Well, I will try to make this as short as possible.

Mods: 98' Z28 A4, 3.23's, approx 87,000 miles, K&N FIPK, LS6 Intake, ASP Pulley, P&P heads, 232/238 .574" .585" 112 cam, Hooker LT's with dual exhaust, PT4000, LS1 Edit, stock screened MAF, ported TB, tr-6's...

Head Info: 2.02 Int. 1.60 Exh.
Supposed Flow numbers, the guy I got them from had these written down, but not an actual flow sheet...

Int Exh
Lift CFM CFM
.3 209 154
.4 267 194
.5 296 225
.6 308 234

The first run on the dyno produced 372 HP and 390 TQ, unlocked. We had the wideband sensor in one of my cutouts, and it was showing way lean. Over the next 3 - 4 runs I tried richening it up a bit with PE vs RPM, it did come down some, but I had almost a 1.6 multiplier in there.

We decided to put the wideband at the tailpipe, this showed better results, as the car went 11:1 or so. Not sure why that happend, but it did read differently. I couldnt seem to get the LTRIMS to zero out either, although they are negateive during driving...

I made a total of 10 runs, the last 5 though, we couldnt get an A/F reading because the dyno kept losing the RPM reading. The last A/F reading I got started off around 11.5:1 at 3500, droped to 11:1 at 5000, and came up to 12:1 by 6500.

On the first run of 372, we noticed 21* -23* of timing. By the time we were finished, we were around 27* with only maybe a 5 HP gain, although the A/F wasnt right. Shouldnt more have been picked up through timing changes.?

I know this car shouldnt be a dyno queen, but 377 doesnt seem right. I have seen lots of A4 H/C cars doing 400 rwhp. It would seem like we did not know what we were doing with LS1 Edit, but my buddy's car, who was tuning with me, put down 377 with a 224 cam, LT's & duals, 4000 Stall, LS6 intake, ASP pulley. His first run was 360, and we worked him up to 377.

I cant see gettin the A/F to 12.5 - 13:1 giving me 25 HP. I dont know where else it could be hiding. I am going to compression test all cylinders this week. I thought maybe it was over cammed, but then thought it would be unlikely since there are bigger cams out there making more power anyway...

Here are links to the dyno graphs, with the corresponding ATap files...

Dyno 1 Run 1 Atap file

Dyno 2 No file for this one

Dyno 4 Run 4 Atap File

Dyno 5 Run 5 Atap File

Dyno 6 Run 6 Atap File

Any ideas? I tried searching for other guys that we having similar problems, but out of all the threads I found, it didnt seem like any solutions ever came about...? Thanks guys...

 

I would say your running out of injector.Thats why it's going leaner at the end of each run.

 

Well 12.5 to 13.1 would be optimum airfuel, I dont know if the 28lb injecters is causing your problem, Id say between the airfuel and timing you can find maybe 10hp more, dyno runs 5 and 6 didnt go lean on you up top , It may be a tuning issue not worked out , and your written down flow #s dont really help you out either, Those are pretty high flow #s in my book , with the right tuning and timing you should be close to 390 hp which is not bad for an A4 , Id put a few more degres of timing into it and see what it looks like, all and all how does the car feel when you drive it.

 

No way his 28's are causing his problems...my 99 injectors are just fine at well over 400hp level that I have.

1st I'd check clogged fuel filter
2nd timing/tune
3rd plug gap

I could go on but u'd probably find ur problem in those area's..especially the leaning part...a clogged filter will do this to u or a fuel pump going bad.

 

I am not an expert by any means but everyone keeps saying don't worry about the dyno numbers on an A4. Take it to the track and see what it will do. JMO

 

Hey Joe

Just what josey said. Looks like you have other issues at work there.
with that combo you have which is simular to mine but your cam is larger should be in the 420 range np if those heads are any good. Where did you buy them? Were they used ? Those #`s are Std also. See if you can get them with the sae correction.
Let us know how it works out

Jeremy

 

The reason the dyno is "losing the rpm" is how it is operated. I used to run into this also. In order to not lose the rpm, make sure the operator terminates the run (hit's the brake button) just before, or exactly when letting up on the gas pedal. If you terminate the run after letting off the pedal, the computer can't cope with the sudden rpm drop and the rpm signal gets severly skewed.

