SkipSauls

quartermile, this data is from Porsche itself, with the HP and torque charts provided on their website and brochures. If you're convinced that Porsche is making a mistake, take it up with them.

As for your "smack talk", I'm not going to stoop to your level, but if we do meet someday on a track I'll be happy to show you what a real GT3 can do. Until then, you should consider lightening it up a bit and enjoying life. It's almost as if you feel threatened by the 997, which is silly since you own a GT3, right?

MetalSolid

Here's an overlay chart...

johnfm

Not sure how you figure that a 997 is a glorified boxster, but everyone is entitled their opinion. You seem very focused on the lineage of the GT3 engine and the 997 engine. I think the total package and the intended purpose of the car are the most important factors.

Mikey

Metailsolid that overlay is incorrect. You are comparing on two entirely different scales -- take a closer look.

Skip, I have an 05 GT3 on order (October build) and could easily take a 997 S instead. My last Porsche was an 02 C4S -- that will be my last Boxster. I choose the GT3 over the GT2 at the Porrsche factory race track, after driving both and spending time in a Carrera GT with a Le Mans champ and factory drivers.

sjsharks

How is it incorrect?

It is fairly common to have HP and Torque incorporated onto the same graph.

If accurate, it appears you need to be one heck of a driver to be much faster in the GT3.

996FLT6

I think from the wheel hp/trq numbers more important then crank numbers. Seems like the GT3 off the wheel dyno numbers far closer to the crank numbers. I like to see how the 997S numbers pan out on the dyno. I believe the GT3 motor is a more efficient running motor with less drivetrain loss which thus yield better wheel numbers correct me if I'm wrong. Regards. Mike

frayed

Yes.

No.

The delta b/t crank and wheel hp is purely a function of drivetrain losses past the crank. I has nothing to do with engine efficiency, and everything to do with the parastic losses from the crank to the wheels due mainly to frictional losses.

FWD/front engined cars frequently are said to have a 15% drivetrain loss, RWD/front engined cars a 17% drivetrain loss. It would stand to reason that RWD/rear engined or RWD/mid engine cars should as a rule of thumb be around 15% loss, a 1.17 correction factor going from RWH to CrankHP.

Assuming the GT3 motor dyno's high for its rated crank hp, it is almost certainly due to the motor being underrated from the factory, or perhaps evidence of a really tight motor from the factory that loosens up to make more hp than rated. I think this is the case based on the 1/4 mile times and rwhp numbers published by some board members.

MetalSolid

Quatermile, I know the graph appears confusing at first glance, but it is correct - take a closer look.

Mikey

Metal the problem with your chart is the torque scale is between 250-400 while the hp scale is absolute. You need to keep these charts separate and specify the source to make them credible.

Below is a typical dyno from a GT3 from another board member. NOTE these are RWHP not crank ~ GT3s are typically 400hp+ machines.


This dyno does not resemble anything posted so far in my judgement.

Source for the chart:
https://rennlist.com/forums/996-gt2-gt3-forum/94297-dyno-chart.html

Mikey

Also don't forget ... the GT3 motor is a race proven bulletproof derivative of the GT1, the 997 motor is coming from the mass produced Boxster. It's like comparing a F16 to a Learjet ~ may be even they have the same hp ... but built for entirely different purposes.

BrianPA

I was going to say the same about the horsepower but I think you're exagerating a bit. The highest stock dyno I have seen is in the 350-360 range. This indicates a solid 400 horsepower at the crank I believe. Regardless the car is clearly underrated at 381 horsepower, there definitely has to be more lost between the crank and the wheels than 31 horsepower. Also I believe 911 turbos rated at 420 horsepower typically dyno within a couple of horsepower of GT3's. I seriously doubt they are over-rating the turbos.


I haven't seen any dynos of the 997 S so I don't know if it's underrated by the same factor or not. I suspect not.

I have driven both and it seems like I'm the only one that believes the GT3 feels night and day faster than the 997s. I also did not notice any great torque advantage in the 997s.

As for the weights clearly the GT3 is a little bit lighter but I'm not sure how much. I would like to know who has a GT3 weighing in at only 2900 lbs because I have never seen that either.

MetalSolid

Dude, the charts are from the Porsche website, simply overlayed... It's obviously done that way by Porsche's web designers to save space, as using Nm and kW on the same scale would double the chart's height.

Mikey

OK, I found the charts on the website. I think you made a mistake somewhere in the overlay steps. I went ahead and scaled to hp and ft/lbs as well, and used an absolute scale. The dyno overlay confirms there were no mistakes. Hold on to your GT3 it's the best thing Porsche ever made.

RSA333

I used the numbers posted on the Porsche website, and converted kilowatts (power) to horsepower. Also, I only performed the measures at every thousand rpms, so peaks and valleys may be missed. There is also missing data for the 997S at 8000 rpm.

RSA333

Here is a comparsion of torque, based on the Porsche data. Again, all the formerly stated caveats apply...