car and driver article - hp fud

[mindlessoath]

What is the GT-R’s Real Horsepower?

Despite what Nissan claims, the GT-R is not making the advertised 480 horsepower.

It’s a ringer,” we said among ourselves as soon as the first Nissan GT-R’s test results were in. Despite a power-to-weight ratio that’s 30 percent worse than that of the similarly priced Corvette Z06, that first GT-R outran the Z06 to 60 mph (3.3 seconds versus 3.4 for the quickest Z06 we’ve tested) and through the quarter-mile (11.5 at 124 mph versus 11.8 at 125). Even allowing for the launch advantages of all-wheel drive, the GT-R’s performance made us suspicious. It wouldn’t be hard for Nissan engineers, we surmised, to crank up the boost and thus jack up horsepower that would result in astonishing track numbers in American car-magazine tests. The GT-R was in such demand and our allotted time with it was so short, however, that we didn’t have time to strap it onto a chassis dyno and measure the horsepower.

We soon tested two more GT-Rs, and supporting our suspicions, they were considerably slower. GT-R No. 2 was 0.6 second behind the No. 1 through the quarter, and GT-R numero tres was a disturbing 1.1 seconds slower. Again, we didn’t have enough time to dyno-test those cars, but it seemed clear that the first GT-R was likely a one-of-a-kind rocket.

We finally got the opportunity to run a GT-R on a chassis dyno in May after Tony Swan returned with the example he used for the One Lap of America competition. The only problem with that car—No. 4 in our series—was that it performed about as well as the first. There were some differences, as you can see in the chart below, but those can easily be chalked up to the fact that the cars were tested on different days at different tracks. Yes, we do perform a weather correction to account for much of the ambient-condition difference, but no correction is perfect.

A brief primer on the Mustang chassis dyno we used: Picture a pair of parallel, supersized rolling pins mounted in the floor. The car is strapped down so that the front wheels are on one roller and the rears on the other. The operator puts the car in gear and, via the tires, spins these rollers, which are attached to a device that measures the applied force. A computer that ties into the car’s diagnostic plug and reads engine rpm calculates the horsepower. This power figure is what’s known as “wheel horsepower,” and it’s less than the engine horsepower that’s listed in our specs because the drivetrain components—transmission, driveshafts, bearings, differential—all have internal friction that soaks up power. How much power is lost in the journey to the road is not accurately known, but a 15-percent loss for rear-drive cars with manual transmissions and a near 20-percent loss for four-wheel-drive cars are good estimates.

On MotorCity Speed’s Mustang dyno in Commerce Township, Michigan, GT-R No. 4 produced a peak of 415 horsepower at the wheels. Based on our 20-percent loss estimate, the engine output was 519, or 39 horsepower more than Nissan’s stated 480.

So what’s up? We called Nissan, and the company says the first four cars we tested were early-build versions that received regular engine-computer software updates, which may account for the varied results we recorded. We then wondered which engine-computer calibration was the one real-world GT-R buyers would receive.

Three weeks later, a fifth GT-R arrived. This one, allegedly, was a production version with the latest—and final—engine calibration. We took it both to the test track and MotorCity’s dyno.

This car performed nearly identically to the fourth car. It smoked the quarter-mile in 11.6 seconds at 120 mph and produced 420 wheel horsepower. We also measured the turbo boost pressure in both cars, and the curves were basically identical.

Though we didn’t get a chance to dyno-test the two slower GT-Rs, three of the five were so close in performance that we believe they accurately represent the GT-R’s capability. Clearly, Nissan is delivering more than the advertised 480 horsepower. And the most likely figure is about 520, which is yet another reason to bow to the best performance value since the Corvette Z06.

