Japan's BestCar buff book grabbed the keys to a new Nissan GT-R and made for the nearest Super Autobacs. Once they arrived, they mounted Godzilla atop a Dynapack chassis dynamometer, removed the wheels and laid down a few runs to get power figures straight from the axles. The numbers are due for publication in the mag's December 25th issue, but our new friend Jeff made Christmas come early.
The dyno chart shows a peak output of 475 hp at 6,115 rpm and 428 lb.-ft. of torque at 5,130 rpm. Those numbers are incredible close to Nissan's claim of 480 hp and 430 lb.-ft. of twist, but we'll have to wait until a few lucky souls slap the GT-R onto a set of rollers to get some idea of wheel horsepower and torque figures.Looking over the chart shows very little happening before 3,000 rpm, which is contrary to a number of driving reports we've read so far. Turbo lag has virtually been eliminated on many new models, the GT-R included, so we're assuming that the Dynapack at Super Autobacs wasn't paying attention until later on in the rev range.
[Source: NAGTROC]
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Reader Comments (Page 1 of 4)
why not the LS2LS7? @ Dec 14th 2007 8:06PM
Turbo lag cannot be eliminated. If only it were so.
You can use variable vanes, etc, and the fact that the turbos stop moving at low revs and take some time to spin back up cannot be avoided.
Joe @ Dec 14th 2007 8:14PM
With increasing lag-reducing technology, the difference is un-noticeable. In addition turbos do not suffer parasitic loss and will be able to make alot of power at the higher end RPMs...
Ask Heffner's Vipers and David Lynch's Outlaw Mustang.
Turbos are not just for Japanese ricers you know.
LOL @ Dec 14th 2007 8:18PM
Joe points out a good point.
Heffner and Lynch have demonstrated that turbos are not just for highway/dyno queens....but they can also be successfully used for a blazing fast 1320 sprint.
chris @ Dec 14th 2007 8:48PM
They said "virtually eliminated", like on a 335i the turbo lag is virtually eliminated compared to an EVO III, or in a Megane F1 R26 the turbo lag is virtually eliminated compared to a Delta Integrale, etc. Or most of all a 997 911 Turbo has virtually no turbo lag compared to a super laggy 930 911 Turbo for example.
why not the LS2LS7? @ Dec 14th 2007 10:13PM
He's not correct, and I own a non-Japanese turbo car.
You can do a lot with response curves at higher revs. A dual-entry turbo, or variable vanes, etc.
But at idle, the throttle plate is nearly closed. That puts a vacuum into the intake and into the cylinders, so that means there's very little air in there to expand while being burned. Little air into the cylinder means little air out, which means little air to act on the vanes in the turbo, which means the turbo spins down or stops.
And that's it. You aren't making boost, so you're gonna lag when you press the pedal. You can screw around with gizmos all you want, only an anti-lag system like used in WRC would be able to produce boost without lag in these circumstances.
Turbo lag isn't gone and isn't even on the endangered list. People just confuse the change in response curve from a high pressure turbo (like an Evo) to a low pressure turbo and think that because the car has some power at lower revs it doesn't have lag. But it still has plenty of lag in regular driving conditions.
And turbos most definitely suffer parasitic loss. They present back pressure, that reduces power. It's not as much as a supercharger under most conditions, that's true.
As to 1/4 mile sprints, they pre-spool the turbo by revving the motor a lot before launch. This works great, but isn't the case on the street.
I'm sorry, as an owner of a German 6-cylinder twin turbo I just tune out when people talk up the 335i. It's great to see some other people join the party, but you showed up late. BMW doesn't have anything on anyone when it comes to turbos.
Anyway, "virtually eliminating lag" isn't the same as eliminating lag and "virtually eliminating lag" doesn't even explain low torque at 3,000rpm anyway. I think the lack of torque at 3,000 is failure of testing methodology more than anything.
