Actually if you take .85 then you come up with 634. Also your conversion is not correct for SAE. The conversion for SAE IS a standard, however based on the correction factor it can be above rated DIN. Several times I have seen the SAE rating higher than DIN when using the corrected numbers.

 

Stephen,

The stock turbo is 415 bhp or 410 SAE. To my understanding 640 bhp would equal about 634 SAE HP?

In addition, if you have a conversion factor, you must work from your rwhp as the starting position. If the dyno renders a rwhp number of 539 what "factor" must you apply to obtain flywheel hp. In the Stage IV case it would have to be about 19%. If you took about 84% of 640 then you come very close to the 539.

So you can multiply your dyno reading by 119% or multiply your fwhp reading by approx. 84%. Six of one and a half a dozen of another. You just have to be clear about what you are talking about so everyone is on the same page.

 

I thought the same thing. Intresting enough the years of dynos I have found that in hot weather and humid conditions the SAE factor corrected is very similar in in some cases a horsepower or two higher. Weird I know. Days like today...105 60+humidity....yuck. At any rate it is a standard conversion factor on paper...

 

The way it should be calculated is take the 640 HP and x by .85 (15%) = ???? RWHP

 

Whatever happened to the butt dyno?

 

Todd's above reply brings on another good question. Porsche advertise 415 hp (bhp @ flywheel). I have seen several stock Porsche's dyno'ed. One as recently as yesterday. They always produce between 370 and 380 hp.

In light of the above neither the 85 or the 19 makes any sense.

 

I guess we should also specify which dyno is used (2 wheel or 4 wheel). I have seen several stock 996TT dyno'd on the Mustang 4 wheel dyno and we all put about ~ 350 HP / ~350 lb ft at the wheels. The difference is quite significant.

 

Chad, Just out of curiosity, how did you come up with your power figures of 805HP and 780 TQ?????

 

But Chad, who knows what the REAL ( vs rated ) HP of the stock cars is ?
375 RWHP divided by 415 rated FWHP would imply only a 10 % drivetrain loss - very unlikely . So.., at a more reasonable 15 % drivetrain loss ( 375/ 0.85 ) , the stock base turbo motor is putting out 440 flywheel HP ?

 

Porsche always seems to underestimate the HP. From the factory the engines are dyoned and any deviations over and under 3% are supposed to be rejected. Atleast from what I've heard.

 

In the case of Stage IV, the correction factor is 15.7%. Take the 640 FWHP x 15.718% and you get 100.59 Hp drivetrain loss. 640 - 100.59 = 539.4 Hp...which is what the EVO dyno shows.

The FWHP x the correction factor = the horsepower lost through drivetrain losses. Take that loss and subtract it from the FWHP to arrive at RWHP.

Or like Todd (and others) said, multiply the FWHP times 85% (for a 15% loss) and that will give you RWHP.

 

Todd,

I multiplied the rear wheel numbers by 1.18.

Is your Stage V still going to be ready by the last week of September? I can't wait to meet you and see the Stage V up here in Northern California.

 

I have an RS-Tuning X-50 here in the US. It is a fabulous product but dealing with RS was a real excercise in patience and persistence. I will say that any technical problems that arose along the way were addressed by RS very aggressively and very quickly. But Nordstrom they are not.

 

Regarding the hp/loss discussion, my stock TT (except for Europipe Stage 2) had 374 peak horsepower on a Mustang four wheel dyno.

 

Chad, Since when are you putting down 683 RWHP????

What are the dates and details?