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Discussion Starter #1
on a dyno print out is it true that the hp an lbft should cross at 5252rpm
why is this !!
 

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'cos hp = torque x revs, essentially.

Most people don't understand torque or hp, but that's another story :chuckle:
 

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Yes and no ......

It is indeed true and its due to the way that the BHP is calculated. The Dyno measures Torque and calculates BHP from that and some other factors. (thats my understanding of that bit anyway)

The lines usually wont cross on most graphs though due to the scales on the graphs not being the same which make it look "odd"

Generally the ones I have seen that do not cross are bigger power cars because the scales have to be adjusted to fit it on the page.
 

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Discussion Starter #4
So how do you know if its been adjusted for reasons of giving different readout or because you have big hp, (which i dont understand to honest i got over 700 an mine crosses)
 

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just calculate bhp and torque at a specific rev point to check the accuracy.
most odd scaled runs seem to be scaled roughly the same on what ive seen and cross at around 7000 rpm due to different bhp torque scales.

torque / 5252 x rpm = bhp :smokin:
 

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So how do you know if its been adjusted for reasons of giving different readout or because you have big hp, (which i dont understand to honest i got over 700 an mine crosses)
Look at the labels on the Y axis (the one which is vertical); for example if BHP is on the left hand side y axis and goes 0, 50, 100, 150, 200, 250, 300 etc. (i.e. each division is 50 bhp), and if torque is on the right hand side y axis and goes 0, 50, 100, 150, 200, 250, 300 etc. (i.e. each division is 50 ft lbs) then it should corss at 5250.

If, however, the bhp scale markings are as above, but the torque scale goes 0, 40, 80, 120, 160, 200 etc. (i.e. each division is 40 ft lbs) then it will cross somewhere else.

In this example the scales are the same (each division is 65) so it does cross at 5250:

 

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Discussion Starter #7
Look at the labels on the Y axis (the one which is vertical); for example if BHP is on the left hand side y axis and goes 0, 50, 100, 150, 200, 250, 300 etc. (i.e. each division is 50 bhp), and if torque is on the right hand side y axis and goes 0, 50, 100, 150, 200, 250, 300 etc. (i.e. each division is 50 ft lbs) then it should corss at 5250.

If, however, the bhp scale markings are as above, but the torque scale goes 0, 40, 80, 120, 160, 200 etc. (i.e. each division is 40 ft lbs) then it will cross somewhere else.

In this example the scales are the same (each division is 65) so it does cross at 5250:

arrr is see thank you very much "ru" i understand now:bowdown1:
 

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hp = torque(lbft) x rpm
5252​
 

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Haha sorry chippy, I was a tad under the influence when I wrote my post so didnt explain it too well LOL its been clarified though so hope you can see what I meant now :)
 
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