993 Dyno question

[stealthn]

We (WWR PCA) had a dyno day yesterday and it was a blast. One thing did come about that I had a question on. One 95 993 pulled 219HP, then another owner put his 97 on and it only pulled 200. I was wondering what would cause this loss of power? I was thinking he should be around 240HP.

On another note the 97 owner did one run and then put on a K&N, then did the second run. On the second run he pulled 4 more HP and 6 more ft. lbs. of torque....

The front one's a kit, but nice...

[Bill Verburg]

219 @ the rear wheels is reasonable for a '95, 200 in comparison is not. But dynos are notoriously fickle devices, any # of things can be wrong w/ the car or the dyno. Were all the other cars reasonably in line w/ the 219?

[stealthn]

Thanks Bill,

I was beginning to think no one had an opinion.

The Dyno seemed pretty acurate, it registered 164HP for a stock 79 SC, 268HP for a 86 Euro Turbo, and a few others that seemd pretty good.
I just couldn't figure out what would cause the loss of about 40HP on the 993???, It had done 3 runs, all about the same. The car seemed to run fine, so I was kind of confused.

Thoughts?

[1fastredsc]

40hp????? i think your confused dude, rear wheel hp is different from flywheel hp. If you 993 is good for 260ish fly hp, then 220 to the rears isn't bad. One thing though, was this figure corrected for atmosphere conditions or is it raw data. Corrected hp and raw hp are two different things.

[Bill Verburg]

Assuming that the vram was hooking up to the dyno ok, one must assume that there is a problem w/ the 993. At a dyno day in the spring another 993vram was similarly down on power, I do not remember the specifics but repairs were made and the car redynoed showing results more in line w/ expectations.

By the way I give credence to the #s you post because they are cross referenced to other cars of relatively well known output. It seems that the dyno oprerator was using his tool correctly rather that just providing big #s which some are wont to do.

When I dyno mine I always ask for the results of other cars w/ relatively well known outputs so a valid comparison can be made.

[stealthn]

RedSC,

I don't know anything about the atmospheric settings, but the cars were very close to their factory numbers. I thought the 97 993 was about 280ish HP, am I wrong?

Factor in 15 drivetrain loss @ 42HP minus the 280 = 238HP, his first run was at 198HP hence my 40 HP loss statement.

The car previous was a 95 993 and it pulled at 219HP run which was close with it's configuration.

[1fastredsc]

Your right, i just read that over and it's still a bit low. If i dyno operator gives you raw dyno data, not corrected, it will always be lower than what it should. In order to sort of form a base line, all dyno runs are corrected to sea level atmosphere conditions (1 bar or 14.7psi) and like 70 degrees F or something. So, say you live in a high altitude like me (12.7psi in the atmosphere), then techincally, my real power to the ground is less than the real output of a similar SC that's closer to sea level and in cooler climate.
I don't really think though that this is the case since other cars were putting out what was expected of them. Good luck with figuring it out.

[Dynamik]

As someone already mentioned, the hp numbers were lower than factory spec because Porsche dynos the engines out of the car and provide you with hp at the flywheel as reference data. Rear wheel hp is going to be lower since you have the load of the drivetrain and wheel friction. I am confused as to why a 95 993 would be putting up higher numbers than a 97. That is still a good question.

[stealthn]

Dyna,

I am quoting the crank numbers....