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    What if 190+mph is sacrificed for different gears?

    Okay, this may be a totally amateur question, but here goes:

    Our cars have a huge Autobahn speed potential when they come from the factory. They also have six speeds, I guess that's a tranny which only makes sense for shaving tenths on the track.

    What about an _optional_ gear box for the USA and other places where there's no hope of getting to 180+mph? Maybe it would have "only" four or five speeds?

    Say it was acceptible to the buyer that the car would only go 150mph, so he'd go for the "usa" gearing.

    What could be accomplished with this trade-off in terms of "low speed" performance?



    Re: What if 190+mph is sacrificed for different gears?

    Well if you had really short gearing, in a car like a 911 wouldn't the times probably be pretty close to the tall gear just because you're shifting more?

    Re: What if 190+mph is sacrificed for different gears?

    I don't get it... Basically, just ignore the 6th-gear (don't use it), and you've already got what you're asking for mounted in your chassis... But it's good to have that 6th gear for optimal mileage on the interstate..

    When you think about it, the Porsche ratios are MORE suited to American driving, than american 6-speeds are, in that fastest speed is achieved in 6th gear, whereas most U.S. and Japanese cars achieve top-speed in 5th...

    You could ask for a 4 or 5 speed gearbox that limited your top speed to 150, but all it would be is the same exact gearing that you ALREADY have with gears 1-5 in your car..

    In other words, the 911 6-speed ratios are already optimized for 0-150 driving... You've already got what you're wishing for... Porsches on the autobahn are using 6th gear where many other cars are using 5th, as their 6th gear is an economy gear that is too over-driven for high speeds...

    Re: What if 190+mph is sacrificed for different gears?

    Quote:
    AndyM said:
    Well if you had really short gearing, in a car like a 911 wouldn't the times probably be pretty close to the tall gear just because you're shifting more?



    The gearing in the Porsche 6-speed is already damn short compared to its competitors... That's part in parcel to why 0-60 and 1/4 mile times are so scorching for the relatively low horsepower...

    Re: What if 190+mph is sacrificed for different ge

    Quote:
    69bossnine said:

    You could ask for a 4 or 5 speed gearbox that limited your top speed to 150, but all it would be is the same exact gearing that you ALREADY have with gears 1-5 in your car..





    Yes, good point, it crossed my mind; now when it crosses I snatch it and hold on.

    I started thinking a lower first gear would increase 0-60 times. But from what you're saying it would just make us shift faster.



    So I guess lower gearing would only make sense on an off road 997?

    Re: What if 190+mph is sacrificed for different gears?

    It wouldn't really make sense for Porsche to come up with yet another option for the US market because then they'd have to deal with a) more R&D money for developing those, b) owners green with envy for those in Europe, c) those who track their Porsches would be left to hang.

    MMD, you're honestly overanalyzing EVERYTHING about the car. I say, get in your car and go drive it. Enjoy the Porsche for what it is.

    Re: What if 190+mph is sacrificed for different ge

    One thing you would get is worse fuel mileage too. The engine would spend more times in the higher rev range. I had 5.0 litre Mustang in my teens with 3.73 rear end gears, it increased 0-60 times but it sucked down gas like mad.

    Re: What if 190+mph is sacrificed for different ge

    Quote:
    atomic80 said:

    MMD, you're honestly overanalyzing EVERYTHING about the car. I say, get in your car and go drive it. Enjoy the Porsche for what it is.



    Hehehe! You're right, funny! I'm just stuck in office and trying to manage stress.

    I also imagine a bunch of guys who come to Rennteam and are happy to find somebody asked the "same" question that was on their minds.

    Though the return is probably low..., Ya never know what we'll learn from even the "dumb" questions... .



    Re: What if 190+mph is sacrificed for different ge

    You're our guy, MMD, speaking our minds for us folks.

    Re: What if 190+mph is sacrificed for different ge

    The 1st-gear in our cars is already such a stump-puller you can barely blink before hitting the rev-limiter...

    The Ford GT can go 0-60 without leaving 1st-gear, for a bit of context...

    It all comes down to how much torque the engine makes, where it makes the power, and across what kind of range, and then you need a clutch that'll hold it..

    Our Porsches are relatively tame on torque, and rev high, so the short 1-2 gearing works to its advantage..