 

quick response before I go to work...

The fuel filter has only been in for about 3000 miles. It possible that it could be clogged, but once we moved the wideband to the actual tailpipe, instead of one of the cutouts, it went rich like in 4,5, and 6. I do see what you guys are saying about it becoming somewhat leaner on the ope though...

The plugs also only had about 3000 miles on them, and when installed were gapped to .035"

Reckless, actually the dyno was dumping the RPM's when he first started the runs. You could actually watch it quit reading a split second after the car went WOT. Instead of seeing a sudden drop, it was seeing a sudden increase. My only idea was that the machine couldnt keep up with how fast it revved? My car was the 3 card done that day, and out of the 20 or so pulls before me, only maybe 3 dropped the RPM's...it was weird...

 

Dyno with a fuel pressure gauge on the car. Might be losing pump.

Are you running stock MAF or ported? Those throw the AF TOTALLY out of whack (I picked up 35RWHP in the midrange going back to a stock descreened MAF)

Run a clean stock MAF without screen. Throw on a fuel pressure gauge and flash the car back to stock and retune. Also change your fuel filter.

Cheers,
Chris

 

The MAF is stock down to the screen. I have some ported ends that I wanted to try on the dyno, but I ended up leaving them at home. The pump is an intank Walbro, installed about a year or so ago. I am willing to basically try anything right now...

I thought about resetting the car to a stock tune, and starting all over, but didnt get to yet....

 

The heads were ported by Speedtek of Dallas, they were new when I got them. The guy I got them from originally had a set of Speedtek heads, but kept losing water, after changin head gaskets 3 or 4 times, he inspected the head and there was a small pinhole through to the water jacket.

He works for speedtek, so they replaced them for him, he decided he didnt want to put them back on, instead opting for 5.3 heads, I bought them relatively cheap...

I think the numbers were standard, I will call and get the corrected numbers to see if there much of a difference....

 

Damn Joe that sucks. I hope you get everything straightened out. You should be in the 385-400 rwhp with that setup. Good luck.

 

Also remember unlocked converter can read real low #'s.I've had a 440hp Cartek car only dyno at 370hp at my shop with an unlocked converter,but he runs the track #'s.

 

I understand that I wil have a decent loss through a 4000 stall converter, but what doesnt make sense to me is that a cam only 98' Formula, with the same 4000 converter put down the same 377. I would think the loss should be the same through both...???

 

.035 GAP!!?? COME ON!! Open those up to at least .045 or .050 and you'll gain a lot of ur missing HP back... .035 gaps for for N20 hogs!!

 

Hmm...you really think? How much could be in the gapping?

 

he beat me to it
i was always told on here to stay in the 50's on gap, when running NA (i always stick to 55, but thats just me)

anyways, you still need to get that AFR fixed
good luck dude

 

The wideband issue, you said in your cutout, not a good place for it. Nor is the tailpipe. Get a bung installed before the cutout, I have mine in just after the front O2. This keeps the readings safe, uncontaminated.
Plugs, yep for NA, get some TR55, at .050 to .055. Add timing up to about 32* total and if no KR your good, maybe use a splash of race gas if you get some KR or back timing off 2* at a time. Theres power there. get the ignition down and get that AFR at 13.2:1 on the Dyno. I run my wideband on the street, and I tune it for a 12.6-12.8:1 since I spray a lot.
Good luck.

 

Its not just about the stall. It also has to do with the str and efficiency of the convertor. I still don't see it robbing that much power from you....but I do agree with the comment on placement of the wideband. Just put the wideband in a welded bung.

 

You can loose 20-30hp depending on gap...trust me I know....I went .030 gap when I did the 100 TNT shot...and it was a dog on N/A...then I opened up to .45 and on or off the gas the thing FLEW!!!!!!!!!