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Karmann the Corrado

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7 minutes ago, Dox said:

I'm no expert, but Dave Walker at Emerald is:-

EmeraldM3D.com - Rolling Road

 

How Rolling Roads Work

power-curveBefore we consider how a rolling road measures power output, it helps to understand what we are measuring.   We often talk about bhp (brake horse power) as if it was something that existed, rather than the reality of it being a convenient number - which we have calculated.  Bhp is a rate of doing work and in order to do work you need to put in some effort and then you need to see a result for that effort.  The effort is, in our case, the torque generated by the engine.  The result is the distance moved by the flywheel (expressed in rpm).  The simple formula for calculating bhp is based on 33,000ft lbs of work being done in one minute.  This amount of work is regarded as one horsepower.  The formula is: HP = Torque x rpm over 5252.  From this you can see that when the rpm is at 5252 the HP and the torque are the same.  If the power and torque lines do not cross here on the graph then someone is telling you porkies!   We use the term "Brake" horsepower because the engine torque is measured on a device called an Engine Brake, or dynamometer as it is more correctly known.  Dyno's measure torque at a given rpm and then we calculate the bhp from there.  With an engine bolted to a dynamometer we take the torque reading directly from the flywheel and without any form of gearbox.

nice explanation Dox thanks 😄

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Posted (edited)

196911c7654d2f2a66a29117ad7dd19d.jpg

If 118kw is at the wheels the above indicates a 32bhp loss over standard due to transmission losses which is about right

Edited by Dox

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Sorry for the delay in sending pics of the bonnet rib cutout. The white is adhesive from the tape i used to cover it. I covered the area with masking tape, and cut through that as opposed to using the dremel directly. The bottom of the pics are towards the engine

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19 hours ago, Dox said:

196911c7654d2f2a66a29117ad7dd19d.jpg

If 118kw is at the wheels the above indicates a 32bhp loss over standard due to transmission losses which is about right

I did those calcs and  gained comfort from them, especially as the car does not feel sluggish or under powered. Thanks Dox for putting this stuff up.

Fla great pictures, thank you.

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