FAO Gareth T and other engine gurus
09-04-2007, 08:27 PM
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FAO Gareth T and other engine gurus
Hi
I am currenlty working through some tuning theories (to understand the engineering principals.
A Graham Bell has indicated that the VE of a 4 valve engine unmodified would be approximatley 90%.
Do we know what the Cossies VE is as stock?
I am trying to work out the CFM of the current setup. So far I have calculated based on my own car, with a peak boost of 28 psi (giving a pressure ratio of 2.9), a peak rpm of 7250.
This comes out with a CFM of 668 approx.(46.8 lb/min)
Does this sound realistic?
Thanks
JJ
I am currenlty working through some tuning theories (to understand the engineering principals.
A Graham Bell has indicated that the VE of a 4 valve engine unmodified would be approximatley 90%.
Do we know what the Cossies VE is as stock?
I am trying to work out the CFM of the current setup. So far I have calculated based on my own car, with a peak boost of 28 psi (giving a pressure ratio of 2.9), a peak rpm of 7250.
This comes out with a CFM of 668 approx.(46.8 lb/min)
Does this sound realistic?
Thanks
JJ
09-04-2007, 08:57 PM
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HI matey
Thanks for that - appreciated but - IF I am using the same formula, then I will need the CFM for the std car.
Doesnt the other equation need temperature details to assess VE?
Oh bugger, I may be getting confused again!
JJ
Thanks for that - appreciated but - IF I am using the same formula, then I will need the CFM for the std car.
Doesnt the other equation need temperature details to assess VE?
Oh bugger, I may be getting confused again!
JJ
09-04-2007, 09:11 PM
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Absolutely correct!
It is a good book, though it doesnt necessarily order the information in the way that I would order it!
I have his other book on performance NA engines, which I was trying to cross reference, but this is leading to more confusion. As such, I am now sticking to this one.
The particular equation that I was using at the mo is
Air Flow (lb/ft) =
0.07 *
(L X RPM X VE X PR)
(----------------------)
5660
Where
L is engine capacity in litres
VE is volumetric efficiency
PR is pressure ratio
JJ
It is a good book, though it doesnt necessarily order the information in the way that I would order it!
I have his other book on performance NA engines, which I was trying to cross reference, but this is leading to more confusion. As such, I am now sticking to this one.
The particular equation that I was using at the mo is
Air Flow (lb/ft) =
0.07 *
(L X RPM X VE X PR)
(----------------------)
5660
Where
L is engine capacity in litres
VE is volumetric efficiency
PR is pressure ratio
JJ
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09-04-2007, 10:48 PM
#10
Professional Waffler
Originally Posted by bud-weis
Originally Posted by GARETH T
sorry,, ive been watching tv,,,
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