MCoupe

So I am at the service department waiting for a new Amp install for the car and read in the manual that Porsche does not approve dyno measurements. Wonder why...First time I see this in a vehicle;s manual.

Edgy01

I saw that, too. I'm guessing because some people are not too brilliant about setting up a automotive or engine dyno. Air flow is critical and they have to remember to appropriately feed cooling air and extract exhaust air away from the car. If you fail to do that you can really trash the engine. Perhaps they are siding on the conservative. You can BET that they do that with their cars in Zuffenhausen.

Dan

MCoupe

My understanding was they did dyno each engine before mounting them...

OCBen

Impossible to do on a dynamometer without the driving wheels to turn the dyno.

I'm sure they use some other instrument for measuring output, which in this case woud be "at the flywheel."

1AS

Ben,
I think the factory uses an engine dyno, not a chassis dyno. Chassis dyno is less accurate, since you have to estimate drive line loss, leading to exaggerations of real hp.
Engine dyno is used for all race engines (final tuning done on dyno). It eliminates the need for air cooling, and allows the engine to be evaluated without power robbing accessories. Manufacturers then correct for this with standardized terminology (DIN, SAE).At least that is my experience and understanding. I've had a bout a half dozen engines dyno'd. Only had one car on a chassis dyno. AS

OCBen

Good point. I knew they evaluated engine power separately, but I wasn't aware that the machine that does it was also referred to as a dyno, since most of the time that we hear that term it's in reference to the chassis type - the wheel driving type.

And yes, driveline efficiency is very difficult to acertain and is often only guessed at, leading to exaggerations of engine hp claims as you mentioned. The only way to assess it accurately would be to dyno the engine separately and then dyno the chassis after the engine is installed. The hp ratio of chassis to engine is the efficiency of the driveline.

MCoupe

Ben...Not cool man! Glad you see what I meant....It hurt deep man, real deep!

OCBen

Ah man, my sincerest apologies then. How can I make it up to you?

MCoupe

Just a public apology + an official letter allowing me full use of your vehicle at my convenience would do!