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      12-30-2008, 08:05 PM   #1
jaeS4
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MotorTrend says Nissan not lying about GT-R horsepower:

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Originally Posted by Autoblog
Last summer, Motor Trend estimated that the Nissan GT-R made at least 507-horsepower at the crank, which is quite a bit more than the manufacturer's official 480-horse rating. Now, MT decided to put to rest the firestorm it created by strapping yet another GT-R to a new type of dynamometer that's reportedly capable of calculating exact drivetrain losses, something that had previously been nothing more than an estimation. Three runs were conducted, and Godzilla delivered figures that were consistently within just a few percentage points of each other. So, what's the scoop?

According to MT, the average of those three separate dyno runs reveals that Nissan's supercar is delivering 485-horsepower @ 6050 rpm and 470 lb-ft @ 3800 rpm. That's nearly spot on for horsepower, but a good deal more torque at the crank than its official 430 lb-ft. -- we're not complaining. These tests also prove that there are indeed significant losses due to the GT-R's twin-clutch, all-wheel drive configuration, though that's also what helps launch the supercar from a dead-stop so quickly. Thanks for the tip, Franz!
If they can only get their hands on that GTR than ran 7:29 in The Ring.
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      12-30-2008, 09:03 PM   #2
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Originally Posted by jaeS4 View Post
If they can only get their hands on that GTR than ran 7:29 in The Ring.
They'd have to pry the one-off from Nissan's hands though, and I doubt Nissan will let that happen. And even so, they've probably backed the power back down to the "production" level anyway.
Funny Nissan hasn't wanted to back that time up with 1 or 2 other production GT-Rs.
The GT-R's engine seems to be so finicky though.
Some seem to run strong enough to trap 120-121 mph, others only 115-116 mph and the average seems to be in the 118-119 mph range.

That seems like a good 50 hp difference between the production cars.
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      12-30-2008, 09:15 PM   #3
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Quote:
Originally Posted by jaeS4 View Post
If they can only get their hands on that GTR than ran 7:29 in The Ring.

Exactly, very insightful IMHO. +1 on the post just above as well. This is the crux - the GT-R's have shown a very large variation, track and strip especially.

Do you have any more information? The quote does not indicate the test method (very curious how they got this without disassembly). Did they mention the total drivetrain loss figures? Wouldn't it be reaonable to assume a near RWD type effect from the advanced transmisson lowering losses during hard acceleration?
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      12-31-2008, 12:26 AM   #4
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Here's more info from MotorAuthority.


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Originally Posted by MotorAuthority
Testing cars for power ratings is a tough and tricky business - accounting for different conditions, locations, equipment and techniques can make it tough to generalize results. And to make matters worse, there is often a lot of guesswork employed to get between real, delivered wheel horsepower and output at the crankshaft, or vice-versa. A recent test of Nissan's GT-R has answered some of the ongoing questions of how it performs so well, however, and taken a good bit of the fiction out of the process.

Rumors and reports from around the web have been claiming Nissan's stated figures for the GT-R's twin-turbo V6 are understated ever since it began its remarkable climb up the many performance charts. All-wheel drive and tons of rubber just couldn't make up for the massive power deficit, they claimed. But it turns out Nissan's claimed 473hp (353kW) figure isn't far from the truth at all, according to MotorTrend. The torque numbers are about 40lb-ft (54Nm), or roughly 9%, larger than Nissan's 434lb-ft (588Nm) rating, and could help explain a little of the car's low-end acceleration abilities.

The key to this latest round of testing is the use of Hyper Power Dynamometer's DYNOmite, which allows testing not just of engine output, but of powertrain drag. After a dyno pull, instead of ceasing to record data, the machine records the slow-down period, and measures the drag due to the car's powertrain, including engine, transmission and wheels.

The end result? As physics would suggest, the parasitic losses of the drivetrain increase with speed, varying from 23hp (17kW) at 50mph to 84hp (62kW) at 100mph. That works out to a real-world inefficiency ranging between 5-17%, depending on speed - quite good for an AWD car.