Source:What is the GT-R’s Real Horsepower? - Column/Larry Webster/C/D Staff/Columns/Features/Car and Driver - Car And Driver


And my response: CBA-R35: Car and driver print blasphemous FUD about hp in R35

[winsome]

with my own eyes i see a few gtr dynoed att 455 wheel and without using launch control, put in auto, brake then floor, racelogic measure 3.7sec,,,,,faster then put in manuel mode though at 3.9, again no launch control.

Winsome

[mindlessoath]

i dunno if you can dyno the R35 in launch control, can you?

and that 455, with your own eyes, what correction factor did they use? thats exactly what im talking about. nissan is claiming less friction loss than everybody is using.

not to mention any dyno is no real indication of actual horse power due to way to many factors and guessing games of correction factors. its a tool to do a baseline before adding parts and then running it again to see the parts gain or loss in hp.

it will never tell you anything exact and even when doing the dyno on differnt dyno's in differnt locations yada yada yada will never give same results.

[winsome]

i didnt write it clear enough they are separate incidents. dyno is one thing but using the racelogic for the aceleration measurement is another. my point is the dyno can give you only a rough figure of the amount of power you have in a car, and a lot of time we are too preoccupy by such figure. the measurement of 3.7 in auto mode already proved the gtr have serious performance, there is no doubt about it. for all of us who have some knowledge about performance cars , the moment we put out foot down the throttle we already know the kind of performance we are looking at. I dont need all these "experts" to tell me so. btw we "own" performance cars, they borrow them.....
I understand some company adjust their samples before they let the press drive them....but i am quite confident that nissan knows this time their reputation is on the line and they know millions of people are going to challange their result.
Also a recent track day event held in the F1 circuit in Shanghai the GTR achieve equal time(i am being humble here) as the 997turbo, lambo gallardo, F360 430 etc. during the same event there was a day which rain pretty heavily and you know the GTR serious outrun the rest. it really is a all season supercar.

[mindlessoath]

not in response to your post, just a comment to add...

the fact of the matter is nissan is not under rating anything. a dyno is not a tool able to find exact engine horse power. especially not when your guessing friction losses and also to many other variables.

not only to mention nissan states 10% drivetrain loss, not 20% like c&D guessed... not even a lambo has 20% loss, and when the R35 has so much more technology than the lambo too.

a dyno is a tool to find out how much horsepower certain parts gave you (or to diag problems and tune ecu's etc).

one thing this article does is spread miss information and lies and it shouldnt be doing that just for web traffic. car and driver does a huge publication fail.

each dyno at each place is going to be differnt because of so many differnt factors, temps, airflow, humidity, elevation, and the guessing game's the Think are reliable (tho they are not) with friction losses.

people have been doing the guessing game for many many many years so everyone things its the right way, even tho its not. its all really annoying.

annother method that anyone can do, and might i add for free, is to do the cost down meathod.

read about it on the web, i have one link here: Horsepower measurement (John De Armond)
hopefully others can take the advice and find out for real since this method will have better results to factor out some of those variables.

[Mega]

Is it just me or does "Car & Driver" have a downer on the GTR?
Mike

[Frenchie]

The better way to find out if Nissan is lying or not is to compare a similar 6-cylinders twin-turbo AWD car - say a claimed 480hp Porsche 911 Turbo (997) - on the same dyno. That's exactly what Edmunds.com did a few months back, and guess what? They both came out with almost the same output!

2009 Nissan GT-R: Dyno Testing Godzilla

So who's lying there? ;-)

[R33_GTS-t]

Originally Posted by Frenchie

The better way to find out if Nissan is lying or not is to compare a similar 6-cylinders twin-turbo AWD car - say a claimed 480hp Porsche 911 Turbo (997) - on the same dyno. That's exactly what Edmunds.com did a few months back, and guess what? They both came out with almost the same output!

2009 Nissan GT-R: Dyno Testing Godzilla

So who's lying there? ;-)

Who's to say that the 911 Turbo is only 480ps?

[Frenchie]

Originally Posted by R33_GTS-t

Who's to say that the 911 Turbo is only 480ps?

