sechsgang

Really? Id expect higher yet...911s don't usually lose that much HP getting to the wheels compared to most...

997TTMeteor

What is typical drivetrain loss on the 996/997 cars?

ToyGuyAZ

Every Dyno reads different and I'd expect the drivetrain loss to still be 12-14%. And as mentioned before the more important thing to consider is the baselines of other cars to compare and the back to back results to see gains in performance parts.

The interesting question would be what does a 997.2 RS rated at 450hp Dyno on GMG's Dyno or on the other shops Dyno. The 991GT3 accelerates significantly faster than all the older GT3 and RS's. In the 1/4mile all results have shown 124-126mph. That's a huge jump from every other GT3/RS. To go that fast given the weight it's definitely making more power than 475hp to the crank

frayed

Huh?

437 rwhp at 14% drivetrain loss = 508 hp at the crank.
437 rwhp at 12% drivetrain loss = 496 hp at the crank.

THis motor is rated at 475 crank hp.

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Fabryce, asking the question again I'm guessing this is for both the headers and center section. Any dynos on headers alone? Not having gotten my car yet, I'm hesitant to make it any louder cause its a street car.

I'm most interested in the tq gain in the bottom half of the revs. To me this motor makes plenty of juice at the top end to get into a lot of trouble on and off the track, but the low end tq bump looks fabulous.

ToyGuyAZ

The dyno sheet they posted is the headers alone.

frayed

Cool. Damn, hard to believe that PAG left this much power on the table. Maybe exhaust/intake/software will be what separates the RS from the 3 (in terms of power).

sechsgang

Porsches have historically had better than average percentages of power to the wheels...at least all my other cars have been this way. +1 on wanting to know what a 997.2 rs dynos on that dyno.

Obviously this is all just curiosity, the gains from the gmg exhaust work make total sense in this scenario.

kosmo

Id say 8-10% for the 997s

chinaman247

are these the same as the 997.1 gmg headers? Any dyno showing the gains on a .1 gt3?

ScorpionT

Drivetrain losses arent a static figure, but instead change with RPM (inversely).

The stock parts are to pass emissions and be inexpensive (they save money where possible).

Macca

I have a fair bit of experience on this subject. Whilst youd probably see 8-9% drive train loss (TLF - total loss factor) with a GT3 on a hub mounted dyno such as a Dynapac 4000, on a roller based dyno those looses would be more like 12-14%.

There are to many variables between runs, equipments etc to get anything other than a comparative value from these....

alpine-al

Based on the dyno chart, the HP and torque gains from GMG's less restrictive exhaust are impressive. I didn't expect to see any gains below 4000 rpms where the stock exhaust is usually more than sufficient to handle the flow.

I wonder if the car was put on the dyno immediately after changing headers/cats or if the car was driven for an hour and the ECU was given time to re-adjust before going on the dyno.

.

gmgracing

The headers are 991GT3 specific along with the dyno charts.

The headers do you use a similar design to the race proven 997 design.



Keep in mind dyno test for the 997 are done in 2wd mode on the dyno and the test for the 991 GT3 are done in AWD mode as the car cannot be dyno tested in 2wd mode due to the electronics in the car.

gmgracing

Headers were installed and vehicle was driven on the dyno only.. No road miles. with the ECU being adaptive we would expect a increase in hp over time and mileage.

SamFromTX

Can you please elaborate on that? Maybe others get it but I am unclear how are the elctronics different from 997? RWS should be a non issue in a straight line. Also, do you test with traction and stability off? Thanks in advance.