[s-cars] An interesting FMIC "fact" (?)

[Mark Strangways]

I think $2000 could be very well spent sizing a better turbo to provide the
flow needed for the HP requirements while keeping it in a more reasonable
eff. range. Some $$ could then be applied to opening up the passage way to
the cylinders so that flow makes it's way easier.
We all throw alot of numbers around here especially in terms of boost, but
lets all remember what pressure is actually doing in the intake system of an
engine. I would certainly prefer to run 500 CFM at 20 psi than I would 510
CFM at 26 PSI. If I make any sense. Reducing the frictional losses in the
intake system, then the boost that gets developed is solely due to the
volume if the cylinder. I am not sure how well Audi flows and at what CFM it
really starts to restrict, but I am sure there are a few on list that do.
Bottom line is (for me at least) a big FMIC is a bit of a band-aid. We only
need it because we run so much boost and generate so much heat. Get the flow
rates up and deliver the air into the cylinders, while keeping a handle on
boost. I think this is a better way to start. Even these RS2 turbo's are
getting outside there efficient operating range and into the super heat
producer, no ?

That's how I see it, I will go to work now happy in the fact that my inbox
will be FULL when I get home tonight with corrections to my ideas above.

Mark S (picking up flame suit later)

----- Original Message ----- 
From: <QSHIPQ at aol.com>
To: <Djdawson2 at aol.com>; <forgied at direct.ca>; <s-car-list at audifans.com>
Sent: Friday, February 27, 2004 7:23 AM
Subject: Re: [s-cars] An interesting FMIC "fact" (?)


> A couple things to consider here gentleman.  First, audi's stock IC's are
> *extremely* efficient for their size.  This means exactly that Bigger IC's
in
> terms of HP gains will be more in tune with the turbo
sizing/efficiency/output
> than actual IC.  Again, if one was to measure the audi IC pressure and
temps pre
> and post core, you will find an efficiency in the 72-85% range (RS2
goodies
> attached), which means if you put on the biggest monster, best designed
IC, a
> gain of 15% IC efficiency translates into a less than 15% HP gain.
>
> Offsetting a change in IC, will be the change in design.  If you are using
a
> really good IC design (audi's do), then any design changes might very well
be
> offset by a bit less efficient core construction, or better put,
optimizing
> the design of given construction may yield no or worse results in measure.
It
> makes perfect sense to me Dave.  It's the nature of tradeoffs in really
well
> designed IC's.
>
> Before I'd even pick a design, get a baseline and get a target.  I'm
pretty
> convinced that what MLP and Hap have done to their engine VE required that
ASW
> change the design of the IC because of the amount of flow required
dictated
> that they do so.  I certainly give ASW credit for achieving the right
goals
> (flow and efficiency increase), but I question the 'automatic bigger is
better'
> that some of you are following.   2 thermocouples, 2 pressure guages boys.
>
> I say get these 4 probes installed and post those numbers.  I've seen
plenty
> of theory and speculation here.  I've seen even theoretical price breaks
> bantered.  I think you all need to take a time out on this discussion and
get some
> hard and fast numbers, then quite possibly one could put the price,
benefit
> and design targets into clear perspective.
>
> I argue, you just might find that what you have is gonna show that
'better'
> is not so easy.  Nor may you find all the 'gains' when the stock audi part
is
> pretty darn good.  Then maybe, 2000USD may be better spent elsewhere
first?
>
> HTH
>
> Scott Justusson
> QSHIPQ Performance Tuning
>
> In a message dated 2/26/2004 11:39:51 PM Central Standard Time,
> Djdawson2 at aol.com writes:
> In a message dated 2/26/04 10:25:10 PM Mountain Standard Time,
> forgied at direct.ca writes:
>
> > Frontal
> > area: This is a rapidly decreasing function. If the proper core size is
> > used, then doubling it will definitely not double the efficiency. More
> > likely, doubling the core would raise the efficiency about 5% and cost
> > twice the  necessary amount and add substantially to the weight.
> >
>
> Yep, right on all accounts.  Those are exactly the points that seem to
> indicate a top to bottom core with more rows than you can get using a side
to
> side
> makes more sense.  The odd thing is that ASW's testing seems to indicate
that
> that rule of thumb isn't applying too well in practice.  That doesn't make
> sense to me.
> Dave
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