[s-cars] Re: More dyno results- Why this is being done (long)

[djdawson2 at aol.com]

 Paul,
Let me explain the loop I'm trying to close.
I've tried to apply some science to my efforts to develop my 20vt engine, and for some other folk's cars.  To do this, I've typically limited the variables to one single change, and then hit the dyno.  1 change... 1 result.  Using this methodology, we've worked on 2 engine configurations.
 
The first is a fairly typical "RS2" modified engine.  Just an RS2 EM, MAF, injectors, and an ECU using the same popular hybrid software/VMAP as many folks on this list.  The variables have been limited to turbo configurations, and mechanical tuning... in an effort to find a Garrett hybrid that is a bolt-up option to the RS2 unit, and provides improved performance.  After no less than a half dozen tries, we've finally come up with a very strong solution... putting down 361/402 atw.  Next step for this car will be the elcheapo FMIC.  The overall goal has been to develop a 20vt engine that is well within reach of the normal UrS nut.
 
The second is a little more over the top engine... but not way over the top  The goal has been to find the easily achieved "limit" of the 20vt without major design mods.  So I've taken a stock engine, rebuilt it completely stock, except connecting rods.  No head porting, no IM changes or fuel system mods, no cams, not even a MAF or an IC... nothing.  The mods were limited to bolt-ons.  These included a header, turbo, DP and exhaust... software and injectors... nothing else.  With these mods, 418/445 atw was achieved.
 
This same engine is now getting some additional mods to try and push this limit further.  These will include an FMIC, a 928/SQ MAF, and different cams.  The FMIC was done, and the results were 442/430, with a major improvement in area under the curve... maintaining 420+ hp from 4500-7500rpm.  Next will be cam and MAF experiments.
 
The goal on this engine has been to understand the limits of the physical engine configuration, and understand what the REAL constraints are.  In the process, I think a few things have become clear.  Porting the head isn't required to develop big power.  Neither are fuel system mods, intake manifold mods, throttle body mods, cam changes, compression changes, valve size increases, or even MAF changes.  At this point (442/430), these things are NOT needed.  Believe it or not, this engine was almost completely financed by the sale of my old RS2 parts.  The big parts changes... header, turbo, injectors, DP and exhaust, cost less than the RS2 counterparts.  For the guy with some mechanical ability, some free time, and some fabrication ability, this is a cheap path to 440+ street friendly horsepower.
 
Here's the problem, and the loop I'm trying to close... folks can't agree that the numbers are good.  I think Pizzo coined some term about the "2004 Dawson Dyno Wars"... arguing correction factors, etc...  Fine and dandy.  Folks don't believe in SAE correction factors, so my numbers aren't "good."  So a bunch of folks said "there's nothing like the 1/4 mile."  OK... I don't really agree with this, but I'll go off to the quarter mile, and we'll see the results.  Numerous folks declared that the trap speed at the end of the 1/4 (run through that "silly" calculator) to be the most accurate figure to work from.  Oddly enough, if you run the numerous trap speed guesses through the trap/hp calculator, everyone is guessing speeds that would indicate that I'm making MORE power than the SAE corrected dyno figures.
 
So, I'd like through testing, to develop some rough standards that all can agree upon.  If I dyno my car in CO SAE corrected, what does that same car do at the dyno... at sea-level, uncorrected?  Finally, how does that compare to hp calculators based on 1/4 mile figures?  What's are these relationships, and how valid are the various data points?
 
I will take my car to the strip to get numbers... and I will take my car to the west coast to get sea-level NCFS dyno figures.  Then we'll know for sure, I hope.
 
So, yeah... I'm having fun... I like a scientific approach... and I like to develop engines ONLY spending money where it makes sense.  That means modifying the true constraints, rather than chasing "perceived" constraints.
 
In the process, I've ended up with a pig 4 door sedan that will do a 4.17 second 0-60 (G-Tech)... and this was before the FMIC.  Yeah, I'm having fun... but I'm going to have to find a stronger clutch!!
Take care,
Dave
 
 
 
-----Original Message-----
From: pkrasusky at ups.com
To: s-car-list at audifans.com; Djdawson2 at aol.com
Sent: Thu, 7 Jul 2005 08:36:22 -0400
Subject: RE: More dyno results- 1/4 mile pool




Hmmmm...  as much as it'd be fun to agree with the results on that calculator... 
I plug in say 4000 lbs (Ms. Piggy mit me and fuel), and my last year's best 1/4 mile E/T of 96.75mph (sea level, 90 degrees, pretty mild launches with 2.1s 60')...  and the calculator shows me 282.73whp.  
 
If I divide 286 by say a (probably conservative) 80% transmission correction factor, that gives me 353.4 crank? 

No frickin way 8-).  Silly calculator. 
But hey I've yet to get my car on the rollers.  Sounds kinda off, even if you don't use a TCF.  I mean, it does run like a muther f'er and I can (and do) hand just about anyone their arse on the road, just doubting 286whp.


Regardless, keep up the good work out there Dave, great to see empirical testing, etc.  Good for you.  Have FUN! 
-Paul 
CT 
'95 //S6 currently lucky to put down 79whp mit misfire