...what speed would i be goin with std rear diff ratio and std gearbox on 215/40/17 fronts and 235/40/17 rears at 7500rpm 7800rpm and 8000rpm

I assume my car could pull atleast 7500rpm in top!

 

8k would be 200mph pal

182 at 7500

 

In theory (235/40 x 17):

7500 - 186
7800 - 194
8000 - 199

You have to factor in wind resistance and tyre resistance etc, so knock about 10 mph off those speeds for a truer indication.

 

....well its limited to 8k but i aint got the horse to reach that in top what about 7800rpm..a possibility?

 

7800 is a possibilty i'd say, more than that and you want solid lifters if holding for long periods.

I pulled 7600 in 5th at brunters, recorded 174 mph (smashed straight into the 7600 revlimiter ) and still had 1/4 mile to go on my T4 / 8 greens engine, but 4x4, in the rain.

So 2wd in the dry with 100 more bhp and you'd hit 7800 no probs!

 

you dont have to factor in wind resistance,,,, if the car is pulling the revs it will be doing that speed

theres nothing that can slip to give a loose between the engine (revs) and the wheels

 

I'll take a on that one Gareth

But in theory i should have been doing 178 mph, so where did those 4 mph go?

 

Could your rev counter have been slightly out?

 

Tyre wear or slight difference in diammeter between the calculated size and actual size.

 

as phil says rev counter,,,,, how accurate are tyre sizes? and of cause the tyres wear so reducing rolling radius

 

what a load of bollocks. all they mean is that you need more power than if they're weren't present

as gareth says, the gearing between engine and tyres is all fixed

if anything you will go faster, as the tyres grow

 

Wasn't rev counter, as it was being data logged (pectel monitor with Uncle Tony operating it at the time), and data logging showed 7600 rpm, as did the peak recall on the SPA rev counter.

Tyres were new Michelin Pilot Sports, but i reckon this is were the theory and reality times are decided, the tyres, different tyre companies have different rolling radius' for the same sized tyre, and they don't match the theoretical rolling radius.

 

Keep you hair on mate, i was wrong and took a for it

 

i don't have any hair to keep on

 

...a fao rod and no rod