If you put one more saddle on it...

[QSHIPQ@aol.com]

...  It's still a dead horse going nowhere
In a message dated 97-11-05 14:00:34 EST, you write:

<<At a specific PR what about optimal for the ENGINE?>>
CI * rpm * .5 * 100VE/1728  Baseline CFM
Baseline CFM * PR = Boosted CFM

>Don't get too excited that we agreed on a point.  I mean it is pretty
>obvious.  What we do not agree on is HOW one determines that one turbo
>is better, when there are too may unkowns for one of the turbos.  Read
>the MAPs and I would say judging by how different they are from one
>another, that they are irrelevant to the turbo in question (especially
>the Aerochargers).  As for quotes, look no further than page 24 top
>half.  "When operating at max. load, the large compressor puts less heat
>into the intake charge"  and " the large turbine creates less exhaust
>manifold back pressure, further reducing heat load."  And the comparo
>between the Porsche and the Nissan turbo applications.  To sum it up,
>"RULE:  Never send a child to do an adult's job"  end quote.

Darn, here I thought I was done. :)  "Targeting" a turbo MAP should be with a
2.0 PR.  No, reading the maps shows the relevency of what turbo should be
chosen as the golden child.  Your quote has to do with single vs dual turbos,
out of context, and frankly Bell actually has to eat some salt on this one, a
really bad example too, that wasn't even the Z's target, the 944t was tho.  I
take exception to that very quote.  So does porsche (AFTER the book was
published, twin turbo 911 arrived).  So, not sure that isn't without some
revision.  Take a Mitsu 3000 and put bigger turbos on it, the child is
kicking Herr Faters butt.  A slam to the japanese ways, before the germans
realized it wasn't all that bad, and jumped.  Many in fact, argue that the
300ZXtt was what killed the 944t, it was a better car (read a plethora of
comparos).  So, although I appreciate your references to Bell, not sure he's
totally correct on that point sir.  No one ever really compared a 911T to a
300ZXtt, apples and oranges. 

 Are there turbos that are intentionlly designed to have higher PR?  You bet.
 A whole other discussion, not relevent here.  The compressor is only half
the equation, so is the larger turbine.  The combination is what makes it
work.  So two separate entities here, I don't have to agree or disagree with
the statement, or need to spell out the answer.  Bottom line is, what was
chosen as the turbo (my conclusion stays the same) is the wrong turbo is
doing the wrong job to the wrong motor.  Why? Cuz massive increase in PR
delivers a low DR AND FLOW.  It can be done better with a different turbo
with the SAME flow.  Assuming again that to be YOUR objective.

>What I was getting at here is that you use two equations that show the
>linearity  of certain relationships within the internal combustion
>engine.  The linear relaion is that if you increase the boost level you
>increase CFM.  Where I am lost is from there you jump to an unkown turbo
>is not as good as the one you sell.  I am glad you mentioned that to the
>list.  My question is how do you know?  I understand fullly all other
>notions that you have mentioned.  I would much rather run lower boost
>levels for the same power output.  I like cars to run, not explode.  I
>also understand the only thing that makes an engine make power is how
>much O2 you can flow through it.  And I mean molecules.  So I fully
>understand the relationship between fuel and O2 for combustion.  What I
>think that you owe to the list is that you cannot sit down and "do the
>math" and put together a car that runs exactly as planned.  There is an
>art to it that you deny with only "the math".  To improve VE, one might
>port/polish the heads.  Science or art?  The numbers get you to the
>ballpark and experience/intuition/luck/elbow grease get you the rest of
>the way.  By the way, I thought you knew Eric's MAP, that is what I was
>asking for, not the other product.  And I mean exactly what I said in my
>original post (76in of boost).
Well Eric is claiming 26psi of boost, which is 55Hg of boost, 83.75 Guage, so
best get this straight first.  30Hg is atmospheric pressure (give or take
your weather front today, your weatherman gives you this number every
morning)=1bar=14.5psi, so 
30/14.5 = 2.068 Hg for every 1psi.  The Hg boost guage therefore is
registering boost pressure at anything over 30Hg at the correction of  1psi =
2.068Hg.  So 26psi = 26psi X 2.068correction + 30 = Total boost read.  That's
83.768 Guage read at 26psi.  76Hg of "boost" pressure is 76/2.068 = 36.75PSI,
specifically that's 106Hg read on a 85 Hg guage.  Are you sure of your
meaning in your original post?  I'm not.

I'm not jumping on the linear relationship concept with you either.  A quick
look at Dave's math shows that there are factors which might affect that
assumption.  You are making this too complicated Randall.  Plug in 100%VE if
you want. Fine with me.  I could argue that that math gives you

136 * .5 * 5500 * 1 (100% VE)/1728 = 216.4 Baseline CFM
216.4 * 2.79 = 603.85 CFM boosted

So, fine let's assume 100% VE.  603 CFM?  Nope, don't show that with my
tweeked RS2 information.  I have built one that is 580CFM though.  So, I
guess I could say for argument, you are absolutely correct sir.  At 100% VE
the RS2 is a bad choice.  Now before you put up a flag, let's check this out
a little bit.  Compare the RS2 car, not just my turbo:

136 * .5 * 5500 * .85 = 183.97 Baseline CFM
183.97 * 2.50 = 460CFM gets 310HP.  

I think you are missing something here Randall.  Density has a big factor
here.  Again, before you go at that (let's use Eric's claim of 26psi, it IS
his car after all), his claim of  2.79PR is measured downstream of all the
mods, every single one.  If you take a gander at Dave L's math, you can see
that if you assume the DR to be some top secret really cold condensing
refrigerator, the PR is HIGHER than 2.79 coming OUT of the turbo.  Since by
definition increasing the DR gives you a lower "effective" PR.  

Randall, you are still agreeing.  You just haven't accepted it yet.  I showed
originally that if you want 513CFM, you got it with an RS2 at a lower PR, and
by definition at a higher DR>CE, than what is "claimed".  Not sure you
understand your own argument.  If I can show the same flow at a lower DR than
what is claimed, I don't need the map.  Neither do you.  Does it exist?  You
tell me where my math is wrong.  If you really understand all of the above,
you agree, by definition.  Really, no kidding, really, you do.

>...There is
>always more to it than boost, no?  Oh, by the way, I forgot to mention
>that the chip that I saw give 76in of boost was a race/drag race chip? 
>The street chip will be lower.  I thought that you should know.

Yup, there is more to it than boost.  DR vs CFM vs CS vs PR.  76Hg of boost?
 Well, take a look above first, I asked this question a couple of posts ago.
 

Randall, I asked in this EGT post that you and Bruce give consideration to my
"back to the cave" promise regarding the horse, Bruce has.  As is history,
you have the "oh one more thing" to an ending thread.  It is getting nowhere.
 It doesn't add credibility to your arguments or the "claims".  YOU are
missing something, and I'm not sure you understand what it is.  As Phil says,
I'm repeating myself, wasting bandwidth.  The math isn't changing the
conclusion drawn a long time ago.  You are making this really complicated,
more than you need to.  And we agree on my conclusion, you just don't
understand why yet.  That is a private post thread I'm happy to entertain.
 Not happy playing polo on a dead "coimbra" horse.  Your agreement
appreciated.

Thanks

Sorry to the rest for the wasted bandwidth.  Phil I buy your next beer.

Scott Justusson