My girlfriend said there can't be much difference between 100 and 140 so I arranged a demo (completely legit on a runway of course)

Topped out at about 5800rpm speedo reading just over 140 but I don't really believe that. Done some quick calculations based on 0.738 5th ratio and 3.545 final drive ratio and I'm on new Toyos 205 50 16s. It's a 97 UK car and I use go faster petrol.

However I do the maths I end up at over 150mph which I don't believe as the car's standard (I think!) I was thinking high 130s would be more likely

Anything I'm missing ?

Girlie agreed there's a big difference though and 90 is slow after flooring it

 

Well, I haven't checked your gear ratio numbers, but with the gearing you've specifies and the revs I get 157.46 mph.

The odd thing is the the speedo should always be over reading, but you say it was only just over 140?! So although I have heard of standard UK cars winding the speedo off the end at 160+ indicated, I'd expect about 10% optimism, so that's probably about 145 really. When my '97 car was standard I saw 145+ indicated and climbing but backed off before it topped out, so an actual top speed fully topped out of about 145 seems quite likely.

It sounds like you have the wrong numbers for gearing, or there is something up with your speedo or car.

Edit: Just been to look here. The final drive should be 3.9:1, which gives 143 mph, which sounds better, and makes your speedo amazingly accurate.

 

Checked out speedo with a GPS and found it to be about 7% low which agrees with what you say.

Perhaps I didn't look at the speedo too closely - we were moving and I really wanted to keep my eyes on the road (sorry runway), but I did check the revs, just so I could work this out, may be we did hit 140+?

I'll investigate gear ratios some more, cheers.

 

Thanks. Just did exactly the same thing. I'm happy with 140 for now - scare's the girlie

 

The gearing equates to approx 24mph per 1k rpm in 5th, this is about 140mph at 5800 (139.something) and the top speed of 168(approx)@7k rpm.

Tony

 

so not near this then????????

 

show off.....

 

 

wasnt me...............

 

i think thats cool just waiting for some pensioner to say far to fast and all that crap!! THAT IS WHY PEOPLE BUY FAST CARS!!

 

You won't get there any quicker...

 

where any quicker????? end of the runway????????

 

thats to fast its dangerous and irresponsible. you should be ashamed.

my mcrae goes 145mph and still wanted to go for more, cough cough was on track honestly officer couldn't have been me on the m1 that late at night, past my bed time

 

final drive is 3.9 in a uK car no question.

rear diff is 3.54, but that is because output shaft of gearbox to rear diff is spinning slower than output to front diff. Overall ratio front and rear is the same at 3.9.

 

5800rpm works out to 144.3mph