Porsche claims it... and oddly C&D never suspected them not to say the truth, did they?

[SEGTR]

Engine Dynos measure engine power output
Hub Dynos measure hub power
Rolling roads measure wheel power
Why don't manufacturers provide us with the engine AND the wheel output then all the pub bullsh1t figures become immaterial.

Magazines constantly make mistakes/exaggerations about transmission losses which just perpetrates these myths.

As some racers say, the bullsh1t stops when the flag drops.

[Eric GTR]

Originally Posted by mindlessoath

not in response to your post, just a comment to add...

the fact of the matter is nissan is not under rating anything. a dyno is not a tool able to find exact engine horse power. especially not when your guessing friction losses and also to many other variables.

not only to mention nissan states 10% drivetrain loss, not 20% like c&D guessed... not even a lambo has 20% loss, and when the R35 has so much more technology than the lambo too.

a dyno is a tool to find out how much horsepower certain parts gave you (or to diag problems and tune ecu's etc).

one thing this article does is spread miss information and lies and it shouldnt be doing that just for web traffic. car and driver does a huge publication fail.

each dyno at each place is going to be differnt because of so many differnt factors, temps, airflow, humidity, elevation, and the guessing game's the Think are reliable (tho they are not) with friction losses.

people have been doing the guessing game for many many many years so everyone things its the right way, even tho its not. its all really annoying.

annother method that anyone can do, and might i add for free, is to do the cost down meathod.

read about it on the web, i have one link here: Horsepower measurement (John De Armond)
hopefully others can take the advice and find out for real since this method will have better results to factor out some of those variables.

coast down method seams even more inaccurate

going over 55 and the cars CD affects the result
footprint of the tyre and rolling resistance
air temp / density
speedo inaccuracy
human inaccuracy in operating the stop watch
road temp, camber, angle and contruction type

[Eric GTR]

tbh I dont care that much what power the engine makes, why would anyone need to know it ultra accurately apart from people tuning the car so they can see what gain they have or sad individuals who want to play the my epeen is bigger than yours on forums (young American males seam very bad for this, especial vette owners)

The caterham superlight has substantially less power but is faster 0-100-0

Autocar Videos - Autocar.co.uk

what matters for me are performance figures 0-100, std qtr etc as a guide to a cars performance, yes they are variable on conditions, but over several reviews you will get a good guide and group tests make the data even more so relevant

lap times are less so important for me as i would never match them in a 100 years, also the type of car makes a difference here as well, i would be able to get closer to the GT-Rs laptime set by a pro as its a well setup driver friendly car compared to an animal of car like the carrera gt that kills the driver as punishment for any mistake.

[R33_GTS-t]

Originally Posted by Frenchie

Porsche claims it... and oddly C&D never suspected them not to say the truth, did they?

The only problem is that at least 2 GTRs have measured ~480bhp@hubs. Now explain to me how negative losses work. What I think is obvious is that some GTRs are less powerful that others.

[tokyogtr]

Originally Posted by R33_GTS-t

The only problem is that at least 2 GTRs have measured ~480bhp@hubs. Now explain to me how negative losses work. What I think is obvious is that some GTRs are less powerful that others.

but there are quite a few other factors to be considered. fuel type, ambient temp and humidity, skills of the tester, accuracy of the feedback, truthfulness, clutch slip (yes, they're getting clutch slip in japan on cars that have been modified with too much boost) etc.

[Frenchie]

Originally Posted by tokyogtr

yes, they're getting clutch slip in japan on cars that have been modified with too much boost

Correct me if I'm wrong but one of the reasons why Nissan blocked the ECU, it's not because the engine can not deliver more power and torque, obviously it easily can, but because they were concerned that the new dual-clutch tranny would not be able to handle it...

There is always a weak point on a car, and on the R35 it could well be its gearbox

btw, is there a limitation on the number of times the launch-control can be used over the car's lifetime?