One thing to keep in mind, however, is that this is just one particular example of the car - power figures can and will vary from vehicle to vehicle. It will simply take time and repetition to see if these results are more or less representative of the general population of Nissan GT-Rs than previous tests. The method, however, is a definite improvement.
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      12-31-2008, 04:04 AM   #5
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^ Thanks. Idiot magazine guys, Motortrend says "significant" losses and MotorAuthority says they are "quite good" for an AWD car. I say if they peak at 17% (100 mph is very close to redline so they should peak there) that is pretty darn good. However, I question the ability of this "coasting method" to properly track losses under WOT acceleration and the control of front/rear power bias through the ATESSA system (as mentioned above).

FYI original Motortrend article here.

Seems there is a small error in their math as well. They claim the losses range from 88 to 93 hp. The graph I saw showed a maximum loss of 98-99 hp. With their actual drive shaft power measurements the losses compute out at 20% (max loss/max hp - not taken at the same rpm). However, at peak hp (about 6k rpm) the losses were 87-89 hp or 18%. Since the cars peak hp is not at peak rpm this distinction matters. Either way I am not sure how they come up with 17%. I'd say 18% is the best figure.
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      12-31-2008, 06:00 AM   #6
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Quote:
Originally Posted by jaeS4 View Post
If they can only get their hands on that GTR than ran 7:29 in The Ring.
I'm not a gambling man but I'd put my money on it that Nissan probably destroyed the 7:29 car after its monumental run.
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      12-31-2008, 08:53 AM   #7
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I bet the 7:29 car is sitting in Nissan's HQ for all to see. Though this does not mean anyone will ever get to test these theories out.

I won't get into a debate on dyno figures with awd cars, needless to say I have ever agreed with any figures produced. Though due to their differing designs I would reckon you couldn't standardize the lose figures in to same way as can be done with either fwd or rwd cars, best to look at the performance results like what swamp has done and guesstimate the HP/weight.

Also best to disregard the 1/4mile figures and look at ingear figures, say 30~130mph to gauge any PTW figures, this way traction is taken out of the mix which will blur figuring cars like the GTR.

BTW, as an example of how different results can be a (stock)GTR has been dynoed at an estimated 560hp in Japan.
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      12-31-2008, 11:28 AM   #8
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Quote:
Originally Posted by footie View Post
I bet the 7:29 car is sitting in Nissan's HQ for all to see. Though this does not mean anyone will ever get to test these theories out.

I won't get into a debate on dyno figures with awd cars, needless to say I have ever agreed with any figures produced. Though due to their differing designs I would reckon you couldn't standardize the lose figures in to same way as can be done with either fwd or rwd cars, best to look at the performance results like what swamp has done and guesstimate the HP/weight.

Also best to disregard the 1/4mile figures and look at ingear figures, say 30~130mph to gauge any PTW figures, this way traction is taken out of the mix which will blur figuring cars like the GTR.

BTW, as an example of how different results can be a (stock)GTR has been dynoed at an estimated 560hp in Japan.
Several cars here in the US have dynoed around 450hp at the wheels which translates to around 550hp if you base it on 18%. Vividracing from 6speed that specializes on Porsches dynoed a GTR at 457whp.
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      12-31-2008, 01:44 PM   #9
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Quote:
Originally Posted by jaeS4 View Post
Several cars here in the US have dynoed around 450hp at the wheels which translates to around 550hp if you base it on 18%. Vividracing from 6speed that specializes on Porsches dynoed a GTR at 457whp.
Well that proves my point, that stock GTRs make upwards on 10% more than Nissan quotes.

MT like many others are stabbing in the dark at guessing the true output of the GTR by using the dyno approach.
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      01-01-2009, 01:39 PM   #10
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Quote:
Originally Posted by Driver72 View Post
The GT-R's engine seems to be so finicky though.
Some seem to run strong enough to trap 120-121 mph, others only 115-116 mph and the average seems to be in the 118-119 mph range.

