Why doesn't the BHP equation work??
 

BHP = Lbft *RPM/5252

Take a WR1 for example.....It produces 310lbft @ 4000 rpm (according to evo)

Pop that in the equation and... 310*4000/5252 = 236.1bhp.

Now according to the stats the WR1 has 316bhp??

Where has the equation gone wrong, or am i not understanding something here??

Is the 236.1 the wheel HP figure??

That's the HP at 4000rpm not maximum power.

Dipster

So it produces 236.1 BHP at 4000 RPM.

The 316 BHP is at higher RPM. From knowing that RPM you could work out the torque at peak power if you want.

There are no problems, and it is nothing to do with wheel power.

Sorry, Dipster got there first :)

Max Power must therefore occur at 5353rpm.

Okay, cheers guys.

If the torque curve is flat.

Dipster

Beastie - no it doesn't. The 310lbft is the torque figure at it's peak of 4000rpm, not throughout the rev range - it will tail off as revs increase from 4000. You'll probably find that the 316bhp is at say 6000rpm (which would correspond to 276lb/ft at those revs). Note that the 6000rpm is a guess on my part.

Yes, if max torque is still available at these rpms.

Subaru figures :

max power = 320 PS @ 5800
max torque = 420 Nm @ 4000

convert to bhp /lbft

power = 315.5 bhp @ 5800rpm
torque = 303.7 lb/ft @ 4000


So at 4000rpm
power = 231bhp
torque = 303.7 lb/ft

So at 5800rpm
power = 315.5bhp
torque = 286 lb/ft

Nice one chrisp, we can all sleep soundly tonight now! :D