niteriderc5

Insideline just dyno'd a GT2 RS - put down 580 horsepower and 518 lb-ft as measured at the wheels on California's "premium" 91

Porsche rated the car at 620 - Amazing figures if you ask me.

I know the POrsche costs more than double but is Porsche being too conservative with their #s?

Zr1 is rate 638 - Stock dyno charts I have seen put it between 530-540 - is that a lot of parasitic drag or what ?
Insideline link to dyno run and chart

http://blogs.insideline.com/straight...2-rs.html#more

overst33r

No. Simply one manufacturer underrating their car, while the other rated it as they should.

Here are the numbers. Porsche is clearly underrating the car. Considering that the ZR1 has less power and weighs 200LBS+ more, the results are right in line, although the trap speeds don't suggest a 200lb and 40whp advantage for the GT2.

GT2

Curb weight, as tested (lbs.) 3,180
Acceleration, 0-30 mph (sec.) 1.7
0-45 mph (sec.) 2.4
0-60 mph (sec.) 3.6
0-60 with 1 foot of rollout (sec.) 3.3
0-75 mph (sec.) 4.6
1/4-mile (sec. @ mph) 11.2 @ 129.8
0-30 mph, trac ON (sec.) 2.2
0-45 mph, trac ON (sec.) 2.9
0-60 mph, trac ON (sec.) 4.2
0-60, trac ON with 1 foot of rollout (sec.) 4.0
0-75 mph, trac ON (sec.) 5.2
1/4-mile, trac ON (sec. @ mph) 11.8 @ 129.0
Braking, 30-0 mph (ft.) 24
60-0 mph (ft.) 100
Slalom, 6 x 100 ft. (mph) 72.5
Slalom, 6 x 100 ft. (mph) ESC ON 70.5
Skid pad, 200-ft. diameter (lateral g) 1.03
Skid pad, 200-ft. diameter (lateral g) ESC ON 1.03
Sound level @ idle (dB) 61.1
@ Full throttle (dB) 85.1
@ 70 mph cruise (dB) 73.0
Engine speed @ 70 mph (rpm) 2,150

ZR1

Curb weight, as tested (lbs.) 3,366
Acceleration, 0-30 mph (sec.) 2.2
0-45 mph (sec.) 3.0
0-60 mph (sec.) 3.9
0-60 with 1 foot of rollout (sec.) 3.7
0-75 mph (sec.) 5.3
1/4-mile (sec. @ mph) 11.7 @ 126.7
0-30 mph, trac ON (sec.) 2.2
0-45 mph, trac ON (sec.) 3.1
0-60 mph, trac ON (sec.) 4.0
0-60, trac ON with 1 foot of rollout (sec.) 3.7
0-75 mph, trac ON (sec.) 5.3
1/4-mile, trac ON (sec. @ mph) 11.7 @127.0
Braking, 30-0 mph (ft.) 24
60-0 mph (ft.) 101
Slalom, 6 x 100 ft. (mph) 71.8
Slalom, 6 x 100 ft. (mph) ESC ON 72.8
Skid pad, 200-ft. diameter (lateral g) 1.02
Skid pad, 200-ft. diameter (lateral g) ESC ON 1.0
Sound level @ idle (dB) 57.4
@ Full throttle (dB) 93.3
@ 70 mph cruise (dB) 75.5
Engine speed @ 70 mph (rpm) 2,000

dsevo

The ZR1 does seem relatively over rated hp wise compared to the competition. The 4th gen Viper dyno's at the same hp if not a little more and are only rated at 600. This is also interesting because Chevy was much more conservative in their rating of the Z06 with only a 10% loss vs. around 15% for the ZR1. Still an awesome car nonetheless.

dvandentop

damn the gt2 sure sounds like a ***** cat on the dyno

the lfa in their link sounds bad *** though

Shurshot

For when the ZR1 is in the shop

racerns

Both the ZR1 and the Z06 are rated using a SAE certification system that uses 3rd party verification of the results. This means neither is under or overrated. The results are what they achieved in the testing on an engine dyno. The difference is that you are trying to compare chassis dyno results to engine results when there are too many variables to really convert back to true engine hp. The ZR1s do not chassis dyno well due to the lack of air flow to provide proper supercharger cooling.

logan1080

[QUOTE=Shurshot;1577445996]For when the ZR1 is in the shop

[/QUOTE

Ahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh hhhh. Pretty much the things I would buy if I won the lottoeek:

Shurshot

Me too, I found those pictures on a Porsche forum.

