[s-cars] Re: [urq] Re: Turbocharging & Elevations

[Djdawson2 at aol.com]

In a message dated 11/14/2004 7:10:35 AM Mountain Standard Time, 
QSHIPQ at aol.com writes:

> Interesting perspective.  I've always thought a chassis dyno only 'helped' 
> tune an engine so that it 'might' perform better at the track.  I never 
> thought 
> it the other way around.

I'm not building a track engine, I'm working on an engine I can drive around 
town 99.9% of the time, and to the track .1%.  Manufacturer's start with the 
math and the dyno, build the engine, and then refine it on the road.  Seen it, 
participated in it.

  What I do see here is comparing chassis dyno to real > world claims "that's 
> more hp than a 996!"  Yes it is, good luck passing him in the real world 
> with no HP or torque below 3500rpm.

That same statement applies to 1/4 mile times.  !/4 mile cars don't make good 
street cars, period.


  Dave, sticking to the dyno is sticking to a number, corrected or not.


No, it's sticking to a range of numbers that portray the performance of the 
engine over the entire rpm span.  A 1/4 miles time is just 1 number based on 
operating the engine in only its peak environment... if you're a good driver.


  I claim that > you don't need all that power ( at the expense of torque) if 
> you target WHAT it is you want to accomplish. 


BTDT, you simply aren't hearing me.

 All that engine can be doused in the real world by a guy focusing more on 
the 
> chassis result, not the single tool and tunnel vision of hp.

You've oversimplified my goals.  How many times to I have to reiterate "area 
under the curve?"

  Even > Audisport played with gearboxes, ratios, and a bunch of other 
> chassis 
> variables.  That was after they popped lower numbers than you guys are 
> seeing.  I see the above and ask again, where do you want to go with it?


To the grocery store... to the airport... and then, once every 10k miles, to 
the track.  The only point in messing with chassis variables is to obtain 
better results in a single environment.  Because my environment is infinitely 
variable, there's no point going there... I can only hope for a happy medium.

> 
> Results of what?  Dyno?  Dynos give a number, Dave, that's all.

Again... they give a full spectrum of numbers.  The 1/4 mile IS limited to 
one number, and in the street environment, a darn useless one at that.


 
> 
> The result is exactly a high hp car that drives like crap on the street.


My point exactly.  Spend your time at the dragstrip and tune for the 1/4 
mile... your end result will be a 1/4 mile car, not a daily driver.  




> Correcting it, esp on a turbo car, doesn't have validity, yet.  Certainly 
> 'correcting' it and comparing it between two racidally different turbo cars 
> has none.
> 
> 

I don't agree.  I just drove a modified S from Detroit to CO.  An otherwise 
nice performer at sea level was diminished to a rather mundane runner up here.  
If there's a difference in performance, there's a requirement for correction, 
if one has any hopes of tuning on a level playing field.

> List it, that's part of methodology.  Give the altitude of the test, the 
> type 
> of dyno, and the temperature.  My point is that correction factors applied 
> to 
> turbo cars aren't realistic to your numbers yet, cuz you haven't given them 
> any validity.  Keep it Simple Dave.

I'm keeping it very simple.  I'm applying the same principals across the 
board... every time.  Listing variances leaves issues wide open to speculative 
interpretation.  Applying a mathematical principal to correct and minimize those 
variances closes the door.  You realize (I hope) that you're fighting the best 
tools developed by the most organized engineering groups.

> Several of us 'old timers' can look at these dyno results and conclude that 
> power curves are less than ideal.  You and mike 'may' have more work to do.  
> The question is where?  You automatically think that needs to be the dyno, I 
> don't necessarily agree.  Finish the paper first, you're already jumping to 
> conclusions.

It doesn't take an old timer to evaluate a dyno sheet.  If I were to purchase 
an engine package based on 1/4 mile times, I'd be in a bad place in the end.  
"Hey, that EVO does 10 second 1/4s."  Great... look closer.  It launches a 7k 
and shifts at 9200.  That has absolutely no value to me.  Similarly, Javad is 
tuning an engine.  It's purpose is unknown to me... but "grocery getter" I'm 
betting it's not.  Look at his dyno sheet... you want that in your daily 
driver?  Not me.  It may meet his goals, but it wouldn't meet mine.  I couldn't 
know that based solely on his 1/4 mile times.

I'm gonna sign off this thread with a simple agreement to disagree.  
Correction factors are a simple scientific principal.  They are required to interpret 
data.  They are found in EVERY aspect of scientific pursuit, and that suits me 
fine.
Take care,
Dave in CO