bovien

Was aprox 20-30 hp more than expected. Is this typical, or might my car have an undisclosed upgrade? Only current mod is a center bypass.

Top red is torque, middel red i fwhp, blue is whp. Green is driveline loss measured by dyno

runet

I don't think a 90hp loss in the drivetrain is correct. Maybe more like 50hp loss.

RennOracle

Does Maha give wheel horsepower? That's a first, Maha dyno always (that I know and saw) give engine power, and it gives 468hp, I don't know what GT3 do you have (if it is a 997.2 gt3 RS a tune might be enough to put around that power), but it might have some mods, ecu for one, exhaust (it would be pretty evident), or just rebuilt with a bigger displacement or cams or something internal.

Do you have photos of the engine bay? Maha aren't known to give faux results, but if you don't even spot an aftermarket exhaust, IDK.

bovien

Sorry. It is a .2 GT3 with a center bypass. Nothing to spot in engine bay.
I asked the seller about mods, which was Cup LSD, endless pads and a track setup.
However, I also suspect changes in gearing or final drive, as redline 6th is 186mph.

Maha does give both engine and whp. Driveline loss is measured with rolling resistance going back down. The tech explained the process and was also baffled over the result

Spyerx

No way if that number is whp. Something is off. Remember these are rated what 435 crank at factory and we know it's a little conservative.

bovien

No, the 475 is fwhp. That's still quite a bit more than the 435, and why im wondering what mods would push this

AudiOn19s

I'm not familiar with this dyno but unless the engine is out of the car and bolted to a dyno bench they are just using a calculation of wheel HP to convert it back to Flywheel.

If you have gearing changes it throws the math off and the run was possibly done in the wrong gear. I believe cars with shorter gearing need to dyno in 5th gear.

Lots of variables, use the numbers for before and after comparisons for modifications not for absolute HP measure

bovien

I would guess 70-ish. 90 seems excessive

bogey1

For comparison: mine is also a 997.2, but has new headers, HF Cats, and side deletes plus a custom Cobb Tune. I had been told driveline loss was 50-60 FWHP.

RennOracle

I don't know, what I know, is that MAHA dyno don't lie (hell manufacturers not only approve MAHA dyno, they use it) unless the run was badly performed.

Spyerx

For comparison sake my plots from cobbs socal dyno are very similar to the ones Bogey1 posted as far as measured wheel horsepower peak. I'm a 3.6.

CosmosMpower

Your 3.6 puts down 410 rwhp on a dynojet?

bovien

Just to clearify a bit: the dyno was done at a more than reputable shop. They are not just some dude doing a tune and exhaust, they are working on the countries premier race cars (well, was until the series when bust a few years back), and have been in the business from before I was born.
I would not question the personal, and apparently the brand of the dyne should be all good. Engines for pro race cars are build and measured here.

So, if we take away the dyno uncertainty, do we have any knowledge of 475 fwhp being a real world number without other mods than a center bypass?

Spyerx

Whatever Cobb has in Costa Mesa ca. I thought it was a mustang. I don't remember. Peak was 406 iirc. I have the charts somewhere.

Regarding this dyno run, no 475 isn't right for these cars it's too high.

Does the 385 number reflect measured wheel horsepower? If so that number is realistic for a non modded 997.

bovien

It does. So it is actually the transmission loss that is measured higher than anticipated.
Strange..