928 S4 Twin Turbo Dyno Results

[Herr-Kuhn]

Greetings,

I finally had some time to strap my twin-turbo down after increasing the boost pressure to 12 psig. The results are as follows:

519 RWHP
505 RW ft-lbs

As you can see from the pull chart the turbochargers allow for a very wide and usable power-band. I've always said for a street car the power should roll on hard around the 3.5-4K rpm and offer a wide and usable power band.

Please note...this is a 1988 car with over 175,000 miles on the engine with no rebuild or internal engine work whatsoever. Not even as much as a valve cover was lifted off this engine during the conversion. It is totally "stock" and has quite some mileage on the clock.

Additionally, these pulls were made in 95 F Kentucky heat...there is at least another 20-30 HP to be had with lower ambient temperatures, maybe even more. This appears to be the last of the warm weather this year.

MISSION ACCOMPLISHED!

[Darien Nunn]

John,

CONRATS!!! Great numbers!

Originally Posted by Herr-Kuhn

Greetings,

I finally had some time to strap my twin-turbo down after increasing the boost pressure to 12 psig. The results are as follows:

519 RWHP
505 RW ft-lbs

As you can see from the pull chart the turbochargers allow for a very wide and usable power-band. I've always said for a street car the power should roll on hard around the 3.5-4K rpm and offer a wide and usable power band.

Please note...this is a 1988 car with over 175,000 miles on the engine with no rebuild or internal engine work whatsoever. Not even as much as a valve cover was lifted off this engine during the conversion. It is totally "stock" and has quite some mileage on the clock.

Additionally, these pulls were made in 95 F Kentucky heat...there is at least another 20-30 HP to be had with lower ambient temperatures, maybe even more. This appears to be the last of the warm weather this year.

MISSION ACCOMPLISHED!

[Herr-Kuhn]

That was the highest HP pull. Here is another from earlier in the day which was stopped at 5,800 RPM. The car was not as heat soaked thus the torque was even higher. The 518 HP sheet was with an additional 1.8 or so degrees of timing added in upstairs. This pull was at 89 F. Also keep in mind I can't get my full charge air cooling capacity sitting still with fans in front of the car...out on the road the ram-air effect will cool the charge much better.

As you can see the car is well capable of pulling massive midrange torque numbers. The tip-in throttle response is incredible, especially mid-range. HP may sell parts, but powerband width is really what you are after, especially on a street driven car. It's a pretty big stick to say the least.

I'm wondering what results I will get at like 45 or 50 F...bound to be better.

The power curve is exactly what I expected to see...peak off just slightly before stock...this is very typical of a turbocharged car.

[Rixter]

congrats John... lots of power there!

[Red Baron]

Congrats!!!! I never doubted you'd get there.

[rhjames]

nice figures for a well engineered set up.......
good work.

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[Herr-Kuhn]

Thanks guys...for those interested the car will be on display today at the Porsche-VW reunion up at GE Park here in Cincinnati, Ohio.

[John Speake]

Congratulations John !

[Fabio421]

[borat voice] Very Nice. Great success!!![/borat voice]

[Normy]

Great work! Keep at it!

N

[porken]

Nice!

SAE puts you under 500, though.

I admit I like to use STD (standard correction) too, because the numbers are better.

[Herr-Kuhn]

Ken, you are wrong. The SAE correction is over 500 HP, it's within a few HP of those numbers.
When I put the car back on once it cools down I'll be expecting to see 530-540 HP or so out of it. It's all good.

[DVC]

Very sweet Shark! Any vids of that beast?

[Herr-Kuhn]

No videos...maybe sometime in the future.

[rhjames]

no offense to anybody listening, but did we need another argument about dyno numbers......

it's a great kit, looks like it belongs there (if Porsche did this from the get go, it might be like this), and near doubling of the factory #'s on modest boost pressures......should be liveable if one doesn't get stupid with it, so what's not to like (?)

Keep after it-----

[Herr-Kuhn]

RH...You hit the nail on the head. I put a 1000+ hours into this development, blow out some sizeable numbers on both HP and Torque in 95F summer heat on a 175,000 mile motor and then someone makes a negative comment about the correction factor used.

You will get different numbers every time you strap the car down...there are a lot of variables at play and the car is sensitive to these variables...temperature probably plays the largest role. No dyno correction program will compensate for a heat soaked boosted car getting minimal airflow over the charge air coolers. Boosted cars are more sensitive to ambient conditions than normally aspirated cars. You can feel the difference by the seat of your pants.

I don't feel as though I need to justify myself any further on this but did feel it was necessary to comment. I know I have a lot of "friends" watching my every move right now. For the record, this morning I'll be having a bowl of plain Cheerios for breakfast with some 2%.

[Danglerb]

Any plans on joining the 200 mph club?

Track events?

[Herr-Kuhn]

Nope...I value my life too much, besides I think it runs out of gear at 197. I'll let Marc Thomas keep that goal, thank you! I set out with an engineering goal and I believe I've met my goal.

I'm looking into options to be able to offer this package "turn-key" as well as "bolt-on".

[porken]

Originally Posted by Herr-Kuhn

I put a 1000+ hours into this development, blow out some sizeable numbers on both HP and Torque in 95F summer heat on a 175,000 mile motor and then someone makes a negative comment about the correction factor used.

You pulled a STD. No big deal. Sounds like you were expecting better numbers.

500ish is a great achievement.

[Herr-Kuhn]

Actually, I am tickled with the results...my goal was 500+ on both torque and HP...ALL GOOD