That seems like a good 50 hp difference between the production cars.
I think you will find that a lot of this difference in either trap times or speed depends on the rubber the GTR is using. Like the lap times the GTR produces, the 1/4mile runs are best done with Dunlop rubber.

In fact all negative comments directed towards the GTR always happen when the car is equipped with Bridgestones and might explain why in the UK at least all 2009 GTRs will be equipped as standard with Dunlop rubber.
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      01-01-2009, 06:18 PM   #11
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Quote:
Originally Posted by footie View Post
I think you will find that a lot of this difference in either trap times or speed depends on the rubber the GTR is using. Like the lap times the GTR produces, the 1/4mile runs are best done with Dunlop rubber.

In fact all negative comments directed towards the GTR always happen when the car is equipped with Bridgestones and might explain why in the UK at least all 2009 GTRs will be equipped as standard with Dunlop rubber.
Interesting but the choice of rubber should make very little to no difference in straight line trap speeds.
I can understand grip off the line (therefore the ET's may very be a couple tenths) and certainly in handling variations with different rubber but unless one of the tires is like glue and the other spit, road friction differences would be minimal and I would suspect so would tire weight. Therefore trap speeds should by minimally affected by the tire choice.
Any car will have a slight variation between each that will affect trap speeds by say 1-2% but the GT-R's trap speeds seem to fluctuate by as much as 5+% on stock cars. That's got to be mostly because of power variations between each car.

Don't get me wrong, I know the GT-R is fast (I did some canyon runs with them and they could easily lose me as my 335i just wasn't up to the handling task of those cars, nor the straight line speed) but I'd be ticked if I bought a GT-R and got one that couldn't do better than 12.0 @ 115-116 mph when others are doing 11.6-11.7 @ 121 mph.
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      01-01-2009, 07:14 PM   #12
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      01-02-2009, 04:57 AM   #13
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Driver72,

I understand what you are saying but when you actually view the tests that have been done, all the slow ones with the one exception have been on Bridgestone rubber. In fact it was commented by one of the magazine (can't recall which) that the second GTR tested was a full 5mph slower and that one was on Bridgestones instead of the Dunlops and they found excessive wheel spin in comparison to the Dunlops.

There may be more to this than first meets the eye, especially as the GTRs incredible times are believed to be the work of it's launch control.
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      01-31-2009, 01:05 AM   #14
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There are variables in tracks and conditions. Even in my car, on the same track, just on different days, I run 13.1@109 vs. 12.4@114.
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      01-31-2009, 01:30 AM   #15
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Quote:
Originally Posted by Driver72 View Post
Interesting but the choice of rubber should make very little to no difference in straight line trap speeds.
I can understand grip off the line (therefore the ET's may very be a couple tenths) and certainly in handling variations with different rubber but unless one of the tires is like glue and the other spit, road friction differences would be minimal and I would suspect so would tire weight. Therefore trap speeds should by minimally affected by the tire choice.
Any car will have a slight variation between each that will affect trap speeds by say 1-2% but the GT-R's trap speeds seem to fluctuate by as much as 5+% on stock cars. That's got to be mostly because of power variations between each car.

Don't get me wrong, I know the GT-R is fast (I did some canyon runs with them and they could easily lose me as my 335i just wasn't up to the handling task of those cars, nor the straight line speed) but I'd be ticked if I bought a GT-R and got one that couldn't do better than 12.0 @ 115-116 mph when others are doing 11.6-11.7 @ 121 mph.
I"m not sure how much you drag race, but you can certainly see a 5mph difference in trap based on a bogged launch vs a launch with considerable spin, or a launch with wheelhop vs a clean launch, etc...Considering tires influence your launch, its not far fetched to believe that better tires will effect trap speed. Now I have seen a considerable amount of fluctuation in 1/4 times/traps for the GTR in the magazines, which is entirely common. Take the M3 for example. I've seen anywhere from 12.6 @ 115 to 13.0 109 from the most popular publications.
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