928DK

320 rwhp equals 376.47 Ehp (or 75,2 hp/liter) accounting for 15% driveline loss, that's more hp than a gts

RFJ

High Drama and +1 on the intake Ken

PorKen

I use 12% for the manual. 360 chp is still pretty good for an old clunker (approx. 120K miles/193K km), comparatively, 292 chp DIN was the factory rating!


Correction factors confused me for a long time. Most simply, it's the air temperature (and pressure) difference between them. I like to use standard correction, which uses a lower air temp (60F/15C) than SAE (77F/25C) which more closely matches the weather where I live - and gives a little higher reading. I have dynoed in the winter with the door open and the uncorrected readings are much higher than in summer. (Duh! You can feel this when you drive on a cold day.) Trying to make big power at 77F is really difficult, I've found.

The correction factors do work pretty well. My S3s have been set up the same way and are remarkably consistent on the dyno. Just by accident, the rims and tires (tire pressure) are the same, too.

I try to go to the dyno on cool days, around 70F/21C, but this last run was at 80F/26C, 29.81hg", so the correction was as follows.

COR whp chp %
DIN 321 360 1.01
STD 321 360 1.01
UNC 317 355 1.0
SAE 313 350 0.99

PorKen

Fred,

They dyno around 250 completely stock. Really tough to say what the individual differences would be. To get over 320 took a combination of everything, working together...I've pretty much tried everything separately.

The airbox S4-up is not well shaped, AFAIK (too shallow). The '85-'86 box is pretty good, and restricts by a small amount, if any, even with the smaller feed hoses.

I like what the retarded cam timing did for the numbers, but it's much nicer to drive when it's advanced. You can't 'feel' the extra HP at high rpm with retard, but you can really feel the torque starting at a lower rpm with advance. I think for around town, advance, highway or track, retard.

It might get better highway mileage with less lower rpm compression when retarded?

Cosmo Kramer

Nice numbers Ken way to go! Amazing how you have exploited the performance capability of the the S3 platform.

Pappy

Makes me want to purchase an 85 to 86.5!

FredR

Ken,

I assumed your model produced a nominal 300 crank HP and that losses would be around 10%. Irrespective, very impressive and that compares well with the 340 rwhp Louie gets with the GT's. Just goes to show what attention to detail can achieve. I'd be happy just to have a dyno available to see what is going on when I play around with my motor. Best I have is my G Tech RR which is helpful [or was until the mount snapped]. Best I can get is when the temps drop to about 20C in January, on a "really cold day" we have seen about 15C in the evening.

I fully agree that one can feel torque improvements but not power increments

Regards

Fred

PorKen

If Louie is getting 340 rwhp, SAE, that would be impressive.

My goal was to match his old (pre-SharkTuner) GT w/X-pipe numbers, SAE. Pretty close at 313/308 (more average torque w/S3).

jbrob007

I have an 86.5 / S3 which Ken has chipped to death - thank you by the way - and it runs like a raped ape Standard exhaust with both cats, no X Pipe (yet), both intermediates and a RMB. I'm sure I could get more HP out of her if I ran straight pipes with the X pipe, but the HIGH decibels inside the cabin kinda suck as I drive my car A LOT - 12K miles in 6 months And, yes the torque is what you feel in the seat of your pants and the back of your neck when you tromp on the go fast peddle The increased HP - not so much. Unfortunately, I've never driven an S4 or GT, etc, so I have nothing to compare it with... For now, I'll just have to settle for LUDICROUS SPEED

UncleMaz

Nice work!

PS, I got my chips and TR's in the mail yesterday Ken. Will install shortly and report back in the Awesomeness thread. Thanks!

mark kibort

I had many runs in the 335 to 325rwhp range, and this was with a vented air box, (sealed to the base of the windshield and front tubes active) as well as equal length headers, boosted fuel pressure and MAF screens removed. cams basically were GT cams. with the 85 cams , modded to the S4 housings, the HP never got over 320rwhp, even with some tweaking of the timing, of up to 8 degrees retard.
I ran 20 or so dyno runs all being within the 318 to 326rwhp over a period of about 4-5 years.

I started at 290rwhp, with no cat as the only mod. pulled off the screens, opened the airbox, put on headers, boosted fuel pressure to 70psi and added the 3.5" straight back exhaust with a nice merge collerctor from devek, which is still on the car now.

FredR

Ken,

The example that made 340 had Devek level 2 headers fitted with the 1 3/4 inch headers and they do make a notable difference top end unlike the MSDS ones that as far as I could ever interpret make little to no difference up there [perhaps better mid range torque?]. So, looked at in that light you are doing very well indeed.

One thing that should never be overlooked is the fact that when Porsche say their engines produce "x" crank BHP what they really mean is that they all produce this amount and some more still. Allegedly the examples that do really well on the dyno are reserved for more exclusive customers who are more likely to be listened to by the press when espousing the virtues of the marque [so that excludes me for starters!].

We had a black 1995 GTS auto here. The local service manager used to tell me how this motor really hauled ***. It came up for sale in Oman but at the time it was out of my price league. About 10 years later after I pranged my S4, I saw a GTS advertised up in Dubai at a very good price. I enquired, had it independently inspected by House of Cars [Dubai] and whereas the car was a bit doggy round the edges the tester commented quote- "crikey- this car doesn't half take off". I put two and two together and sure enough it was imported from Oman by a previous owner. Dammed that due to a visa technicality I could not purchase that car and bring it back to Oman. It needed a paint job and a number of mechanicals like brakes etc but how I rue that miss. Bottom line we theorised that that example was likely making 360 bhp if not more.

Regards

Fred

rad_951

Ken,

Is your 5-speed making about 75-80 rwhp more than the dyno runs done in Conn?

PorKen

Tony - good Q.

I dug out it's old dyno sheets. There were two sets, which I assume is stock and then with the X-pipe (Motorsports/Utah) installed. Runs were made on a DynaPack (wheel hub mounted) dyno which often read a touch higher than a DynoJet, so the increase may be a little more.

(All figures rear wheel, SAE.)

tune _HP_TQ_
stock 257 242
xpipe 271 283
S300 313 308

tune_HP+ TQ+
stock 56+ 66+
xpipe 42+ 25+

rad_951

I think the drive train loss should be more like 18%. This is the value the Bimmerworld folks use for their race car. The M3 trans uses ATF where the 928 trans uses gear oil, which is thicker.