i'm pretty sure MT has put the GT-R on a dyno before...

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I give up.

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you might want to recheck your math, wntl2l7. each wheel doesn't put down 393 lb-ft of torque. that would put the combined torque at the crank to be over 1200 lb-ft. that 393 lb-ft of torque is distributed to all 4 corners (98.25 lb-ft/wheel). gt-r's torque can be diverted 100% to the rear wheels or split it 50/50.

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The true amount of torque measured at the wheels is actually significantly greater than engine torque, thanks to gearing.

For example, look at that Audi e-tron concept shown a while back. Audi reported it made 3319ft-lbs of torque at the wheels, which is true. Then you realize the "at the wheels" number is actually more around around 252ft-lbs once you adjust for gearing, tire size, ect.......like a dyno operator does.

Think of it this way. In a hypothetical situation, lets say an engine is putting out exactly 300ft-lbs of torque on a perfectly accurate engine dyno.

Then you put that engine in a car connected to a transmission, differential, wheels, ect....which each manipulate that torque. When you then measure the torque on a wheel dyno, the dyno might spit out a number like 4,200ft-lbs. Which, is the actual amount of force that wheel is generating. The operator then enters a correction factor for the transmission gearing, differential gearing, and tire size. Depending on the correction he get an "at the wheel" approximation, which might be 280ft-lbs or so. This is the "at the wheel" number we see on chassis dyno printouts.

Then, to figure out roughly what the engine tq actually is, we can correct again for drivetrain losses (this is where that ~7% or so approximation that people use to correct from 'rwhp' to 'engine hp' is used). At that point , we then get 299.6ft-lbs of torque. This is our best approximation of what the engine is actually putting out. If we've done everything right, it should be reasonably close to what the engine would register on an engine dyno.

Remember though, that a chassis dyno is not a perfectly accurate measure of engine hp and torque. It uses calculations and correction factors in order to arrive at a best estimate. In fact, you could run the same car on the same dyno multiple times and never get the same numbers. This is why a dyno operator will often do multiple runs, then average them, hoping to get the best possible estimate.

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That's why you don't dyno a car in first gear, or you will come up with something crazy like 1200 lb-ft of torque. You do it third or fourth, something that is close to 1:1 ratio to get an accurate reading.

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LS2LS7, you are right. I wasn't here for the debate last week, but it sounds like an interesting one. Anyone that truly believes the GT-R can only produce 393ftlbf at the wheels must not have passed high school physics.

The "at the wheels" torque number that is often quoted is actually an estimated crankshaft torque minus drivetrain losses. It's actually a quite useless number, since that actual torque value is probably not seen at any point in the driveline.

Yes, it's quite common for dyno operators and magazines and even other industry professionals to quote numbers like that "at the wheels", but anybody with a basic understanding of physics should know that they are incorrect. I would guess that most of the professionals using this terminology also understand that it's wrong. They use it because it's the common and accepted way of representing torque numbers. But everyone should know that it is not meant to be taken literally.

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ripiopower
11:42PM (12/07/2009)
This is one of those cases --- The Nissan GT-R there nothing bad tah anybody can say about this car when it comes to performance.

People try to compare this car to everything out there and it will never make sense . Why?
because there nothing out there that can make a better performance car for the money'''
at least not for now. it just one of those cars'''

This car is a beast in every category''


But we all know that the Mustang is losing traction, that's a given.

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The GTR maybe be faster in every way but my God does the GT500 sound amazing.

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Who ever was driving the GT500 must have been asleep at the wheel. Could you even consider that a launch?

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Tourian,

Even when you dyno a vehicle in its one-to-one gear (which isn't always possible depending on the vehicle), you still get a ridiculous torque number as the actual input. Remember that there are gears in the differential that aren't typically 1:1, then you've got the wheels and tires, which also manipulate the number heavily. Those are just the biggest factors, depending on the car there can be other factors that play with torque output.

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Lar7789789,

Of course traction lost will be a given for a car like the Super Snake. But the cars are being compared stock for stock.

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Now, the question is: which tranny will last longer doing those launches?

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yeah was surprised as well, given the GT-R is a heavily track biased car.

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Haha, right, John?

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its only if the owner turns the VDC off and even with it on it can take the mustang on the track.

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This is one of those cases --- The Nissan GT-R there nothing bad tah anybody can say about this car when it comes to performance.

People try to compare this car to everything out there and it will never make sense . Why?
because there nothing out there that can make a better performance car for the money'''
at least not for now. it just one of those cars'''

This car is a beast in every category''

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@John H.

I applaud your comment! :) It was witty!

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@ John H.

I guess your trolling is a little out of date, launch-control is warranty-covered on the GTR now with the new ECU update. No worries of transmission failures.

http://www.exoticsandluxury.com/warranty-voided-gtr-launch-control-warranty-safe

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