lower base pressure and use the SAFC to add fuel rather than subtract fuel. There are countless posts that confirm that is a safer way to go - at least on the 3s. Check out the power primer on mrcontrols.com for more info. You probably already know that but I thought I would mention it JIC. Good luck.

- Jay

08-29-2005, 11:29 AM
just an update to say, i never ended up having to take out any fuel with the SAFC, i had to ADD ADD ADD!!! VERY lean, DANGEROUSLY lean.
i had to add almost +20 in some spots (with the craptastic 315's)

08-30-2005, 04:01 AM
I would get some DSM 450's. You can use that, then go for an ajustable fuel pressure regulator. This way, you can decrease your fuel pressure so you can idle. From there, add fuel w/ the safc. At this point, you will need very little correction on the msd btm.