How fast am i going?

[turbotoaster]

I have just measured the diameter its 626mm (oh and they are 255/40/R17) oooops.
Can you do a little list of speeds for that matey

ok on brand new 255/40/17

6000rpm 133mph
6500rpm 144mph
7000rpm 155mph
7500rpm 166mph
7800rpm 173mph
8000rpm 177mph

on your used tyres

6000rpm 131mph
6500rpm 142mph
7000rpm 153mph
7500rpm 164mph
7800rpm 170mph
8000rpm 174mph

if you have any other rpms, diff/gearbox ratios and tyre sizes let me know.

If you also want to give me a horsepower assuming your on a stock body i can tell you roughly what speed you will hit within 1.5miles and also with unlimited distance

[DR SCHNITZEL]

Ok mate lets say i have about 420 at the hubs, t04r at 1 bar standard ports. i have taken about say 60 kilos out of the car

[DR SCHNITZEL]

post up the formulas

[raceralexuk]

Turbotoaster, none of your calculations make sense according to the numbers I have.
 
What are you using as 5th gear ratio in your calculations?

According to the info I have internal gearbox ratios are as follows:

1st - 3.483:1
2nd - 2.015:1
3rd - 1.391:1
4th - 1.000:1
5th - 0.719:1
 
Which on new 255/40/17 would in 5th gear give:

6000rpm 153mph
6500rpm 166mph
7000rpm 179mph
7500rpm 191mph
7800rpm 199mph
8000rpm 204mph

[raceralexuk]

Ok mate lets say i have about 420 at the hubs, t04r at 1 bar standard ports. i have taken about say 60 kilos out of the car

First thing I\'ll say is that weight has no direct impact on terminal velocity (when power is equal to drag) only by the amount it\'s pressing the tyres into the ground, causing friction. Weight affects acceleration but at terminal velocity there is no acceleration.
 
I\'ll have to think about calculating this one as it means rearranging a couple of big equations.

One other value will be needed - the frontal area of an FD.

[turbotoaster]

Ok mate lets say i have about 420 at the hubs, t04r at 1 bar standard ports. i have taken about say 60 kilos out of the car

Ok assuming you had perfect gearing and unlimited distance it would be possible to hit 197mph, but we are talking bonnieville type setup or the place that VW use.

if we say 1.5miles then your looking at 177mph with perfect gearing, since that isnt normally possible, it all depends on where your making max power and how much it drops off after peak power.

say for example you made 420 at 8krpm, that would be perfect for you 1.5mile run as at max speed your making max power.

if for example you made 420 at 7krpm and 370 at 8k then you would find your losing power when you need it the most and your top speed would be less, say 173mph

Turbotoaster, none of your calculations make sense according to the numbers I have.
 
What are you using as 5th gear ratio in your calculations?

According to the info I have internal gearbox ratios are as follows:

1st - 3.483:1
2nd - 2.015:1
3rd - 1.391:1
4th - 1.000:1
5th - 0.719:1
 
Which on new 255/40/17 would in 5th gear give:

6000rpm 153mph
6500rpm 166mph
7000rpm 179mph
7500rpm 191mph
7800rpm 199mph
8000rpm 204mph

Yes it looks like you cant understand it because the 5th gear ratio  is actually wrong, its actually 0.820:1 for some reason the 5th gear was published wrong which is why alot of people think they are going faster than they actually are.

The ratio I use is something i worked out and tested myself and its spot on, so you wont find that ratio anywhere online though.