I know it's been done to death but I've been thinking again

Right, we all know that BHP at the flywheel is the most variable figure and most people will happily accept BHP 'at the wheels' much more readily. The thing is, BHP is calculated from torque( (RPM*lbs/ft)/5252 ), so my question is: Where do they get the BHP @ the wheels figure from then, torque at the wheels? When I asked the guy in the RR shop, he told that me there is no such thing as 'torque @ the wheels' so I’m now even more confused… Where do they get the torque from to calculate the BHP @ wheels?

These things get on my nerves

The dyno measures wheel torque, this gets converted to wheel power via the above formula. The flywheel torque and power is produced via a coastdown measurement to determine parasitic losses through the whole drivetrain. Some rollers like Dyno Dynamics in "Shootout" mode (same as your recent power run) apply a correction figure to the wheel power based on their calculations for each make/model on what the transmission losses are likely to be.

So the coastdown part measures the resistance in the engine with no throttle? They then add that to the wheels figure?

I find the correction figure used to be the most confusing...

No matter what way you look at it the only way to get the true flywheel figure is to have the engine in a dyno cell.

Different RR dynos measure different ways of coasting and to be honest the flywheel figure is always BS. PT's dyno is the most accurate I’ve seen however the flywheel figure will still NEVER be true just more realistic and not so pubby . Only WBHP & FT/LB figures actually matter as that is the true usable power (excluding traction).

Something well worth asking google about i think.
loads of reading into calculations and such.

I remember at uni we had a smokey 1600 cvh on the dynomometer, im not sure we plumbed in the exhaust right!
I really wish id of paid more attention to the practical lessons than to women and beer!