Franz @ Dec 14th 2007 10:36PM
why not the LS2/LS7?:
I agree with you 100% that you can never truly eliminate turbo lag, without the use of an anti lag device such as those employed in WRC. The difference is whether or not you feel it in normal driving conditions. If an engine is naturally torquey... like a big block V8, or even a Nissan KA24 or QR25, a correctly sized turbo that builds boost in a linear fashion will only add power and not exaggerate the lag that is there. The transition between on boost and off boost behavior will be seamless. So in a sense I understand when people use phrases like eliminating turbo lag. Turbo lag is something you feel, and if you can't feel it, it really isn't there... if you know what I mean. I'm not contradicting you. Just expanding on your original point.
Matt @ Dec 14th 2007 11:31PM
"Turbos are not just for Japanese ricers you know. "
But the Nissan GT-R is!
John R @ Dec 15th 2007 8:21AM
Wow thanks a lot, Matt. That comment was a par to the ones above. Great contribution to the conversation.
Ligor @ Dec 15th 2007 3:18PM
well, if you tune your engine so it makes good power down low, you can work withengine management to make the turbo spool so that you cn not feel it.
just because the turb's aren't spooled up does not mean the engine has no power.
Duncan @ Dec 15th 2007 3:30PM
The lack of power (if it's real) under 3000 RPM has nothing to do with turbo lag as a dyno chart doesn't tell you anything thing about turbo lag.
A lot of people confuse turbo "lag" with the boost threshold of a turbo engine (being on or off boost).
Lag is the time between when you put your foot down on the accelerator and when the engine is at full power for that particular RPM. Even if your RPM is near redline. This is the lag that has been more or less eliminated from modern turbocharged engines. Turbo lag is essentially a muted throttle response.
Not having enough exhaust gases to get the turbos spinning fully at low RPMs, the boost threshold, is still a characteristic of many turbo engines. If the graph is accurate, you're looking at a boost threshold around 3000rpm (which wouldn't be surprising), not turbo lag.
The same solutions (apart from an anti-lag device dumping fuel into the turbo housing) to reducing turbo lag, however, can also lower the boost threshold: smaller turbos, variable vanes etc.
Justin @ Dec 15th 2007 4:14PM
all semantics. turbo lag is the what automotive journalists refer to the delay between idle and "boost threshold" as you refered to it.
throttle response is what you're referring to. just because you presumably have a car with a crappy slow response wastegate, DBW, and sloppy engine mounts doesn't mean you have turbo lag.
synchronic wastegate, dbc, and stiff engine mounts problem solved.
i know the argument ensues, but before we get into all that, answer this: have you driven a 2.0t vw/audi (with a manual gearbox) or a 335i/535i (manual gearbox as well)?
i'm too lazy to read 4 pages of comments, but I'm assuming someone corrected auto blog. those are dynapacks, meaning there's about 160 pounds of unsprung weight missing from the drive train. the actual number at the wheels is going to be lower than that.
Duncan @ Dec 15th 2007 4:44PM
It is of course all semantics, but semantics, in this case, are important because there seems to be a disagreement between which part of the "lag" you can eliminate/reduce/whatever. And yes, what I'm talking about is throttle response, and it is affected by things like wastegates.
There is a difference between the throttle-response of a turbo-charged engine at mid RPM and the low-RPM power-curve of a turbo-charged engine due to the boost threshold.
The former is "turbo lag" the latter is not. But even if you want to call the latter "turbo lag" the former is what engineers (and respectable auto journalists, though certainly not all of them) are referring to when they say "turbo lag is imperceptible". They're talking about the turbo's effect (or lack thereof) on the throttle response. You don't see the effect of a turbo on throttle response on a dyno chart.
LS2/7 is correct in saying that you cannot eliminate "turbo lag", you can't really ever eliminate either of the two types of "turbo lag". However, the "throttle response" one is easier to fix, and the "boost threshold one" is the one shown (possibly) in the dyno chart above.
