924Board.org

[Cedric]

So, finally i took a day of at work and went to a company that had a really good hub dyno. I have been planning this for some time, but stuff has just come in the way, both for me and the company. There are more companies around here with roller dynos, but that is of no value to me, I rather use the but dyno for free .

So the purpose was to get a feeling of how good shape the engine is in, and of course doing a baseline run before anything is upgraded. Consistency is the whole point of it since i will return in a year or two when I have upgraded stuff to see the difference in detail, so hub dyno was the only option. And as a bonus, there are an archive with hundreds of cars, measured in exactly the same way, http://rototest-research.eu/index.php?DN=29 .


First we ran static load points at every 1000 rpm from 1000 to 6000 to check lambda and that any other problems such as knock wouldnt occur. It was horrible hearing the engine screaming at 6k rpm full load for maybe 15 seconds, but it worked out fine and the lambda looked good as it used to. The K-jet got good compliments for the extremely stable lambda at the different steady load points, no flickering or jumping around at all..

Next of we ran dynamic sweeps at a rate of 300rpm/s,, this was kind of an average of where I use my car mostly on track in 3rd and 4th. So It is a pretty good representation of where i use my power. Sweep time affect the power curve a lot, so its a very important factor to have in control. we ran the tests from 2k to 6500rpm. All runs were made in 4th gear, the oil I used is 20w60 shell racing.

Engine spec:
S2 engine
Turbo from my old s1 engine, 2664G4.10
S1 WG spring, not big difference.

We ran several powercurves and this is the last. heat soak was not that visible:

So this is the baseline, very happy with the results. Power curve looks really good, topping out at 165hp @ the hubs. Torque curve looks surprisingly wide and flat. What I like is that the power keeps increasing all the way to the top, maybe not the most efficient. But much more fun




In the next post I will plot data from a run with a KN filter I had lying around (got it for free but never used). Very interesting results


BTW. if anyone have a stock s2 power curve from the manual, could you post it here?
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1980 924 Turbo
www.instagram.com/garagecedric/

[morghen]

Had a power/torque graphic in the manual but gave it away with the 932.
But from what i remember it looks very similar. Your power curve seems to climb more around 3500RPM but thats just from my memory.

Very curious about the KN filter results.
Thanks for sharing !
_________________
Supercharger and EFI kits
https://www.the924.com

[Cedric]

An even more interesting plot I will add later is Swedish DITC vs the ROW DITC I bought from ebay.uk. To bad I have to work

I dont have all the daa points though, I only have data points of every 500 rpm. That makes it a little hard to do my own curves and plot them on each other, will try to contact the company and see if I can get the data in better resolution. The graphs are though full resolution.
_________________
1980 924 Turbo
www.instagram.com/garagecedric/

[gegge]

Nice!
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Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs

[Cedric]

Went down over lunch to visit the company again, now I got the full raw data. Nice !
_________________
1980 924 Turbo
www.instagram.com/garagecedric/

[morghen]

Can you plot starting from 50HP and Nm as we are not interested in below and to read values you have to scroll up and down to read RPM.
Cant wait to see the KN and DITC runs.
_________________
Supercharger and EFI kits
https://www.the924.com

[Cedric]

So while the car was rigged up I had some time over, and I had a KN air filter lying around. I never used it, but it came with the engine when i bought it. I kept the air filter if I would ever go to the dyno, since its so easy to change. Take a look at the results yourself, not that impressive.



I also did some runs with my spare DITC I had lying around, the one in my car is sweden/switzerland version, I was curios to see if there was any difference. And there was, the ROW box seemed to have a different ignition curve at high rpm that held the torque up a little bit. No big gains but interesting result for me

This plot is raw data from the dyno, its a little noisy so had to to some getto lowpass filter in excel. Will try some more sophisticated method if I have time



KN filter


ROW DITC


To sum it up Im really happy with the performance, after studying loads of graphs in the library I was hoping to get at least 150HP at the rear hubs (the bad cars had around 15% loss on the hubs compared to the stated performance). Now I have a really good baseline for forthcoming changes, and a really good way of tuning and verifying the results.

Enjoy!
_________________
1980 924 Turbo
www.instagram.com/garagecedric/

[Cedric]

Forgot to post the lambda curve, looks like it use to. leveling out at constant 0,76 where i want it. These measurements are taken from steady state measuring points at the different RPM at full load. They did not yet have the dyno installed in the bespoke dyno room, so all the data acquisition was not installed, otherwise it would have been logged in the sweeps.


_________________
1980 924 Turbo
www.instagram.com/garagecedric/

[Rasta Monsta]

In case anyone else is wondering, the "lambda scale" above uses stoich (14.7) as 1.0.

Therefore, when Ced's car hovers around .75, it is running around 11 (14.7 x .75) on the scale many of us are accustomed to. . .right where it ought to be under boost.
_________________
Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[Carrera RSR]

K&N, a standalone cone or panel filter in original aribox?
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252

[Cedric]

[Carrera RSR]

I prefer the induction/boost noises achieved with a cone versus the stock airbox even if no performance benefit. My current set up is just right without sounding like a boyracers dump valved turbo eurobox.

I need to run my car on a dyno again having had huge gap in results at the start of the year. However the butt dyno says all is good regardless of the numbers

Thanks for posting your results Cedric.
_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252

[Cedric]

[Cedric]

Made some nicer graphs, finally

"ref" in this case is from the s2 handbook. I adapted a powercurve to fit an image i got from the handbook, worked out pretty well. The sweep I made are pretty close to steady state numbers, which most likely is what the factory curve is based on. I could probably have boosted low en power a tad more by going slower, but as I wrote earlier, this sweep time was the most relevant for me.

you can definitely see that the power curve has been altered a bit by the turbo change. You could feel it to after I swawpped turbo. The old s2 turbo alwys felt a bit soft up top, especially on track when the heat built up. But I lost a bit of low en response with the turbo change, that was also obvious, nice to have it on paper




_________________
1980 924 Turbo
www.instagram.com/garagecedric/

[Carrera RSR]

Your current turbo is an S2 spec is it not? It's using the #4 turbine and not the #6 used by a RoW series 1. (Tries not to start a confusing turbo spec argument!!). RoW S1 was K26 2470 6.10, Row S2 was K26 2660 4.10 although some replacement turbos appear to be K26 2664 4.10 and were fitted retrospectively to both S1 and S2 cars, certainly some I have found. I'm now running the same 2664 compressor wheel but with #6 turbine as used on the CGT's. My head certainly hurt a lot in trying to determine the various historical RoW versus US specs of original and replacement turbos.

The 2664 compressor should feel better then the previous 2660 even if the same 4.10 turbine housing was used on your car I guess

Sorry if this comes across as a challenge to your information. It's not meant to be. Its a minefield of info out there. We have a turbo specialist in the UK who believes that the S2 spec 2660/4 with 4.10 turbine provides better performance than than the original S1 spec. Agree with the 2470 compressor, not so sure with the 4.10 turbine.
_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252