This is my first question post so please be gentle and if I've posted in the wrong place sorry
I've just picked up a sylva stylus and was given a dyno readout sheet with the paper work and something doesn't look right, the point where
the torque and bhp lines cross is not at 5250 rpm?
I come from a bike back ground and always thought that if the lines didn't cross at that rpm then the dyno was out or something?
Can any of you fine chaps help?
Shooter63
BHP and Torque are related, and as you say should cross at 5252rpm
Just looked at my 2 litre zetec ones in various states of tune and all cross at 5250, don't know why hopefully some one with more knowledge will explain
:-) check that the scale is not on the same axis....I suspect he torque is on a different axis :-)
Just looked at my zetec graph and it crosses at 5250ish too. Post up a pic/scan of it and lets see as it might be looking at the wrong scale/axis?
Was it a just a power run or part of a tuning run?
[Edited on 23/3/15 by Alfa145]
Surely this is dependent on the axis for power and torque being used. I assume from the previous comments that they may cross around this point if both rear wheel (or is it calculated fly wheel, that would also make a Difference) hp and torque lb.ft are plotted on the same numerical scale. If ether is on a different scale then they would cross at a different point.
Power (hp) = [Torque (lb ft) x Engine speed (rpm)] / 5252
Therefore at 5252 rpm, the power and torque figures (in hp and lb ft respectively) will be equal.
The constant 5252 is derived as follows:
One horsepower is defined as 33,000 foot pounds per minute.
33,000 / (2 x pi) = 5252
quote:
Originally posted by softfeet
Power (hp) = [Torque (lb ft) x Engine speed (rpm)] / 5252
Therefore at 5252 rpm, the power and torque figures (in hp and lb ft respectively) will be equal.
The constant 5252 is derived as follows:
One horsepower is defined as 33,000 foot pounds per minute.
33,000 / (2 x pi) = 5252
quote:
Originally posted by Jenko
:-) check that the scale is not on the same axis....I suspect he torque is on a different axis :-)
This forum is fantastic,. learn something new everyday
frequently this is a display issue on the graph or the power runs where in Nm/PS etc, ie not HP which is where the the constant is derived from.
Anyway....post up the graph and lets have a look.
[Edited on 24/3/15 by jeffw]
quote:
Originally posted by will121
Just looked at my 2 litre zetec ones in various states of tune and all cross at 5250, don't know why hopefully some one with more knowledge will explain
Thanks for all the answers, I've been in touch with the dyno operators who have sent me a read out, the car made 159.5 bhp on the rollers with
the torque crossing at 5250 rpm.
So alls well that ends well.
Shooter63
I seem to remember some big cc v8 readouts having a massive flat torque line that was constantly above the horsepower line?
Sure my 430 HP daf truck makes a fairly constant 1200ft/lbs of torque at 1300rpm...