[Tahoe968]

Flash & Company, what's the top speed the D1R SC makes? Verified?



If I'm choosing "W" speed rated tires am I "safe"? Go with the "Y"??

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[Rap]

I've been at 140 on the backstretch at Pocono and 130 on backstretch at Watkins Glen. Remember with the 18's on my speedometer is not correct but I've been told the incorrection is positive. So who knows the top speed.

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[vliegwielolaf1234]

I have done 149 / 240 kmph , it was taken from my garmin gps .

And there was more there but had to take the exit .

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[jaap]

Mine without supercharger still reached the manufacturer claimed topspeed (156mph /252 kmph) so I assume it would be more than that.



Jaap

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[type968]

I thought I read drag limit on the car was 155 or so and theoretical with gear at 6th and 6800rpm was 185?



All from memory, so don't quote me. This is with a non-sc car. Either way, they are tires, an important safety device, get the best you can afford.

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[Mark]

For me it is not about overall top speed it is about being quicker to high speed which should increase your "top" speed on a given stretch of asphalt. Rap what was your top speed on those sections of track without the super charger?

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[flash]

there are way too many variables to determine top speed. even ride height will affect it. things like wider tires, broken grills, and maladjusted headlights lower top speed. when you get up there, the littlest things will mess things up.



that being said, the speedometer is not accurate, so you can't go by that. the reviews and manual say top speed of a stock car is 156. given that it is a geometric progression of power to speed, you should probably be able to hit 165 or so.



p.s. - with stock gearing and tire diameter, the top speed at the OEM redline of 6700 is also about 165

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[94SilverCab]

[quote name='type968' timestamp='1407500033' post='160986']I thought I read drag limit on the car was 155 or so and theoretical with gear at 6th and 6800rpm was 185? All from memory, so don't quote me. This is with a non-sc car. Either way, they are tires, an important safety device, get the best you can afford.[/quote]



I think what you mean is that the 968 was governed by the ECU to 156 MPH, with a aerodynamic limit of approximately 185. That is correct, per my understanding. I still have an NA motor, but the limits are off by virtue of a custom chip.



My guess would be that the SC 968s could theoretically do 185, I would love to see some real life testing (on a close course naturally).



Jay

And, as Mark said, the SC will add quickness, moreso than speed...



Jay

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[flash]

nope. no governing. it just runs out of poop there.



no chance in hell of 185. that would require about 550hp, and a whole lot of aerodynamic work. the car starts lifting at about 150 and will get REALLY light at about 165 or so. a splitter and a turbo s wing could possibly allow you to get up around 175, if you have a bit more power than the SC puts out. the turbo s had an untested estimated top speed of 175, and while it only had 305hp, it had a LOT more torque.



i'm still not sure the SC will make the car much faster on top end, and the power curve flattens out just before 6k. previous peak speed was at about 6200. not sure it will go much beyond that the way the kit is now. you would have to ask dave n, who blew up his engine finding out.



again, the revs will be the limiting factor too. take a look in your owner's manual. you'll see that in order to go 170, you need to rev 7k (well beyond the stock redline of 6700, and past the power peak of the SC). redline on the SC is 7100, so even if you could hit redline, you could only do about 172.

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[ds968]

I know you guys are waiting for me to do a real live test and report the results, lol, and ten years ago I would have not hesitated for a moment but now older and much more cautious I'm just not willing to take either car to those kind of speeds anymore ; too many risks .

No guarantee even new tires will be 100% safe , some critter could cross my path , I could lose focus / control for a fraction of a second and that's all that it would be needed for a disaster, any given part of a 20 year old or even the newer suspension can fail, airbags can explode for no reason, LMAO ..and of course there's the highway patrol :-(. And I can't think of any closed roads , but even if there were, see previous uncertainties. Oddly enough I've had the new one to about 140 and then just chickened out , but 140 does not feel all that fast and it's also fairly easy to do with an SC on a very long highway onramp or a straight stretch of road where you're absolutely certain there is no police. However, having had the six speed when it was N/A ( chipped and all that , but still N/A ) at over 160 on speedometer mark...was actually almost at 170 - so no idea what that translates to in terms of real speed - I can say that every incremental 5 mph over 130 or so started feeling as the car was going exponentially faster not just a little faster and as solid and planted as the car may have been by the time the speedometer got to 160-ish, I was getting pretty nervous. The thought of going at a real speed of 175 + in a 968 is not at all comforting.

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[94SilverCab]

I meant governed (see article)



http://en.wikipedia.org/wiki/Governor_(device)



Cars[edit]



Today, BMW, Audi, Volkswagen and Mercedes-Benz limit their production cars to 250 kilometres per hour (155 mph). Certain quattro GmbH and AMG cars, and theMercedes/McLaren SLR is an exception. The BMW Rolls-Royces are limited to 240 kilometres per hour (149 mph). Jaguars, although British, also have a limiter. As do the Swedish Saab and Volvo on cars where it is necessary.



German manufacturers initially started the "gentlemen's agreement", electronically limiting their vehicles to a top speed of 250 kilometres per hour (155 mph), since such high speeds are more likely on the Autobahn. This was done to reduce the political willpower to introduce a legal speed limit.



