What's my rpm?

[Brisbarnz]

Howdy, my vh still runs 6cyl cluster but drive line is vnv8/t700 and 3.45:1 ratio. At 110kph on dash. (100kphGPS) tacho reads 2800/2900 in o/d.
Now what's the calculation to work out what rpm I'm actually doing at 100?
I have the math to do it in a magazine but I've got no idea which one.
Thankyou

 

[the_boozer]

http://www.osella.com.au/gear-ratios.htm
any help to you you'll still need to work out your total tyre diameter

 

[Brisbarnz]

I'll give it a go and report back. Cheers

 

[ari666]

why not just divide the difference between a 8 pulse and a 6 pulse per rotation?

i.e.
youre sending 8 pulses to a tacho
tacho reads at 6 pulses and says 1rpm
so you have 2 pulses spare
2 goes into 6 3 times so youre reading .333 hgher than true
so 3000 rpm is 2000 rpm....

lol i love math, thats probably TOTALLY incorrect, but for the lolz, im gonna post this anyway and watch people correct me.

 

[ari666]

wait ok.. so 8 divided by 6 is .75
2900 X .75 = 2175...

that sound about right?

 

[Brisbarnz]

Yeah ari that sounds about right, I was thinking around 22/2300 buy the sound of the motor.
Cheers for that