924Board.org

[Cedric]

Nice with some dyno graphs! Did you run on rollers? Do you have the same graphs with whp? How do you know you are low on hp? did you run before and after? Otherwise there is just to much guessing to conclude anything

What AFRs did you run? Do you have a curve on that to?
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1980 924 Turbo
www.instagram.com/garagecedric/

[9xx]

Yes it was run on rollers, no whp graph but I got the other datasheet now. Looks like it is almost too rich mixture? There was no before IC and after IC runs, just this one. But the question is that did the IC actually do anything beneficial, after all it got quite warm. Would the result have been the same with stock charge tube? But on general level I don't think it is low on power. Torque is for example on Carrera GT level, 276 Nm. Of course boost pressure is slightly higher too.


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Mikko

All gone: 931 '82 Alpine White, original option "220" G31 with LSD + 3 x 944

[Carrera RSR]

Actual numbers for my latest modifications and running just 0.7 bar boost

180whp (est 210.4 hp at the flywheel) at 4829 rpm which is when we came off the gas
198.09ft/lbs torques (est 229.47 at the flywheel) at 4278 rpm. Of which this figure was fairly flat from 3500-4829rpm when we shut down

This is still with the restrictive K&N air filter and not the larger ITG which will be fitted in due course. This is hitting an AFR of circa 10.x at WOT which is too rich, but safe. Timing was set at 8.7deg at idle. CGT spec turbo, Piper 270 cam, forged pistons at 8.2:1 CR, 951 FMIC, modified intake manifold and S2 TB. Running stock S1 CIS and ignition.

I am happy as I thought it would be circa 200 bhp at 0.7 bar. Sense prevailed today in not pushing it too hard to soon on the rollers. Now its running its best to take baby steps to getting the bigger numbers and getting the set up right first. Next step is to modify the WUR to be adjustable and remap the advance/retard curve by having the dizzy rebuilt.
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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]

You have to be reeeeally careful in comparing roller dyno HP (especially guessed engine HP) numbers with factory numbers. There is so many factors in between that you cant really say anything accurate, its more of guidelines. And comparing one roller dyno setup with another one should be taken carefully. But I think it could be quite reasonable numbers, maybe lean out the AFR slightly will give you more HP, but the extra knock margin is also nice. Mine runs pretty flat AFR wise from 4k rpm to redline, just some very small fluctuations bewteeen 11.1 and 11.3, it an s2 engine at 0.7bar with s1 2664 compressor .

The FMIC would probably be much better than TMIC at very low coolant air flow, so that will likely affect you results a lot.

Would be really nice if you had some log data on a full acceleration run, that would be a great comparison. I have some full throttle logs that I did down an airfield. Would be nice to see the actual in gear performance changes with your upgrades !
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1980 924 Turbo
www.instagram.com/garagecedric/

[Carrera RSR]

Cedric, I appreciate your watch out on roller inconsistencies. I guess I should have put a legal disclaimer at the bottom of my post that numbers are only guidelines and liable to change!!

Haven't seen your results posted?
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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]