Norton928

Torque peaked at 3300-3400rpm. Secondary lower peak around 4500rpm.

HP peak was around 6100rpm.

Tom. M

Depending on the dynojet model, if you run in 4th (drive) on the rollers, your wheels will be spinning at around 200ish mph at below the HP peak of 6200 rpm and the dyno may cancel the data for the run. This happened to me several times before we could figure out what happened. It was an older model Dynojet though so maybe the new ones don't do that.

Running in 3rd is pretty much the accepted gear for the 87/88 S4's. I assumed you disconnected the the Bowden cable and kickdown switch and manually shifted into 3rd...slowly rolled up to around 2000 rpm and then floored it? Also, check the A/F ratios...If you didn't got to WOT..then the A/F would not be right ...leaving some power on the table..

Tom. M

Sounds like the flappy is working then, and the HP peak is about right...

Norton928

This is getting interesting. So much to learn

The dyno at the shop is one of the newer Dynojets and I was told it can do over 200mph before cutting out.

I had read about disconnecting the kickdown switch and bowden cable, so I did that, and it was manually shifted into 3 (3rd). Gentle roll up to 2000rpm and then floored until 6500rpm.

The shop said air/fuel data may be off by as much as a 1 point given the car has a cat, and resulting exhaust would have been filtered by the cat. The graph showed the air/fuel ratio was 14:1 from 2000-3600rpm, dropped to 13:1 from 3600-5900rpm, and then to 12.5:1 from 5900-6500rpm.

Tom. M

Based on what you've posted, I'd say you have some good baseline data from which to work with. A X-pipe, do some cam timing with Porkens 32Vr, and get a rising rate fuel pressure regulator on there. Then the final ...do a tune with a Sharktuner to match those mods...and you'll be good to go .

edi1

hi give you the numbers dyno run 1 max power 279 max torque 296.4
second 278.8 296.5
third 282.2 297

AO

When you post dyno numbers you should pay attention to the "Correction Factor." This is what they do to compensate for humidity, temperature, phase of the moon, etc. Standard correction will often give you a slightly higher values than SAE. Just thought I'd throw that out there.

Norton928

Point taken.

My posted dyno numbers are SAE according to the printout I was given.

jcorenman

Yes, but are your tires are rated for 200mph? A tire failure on a dyno is not a pretty sight. Stick with 3rd gear.

You are only getting a "filtered view" of AFR with a tailpipe sensor, but this sounds normal for an S4. The LH (fuel brain-box) will be running open-loop at WOT with the fuel determined strictly by the mapping. Your best power is going to be in the 13:1 range, S4's are mapped too rich at the top to be "safe", typically 11.5-12 at WOT, 6000 rpm.

MAF's tend to read low as they age (i.e. indicate less airflow, which means less fuel, which means lean mixtures). Setting them up to rich at the high end accommodates aging MAF's without going lean. You can hit it closer with a Sharktuner and pick up a few HP, Autothority chips add fuel and makes it worse.

You are in the right ballpark, I wouldn't worry.

If you want to do some fiddling and look for another few percent, the first thing to do is get your hands on a 32V'er and set the cam timing accurately (as was mentioned above). It's not hard, all you need to take off is the two top covers, not the lower cover.

Then find someone with a diagnostics tester and make sure that all of the sensors are working correctly. A sensor fault (e.g. a bad knock sensor) will knock 6 degrees off the timing which costs some hp.

RMB's with an otherwise-stock exhaust makes for a very pleasant sound, IMO, but no horsepower. (The S4 rear muffler is a pair of straight-thru perforated pipes with lots of fiberglass to scrub the sound but not the flow). X-pipes are worth some HP, but in combination with an RMB make for a nasty resonance around 2000-2400 RPM (highway cruising RPM for an S4) that we find annoying.

edi1

hi numbers 3 runs #1 279.6hp torque 296.4
#2 278.8 torque 296.5
#3 282.2 torque 297.0 with no adjusting anything

pcar928fan

Those would be high and very good for an automatic S4...

PorKen

Uncorrected dyno numbers + headers + X-pipes - cats.

brianrheffron

My '89 S4 is also the first Autop I have ownned/ driven
so there is a lot I don't know about auto boxes.
I read for a dyno run you disconnect the kickdown switch
and take off the bowen able so that the box will stay
in the gear that you select via the shift lever.
Can the car be driven like this giving full manual
control of the auto box?

Rick Carter

And still lower than a tuned 85/86.

paul928s4

These are only my observations after 5 years of lapping, and as always YMMV. That said, here goes:

The best I've come up with for manually shifting my '88 S4 auto on the track is the following:
- bowden/tranny cable disconnected or with lots of slack
- kickdown switch disconnected and kickdown relay removed
- throttle linkage tighened a bit to raise rpms when foot off the gas (faux throttle blip for downshifts)

This is the most predicable setup for me, as I don't have to worry about any unexpected downshifting by the tranny when I hit the gas hard.

As there are only three shifter positons (2,3 and D) for four forward gears, getting 1st gear starts and downshifts can be more tricky in an S4 auto. I start from a full stop with the shifter in 2, which selects 1st gear. The shifter can be left in that position and the tranny will upshift to 2nd gear at redline, or the shifter can be moved quickly from 2 to 3, and back to 2, to upshift to 2nd gear.

Shifting to 3 gives you 3rd, and 4 is 4th. Downshifting to 1st can be done at 40kph under kickdown (which is disabled in my case), or at 20kph. The tracks I frequent don't require downshifting into 1st gear, so it's a non-issue for me. For autocross, that may be in entirely different matter.

Others have mastered the art of left-foot braking to better equalize rpms, but I'm still working on it.

If there are any other tricks out there, I'd love to hear them.


Paul