Wikipedia has a decent discussion on the difference here:
http://en.wikipedia.org/wiki/Turbocharger#Lag
Nick Vrana @ Dec 14th 2007 8:17PM
Am I just used to seeing a different style of dyno sheets or are those curves rediculously steep?
Franz @ Dec 14th 2007 8:31PM
The steep dyno curve just proves how quickly the GT-R makes power through the rev range. If you really take notice, you'll see that it builds horsepower exponentially from about 3000-5000 rpm, then it starts to level off. The torque curve is equally impressive, although I would've preferred it peaking earlier.
Also, the figures seem spot on with Nissan's initial claims. 2 or so hp is really nothing in a dyno test. I dunno about these claims being different than whp figures though, like on a dyno with rollers. Dynapak dynos I've used before corrected the figures to show whp. Maybe this one doesn't. And dyno figures rarely correspond across different models.
Paul P. @ Dec 14th 2007 8:28PM
Um, a dynapack does measure "wheel HP". It isn't measuring crank HP. The engine would have to be out of the car to do that. When you set up a dynopack you put in the final drive ratio for the gear you're making the run in and the tire size. It compensates for those changes in gearing, giving you a wheel hp number.
With that said, my friend owns an AWD dynapack and I've seen a lot of cars run on it. Compared to a dynojet it's numbers are usually slightly lower, however it's definitely a more accurate dyno. On a dynojet I bet the GT-R would put out 480hp.
With that said, if it's putting down ~480hp at the wheels it has to be making well over 500hp at the engine. Even if it only has 10% drive train loss it's still over 520hp at the engine. If it loses 20% (which is more in line with a typical AWD car) it's putting out over 560hp at the crank.
It makes a lot more sense now as to why the GT-R is putting out similar numbers to the Corvette Z06 even though it's much heavier.....it has a lot more HP. At a minimum it's probably putting out 550 crank hp. I don't know how they got around the SAE's certification test, but it's definitely not a 480hp car. It's very under-rated.
Franz @ Dec 14th 2007 8:36PM
I agree completely with your assessment. I use a Dynapack all the time on my Evo IX and it is very consistent, although it usually shows lower numbers than a Dynojet. But consistency is more important to me when evaluating mods than a really high hp figure. I did, in a previous post hint that the GT-R was under rated. I think this independent test proves as much.
Josh @ Dec 14th 2007 9:08PM
Yup, you're right on the money. Those being wheel HP numbers also go along with the reports that the GT-R is competition for the 500HP Super GT class 350Z race car.
Billy @ Dec 14th 2007 10:13PM
I cant make a claim for consistency, which obviously you have found what is best in that case, but for all out numbers, there is a calibration screw on all dynos somewhere. you can make what ever horsepower you want.
In essence, numbers mean nothing compared to consistency and other factors.
Having used Superflow Engine Dynos to evaluate OEM engines, all of ours are set to read low so that the numbers are guaranteed accurate (because nobody will complain if they get more)
Paul P. @ Dec 14th 2007 10:24PM
That's very true. By entering a TCF or playing with the gearing they can get a properly calibrated dyno to say whatever they want, never mind what they could get an improperly calibrated dyno to say. So it's very important to get numbers from different dyno's to get an average. Therefore, these numbers alone don't really say anything alone. We have to wait for a few more runs to see if it pans out.
If it does though, that's very impressive and it explains a lot.
(By the way, if anyone seriously has a GT-R and wants to run it on another AWD Dynapack to compare, I can make it happen. You just have to get it to NJ.)
Chris @ Dec 15th 2007 12:48PM
And isn't it irritating to see Autoblog make that mistake? I felt the same way when Top Gear tested the Shelby GT500 and were disappointed it wasn't putting down "500hp like claimed." IT'S AT THE WHEELS, NOT AT THE ENGINE! Oy.