[Diy_efi] BHP calculations

Bernd Felsche bernie at innovative.iinet.net.au
Tue Jul 30 03:13:15 GMT 2002


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
\ /  ASCII ribbon campaign | I'm a .signature virus!
 X   against HTML mail     | Copy me into your ~/.signature
/ \  and postings          | to help me spread!

_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://www.diy-efi.org/mailman/listinfo/diy_efi



More information about the Diy_efi mailing list