[Diy_efi] BHP calculations

Mark Claywell clay0052 at umn.edu
Tue Jul 30 03:40:31 GMT 2002


Hello, 
 
I guess I did appear as being pedantic. My only point was that the 02 level
has nothing to do with the accuracy of his math model. Didn't mean to
offend. Hope you can see what my point was. 

mark

> 
> The original post was how to calc HP.
> If the O2 level varies that will effect the HP generated.
> Excuse me for ignoring your attempt to change the topic of discussion
now,
> so that you can attempt to be correct.
> Bruce
> 
> ----- Original Message -----
> From: "Bernd Felsche" <bernie at innovative.iinet.net.au>
> To: <diy_efi at diy-efi.org>
> Sent: Monday, July 29, 2002 11:08 PM
> Subject: Re: [Diy_efi] BHP calculations
> 
> 
> > Bruce tapped away at the keyboard with:
> > [top-post fixed]
> > > From: "Bernd Felsche" <bernie at innovative.iinet.net.au
> > >> Bruce tapped away at the keyboard with:
> > >> [top-post fixed]
> > >>> From: "Bernd Felsche" <bernie at innovative.iinet.net.au
> > >>>> Bruce tapped away at the keyboard with:
> > >>>> [top-post fixed]
> >
> > >>>>> From: "Bernd Felsche" <bernie at innovative.iinet.net.au
> > >>>>>> Hugh Keir tapped away at the keyboard with:
> > >>>>>>> I am working on a spreadsheet to calculate BHP from datalogged
> > >>>>>>> information.
> >
> > >>>>>>> The basic formula I am working to is:
> > >>>>>>> Engine BHP = acceleration BHP + wind drag BHP + transmission
loss
> BHP.
> >
> > >>>>>> Don't forget about rolling resistance.
> >
> > >>>>> What about the humidity?.
> > >>>> Accounted for in aero drag.
> >
> > >>>>> Variances in the gravitation pull of the earth?.
> > >>>> Accounted for in rolling resistance.
> >
> > >>>>> Difference in weight for fuel used during the *event*.
> > >>>> In rolling resistance.
> >
> > >>>>> Reduction in tire diameter for tire wear.
> > >>>> In rolling resistance.
> >
> > >>>>> Increase in tire diameter due to heat, as applicable.
> > >>>> In rolling resistance.
> >
> > >>>>> Variances in ambient O2
> > >>>> Aero drag.
> >
> > >>> O2 variences have no effect on HP?.   That's interesting.
> > >> Aerodynamic drag is largely determined by the density of air. (At
> > >> least for bluff-bodied cars.)
> >
> > >>> How do you take into count all these changes, in one event?.
> >
> > >> Too much to write here:
> > >> See Bosch Automotive Handbook - chapter titled "Motor Vehicle
> > >> Dynamics" - p338ff in 5th English edition or chapter titled "Dynamik
> > >> der Kraftfahrzeuge" - p330ff in 22nd German edition.
> >
> > > So you sticking to O2 levels having no effect on HP, interesting.
> >
> > Beyond the effect of aerodynamics (very slight), the amount of
> > oxygen in the air has no effect on the power *required* to maintain
> > a speed or to accelerate.
> >
> > --
> > /"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
> 
> 
> 
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> 



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