[urq] Turbocharging & Elevations

[Djdawson2 at aol.com]

In a message dated 11/13/2004 1:31:35 PM Mountain Standard Time, 
QSHIPQ at aol.com writes:


OK, I'm gonna throw one last (good natured) argument out there... this is 
simple scientific methodology.

> I'm a 1/4mile guy at heart, several of us old timers (pre gizmo guys) have 
> those tables and conversions in their head.

We're talking engine tuning here... or at least that's where I think it 
started.  So I'm personally looking for the most scientific means for evaluating 
the situation.  Now I won't argue that a 1/4 mile time is a good, no BS approach 
to answer the question: "What'll it do?"  However, it doesn't assist us in 
improving an engine's state of tune.  Neither does a lap time.  Reviewing 1/4 
mile times to tune an engine is like measuring a cylinder bore with a yardstick. 
 Why?  It introduces a myriad of other variables.  Good launch?  Gear ratios? 
 Tire circumference?  Tire pressure?  Weight of the car?  Shift points?  Wind 
speed and direction?  Get my point?  Oh yeah, and there are those other 
meaningless variables... ambient temp, humidity, pressure???

So, bottom line, anything related to track testing is simply not a scientific 
approach to engine tuning.  Any of you PE's out there, feel free to chime in.


  This thread dragged a long way from > uncorrected chassis dyno horsepower.  
> The problem I suspect is that uncorrected numbers aren't impressive, I 
> suggest that they are useful tools/numbers unto themselves.


Possibly useful, but not as useful as they could be.  I'm not in search of 
impressive numbers, I'm in search of results.  If "normalized" numbers can't be 
recorded, you're not taking the right approach.  Figures can't be normalized 
without correction to offset variances in the test conditions.  Open any 
chemistry book... things aren't calculated based on "uncorrected" information.  
Every known element to man is defined within the constraints of "STP" (standard 
temp and pressure).  To state that engine tuning is exempt from these principals 
is simply an uninformed statement.


  Trying to 'correct' it, IMO/E means that it's no longer the right tool, or 
one is trying 
> to change the purpose and intent for using it.

Respectfully, I disagree.  The vehicle itself is equipped with all sorts of 
means to "correct."  The O2 sensor, the barometer, the MAF, the intake temp 
sensor... funny how these are all the sorts of variables that several folks have 
been claiming as meaningless to our engines.  If they were meaningless, we 
wouldn't need these parts to constantly correct for variances in the ambient 
conditions, would we.  When the conditions surrounding the operation of a piece of 
equipment are variable, corrections are essential.  Likewise, if the 
conditions surrounding ANY test (dyno or otherwise) are variable, a correction MUST be 
applied to derive anything meaningful from the results.  

Tune your engine, throw it on the "uncorrected" dyno, and look at the graph.  
Then spend hours troubleshooting and trying to improve.  Back to the dyno, 
uncorrected.  Hmmm... 10hp in the hole over your last attempt.

While crying in your beer over your failed attempts to improve performance, 
it dawns on you... it was 15 degrees hotter today than it was when I ran the 
first time.  That may not matter to you "uncorrected" bible thumpers, but to me, 
that is critical info.  I believe that you know it is too.


> 
> Put it on the chassis dyno, whiskey straight up.
> 

Well, have it your way... but I think you're missing the boat.  I'll never 
argue that SAE correction hits the nail on the head, but I'd prefer to have the 
same correction applied every time, rather than none at all.

The last point I'll make...  Cody just posted 386.  I've posted 418, Hap 
about the same, and MLP a 430... all at the same dyno.  Now, take all those 
engines and install them into the same car... use the same driver... and run the 
same track.  Who's gonna have the best lap time??  Hap's or Cody's.  MLP's and my 
own power curves suck, that's why.  Mike and I have work to do... nice peak 
power, but less than spectacular area under our curves.  I wouldn't ever see 
that without corrected figures.

That's all I've got...
Take care,
Dave