Shooter63
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| posted on 23/3/15 at 07:14 PM |
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A question about dyno read outs
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
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theduck
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| posted on 23/3/15 at 07:25 PM |
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BHP and Torque are related, and as you say should cross at 5252rpm
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will121
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| posted on 23/3/15 at 07:53 PM |
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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
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Jenko
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| posted on 23/3/15 at 08:06 PM |
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:-) check that the scale is not on the same axis....I suspect he torque is on a different axis :-)
MY BLOG - http://westfieldv8.blogspot.co.uk/
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Alfa145
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| posted on 23/3/15 at 08:40 PM |
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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]
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Ugg10
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| posted on 23/3/15 at 09:02 PM |
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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.
---------------------------------------------------------------
1968 Ford Anglia 105e, 1.7 Zetec SE, Mk2 Escort Workd Cup front end, 5 link rear
Build Blog - http://Anglia1968.weebly.com
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softfeet
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| posted on 23/3/15 at 09:33 PM |
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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
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will121
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| posted on 23/3/15 at 09:44 PM |
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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
I knew someone would explain a logical reason
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The Black Flash
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| posted on 23/3/15 at 10:37 PM |
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quote:
Originally posted by Jenko
:-) check that the scale is not on the same axis....I suspect he torque is on a different axis :-)
Must be this.
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HowardB
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| posted on 24/3/15 at 08:18 AM |
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This forum is fantastic,. learn something new everyday 
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again and goes zoom)
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jeffw
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| posted on 24/3/15 at 08:42 AM |
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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]
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will121
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| posted on 24/3/15 at 05:44 PM |
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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
Here's one of mine
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Shooter63
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| posted on 25/3/15 at 09:56 PM |
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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
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coozer
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| posted on 25/3/15 at 10:01 PM |
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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...
1972 V8 Jago
1980 Z750
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