As a point if interest what sort of top speed have people geared to with their cars (with respect to RPM v MPH in top) - ok understanding that BECs will be doing 200k rpm at 30mph?

I am doing about 95 at 4000rpm.

Nick

Mines more like 85mph at 6000

3000rpm@70mph

About 3500rpm at 80mph
limiter set at 7000rpm

80 mph @ 4000 rpm in 5th
3.9 diff, 185-50-14 tyres

Geared to 13,750@70+... in first, or 6500 in top. Max just under 150.

I have just done a quick calc using my tyre size of 215/40/17 and my final ratio comes out at 2.977:1.

This gives me a final top speed (theoretical) at 5500 RPM (Top of torque curve) of 130mph providing the power and aeros will let it get there.

This is a good calculator: http://www.kouki.co.uk/utilities/visual-tyre-size-calculator


Nick

Mine went to 140mph at 7200rpm on the RR. That was a 3.62 diff with it in 4th - ratio 1:1

I've since changed it for a 3.92 thats made it a lot more lively and so far I've seen 128mph....

mine is geared for about 338mph in top (never get there, but is a result of axle ratio and .5 overdriver ratio in 6th, and gearing for 60+ in 1st) so 70 would be about 1200rpm, 61 mph in first, almost 600lb/ft so should just about pull the gearing at all speeds i have the balls to use it at, but then that was with old engine