Hey guys,

im abit stumped right now, ive got a dyno sheet and the bottom axis is in km/h, i need to convert it to rpm but i dont know how too, ive looked everywhere! im sure there was a thread on this site a while back about how to convert it. With formulas etc..

cheers

ok car is EF with 3.08 rear diff, EA manual..

rear tyres are 215/60/R15, total wheel diameter of 25.16 inches
so im using these online converters and they say at 6000rpm i should be pulling 145mph! not possible so what have i got wrong?

i know so far that at 2k rpm its doing 78km/h

this is in 4th gear 1:1 ratio

KM/H x (1000/60)

This gives your speed in meters per minute.

pi x Diameter (in metres)

This will give you the cirucumference of your wheel in metres.

Speed / Circumference

This gives how many rpm of wheel per minute.

Then divide by diff ratio if in 4th. I haven't got a calculator but I think that should come close to checking out for your 78km @2000rpm.

thanks mate, helped so much

ive just realised that the dyno run only went to 5k rpm when the limiter kicked in at 180, still made 142kw though

When i had my old EF, it had the 3.08 diff, ED t5 and an xr6 manual ecu. So the rev limit kicked in at 5750rpm with no speed limiter. I saw it go off the clock to around 240kmh before it hit the rev limiter. (Dyno run was done in 4th gear of course)

Just something to go off.