The owner who posted that picture was impressively humble and down to earth in all that I saw within his posts........ in addition to having impeccable taste

Leonie

One thing to think about: the Porsche indeed has a bit less parasitic loss, because of its engine directly mounted to the trans, like a typical FWD car, only the other way round.

But the difference is not as big (or I might say should not be as big) as these numbers suggest.

A long time ago (might not be current state of technology?) I learned like 12% drivetrain loss for FWD cars (and Porsche 911´s), 15% for "standard drivetrains" (front engine / rear drive) and 18% for most AWD cars.

Please correct me if wrong, or better, not "up to date".

Best, Bernd

range96

You're correct in Porsche's lower driveline powerloss. There is no torque tube or driveshaft. The layout is a little different from a FWD turned 180, though. Actually, more efficient than FWD layouts. The only negative is: the whole engine is aft the rear wheels.

Kelly100

I use to get really irritated at people who said "best bang for the buck" . But after owning 2 911 TTs and doing a few mods and paying porsche service costs--and since I have driven both extensively, I gotta say that I still get the biggest Kick out the the old detroit iron ZR1. So while I can admire the above porsche model for what it is, I cannot generate any interest in it. Just IMHO.

355Spider

Then how does this explain that a Z06 and a Zr1 on the same dyno, same day will dyno a 70-80hp difference. No where near the advertised 133hp difference. And they have the same tranny, diff etc...

dsevo

+1, that was my point.

Shurshot

I thought the tranny and diferential were different from the Z06 to the ZR1?

For sure if they are different someone needs to call GM and let them know that there is something the ZR1 has that is not being shared with everybody else

Notch

It's not a negative in terms of acceleration traction.

range96

Racerns already addressed this: "The ZR1s do not chassis dyno well due to the lack of air flow to provide proper supercharger cooling."

racerns

You missed this part:

Other things that can factor in are things like the SAE correction factor which when applied to a supercharged engine can give you an artificially lower number in certain conditions. This is just not me saying it this was also from Katech who has engine dynoed both the LS7 and LS9 engines and find them to be within a few HP of their advertised rating. By the way the ZR1 does have some beefier drivetrain components like the clutch and rearend that would cause a little more loss than the Z06. The point is that there are way too many variable to accurately relate back to true engine hp using chassis dyno data.

What is missing from the Dyno results from the GT2RS is what correction factor did they use and what were the test conditions as thoes things can affect the results greatly.

range96

Minor differences that would affect powertrain loss differences slightly. Both cars run in 4th gear on the chassis dynos. The gear ratios are different, differential housing is beefed up. Not sure about the robustness of the drive shaft. The half shafts are heavier.

And racerns reminded us about the heavier clutch, of course.

Andrew M

Same day same dyno the zr1 makes roughly 20-30 rwhp more than the gen iv viper which puts them right inline with each other.

That gt2 RS dyno is very optimistic, my buddies 997 GT2 with all the bolt-ons and tune made 600rwhp. Our other buddy with a stock GT2 RS has raced him on multiple occasions and the result is always the same the modded GT2 makes the GT2 RS look slow, if I had to guess my bet would be about 50-60rwhp difference between the two.

The owner of the GT2 RS bought it intentionally to beat the GT2 and to be the baddest P car in the group, which at the moment is proving to be impossible until the mods start rolling in.

Kappa

I think that dyno is off. Their numbers always seem high.