James King Posted October 13, 2001 Share Posted October 13, 2001 I've just been out for a bit of a blat, good weather etc. I havn't driven the car for a couple of weeks, so i eased her in gently, let her warm up fully but I noticed that i could only just get to a 3 figure speed. I've got a 6 speed box, 15 inch wheels and at 6000ish rpm I was nudging a hundred but there was no more to give. I have not had the car long, but surely the vvc should squeeze a bit more than that on the straight. So I guess I have problems.. any thoughts? Link to comment Share on other sites More sharing options...
murph7355 Posted October 13, 2001 Share Posted October 13, 2001 When you say there was nothing more to give, what do you mean exactly? The gearing sounds about right for a car with a std. non-LSD diff. It may be that your speedo's not reading accurately, but 16.7ish mph per 1krpm in top is about right (so 6k revs is a smidge over the ton). I think the VVC revs to 7100 or so, giving you a theoretical max of about 120. Any 7 with about the power of the VVC or less struggles once you get around the 100 mark due to the aerodynamics. It's over that speed that you really notice lots more power, but the fuel consumption dies with it! If it was revving freely round to the redline in the lower gears and simply seems to need ages to wind up to top speed in 6th, I'd say there's nothing wrong and that physics is playing its part. There are a few threads elsewhere with links to gearing calculators. Put in your wheel size and diff and out come your theoretical max. speeds in each gear (I think your diff will be a 3.92), assuming you have enough power to push it through the air. Link to comment Share on other sites More sharing options...
James King Posted October 14, 2001 Author Share Posted October 14, 2001 Thanks Andy, It seems ok in the lower gears, but it was just taking ages to squeeze up to the higher speeds. Probably find that i've put on a few pounds and need a haircut! Link to comment Share on other sites More sharing options...
Nick VVC Posted October 14, 2001 Share Posted October 14, 2001 My VVC runs on 13" wheels & 5 speed box; on track flat out and at the end of a decent straight, the standard speedo (when it's working!) typically shows anything between 105 & 120mph. I've also got a Stack unit fitted, calibrated off a wheel sensor, and this typically shows a maximum speed of around 105/108mph which I believe is far nearer the truth! Nick Link to comment Share on other sites More sharing options...
Lali Posted October 14, 2001 Share Posted October 14, 2001 James, Check your speedo, if you have the use of a friend a second car and a dual carrigeway check your 30, 40, 60, 70 and if you really want 100mph against a run of the mill family type mode of transport. What profile tyre are you using?, if this is different to when the speedo was configured then it will be "out" now as teh circumference of the tyre and so the distance traved per wheel rev has changed. I have a stack unit and I run on 60profile 13" rims, I get a reading of 125-133 on most tracks but it is somthing i need to check. Lali VVC-ya wouldnt wanna be ya!! Link to comment Share on other sites More sharing options...
murph7355 Posted October 14, 2001 Share Posted October 14, 2001 What circumference are you using on the Stack Lali? And which tracks? Link to comment Share on other sites More sharing options...
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