Damn that was funny - I took the car out on the freeway; at 7 psi boost, around 5000 RPM, I was getting 9.8:1 and RICHER A/F ratio!!! Tuned it down with the VAFC and logged a couple runs in 3rd gear up to redline, now its between 11.1 and 11.3 for almost the full RPM band at WOT. I'm pretty impressed. I'll dump the data at work and put up some plots just so everyone can see.

Fuel config is stock pump, stock FPR, 450cc DSM injectors, and VAFC wired to sense load from the MAP sensor rather than TPS. With the VAFC trimmed allllll the way down, running in open-loop, it idles at about 15:1 and cruises on the road or freeway at 12:1 no matter how much I try to reduce the fuel.

Just a side thought - if the J&S was lighting up 3-4 bulbs at WOT when I was at 9.8:1 AFR, retarding 1 deg/psi already; do you think I can turn the sensitivity down just a wee bit? When I leaned it out some more it actually seemed to eliminate most of the J&S activity - is it possible to detonate running that rich??

 

Just curious...what wideband setup are you running?

 

It's called an AFRecorder 2400 by ECM systems. It's more of a benchtop unit but has 12V power so it can be used in-car. Has input for RPM, manifold pressure, spark timing, and wideband O2. Can log several runs in memory to be downloaded off it later.

 

Awesome dude

Makes me feel a little more comfortable about my setup. How much were you trimming at WOT under full boost?

 

I think right now it only comes up to about -10% at full boost, but that's also at 7 psi - I normally run 8-9 but my MBC seems to be slacking off on me.

 

And those 8-9psi are still with -10% trim? Just curious cause i'm trimmed -10% up top too, but this is at 10psi (but on a smaller GReddy) and I noticed some faint dark smoke out of the exahust when I', gunning it under boost. Just wanted to compare AFC #'s with somebody with a similar setup. BTW, how's the AFC hack treating you?

 

What was the cost on that wideband setup? Any website for info?

 

I found their site...too bad thier not located in the USA

www.labcell.com/afrpage.htm

 

who did you buy it from?.was it direct from site above? and what u pay?

 

It's owned by my company - and I would take a wild stab at it costing several thousand dollars.

 

can you list your setup for us??? thanx

 

'96 GSR, stock internals
0.48 Stg 1 T3 / T04B S-3 @ 7-9 psi depending on phase of the moon and alignment of planets
MaxRev Mani
Custom pipes
Modified Starion IC
2.5" exhaust / test pipe

450cc DSM injectors (10-ohm resistor spliced into each lead)
VAFC
stock fuel pump
stock FPR
J&S ultra v.2

 

what rpms do you start & finish spooling usually with that turbo? I've heard a lot of #s for t04e's but not as much for t04bs...

i should be doing some wideband tuning on my friend's si tonight :D

-Xerxes

 

Boost usually "begins" (over atmospheric) a little over 2000 and I'm usually at full boost before 3500. Depending on circumstances; sometimes I've seen full boost at 3k, sometimes not until 4k. But since all the T4s have roughly the same mass compressor wheel, the spool time is more dependent on the turbine size and trim.

 

"Fuel config is stock pump, stock FPR, 450cc DSM injectors, and VAFC wired to sense load from the MAP sensor rather than TPS. "

Whats the advantage of wiring to the MAP rather than the TPS?

 

The advantage is that on a turbo the actual amount of air reaching the engine is rarely if ever directly proportional to the throttle position - you can be at very light throttle and still be boosting and you can be at full throttle and not yet be making any boost; so if the VAFC dumps fuel in just because you put your foot down, it's going to bog like crazy until the turbo spools up. Any real ECU on a turbo car maps fuel based on manifold pressure or air flow, not on TPS... so I decided to make the VAFC do the same.

 

I just got my VAFC the other day, could you explain, in as much detail as possible, what this VAFC hack includes and how you hooked it up. (VAFC wires to ECU wires)
I'm currently running a b16 w/ ITR head, IM ,TB, 9:1 JEs; Drag 3; 370s; 6:1 fmu; B&M fpr.

Thanks