[s-cars] FMIC info digested...

Wed Nov 2 15:36:09 EST 2005

We measured pressure drop using 2 gauges... one on the IM, and one at the turbo outlet.  We did steady state full boost at a fixed rpm (yes, high brake wear).  We recorded, and then switched the gauges to eliminated the possibility of a significant variance between them.  We never saw a full 1 psi delta between the gauges.

Not a 100% controlled environment, but certainly good enough for what we're doing.

Dave

-----Original Message-----
From: Trevor Frank <tfrank at symyx.com>
To: djdawson2 at aol.com; mswanson at sonitrol.net
Cc: gcmschemist at gmail.com; tmullane at gmail.com; s-car-list at audifans.com
Sent: Wed, 2 Nov 2005 11:49:59 -0800
Subject: RE: [s-cars] FMIC info digested...

Umm...how did you measure the pressure drop? And relative to what, I
mean I have always's suspected that mine is quite large compared to a
top down configuration, I would like to measure the pressure drop and if
I could find someone else with some data on another core we could then
get some data points so that we knew what was high and what was low.  It
would be interesting to then use that and map temperature rise with a
given turbo so that we can directly measure how an inefficient
intercooler correlates to temp rise in the core.

If anyone else has this data, pressure drop, I would love to see it.
Also how it was measured, I have my ideas on how to do it and collect
the data but it would be interesting to see how everyone else is doing
it.

-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com] On Behalf Of djdawson2 at aol.com
Sent: Wednesday, November 02, 2005 10:08 AM
To: mswanson at sonitrol.net
Cc: gcmschemist at gmail.com; tmullane at gmail.com; s-car-list at audifans.com
Subject: Re: [s-cars] FMIC info digested...

Less restrictive is not accurate.  Some are, some aren't... depends on
design.  To state it as an advantage is not correct.  I've measured my
pressure drop... it isn't an issue.

Lower mass... you need to think this through.  When drag racing, an
engine is typically doing little more than idling prior to the run.  It
will not heat soak at idle, because turbo outlet temps are basically
ambient.  BTDT at the drag races.  It remains very cool the entire time.
In fact, during that first 100 feet, the tube and fin will heat up more
because airflow is low, and stored energy is low.  We're talking
thermodynamics 101 here.

Trucks... hmm.  I'm currently sitting in a truck shop on Portland, OR.
It's full of N14 Cummins powered Volvos and Kenworths.  Yep, they are
tube and fin.  There are several reasons for this.  First, they are dirt
cheap.  Second, there are no space limitations... these ICs are about 3
feet by 4 feet.  Third, they can use HUGE tubes, due to the lack of
space limitation... they look remarkably like a typical bar and plate,
except they have plastic end tanks.  When we're talking trucks, however,
we're comparing apples to oranges... low rpm, detuned/huge displacement,
very low output vs displacement, etc...

We're talking S-cars here... and since space is one of our greatest
limiting factors, bar and plate is, in fact... better, hands down, no
questions.

In the interest of friendly banter, however... if you want a tube and
fin... give it a try.  Let's see some before and after dyno runs.  Data
is data, and conversational speculation is kind of... well... just
speculation.

Dave

-----Original Message-----
From: Marc Swanson <mswanson at sonitrol.net>
To: djdawson2 at aol.com
Cc: gcmschemist at gmail.com; tmullane at gmail.com; s-car-list at audifans.com
Sent: Wed, 02 Nov 2005 12:33:18 -0500
Subject: Re: [s-cars] FMIC info digested...

On Tue, 2005-11-01 at 23:39 -0500, djdawson2 at aol.com wrote:
> OK, let's say "inefficient."  It's a well established fact that the
tube and

fin IC doesn't perform as well as a bar and plate of equal size.

You're missing a few advantages that tube and fin intercoolers enjoy:

- less restrictive (lower pressure drop)
- less mass (lower weight)

Bar and plate ICs are physically more massive than tube and fin and as a
result, they hold more heat.  This can actually be a liability,
especially considering situations such as drag racing.  You'll spend a
good 10 minutes miniumum getting your car to the starting line.  During
that time, your intercooler has soaked up as much heat as it possibly
can, and will likely spend the fist 100' or so getting rid of it whereas
the tube and fin core has less mass and thus would take less time to rid
itself of the accumulated heat.

>   You can read about it anywhere, and often... so why would one choose
that

route?

I'm not doubting that bar and plate is more efficient, because it is.
But there are other factors involved.

> 

> Bar and plate intercooler cores function basically the same as a tube
and fin

core. In a bar and plate core, the charge air travels through passages
that have

more surface area... about a 35% larger surface area for cooling.  Yes,
you CAN

have a tube and fin IC that provides good results.  However, if you are
limited

in space (and we are) a tube and fin of size "x" will never provide the
same

heat transfer capability of a size "x" bar and plate IC.
> 

> Another point to consider is the mass of the BAP, compared to the TAF.
TAF

cores are very light... whereas the BAP is quite heavy.  The BAP has a

substantial ability to "store" energy... using it for those typically
short

periods of high output.

See above.  I see that as a liability.

> As a data point... see if you can find an OE tube and fin IC in any
German

performance car.  I certainly haven't seen everything... but in
everything I

have seen, it's been bar and plate.

Just going off of what I've had in my hands, the UrQ is tube and fin, as
are the big diesel truck ICs.

> But hey, YMMV, and if you like tube and fin, go for it.

I think I'm just trying to level the discussion and point out that bar
and plate is NOT necessarily better, hands down, no questions.

--
Marc Swanson
95.5 //S6 Avant
90 CQ 4.2 V8 project car
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