Quote:
Originally Posted by swamp2
OK first of all MASSIVE and in all caps may have been a bit dramatic/overstated, maybe even a bit premature. There is, however, multiple forms of evidence pointing to an under-rating. Part of the reason for my word choice was based on the dyno results showing basically the claimed crank output at the wheels. I was a bit short sighted on the subtleties of that particular dyno in that it typically gives figures much higher than other dynos. However, even if it rates things about 10% too high with a 20% total drivetrain loss, the GT-R still comes in at 530+ crank hp, and I guess I would still call that massive. The N'Ring regression analysis also points to the possibility of a fairly substantial under-rating (or a variety of other effects working in tandem such as great driver+DCT+great tires ... or alien technology of you prefer that explanation  ...). The last piece of evidence is the 1/4 mi time and it too point to under-rating (the number I have heard is 11.7s). I'm not sure how much more evidence we will need.
Back to the simulations. Getting fantastic agreement from a simulation vs. test results may happen but it may also be a case of getting it right for the wrong reasons. I'm fairly sure this is the case for your 911 Turbo results. If Q. Jr. can predict RWD times in a reasonably well validated fashion and it has absolutely no wasy to account for AWD, then it simply (almost by definition) can not also get AWD performance figures accurate for the right reasons. Doesn't this make fundamental sense? We all know and understand that AWD cars get a harder launch but then suffer much greater parasitic drivetrain losses which hurts the cars performance more at higher speeds. You can not just rely on a simulation tool blindly and rely on it as a black box to just turn the crank, get the answer and not question the results in any way. It appears that this is what you are doing here. "Responsible" and intelligent use of simulation DEMANDS contstant questioning of the model, the inputs and results. CarTest offers complete control of a huge number of input variables including FWD, RWD, AWD and a plethora of other user defined inputs (you can see some screen grabs of the amazing number of inputs possible in CarTest on other threads here on the forum). One reason I am a bit hesitant to use and post results for cars like the 911 and GT-R is that I have not had great luck simulating Turbo charged cars yet. I will probably work a bit more on the 335i and making sure I can get good results for known/justifiable reasons before relying on CarTest too much for such cases. In any case I think my preliminary runs with CarTest for the GT-R showed it required about 520 hp to get a 3.5s 0-60 and 11.7 1/4 mi. I did use very short 0.03 s shifts as we can expect from its dual clutch system and of course the AWD option. |
First of all, let's agree on terms. You have no
evidence at all. None. Neither do I, for that matter. What we have are data points that may give us an inclination - or not, when taken together.
- I contend that the dyno test is an unknown quantity. We don't know about the dyno, we don't know about the particular car (chipped or not, for instance), and though I haven't glanced at the results myself yet, now it seems that there may be an issue with the validity of everything about that test.
- The 'Ring test isn't indicative of anything I can think of other than it's a flyer. The car may be naturally fast (more on that in a minute), or in fact the car may be under-rated.
- And for quarter mile times? I think they're pretty much spot on where they ought to be.
When I simulated the GT-R and came up with results that were very close to spot on (according to Nissan's numbers), that was kind of interesting. When you reminded me of the drivetrain differences (properly, I thought), I ran the Porsche not to somehow validate the tool, but to find out how the Porsche simulation would also turn out. Obviously, if it too came out pretty much spot on (which it did), then looking at the compared results makes sense, since both cars have awd with the resulting penalties.
Result? The Porsche was faster then the GT-R in the standing quarter mile (by a tenth and a single MPH), and if you do power to weight, it should've been two tenths and two mph faster. Wow! That's a whole tenth and one MPH those Nissan bastards aren't owning up to.
But wait! The Nissan has the hot-damn trans and the Porsche (equipped with the "better" of its two inferior choices) has a damned torque-converter automatic, which we know (especially you) takes power to run.
The fact that these cars are so close, with the Porsche being a little faster according to Car & Driver vs Nissan marketing, should give you pause, Swamp.
On to the 'Ring. My contention is that the GT-R is a superior handler compared to the Porsche Turbo, and while everyone on the planet hasn't tested the GT-R yet, those who have think the handling is the best part about it, while we *know* what test drivers think of the Porsche at ten tenths. My favorite quote is "It takes three feet to driver a Porsche Turbo fast."
OK, the current 911s are the best ever, but they still wield the threatening sword of physics at ten tenths. The Nissan is nearly as fast in a straight line (probably due to its transmission), but definitely quicker in the twisties. It turns out the Nissan is a little quicker around the 'Ring, and I'm guessing that while it was undoubtedly very exciting during those laps, it was very relaxed compared to the Porsche Turbo. My guess is that the legendary Rorhl ran up a dry cleaning bill during that 7:40 pass.
Then there's the Edmunds article, which waxed poetic about GT-R handling, but declared the Porsche to be quicker in a straight line (out on the street) in side by side and follow the leader runs. The Porsche could not keep up in the twisties, but was the quicker car in a straight line.
Swamp, why doesn't
that give you pause. The Porsche
should be mildly quicker in a straight line and apparently
it is.
As for your CarTest runs, I have trouble with giving them any credibility at all just yet. However, I'm betting that if you run the Porsche, it will be a bit ahead of the Nissan, just as in my simulations, but you'll also show the Porsche as being under-rated.
Finally, there's that whole SAE thing. Almost certainly, the Nissan will show "correct" numbers on the dyno or the SAE will throw them out - and of course if you're correct then the GT-R will be a comparitive pig when our magazine guys give it a run. Won't happen, though. I'd bet quite a bit that the SAE numbers have already been run under current (SAE representative present) rules.
Nissan is not only betting at least a couple of decades of legendary performance by past iterations of their baby, they're also betting that the car will be a worldwide legend, or the entire Japanese car industry loses face.
Remember "The Usual Suspects"? "A legend isn't a legend if it doesn't die."
Nope. The data points we've discussed collectively point to the fact that the jury is still out. Personally, I think the Nissan will be on the up and up, but we'll see.
Bruce