Gearing need to race at Spa

[andy robinson]

How much fasters will I be going at spa ??? anybody tech ideas or experience ?

other than u tube videos, anyone know a way of working out what gearing I will need, dont want to overgear the car & kill it coming out the corners but neither do I want to bouncing it off limiter.
Here the details
1600 kilo V8 supercar 650 bhp, fairly decent aero but will be braking fairly early
1:1 top gear, 6500 limiter, 680 height tyres
I currently run a 3.25 diff at the fast uk tracks silversotne/snetterton & a 3.5 at the rest of them, which is perfect, ie nearly on the limiter at the fast parts of the track.
Im guessing a 3.0 would be ok ie 10 % higher top speed, beacuse wont be going that much faster than snetterton ?

[GORDON STREETER]

I would think you are about right in what you think as the only time I have ever used my highest diff is at Spa.
As I can change my back axle ratio in about half an hour it's not a problem and IMHO it's best to over-gear a car for an unknown track then at least you won't run out of revs in practice/qually !

[andy robinson]

cheers Gorden, 3.0 it will be for me then, because even though the striaght is a fair bit longer at these sorts of speeds you coving the ground so much quicker, dont thinks ill be going more than 10% faster than say snetterton

[GORDON STREETER]

Andy, not knowing anything about your car is it easy to change ratios ?

[andy robinson]

ford 9" so not too difficult as long as you have a spare diff built up, just like any other rwd, half shafts out, prop off, pig's nose out

[Al Weyman]

I surprised it weighs as much as 1600kgs Andy, I was weighed at Donington the other week in my black car and it came in a very respectable (I thought for a mostly steel bodied saloon) under 1300kgs.

[Notso Swift]

It should be lighter than 1600
IIRC they are 1400 with "minimum race weight", so inc driver, and all fluids but no fuel.

You obviously don't still have a Supercar motor in it, is it now a 6 litre, or a 351(5.8) stroker? (common to be done to older cars that go through Sport Sedans here)
Why only 6500 rpm?

[Stacy]

Hey Blair,

I think Andy is running the full motor. Here he is in my last vid;

26s and 3.00 in the damp.

3.15 on the dry stretch. Made my doors rattle..

http://www.youtube.com/watch?v=K0TewYbIxZU&sns=em

[andy robinson]

Originally Posted by Notso Swift

It should be lighter than 1600
IIRC they are 1400 with "minimum race weight", so inc driver, and all fluids but no fuel.

You obviously don't still have a Supercar motor in it, is it now a 6 litre, or a 351(5.8) stroker? (common to be done to older cars that go through Sport Sedans here)
Why only 6500 rpm?

this car has never weighed 1400 kilos race ready, pwr chassis no 001
now has sallen s7r 7 ltr small block

[Notso Swift]

So long since I have been on, sorry, being Paul Wheel that is obviously a really early chassis but I am still surprised it is so far above minimum.

What gearing did you end up with? with a Low revving 7 litre at least you would have the torque to push it!

[andy robinson]

3.00 is what im going to use