Thanks Dock.

 

Agreed. Take it to the track...

 

thanks for the explanation

 

Curb weight of the GT3 is 3,043lbs. Turbo is 3,505lbs. Pointless to use "test" weights because who knows how much fuel they were running, how the scale was calibrated, etc. Why not use factory figures and use the delta between them as the constant figure?

That is a difference of 462 lbs. So what are the new thrust to weight figures with those in mind?

 

What Dock said.... The large torque difference erases the advantage in power to weight of the gt3. I've been told hp sells cars and torque wins races.

I think the turbo still has an advantage in thrust with those weights.

 

Curb weight of the '01 911 turbo is 3395lbs. I know that for a fact. The '01 911 is the lightest of the 996 turbos if I remember correctly.

 

Like I said, weights can be played with, and the true measure is to weight the actual cars in question on racing scales.

Porsche claims the GT3 weighs 3043 lbs dry, and for the '02 Turbo Porsche claims it weighs 3395 lbs dry...for a 353 lb difference.

My '02 Turbo weighs 3480 lbs with a full tank of gas and no occupants (measured on four pad racing scales), so Porsche's dry weight of 3394 is reasonable given the weight of gas at 6 lbs/gal (although my Turbo weighs less than 3395 with no fluids).

Based on the dry weights above, here are the thrust to weight ratios for each car...Turbo first.

1st gear ---> 1.61/1.23
2nd gear ---> .86/.69
3rd gear ---> .59/.50
4th gear ---> .47/.39

 

Very nice, Dock.

 

Okay, so the turbo is faster in a straight line....

 

Dock your figures don't take into account drivetrain losses, and how much power/torque is actually being put to the ground. "(gear ratio x final drive ratio) x torque" how does this equation account for the differences in redlines? If the your thrust to weight figures were correct wouldn't there be a bigger difference than what we're seeing?

 

Just look at the trap speed to get your answer. Trap speed is typically a function of horsepower to the ground and gear ratios in the 1/4 mile. Your ET is more of a function of the driver's ability to shift and the car's ability to "hook up" on the launch.

The turbo was trapping higher than the GT3.

 

Agreed , ditto, you're only going to tear these cars up at the dragstrip, go to a real track where these cars come alive.

 

Hmmm... so what made the '04 Turbo gain over 100 lbs. in weight?

In any case, I still think the two cars are too close to call. After all, even a GT2's quarter time is only 3/10sec. slower than the GT3. And I'm pretty sure GT2 is considerably faster than a stock 996TT.

I would not be suprised if the Turbo is faster at speeds above 80 or from a roll on, given that it has loads of low end torque. That's probably what accounts for the high trap speed figures, the flat torque curve that you get once the Turbos get going.

In any case, it's all good. I still know which car I'd rather have.

 

Good questions.

Transmission losses can normally be assumed to be equal, so they cancel out in the formula.

The formula is computed at a specific point on the power curve, and the curve is defined by rpm. So at any rpm there is a specific torque value associated with that rpm. It's easier to just consider peak torque, then look at the engine's torque curve and decide which car has higher average torque across the power band. The Turbo's torque curve is prettty flat and peaks much earlier than the GT3's.

As for what the thrust to weight numbers say in terms of "differences" we're talking about 0.2-.04 seconds in the quarter mile.

What the thrust to weight numbers also tell us is that regardless of the 0-whatever results are, the key to the seat of the pants feel is *longitudinal g*. The higher the number, the bigger the push in the back is under WOT acceleration. This happens to be one of the primary reasons I bought the Turbo...it generates one of the highest (if not *the* highest) longitudinal g loads available in a production car. For me, the "shove" is something I use almost every time I drive my Turbo. It's something I can use *way* more often than the cornering abilities of the car. The percent of time I spend at WOT far exceeds the time I spend at max cornering g, and the high longitudianl g is huge fun.

 

I believe Porsche used the *wet* weight in '04. I asked a friend at PCNA about this, and he was evasive with his answer.

I agree that the two cars easily fall into the "driver error determines results" category. Even cars that are within a second or so of each other in acceleration times can be easily equal based on the driver.

The Turbo, GT2 , and GT3 each bring different things to the table in terms of how they "deliver" the experience, and they're all great in their own ways.