• Dec 14th 2007 at 8:03PM
  • 58
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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  • 58 Comments
      • 7 Years Ago
      This is wheel hp???! Or are they estimating the crank HP with an educated guess ont he driveline losses?
        • 7 Years Ago
        Now I'm extra confused.
        • 7 Years Ago
        On top of the Dynosheet is clearly named Fly Wheel Power Curve...
        You can maensure the drive train lose and clock the Power at the engine... in the metric world no one rate power at the wheel... always crank hp..

        This car is not unterrated...it has exactly the power claimed by manufactor
        • 7 Years Ago
        There is no torque correction factor applied, so it's measuring 482 pferdestarke (PS) at the wheels (assuming they entered the wheel and final drive ratio info correctly). 482PS is 475.4 hp SAE.
        • 7 Years Ago
        Reading the original article it does seem to say that's the HP to the hubs.
      • 7 Years Ago
      Yeah so it looks like the GTR is closer to 600 crank hp. This would make more sense how they were able to run that 7:38 that many said (me included) could not be done with 3800lbs and 480hp.
        • 7 Years Ago
        Funny that no one take a closer look at the dyno sheet

        http://carview-img01.bmcdn.jp/carlife/images/UserDiary/7132676/P1.jpg

        on top of the Dyno sheet is exactly named that this power is FLY WHEEL POWER CURVE

        Means at the wheel the GT-R has much lower power as 480hp


        • 7 Years Ago
        Paul P.
        no one in the metric world (where this dyno sheet was taken (DIN PS!!) ) looks for wheel hp..here they always clock crank/flywheel hp.. to get that number the dyno meansure the drivetrain lose... and correct the number automaticly to get the real engine power
        • 7 Years Ago
        Actually I figured 20% with this being an AWD car. 20% of 600 is 120. 600-120 is 480. Thats about a 3rd grade calculation. I would guess this motor is closer to 600hp than 480 or 500. Or have I mistaken this article and it is not 475 whp?
        • 7 Years Ago
        Rob, 20% of 480hp is 96hp. 96hp+480hp is 576. You need to take 20% of the wheel HP and add it to get approx. crank HP. Going from approx. crank HP to wheel HP doesn't work. I can't explain it well, but you take the percentage of the lower wheel hp, not the higher crank HP; doing so inflates the numbers.
        • 7 Years Ago
        The metric version of the dynapack must be set-up to automatically add a fixed percentage to the wheel measured numbers then. Because my buddies dynapack spits out power and torque at the hubs (with a wheel correction and gearing correction), if you want crank numbers you have to add a TCF percentage.

        If that's the case, what is the drivetrain loss they use? How is it applied, since it isn't done through a TCF? If that's the case Metric dynapacks have to be setup very differently from their standard counterpart. If so, I stand corrected. I'll have to shoot an e-mail over to dynapack to see about this.
        • 7 Years Ago
        Then as an idiot I stand corrected. I thought it was a 15-20% approx drivetrain loss, not correction. And that is very interesting about the flywheel hp on the graph.
        • 7 Years Ago
        Funny that no one take a closer look at the dyno sheet

        http://carview-img01.bmcdn.jp/carlife/images/UserDiary/7132676/P1.jpg

        on top of the Dyno sheet is exactly named that this power is FLY WHEEL POWER CURVE

        Means at the wheel the GT-R has much lower power as 480hp


      • 7 Years Ago
      The dynapack takes away one half of the component of rolling resistance. Where is the deflecting sidewalls of the tire?
      If you lowered the suspension onto jackstands, then the wheel bearing loads would be nearly eliminated too.
        • 7 Years Ago
        Are you trying to debate fractions of a percentage of power ? When you don't even know the tolerance of what the machine will read ? How the stack up of tolerances, can change the overall figure ?

        Don't use a dyno as a p-nice measuring device. I can make a dyno read anything I want , or nothing I want. Its not hard. Plus or minus 20 hp is very easily a zero point in a 500 hp car.

        A Dynapack, and a Dynojet will show very similar readings. I have run the same cars on the different types and styles of dynos and always get similar figures +/- 20 hp.
        • 7 Years Ago
        Mike,

        I think maybe you misunderstand what purpose a dyno is designed for. It is NOT to try to determine what a car's 1/4 mile or 0-60 will be, things where sidewall flex or tire rotational inertia come into play. Those are best determined in real life at a drag strip. The purpose of a dyno is to try and get the most accurate, repeatable power figure of the engine, as simply as possible. This allows you to test changes that you make to the engine accurately, with as little other factors as possible intruding.

        At first this was done by strapping a car down onto rollers, but that introduces variables that you mentioned, sidewall flex, etc., that DETRACT from the accuracy of the engine power reading, not improve it.

        The next step is a dyno that attaches to the hub as discussed here, which removes these variables that can vary from run to run on the same car, interfering with getting an accurate, repeatable engine power reading. Yes, you could remove more variables by hooking the dyno up to a driveshaft, or by removing the engine and testing it directly. However, these steps introduce extra costs and difficulties, and do not do very much to improve the repeatability of the results.

        A dyno works by timing how fast a car's engine can spin a known mass up to speed and calculating it's power using that time and mass. Adding the unknown friction and mass of non-driven wheels to a dyno would only worsen the accuracy of the calculation that determines the car's power, not improve it.

        For more info, check this link:

        http://en.wikipedia.org/wiki/Dynamometer#How_dynamometers_are_used_for_engine_testing
      • 7 Years Ago
      Hello People ..

