Re: [T3] Horsepower at the wheels.

[John Jaranson <jaransonT3@comcast.net>]

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On Sep 1, 2004, at 7:53 PM, Jim Adney wrote:

> On 31 Aug 2004 at 23:42, John Jaranson wrote:
>
> > The number I kept hearing at the car show was 20%.  Rule of thumb was 
> > a
> > 20% loss from the flywheel to the road with a manual transmission.
> > Don't know about an automatic.  I will ask a few of my powertrain
> > buddy's at Ford this question tomorrow.  20% seems consistent with
> > numbers I got for Sophy.
>
> The Bill Fisher book has some interesting comments on dynos and their 
> use. He
> mentions that every dyno operator has his own "correction factors" 
> which he
> folds in to "correct" the inaccuracies in his dyno measurements. Oddly 
> enough
> these factors are always greater than 1. It seems that no one likes 
> the numbers
> that come out of the dyno as-is, so they always do something to make 
> the
> numbers bigger.

I looked in the Bill Fisher book too and think he was talking mostly 
about correction factors to get from the chassis dyno (rear wheel HP) 
figures back to flywheel HP figures.  Everyone at the car show was 
happy to compare rear wheel HP since that is all that really matters.  
The dyno guys do use a correction factor to get things back to a 
normalized air temperature and humidity since that can effect the power 
figures.  These factors are not all greater than 1 since it is 
dependent on the ambient temperature and humidity on the day of the 
test relative to the calibrated temperature and humidity.  It does 
allow comparisons of tests done on different days or at different times 
of the day.

Later,
John Jaranson
'66 Square (Sophy)
'71 Fasty (Jane - darkside project in waiting)
various parts.....don't we all.
http://mywebpages.comcast.net/jaransonT3/jaransonT3/
http://mywebpages.comcast.net/jaransonT3/2004Invasion/
http://mywebpages.comcast.net/jaransonT3/notavwclub/

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