In European markets, General Motors Europe sometimes choose to discount the agreement, meaning that certain high-powered Opel or Vauxhall cars can exceed the 250 kilometres per hour (155 mph) mark, whereas their Cadillacs do not. Ferrari, Lamborghini, Maserati, Porsche, Aston Martin and Bentley also do not limit their cars, at least not to 250 kilometres per hour (155 mph). The Chrysler 300C SRT8 is limited to 270 km/h. Most Japanese domestic market vehicles are limited to only 180 kilometres per hour (112 mph) or 190 kilometres per hour (118 mph).[sup][3][/sup] The top speed is a strong sales argument, though speeds above about 300 kilometres per hour (190 mph) are not likely reachable on public roads.[sup][citation needed][/sup]



Many performance cars are limited to a speed of 250 kilometres per hour (155 mph)[sup][4][/sup] to limit insurance costs of the vehicle, and reduce the risk of tiresfailing.[sup][citation needed][/sup]

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[flash]

170 indicated is about 153. there is an article out there where they checked the speedo, but only got to a real speed of 130 before they stopped the testing:



true speed - - speedo

30 32

40 42

50 53

60 64

70 75

80 86

90 97

100 107

110 118

120 129

130 139



you can extrapolate from there. by the time you get to 160, the gap will be about 15mph



re: governing top speed, while many cars do indeed have limiters, there is no mechanism, electronic or otherwise, built into our car to limit top speed. perhaps they chose gearing and redline to limit things, which would explain the short jump between 5th and 6th, and the relatively low redline.



i think we are straying far form the point of the question though. he wanted to choose a tire for the capabilities of the car.



my recommendation is not to worry about top speed capabilities, as you will never find a road on which to go that fast safely. instead, choose a tire that gives the best grip in the conditions to which the car will be subjected.

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[williamoss]

the one time I went I Portland International Raceway with my non supercharged car, but with a RS Barn chip I got my car up to 147 on the front straight. SO with a super charger you should be doing much more than that. Of course I did scare the willies out of my instructor as he said I went into the corner a little to fast for him, but the car did not skid at all.

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[flash]

sigh - power is not everything in top speed. there are a LOT of other factors



you will NOT gain much more in top end with the supercharger. stock top speed is achieved at 6200 or so. by design, peak power of the supercharger flattens out at about the same point. it is entirely possible there will be NO gain in top speed. you will get there faster, but you may not go any faster. if you do, it won't be all that much.



again, we are off topic. the question was related to tires, which is why this thread has now been moved to the TIRES section.

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[Tahoe968]

[quote name='flash' timestamp='1407511422' post='161000']

sigh - power is not everything in top speed. there are a LOT of other factors



you will NOT gain much more in top end with the supercharger. stock top speed is achieved at 6200 or so. by design, peak power of the supercharger flattens out at about the same point. it is entirely possible there will be NO gain in top speed. you will get there faster, but you may not go any faster. if you do, it won't be all that much.



again, we are off topic. the question was related to tires, which is why this thread has now been moved to the TIRES section.

[/quote]



Yeah, it was both - a question of "what's the top speed of the SC " (answered above) and then also "does it really make a difference if I get "W" or "Y" speed rated tires. Getting the "best tires I can afford" is one way to go about it, but in that case we'd all be driving Michelins I guess. : )



I was just curious how many of you are running "W" vs. "Y" or better. Given that the top speed of the car likely won't surpass the "W" rating of 168mph, that does open up quite a few more tire options for me.



In my area here in Carson City (which has a range of good/poor road surfaces) I tend to use discounttire.com - they built a brand new store just down the road from me, the service is good, and the prices are pretty low. For example you can get the "W" rated BFGoodrich g-Force Sport COMP-2 in a 255/40/17 rear ($112) and a 225/45/17 front ($103) which is pretty good value...

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[banditsc]

It's more a question of if you think you will be driving at speeds of 150+mph for extended periods of time? Making a brief burst to 150 doesn't require a tire rated at 170 mph, a tire rate even at 140 could sustain a quick burst to higher speeds, its the sustained speeds like driving at 150mph for 20 minutes on the autobahn that you need the speed rating for.

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[MCL968]

You need to check out Tire Rack, they are local and you can pick them up and find a local shop (I have one) to do the swap for you. Saves a bunch.



But, Discount Tire had a great price on the Sumi HTRZ3's

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[Tahoe968]

[quote name='MCL968' timestamp='1407544840' post='161017']

You need to check out Tire Rack, they are local and you can pick them up and find a local shop (I have one) to do the swap for you. Saves a bunch. But, Discount Tire had a great price on the Sumi HTRZ3's [/quote]



I know they are local, but I did the math on what the local install would cost on top of the tires - then added the gas in my truck to drive the hour + each direction - and the next time I want them rotated, or my other wheels put on, or a need a fix a flat, etc., etc. - and it just doesn't pencil IMO.

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[MCL968]

I agree, I did the same calculations and found Discount Tire was a better deal on many of the tires I was interested in.

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[Rap]

Mark it was in my first year on a different 968. So no comparison!

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