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    Feb 25, 2005 1:47:18 PM

    Carlos from SpainM
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    Just out of curiosisty, 997S HP figures...

    Just got a magazine with a comparison of the 997S Cab Tip vs Jag XKR cab. I darted straight to the dino info and the 997S pulls 361HP (vs factory 355HP) and a torque of 426Nm (vs factory 400Nm), yet the Jag performed slightly under factory specs as is usual with the magazine dinos. On a another two diferent magazine tests the 997S resulted in 358HP. Seems like the engine may be giving more horses, just a few, than factory specs and would help explain its acceleration figures compared to similar cars. In one of those tests (358HP) I refered to, the 997S out accelerated in every acceleration test (from standstill and on roll-ons) the M3-CSL which has tecnically 5HP more and 35Kg less.

    Does anybody have anymore magazine dino tests for the 997S 3.8l engine?

    Feb 25, 2005 1:59:18 PM

    J.Seven
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    Reply to: Carlos from SpainM

    Re: Just out of curiosisty, 997S HP figures...

    Can you post the performance figures of the Jag and 997S tip? Thanks

    Was it Automovil magazine? They use to make dino on cars they test, and I've the mag. where they tested the 996 Carrera 2 coupe. I believe it made 286Hp at the time instead of 300Hp, but accelaration numbers were great, something like 5,2Sec to 0-100Kph.

    J.Seven

    Feb 25, 2005 2:01:51 PM

    J.Seven
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    Reply to: Carlos from SpainM

    Re: Just out of curiosisty, 997S HP figures...

    Quote:
    Carlos from Spain said:
    Just got a magazine with a comparison of the 997S Cab Tip vs Jag XKR cab. I darted straight to the dino info and the 997S pulls 361HP (vs factory 355HP) and a torque of 426Nm (vs factory 400Nm)



    Is it plausible to think that if it was a manual 6 speed transmission equipped car, it could have done even more HP than the Tip ?

    J.Seven

    Feb 25, 2005 2:36:23 PM

    Carlos from SpainM
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    Reply to: J.Seven

    Re: Just out of curiosisty, 997S HP figures...

    This one was Auto Hebdo Sport (but the other two were I mentioned were Automovil and Autopista), and the acceleration figures for the 997S Cab Tiptronic vs Jag XKR Auto (supercharged V8 400HP, 1800kg) was:

    0-100kmh = 5,1sec(997Scab), 5,6sec (XKR)
    0-400m = 13,3sec(997Scab), 14,2sec (XKR)
    0-1000m = 23,9sec(997Scab), 25,3sec (XKR)



    (BTW, in the subjective point marks, the 997S beat the XKR in engine, performance, handling, gas milage, build quality and termination of interior, and sportiveness. The XKR beat the 997S in price, standard options, and trunk and room.)

    Ii wouldn't make any difference on factory flywheel dinos but I'm unaware if the Tip tranny has any positive or negative effect on normal dinos

    Feb 25, 2005 2:51:36 PM

    69bossnine
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    Reply to: J.Seven

    Re: Just out of curiosisty, 997S HP figures...

    Let's make sure we're looking at apples to apples. How are they dyno-ing these cars? On a dynojet "chassis" dyno, where the car's rear wheels are strapped down onto a spool? This measures rear-wheel horsepower, not SAE net, which is measured at the input shaft. Manufacturers typically list horsepower as SAE net, whereas when magazines want to dyno a car themselves, they typically visit a chassis dyno to measure rear-wheel h.p., as it's not very practical to remove the engine and all accessories and exhaust from the car to set it up on a proper "engine" dyno. Obviously, rear wheel horsepower on a chassis dyno is always LOWER than SAE net on an engine dyno, due to the parasitic drag down the driveline, from the tranny, to the diff, to the wheels & tires. The percentage of power loss depends on the design efficiency and precision of the entire driveline (which I'm sure is one of the many reasons that 911's seem to perform well compared to higher h.p. competitors, because of their premium engineering and precision, they don't scrub off as much power transferring it to the wheels) (I may be boring you guys with stuff you already knew). BUT, I would think that the example mentioning the 300 h.p. 996 "dyno-ing" at 286 would be indicative of a chassis dyno rear-wheel measurement, which would actually indicate that the factory's 300 h.p. SAE net rating was actually a bit UNDER-stated, as driveline loss is typically in the 10-15% range. That would explain why the 300 h.p. 996 performed a bit better than you would expect from the h.p. rating.

