[s-cars] Re: Turbocharging & Elevations

[QSHIPQ at aol.com]

Dave:
Comments inserted over coffee....
In a message dated 11/14/2004 2:20:41 AM Central Standard Time, 
Djdawson2 at aol.com writes:
>>OK, I'm gonna throw one last (good natured) argument out there... this is 
>>simple scientific methodology.

Simple Scientific Methodology is putting up the numbers you got, and how you 
got them.  Interpretation or 'correction' of results would not be in the 
Methodology section of the paper Dave, that would be in the summary or conclusion.  
My claim is that the methodology is somewhat flawed, let's just accept that 
for now.  Premature to 'correct it' IMO.

> 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. 

Which applies to your car where you put it on the dyno.  Then the only 
variable that should be 'accounted' for, is ambient temp.  With the size of the 
variables you guys are changing here, I'm guessing ambient temp is a minor 
variable.  Then again, I don't think I've seen 10 degrees variance in ambient temps 
posted in the methodology anyhow....

>> 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.  

But it can (and used to for years before chassis dynos became more common) be 
used to tune.  The chassis dyno might be a better tool for the HP part, but 
NOT the chassis dynamics part.  Just like mulitple runs to the chassis dyno 
reduces variables down to temp, many of us can get 1/4mile times down that way 
too.  I'm only a occasional weekend warrior on my motorcycle, and I can whack a 
consistent 1/4mile within a single night AND compare them to prior quarter 
miles.  Not correcting for a darn thing (ok, rain doesn't work well;)

>>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???

Darn those new school boys:).  The 'old' school boys take a chassis or engine 
dyno run and use unscientifc (but high 'n') formulas to predict what the 
quarter ET/MPH "should" be.  Then it takes you into chassis dynamics (including 
shift points, gear ratios, weight shift, tire circumference) on how to get your 
theoretical ideal closer to measured results.  That's the tool I find more 
useful.  Dyno guys are stuck using a tool for tuning.  Take the next step Dave.  
If you don't have all you should under the curves and or the chassis isn't 
right (er, FYI, race weight is factored, so it's optimizing a 'given' chassis), 
your actual MPH/ET won't be close to theoretical ideal.  Don't sell it short.  
After all has been said and done, the 'n' on 1/4 mile tracks gets millions of 
tests to it's own validity. 

>>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.

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

>  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.

Results of what?  Dyno?  Dynos give a number, Dave, that's all.  Whats it 
mean?  Why do you target 'more' torque?  Why more HP?  Many of us have questioned 
this for years.  I've driven many machines that will make ungodly hp numbers. 
 The result is exactly a high hp car that drives like crap on the street.  
Where are *you* taking Miss Piggy On a Leash (MPOL)?

>>  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.

If you use the same dyno, pressure is a constant (ok watch the weather if you 
want).  Standard temp is certainly a dyno variable, that's pretty easy to 
isolate if you so choose.  Just label it and give the raw data, that's 
methodology.  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.


>  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.  

Two separate arguments.  The motronic tries to optimize the conditions you've 
given it.  Again, using the same dyno at the same temp, should cause motronic 
to call for the same point on the map (that's your argument actually Dave).  
If the temp increases, the computer might call for a different point on the 
map.  If the temp decreases however, one should be able to argue that should 
mean more power.  That's just logic, you don't need to 'correct' for that, only 
maybe celebrate the conclusion that the latest tuning trick showed the above 
*didn't* happen.

>>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.

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.  Given the level of tuning, and the level 
of variables you haven't even addressed, it's a bit premature to use more than 
a temp correction given your methodology.  An engineering type who has done a 
dyno run here in Chicago, doesn't have any more validity than you to compare 
his results to yours yet.  Want a number here?  Ok come on down.  Be prepared 
to correct some things.

> 
> 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.

It's only another number.  Screw the correction Dave.  USE the tool to get a 
result.  This list is caught up in dyno numbers.  Javad pops them FYI 
uncorrected, AND he goes to the quarter mile track.  That's validity and 'correction', 
conclusion and summary.  Want to be 'scientific'?  Fine, the experiment is 
performance.  The Null Hypothesis is that a higher dyno result will yield no 
difference in Quarter Mile or ET.  Or (insert goal)...?

>>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.

Sure you would, you just have a better tool for evaluating it.  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.

My .02 uncorrected to the peso

Scott 'Factor' J