    Making first even steeper would likely be counterproductive, exceeding the engines ability to spin-up..

    Just postulating..

    Re: What if 190+mph is sacrificed for different ge

    But it would certainly improve the acceleration of a tip.

    Re: What if 190+mph is sacrificed for different ge

    Put in a cup car ring and pinion and you effectivly lower your gear ratios. I did the calculations on here a while back talking about a GT3. 1st gear becomes something that is only for getting you moving, but the extra grunt in 3rd -5th gears would feel like getting another 50+ hp... I belive top speed would end up arounf 155mph or perfect for track use.

    Re: What if 190+mph is sacrificed for different ge

    So here are the numbers with a Stock 997S gearbox. At 7300 rpm 1st is good for 43mph
    2nd - 72mph
    3rd - 103mph
    4th - 130mph
    5th - 154mph
    6th - 189mph.

    Putting a Cup Car/RSR Ring & Pinion (8/32 aka 4:1 versus the stock 3.44:1) would make for a much faster car in all conditions (except top speed, but it would get up to its top speed of 159mph much much faster...)

    The gears would then be good for:

    1st - 36 mph
    2nd - 60 mph
    3rd - 87 mph
    4th - 109 mph
    5th - 129 mph
    6th - 159 mph

    Re: What if 190+mph is sacrificed for different ge

    Quote:
    Mithras said:

    Putting a Cup Car/RSR Ring & Pinion (8/32 aka 4:1 versus the stock 3.44:1) would make for a much faster car in all conditions (except top speed, but it would get up to its top speed of 159mph much much faster...)




    Is that a fact? Yeah Mithras! That's what I'm talking about!

    _Now_ I can imagine ordering this car with a 4.1 unit you speak of AND a PDK tranny.

    The PDK would be to so it becomes possible for a mere human to blow thru those lowered gears like lightening.

    Why _not_ offer the lower gearing as an option in non-Autobahn countries?

    Re: What if 190+mph is sacrificed for different ge

    As you lower the rear ratio, you compress gear spacings, and shift frequency... In an old-school manual, you reach a point of diminishing returns, and even in a PDK car, I'd think that professional drivers would deem overly compressed and prolific shifting as a distraction/nuisance from concentrating on line and grip...

    I've got some old detroit muscle cars with 4-speeds and 4.10 gearing... On the street, it's just a pain in the rear, and you find yourself falling into the routine of simply SKIPPING gears 95% of the time, i.e. 1st-3rd shifts, or 2nd-4th...

    In my new beater ('06 GTO LS2 6-speed) it's got so much beefy low torque that I usually shift 1st-3rd-5th driving around town, the other gears only come in handy for "playing", which of course is a good thing too!!!

    Re: What if 190+mph is sacrificed for different ge

    When I first read MMDs initial post, 69 bossnine's comment on the 4.10 gearing came to mind. IOW, change "rear end" gearing.

    Too many years ago (geez, I'm old) a buddy had a '58 Del Ray with a 348, 3 2 bbl carbs, floor mounted 4 speed and a 4:56 rear end! Great acceleration, but top speed? Eh, maybe 110 or 115?

    Re: What if 190+mph is sacrificed for different ge

    With stock gears and a cup R&P you are in essence getting rid of 6th gear and adding another gear between 2nd & 5th.

    I think it would make for a better track box as 3rd-4th-5th are pretty spaced out (in fact on many tracks 5th & 6th gears arn't used on a 996/997). It would however be on the cusp of too cluttered. Esp. for the street. I think it would work all right though.

    Now for a GT3 with its marganially higher gears I think putting in a Cup R&P would transform the car and only for the better.

    Re: What if 190+mph is sacrificed for different ge

    Had a BMW 2002tii (another car I should have kept) with Alpina close ratio 5 speed and "racing" shift pattern (1st low and left). 1st gear was rather long and it was a great car.

    Re: What if 190+mph is sacrificed for different ge

    There are a few people who installed a short-ratio final drive on their GT3 cars, surely improving performance. There is still a small difference between those two models, the turbo achieving performance by torque, the later by revolutions. The GT3 engine surely profits more from this layout, as 69 mentioned a shorter ratio would become counterproductive at a certain point.

    One could judge MMD's posts by just looking at the topic itself. Nobody adresses revolutionary issues like he does...

     
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