Re: EGT, not relevent here - LONG

["Randall C. Markarian" <asenna@accessus.net>]

QSHIPQ@aol.com wrote:

> In a message dated 97-11-04 15:04:18 EST, you write:
>
> <<
> > 1.  A faster spinning turbo does not make more air flow?  Obviuosly,
>
>  >there is a moment of peak efficiency for the turbo, and if you go
> beyond
>  >that there is no gain.  At least that is what I think you meant.
>  >Correct me when I am wrong? :-)
> No, not quite what I meant at all.  Given a turbo, spin it faster,
> what do
> you get.  In Eric's case you get a higher Density Ratio and Low Flow. 
> Take a
> k27 for instance.  For a porsche 3 liter motor I showed that with a
> 2.08PR,
> the flow is 500cfm.  Now, let's put that on a 136ci motor.  Flow is
> still
> 500cfm, but the PR is 2.80.  This is an exhaust velocity issue.  A
> smaller
> motor needs more exhaust velocity than a larger motor to spin a given
> turbine.  Now, if it takes 2.80 to make 500CFM, then the efficiency of
> the
> turbo is low, by definition.  You can easily raise the CFM  up AND
> lower PR
> AND DR, by using a smaller turbo, which means turbo efficiency is
> higher.  My
> example and quote was to show that a very high velocity of MC exhaust
> is
> required to make a relatively LOW CFM.  A quick look at a variety of
> turbo
> MAPs says this "indicator" is very true.  Wrong turbo.  So, backing
> this up,
> With a bunch of hybrids I can get closer to the CFM at a higher CE. 
> Again, I
> will "assume" here that you WANT that CFM.

I think that is what I was saying Scott.

>  
>
>  2.  What is the optimal flow for an Audi 2.2l?  In a boosted engine
> can
>  you not flow as much air as you can compress until some point where
> the
>  head flies through the hood?  I would think that as much flow as you
> can
>  get you get more power.  Did F1 engines use (apples and oranges here)
>
>  unlimited boost.  Granted the engines were bombs at that point, but
> they
>  tried.  Had they known someone to help them, they might have used
> less
>  boost/more power.
> *************************************************************** If you
> must
> increase the boost significantly for very
>  little increase in flow, I would agree that the mod is wrong.
>  ****************************************  RANDALL:   Then sir, stop
> now.  We
> agree.  My posts and points EXACTLY.  I proved it with the math on the
> RS2
> already.
>
> Exactly my point.  The optimal flow can be calculated by taking
> CI * .5 * rpm * 100(VE)/1728 * PR = Boosted CFM

At a specific PR what about optimal for the ENGINE?

>  
>
> Take a 2.0 - 2.5 PR and plug in the results, that's the map you want. 
> Doing
> it at a higher PR increases the turbo speed required to get that CFM,
> wrong
> turbo.  Street vs track.  Any CR, and racing fuel ups the allowable
> PR.  We
> don't have that for this example.  The redline/PPO on those motors was
> a wee
> higher too.  Plug and play.
>
> Look, you are trying to put a whole bunch of points up here, that you
> don't
> understand Randall.  Not trying to judge it, just observing.  My point
> is:
>  Accepting Eric's claims, then the wrong turbo is doing the wrong job
> on the
> wrong motor.  You accepted and agreed above.  Get as many MAPs as you
> can,
> look in Bell's book page 30.  Where is 2.8PR?  Read the caption on 3-7
> and
> 3-8, page 192 on PR.  201 on MAPS.

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.

>  
>  
>
>  3.  If you increase displacement, cfm of flow increases linearly?  If
>
>  you increase boost the cfm of flow increases linearly?  According to
> the
>  equations you used at least.  Then you look at the turbo maps and
> say,
>  "The RS2 is the ONLY turbo that works for the Audi 2.2l."  And then
> say
>  some other turbo, whose configuration you are not sure of, "that map
> is
>  not optimal for this engine."  Where did you find the map, I owuld
> like
>  to reference it so I can be privy to the info that you have at your
>  disposal.  When I see that then I will listen.  Until then all I can
> say
>  is that I saw the boost guage on Eric's car read what I posted
>  originally.
> Well Bruce can help you with that a little bit.  Look, audi gave
> porsche the
> ckbook and said, "we want to build a very killer car (read hi VE, cuz
> CI
> doesn't change on the RS2 car) with this CI, you spec the turbo any
> way you
> want.  Again you are denying some math here.  Given:  A) I only know
> you from
> the net (bruce as well), and b) your relationship with Eric, and c)
> this is
> part of my business, me giving YOU the RS2 map is really kinda silly,
> nice
> way of saying no.  And, it is not available to anyone via conventional
>
> sources.  Maybe Ned can/will help you.  This is my business, and
> frankly, if
> you read the math as presented, YOU don't need a MAP.  So, are you
> going to
> tell me that you SAW 85Hg on Eric's guage Randall?  That was not
> posted by
> YOU originally, but by Eric.  Tell ya what, you give me Eric's turbo
> MAP.  I
> don't need it.  Neither do you.  You are letting the ego out again.
> Math is
> very cold to it.  And we already agree (see above)

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).

>  
>
>  4.  One last aside.  In you calcualtions, you showed that there is
> some
>  increase in actual cfm over the k26 or RS2 with the mods Eric has
> done.
>  If so then the fuel requirements must be higher that the RS2 and not
>  lower as inferred in your post.
>   NO RANDALL.  Density Ratio.  Think in POUNDS of Air vs POUNDS of
> fuel, not
> CFM.  Turbo heads call this cubie theory, that boost is cfm.  It's
> flow vs PR
> vs DR.

I understand, See above!

> Higher DR requires more fuel than a lower DR, the flow is the SAME. 
> Hot
> expanded air has less mass than cold compressed air.  Exactly how the
> sport q
> gets 350hp at 18pounds of boost.  Think on that fact HARD.  You are
> missing
> the third part of the equation, the important part.  Now before you
> give me
> Eric's top secret mod, remember his PR is measured AT the intake
> manifold,
> UPSTREAM of the IC.

What turbo does a Sport Q use?  The Trans Am Q?  The IMSA Q?  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.

>  
>
> I read that you agree with me, yet still want to point.

No just want to learn.  No bats out, in case you did not notice.  God I
love atmospheric engines!  Viva la V8!  
--

Randall C. Markarian

No cars listed so as not to offend any sensitive list members

Saint Louis, Missouri