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Some dyno numbers from A+WE

From gti-vr6-owner@ccsi Mon May 24 15:48 CDT 1999
From: Uwe Ross <Uwe.Ross@pobox>
To: GTI-VR6 <gti-vr6@cobra.ccsi>
Subject: [gti-vr6] Todd's Dyno Numbers (long)
Date: Mon, 24 May 1999 16:45:04 -0400
Cc: Todd Sager <AWE16VR6@aol>
Organization: http://wso.net/ross/Uwe
 
> Date: Sun, 23 May 1999 22:46:03 -0500 (CDT)
&gt; From: Andy Nguyen &lt;&#97;qn&#64;dev.tivoli<img src=/i/dc.gif border=0 width=35 height=15>&gt;
> Subject: Re: [gti-vr6] AWE Dyno Day

>   I may have missed something in all the "dyno day" emails, but I
>   don't think I saw the HP figures for the stock GTI VR6 that
>   Garrett "worked" on.

Nor will you see any exacting figures from me.  Keep reading.

>   I can understand if Garrett & Todd do not want the after-chip
>   figures to be made public, but I would really like to see the
>   figures for the stock engine, mainly because I am having a
>   really hard time believing the reported figures.  They are all
>   completely unlike what I have seen in the past for the same
>   kinds of mods.   (Also, I assume that everyone is reporting 
>   the "corrected" figures, not the "measured" figures?)

Yes.  Keep reading.

>   Eh?  Corrections?  Do you know what kind of corrections?
>   Shouldn't the only corrections be the automatic corrections
>   that the dyno's computer apply to account for atmospheric
>   pressure, humidity, intake air temperature, etc.?

The numbers everyone has been quoting are indeed "corrected" to to reflect
crank horsepower.  The correction factor is a somewhat arbitrary.  Bear with
me an I'll explain.

Todd's dyno is a bit strange.  It is excellent for comparing two cars, doing
before/after mod comparisons, and doing mod development.  It is a load-type
dyno rather than an inertial-type, so if you wanted to, you should be able to
hold a particular rpm or road speed under full full load indefinitely while
you twiddle with the car.  You simply can't do that that with an interial-type
(Dyno Jet or equivalent)!

Unfortunately, the "absolute" numbers it comes up with are off-base; no matter
whether you look at his dyno's "wheel" or "crank" figures, they are always
obviously WAY low.  This means you have to manually apply an "arbitrary"
correction factor to come up with absolute figures, and this is why I have
been so bloody vague about posting any "absolute" numbers. 

Todd is working with the manufacturer to resolve this issue. 

Still don't understand?  Ok, have a look at this example, recorded on
Saturday.
http://www.wso.net/ross/Uwe/VR6/misc/Uwe-vs-Miguel.gif

First let's look at the numbers in the bottom right.  The "base" figures are
my car (slightly strange G.10 chip, de-coned airbox), the "test" figures are
Miguel's car (airbox mods, Garrett Cam Chip, 268's, and exhaust).  These
numbers are already "supposed" to be corrected to crank hp by the dyno's
software after running some parasitic drag measurements, and using a
temperature, air pressure and humidity input.   Obviously they are NOT correct
and  Miguel has some mid-14's time slips to prove that he's making a hell of a
lot more that 157.9 HP at the crank..

We obviously still need to apply a "correction factor" of some sort.  If we
use my car as a baseline, and ASSUME it was a bit weak from the factory,
170hp, but picked up 7hp from the chip then mine is really making 177 at the
crank.  My ASSUMED 177 divided by my MEASURED 141.6 gives you a "correction
factor" of 1.250.   Apply the same factor to Miguel's "measured" 157.9 and we
think he's making 197.4 HP at the crank, which seems in-line with his mid-14's
time slips.  

So there's little doubt Miguel is making roughly 20 hp more than I am, but the
exact figures of 177.0 and 197.4 are open to debate.  The only thing I will
say with absolute confidence using this example is that Miguel's car makes
11.5% more horsepower than mine.  

Now look at the curves.  Miguel has a tad less less torque than I do under
3000.  From 3000 to 5000 we are in a dead heat.  From 5000 on up, Miguel waves
bye-bye!  Where my car makes peak HP at 6000, Miguel's keeps pulling to 6500. 
The difference at that point is even more dramatic, probably close to 25hp!  

Todd, when did you say you could install those 268's for me?..:-)

Wanna see another example?  Here's Bill Johnson's car, before and after 268's:
http://www.awe-tuning.com/gallery_tech.cfm#42

In this case, we're looking at the Dyno's measured wheel horsepower, also
obviously WAY low. To get to crank HP from here, you have to use a correction
factor of about 1.7.   

Also notice Bill's peak power didn't move up 500rpm.  I assume the difference
in the curve is above 6000 is due to Miguel's exhaust.

Scroll down a little and you'll see Bill's car again before and after the
Schrick VG (but with the cams).

Todd, when did you say you could install those 268's for me?..:-)

-Uwe-

PS: Todd, if I've explained anything incorrectly, please jump in and set me
straight.
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