      Let's get some stuff straighten before there's MORE confusion.

      The dynapack measure torque at the hub, aka Axle. If one was to look at the axle power (wheel power), the graph would have said .. "Axle Power". Instead of having 59.2 kg/m, it would have been 275 kg/m (59.2 X 4.660).

      4.660 .. what is that? That is the total gear ratio. Which ever gear that's closest to 1:1 and the finial gear ratio. Assuming 4th gear is 1:1 and the finial ratio is 4.660 .. total gear ratio is 1X4.660 = 4.660

      If an engine makes 59.2 kg/m at the flywheel, the transmission multiple the torque by the gear ratio/finial gear: 59.2 kg/m X 1:1 (4th) X 4.660 = 275 kg/m -- (fiction lose - 15% on transaxle, 17-20% on front engine RWD, 20-25% on AWD) = 220 kg/m (20% because of AWD)

      That's the ACTUAL torque measure at the axle.

      Because of Dynojet and their 'whp', Dynapack has the option to show 'whp'. The program divides the ACTUAL measured torque by the total gear ratio. (The number entered in the back "ratio" box.)

      So, when the drive train is eliminated from the equation, the next part is the FLYWHEEL. That's why is graph says FLYWHEEL Torque & HP.

      DynaPack Flywheel Torque & Hp = DynoJet WHP

      DynaPack Axle Power = DynoJet doesn't have it.

      Also, what's stupid about DynoJet WHP is that it doesn't include the tranny. If an engine makes 160 rwhp @ 4th on a DynoJet. So that means the engine only makes 40 hp at the flywheel once you eliminates tranny with a 1:1 4th gear and 4:1 final gear yet Toyota says it makes 200 hp at the flywheel.

      Hopefully that makes sense.

        • 7 Years Ago
        Unlike torque, HP doesn't change as it goes through gearing (except for losses).

        This is because at a 4:1 gearing for example, the speed may drop to 1/4, but the torque goes up 4x to compensate.

        You cannot create HP with gearing, which is why it is the key measure of engine performance instead of torque.

        So the Corolla isn't making 160HP at the wheels and 40HP at the flywheel.
      • 7 Years Ago
      Also, the power curve looks steep BECAUSE of the X & Y axises range. If it was spread across a 8X11.5 sheet like a DynoJet reading, it wouldn't look as steep.

      • 7 Years Ago
      A dynapack supports the weight of the vehicle on the hubs (just like the tires do) so you don't have to worry about loosing the friction of the wheel bearings.

      As far as loosing the rolling resistance of the tires, you're not. You're loosing the added momentum of the heavy steel rollers. It's more comparable to running a car on the road than a regular roller dyno is. A dyno with rollers that also applies a separate load to cancel out the rollers added momentum is more accurate, but it's still only about the same as a dynapack.

      Either way, a dynapack usually puts out the lower numbers compared to a dynojet (which typically puts out the highest numbers) and even so it's rarely by very much. So you can be assured that what it put out on the dynapack is going to be close to what it will put out on a roller dyno. (As long as there isn't any "funny business" of course.)

      Like I said before though, numbers from one dyno and one run are useless. You have to get an average from different dyno's and different runs to get a better idea of where the car stands.
      • 7 Years Ago
      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.
        • 7 Years Ago
        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.
        • 7 Years Ago
        Dynojet overates cars. The best is mustang dyno. Incidentally, if the engine hp testing doesn't meet the SAE guidelines, its junk. Anyway who cares how much crank hp this has? The truth will be in the whp, after its gone through that heavy driveline.
        • 7 Years Ago
        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.)
        • 7 Years Ago
        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.
        • 7 Years Ago
        "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."

        no, the story you are refering to had the gtr faster than a super taikyu class 1 350z racecar. that is according to wikipedia "showroom class" racing.

        so think stripped 350z with racing tires

        no street car comes close to full on racecars like a jgtc 500 car








        • 7 Years Ago
        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.
      • 7 Years Ago
      It's a bit blurry, but it looks to me like it says "Fly Wheel Torque" and "Fly Wheel Power" at the top of the image. Obviously it measures at the axles, but they have already factored in drivetrain losses to get the figures. So adding another 20% doesn't make any sense.

      So what I'd like to konw is, how did they come up with the figures that they used to turn wheel numbers into crank numbers? And what were those figures?
      • 7 Years Ago
      SICK.
      Absolutely Sick. I'll take one in black.
      • 7 Years Ago
      I didn't know any manufacturer was publishing whp rather than bhp. No wonder it can haul all that weight around.
        • 7 Years Ago
        VW GTI and GLI's are regularly recorded at 200 whp, so VW's also playing this game, and like the comments pertaining to the GT-R and Z06 and the GTR keeping up with the Z06 despite extra weight, so to do GTIs not have an issue beating SIs ever so slightly.

        I'm expecting this to become a more prevalent trend as more manufactures start to produce numbers which simply keep us scratching our heads.
      • 7 Years Ago
      and that is stock boost. i cant wait to see results when they raise the boost up.
      • 7 Years Ago
      nagmashot @ Dec 14th 2007 11:15PM


      It's WHP, nagmashot is an idiot.

      The Dynapack machine has the ability to convert but in the picture you look at the "TCF" box and that tells you what is the conversion calculation being used. In the pics it says "1.00" so that is what the car's making at the wheels.
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