    NOW, this gets me to the 997S.... You say that a magazine dyno'd the 997S, and came up with 361 h.p.?? This is where we need to ask the question, "what kind of dyno did they use?". Did they:

    1. Remove the driveline and dyno it on an engine dyno to achieve an SAE net figure that would be apples to apples with Porsche's published SAE net figure, or..

    2. Strap it to a chassis dyno, which is the only practical method for most magazines. If they measured 361 h.p. at the rear wheels on a chassis dyno, THAT'S HUGE. That means that the 997S would be making somewhere in the order of a corrected 390-410 h.p. SAE net!!!! That would certainly explain why the new 400 h.p. Corvette can't seem to shake the 997S in a drag race. But it also seems a bit too good to be true, and I doubt that Porsche would "sandbag" their SAE net figure that friggin much, which brings me to my last possibility/question..

    I just find it hard-to-believe that these magazines are spending the serious dough to remove and dyno a powertrain using the same methods the factories do. Or, are they simply measuring at the rear wheels and then "correcting" the rear-wheel figure by using a factor provided by Porsche for driveline loss. And lastly, I'm very curious how much driveline loss there is in a 911, since they seem to over-achieve so much beyond what their factory horsepower ratings would cause you to expect. I've seen alot of "there's no way that a 355 h.p. car could do 0-60 and the 1/4 that quickly, at that fast of a terminal speed". But realize that the 400 h.p. Corvette is probably only putting about 345-355 of that 400 h.p. to the pavement. If Porsche is somehow managing, through engineering, or possibly just by way of advantages inherent in the rear-engine/trans/diff layout, or both, to achieve a far lower percentage of driveline loss, that would explain a ton. After all, performance has NOTHING to do with how much power is being generated under the hood, it has everything to do with how much power is meeting the asphalt.

    Feb 25, 2005 3:18:25 PM

    Carlos from SpainM
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    Reply to: 69bossnine

    Re: Just out of curiosisty, 997S HP figures...

    As far as I know they are ALL chasis dino's that measure to the rear wheels (never seen an independant engine dino test in a mag, but when the dino was especifically listed in the mags I havve seen here it was a normal rear-wheel dino).

    But I believe they compensate the rear wheel horsepower for the driveline loss of HP by using a formula and hence the HP rating they give are an aproximation to SAE. Its not rear whell HP since like you say, 361HP rear wheel HP would be incredible.
    Since they are compensated numbers I believe thats why magazine dino results are not perfectly accurate by themselves but rather used for comparison between tested models (not to mention that the same car's dino results can vary a bit form one day to another).
    So thats why I was asking for more results, to have a broader perspective to see if many similar results would confirm that the 355HP power figure is a bit conservative. I believe the same same happened with Porsches X51 and X50 powerkits, they power rating was very conservative.

    Usually I find that in the magazines (in spansih magazines they tend to do independant dinos in the tests) when I look at dino results they are a bit under factory specs, but the 997S has been so far 361HP, 358HP and 358HP which strikes me a bit odd since that is not usual, and didn't happen with the 996 for example. Also the acceleration numbers are more than you would expect from 355HP in the tests

    Feb 25, 2005 3:37:06 PM

    69bossnine
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    Reply to: Carlos from SpainM

    Re: Just out of curiosisty, 997S HP figures...

