Why doesn't the BHP equation work??
13 February 2005, 05:44 PM
#1
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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??
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??
13 February 2005, 06:03 PM
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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
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
13 February 2005, 06:15 PM
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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.
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13 February 2005, 08:22 PM
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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
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
Last edited by chrisp; 13 February 2005 at 08:25 PM.
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