Bernie930

Max hp on the gt3 is at 7600rpm, compared to the RS at 7900rpm which is higher, but the torque is the same. Top end is virtually the same, the gt3 being faster by 1mph (factory porsche numbers). What is really responsible for the HP increase? Different cam timing and /ecu mapping? But until someone posts REAL dyno numbers (from an unmodified car of course) who knows.

Boxster Coupe GTS

Andreas Preuninger also commented that the increased power in the new GT3 RS engine is largely due to the "olympic lungs" provided by the new enlarged air-intake, which - as a bonus - also provide a greater air ram-effect...

mikymu

That adds another 15 hp at the wheel!

Bernie930

GTS coupe, You are serious right? Our 3.6 grand am motors make around 400-20rwhp (measured on proper dyno's like dyno dynamics or dyna pack, not a joke like a dynojet or mustang), these are pretty much just like your street motor, less the adjustable cam timing (some have a little different cam), given some PMNA tricks,l98 octane fuel and old school bosch ms 3.1

Bill996

I believe he said the number would be closer to 460 hp.

GT3

My stock 2010 GT3 dyno'ed that. 414 whp corrected, 4th gear, dynojet, car only had 250 miles, and only 1 pull was down at operating temp. Im quite interested in seeing a 2010/2011 GT3 RS dyno graph...

That same dyno showed a 997.1 GT3 with SW track exhaust, evoms software and BMC filter at 397 whp using the same correction and weather; so its not a high reading dynojet.

Bob Rouleau

Porsche HP figures are always a bit conservative. The 997.1 claims 415 engine HP - and yours 435. With the usual 15 percent correction from wheel to engine HP this suggests that the dyno readings for both cars are a bit over stated.

10 GT3

How about posting the dynosheets or is this just heresay?

Factory HP figures are rated at the flywheel. You normally add 15% to wheel dyno to compensate for the drivetrain losses to get to flywheels numbers. For example, a 435 hp car would put out about 378 hp on a wheel dyno and a 415 hp car would put out about 361 hp. For comparison with other cars, a stock 414 hp E92 M3 puts out 350-360 hp at the wheels on a dynojet. Yes, a 997.1 GT3 consistantly makes more than this and is underrated by Porsche. 415 at the tires is around what a stock F430, Gallardo or GT-R all put out on a Dynojet. If a 997.2 GT3 can put this much out, it is actually in the 475-480 hp range at the flywheel. That seems lofty even for Porsche's typical underratings. I won't believe it until I see it. I won't be dynoing mine until I get a couple thousand miles on it, in a couple of months.

GT3

997.1 GT3 with SW track exhaust, evoms software, and BMC filter:
http://www.6speedonline.com/forums/g...e-evomsit.html

MY 2010 STOCK GT3 (250 miles):

GT3

Porsche and BMW do not have the same drive train loss %. Its about 17%-22% for BMW E9x M3s and 10%-12% for rwd Porsches.

You should not track your car either until it has over 10K miles

You must have missed this thread: https://rennlist.com/forums/997-gt2-...-2010-gt3.html

10 GT3

No, I didn't catch your thread.

I am not sure where you are getting your drivetrain losses, but this is certainly not true. We could only wish for 10-12% drivetrain loss on our cars. First, 986 Boxster S' consistantly dyno 220-230 rwhp, 996 3.4l consistantly dyno 250's rwhp, 996/997 3.6l consistantly dyno 270's rwhp and 997.1 Carrera S' are consistantly in the upper 290's/low 300's rwhp on a dynojet. 15% is actually on the low side, but is close with the strongest of our cars. Keep also in mind that these are all SAE on a Dynojet only. Percentage of drivetrain loss is more of a factor of torque of the engine over anything else.

Remember that HP is just torque calculated at engine speed. Driving a flywheel is no different than driving a crank pulley as both are just resistance to an engine that has to be overcome. The greater the torque, the lower the percentage of drivetrain loss. At the rotational speed if you put the same accessory drive, transmission and differential (think of an LS2 and an LS7 in a Vette) with 2 different engines: one producing 400 hp and the other producing 500 hp. The drive train consumes the same amount power from both at the same rpms and the higher HP engine has a lower percentage of drivetrain loss. Another way to think about it is the resistance to movement is always the same with the same drivetrain components so the force to overcome that resistance is always the same. As a result, adding a lightweight flywheel does not add any power to the engine, but it reduces the amount of power needed to turn the flywheel and hence reduces drivetrain losses. If you have 2 engines that make the same power with the same drivetrain, but one is smaller displacement and makes the same power at higher rpms; the higher rpm engine will always have higher drivetrain losses. This is because it takes more power to turn the accessory drive and drivetrain faster/at higher rpms. If we had the torque of a Viper we might be able to get into the 10-12% drivetrain loss, but we don't. Despite the higher power, the higher reving nature of our engines increases the drivetrain power loss.