    That answers my questions perfectly. And yes, I agree that the 355 SAE figure must be a bit conservative. You can only "explain away" so much by citing precision and rear-weight bias. But the fact that the 997S has ROUTINELY been finishing the 1/4 mile sprint at 112.5 - 115 mph indicates that regardless of how quickly it's jumping out of the hole, there is more POWER pulling it up to that terminal speed than just 355 h.p. IMHO. The C5 Corvette had an honest 350 h.p., at similar weight to the 997S, and could only muster 108-110 mph trap speeds, in magazines, and with my own personal experience of driving those cars at the dragstrip. Ever since the magazine tests of the new 997S have been coming out, and ever since I took my test drive, I've been very confident that the factory-rated 355 h.p. number was "conservative", "sandbagged", "low-balled", however you want to say it!!!

    Feb 25, 2005 4:50:12 PM

    Carlos from SpainM
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    Reply to: 69bossnine

    Re: Just out of curiosisty, 997S HP figures...

    I haven't tried the 997S version yet but thats the impression I'm getting as well from the magazine tests and dinos.
    To think that a "carrera" with only 355HP (with rear seats and PSM) tilting the scale just over 1400kg can lap the ring under 8 minutes on street tires is incredible and unprecendented, I know the new 997's chasis setup, wheel&tire combo and specially -20mm with rear LSD suspension has a lot to do with it, but I'm inclined to believe a couple of hidden extra ponies may have helped too

    Feb 25, 2005 5:30:16 PM

    69bossnine
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    Reply to: Carlos from SpainM

    Re: Just out of curiosisty, 997S HP figures...

    I've only driven the 997S, I've not driven a standard 997. But I drove plenty of 996's. All I know, is that when I got out on the road, not even in "sport", that I was just going "WHOA!!!, this thing cooks!" It was MUCH stronger, everywhere on the tach, whether you were just torquing through the gears at half throttle, or wringing out 3rd gear to the redline (I don't know about the standard, but the S kicks like a rabid mule in the last 1500 rpm!) All I know is that my drives in 996's always left me fairly luke-warm in the power category. Fast enough, but nothing like the 997S.

    Who knows, I go to alot of muscle car shows where portable chassis dyno's are rolled onto the lot for anybody who wants to pay for a few dyno pulls. Once my 997S is properly broken in, I'll roll her up onto one of those rigs and see what I get!! I'm sure that at the very least, it'll draw a crowd curious to see how a n/a 6-banger fairs compared to all the supercharged V8's !!

    Feb 25, 2005 11:20:59 PM

    AshD
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    Reply to: 69bossnine

    Re: Just out of curiosisty, 997S HP figures...

    Guys, also be aware that EU regs for manufacturers state that the real power figure can have a maximum negative variance of 10% on the figures quoted by the manufacturer. We all know that each engine is unique and some push a few more horses than others....the key thing is that the Porsche approach to manufacturing is quite conservative, the figures they quote are always a minimum, no S engines leave the factory less than 355 - which means there are a lot of cars out there with more than 355. Basically they treat the figures they quote as guaranteed minimum, rather than other manufacturers regularly turning out cars with upto 10% less power than the figures quoted....

    Feb 26, 2005 3:00:54 AM

    macsak
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    Reply to: AshD

    i was told at the factory

    that german regs require the engine to be within 3% of rated horsepower plus OR minus
    if it is further out of spec than that, it is placed in a separate room where special technicians adjust components to bring it back in line
    i was told that these techs can look at a dyno sheet and be able to tell immediately what has to be changed

    aloha

    steve

    Feb 26, 2005 10:21:31 PM

    fritz
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    Reply to: macsak

    Re: i was told at the factory

    "Negative variance of 10%", "power output tolerance of plus/minus 3%"????

    If I'm not very much mistaken, European "Type Approval" regulations permit a max power output tolerance of plus or minus 5% on the declared figures.
     
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