I saw you used STD. I found your thread on 6speed and they said it is around 405 rwhp SAE, which is pretty good...about 10 hp more than what I would expect. What were your run conditions? Humidity? Temperature? What was the correction factor? The difference between SAE and STD is not weather. It is the temperature and pressure basis for each factor. SAE corrects to 29.23 in/hg and 77 degrees while STD corrects to 29.92 in/hg and 68 degrees. If you have your run file, you can use Winpep to view it. Changing your viewing options will show the test conditions. It is too bad they didn't get a torque reading. Did they not know where to hook up the tach reading or did they not try to hook it up? It is actually easy to get a reading off the passenger side bank from inside the engine compartment.

Why wait a couple thousand miles to dyno? To give time for the motor to loosen up. They usually pick up power as the loosen up. After the X51 swap in my 996, I dynoed too soon. I dynoed at 1500 miles and the motor was so tight it didn't really want to rev past 6000 rpms. It didn't loosen up until around 3500 miles. I have no idea of how long it will take the GT3 motor to loosen up.

GT3

Front enigine RWD cars do not have the same drivetrain loss as rear/mid-engine RWD cars. I do know that 10% DT loss is conservative, and the real DT loss on 997 GT3s could very well be 15% Regardless, it does not chance the fact that the bone stock 997.2 GT3 put down 414 whp (STD)/ 405 whp (SAE) Vs 397 whp (STD) 997.1 GT3 with SW track exhaust, evoms, and filter, on the same dyno, same weather, and same correction fomula. Dynos are just a tool to compare differences in gains, etc. Not really just to determine absolute power.

You stated, "As a result, adding a lightweight flywheel does not add any power to the engine, but it reduces the amount of power needed to turn the flywheel and hence reduces drivetrain losses", which is correct, so there is obiously less drivetrain loss on a rear engine RWD car (GT3) that does not really have a driveshaft unlike a front engine RWD car (M3) that does. Both cars do not have the same drivetrain loss. Stock M3s do not dyno 350-360 whp on a dynojet SAE corrected. That is a myth. More like 335-340 whp. http://bmw.pencilgeek.org/DynoDB.html I know, because I just sold my 2008 BMW M3 with a 4.6 stroker motor 534 HP/433 whp (almost 20% DT loss) .

I do not have the dyno files of this run, the shop does. The reason they posted the results with the STD correction, was to compare the results with their modded 997.1 GT3, which used the same STD correction. The SAE correction was later "plugged in", whcih is why I know it was 405 whp SAE. If you re-read the thread on 6speed, they state that the RPM cable they had could not get a proper reading, they had order a new one.

As far as break in, many have different opinions. Running the car near the redline every once in a while (2-3 times a day during operating temp) wont hurt the engine, its actually good for it since by not doing it (especially during the very very first miles) the rings may not seat properly. But maybe they did back at the factory when the engines are being tested. Sure it will open loosen up as more miles are put on, but these engines are dyno'ed at the factory for 10-15 minutes at their peak prior them being installed in the car in the car to ensure the 100-105% at least of their advertised output. Why does Porsche not require an oil change at first 1,200-2,000 miles, but at 12,000 miles, unlike the M3s which require an oil change at first 1,200 miles due to break-in?

But again, all this does not chance the fact that the bone stock 997.2 GT3 put down 414 whp (STD)/ 405 whp (SAE), one pull only was done, Vs 397 whp (STD) 997.1 GT3 with SW track exhaust, evoms, and filter, on the same dyno, same weather, and same correction fomula. Thats 17 whp difference over a modded 997.1 GT3.

YearOne

A bigger engine will do that for you, is it surprising? I would think that the RS will put down 430+whp on this dyno.

10 GT3

E90 an E92 stock dynos. Both are SAE, which is about 2.6% lower than STD.

911dev

Yes, but the RS makes more power as the revs rise.