[s-cars] FMIC info digested...

[Marc Swanson]

On Wed, 2005-11-02 at 13:07 -0500, djdawson2 at aol.com wrote:
> Less restrictive is not accurate.  Some are, some aren't... depends on design.

All the bar and plate cores I've seen have very tight spacing between
passageways in comparison to tube and fin.  This seems to be by design.

>   To state it as an advantage is not correct.  I've measured my pressure drop... it isn't an issue.

This discussion deserves more numbers.  I have come across a bar and
plate core that is dimensionally the same as the tube and fin that we're
using in the 034 FMIC kit.  I'd be happy to run back to back #'s on the
dyno, and let conclusions be drawn from the facts.   I would like to
measure the following (ideally between all three setups:  stock, bar and
plate FMIC, tube and fin FMIC):

- pressure drop
- temps
- HP
- effect of heat soak (back to back dyno runs, with no rest)


We've run some of these test for the stock IC vs our tube and fin FMIC.
I'd be happy and eager to do the same to note differences between FMIC
styles.


>  
> 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.

You are ignoring two factors:  mechanical heat transfer from the engine
bay, and airflow through the intercooler (both internal, and external).

Ever wonder why your intake manifold is screaming hot when you open the
hood with the engine running?  Intake manifold temps rise when the
vehicle comes to a stop, significantly.


>   BTDT at the drag races.  It remains very cool the entire time. 

Are you saying an intercooler can do its job with no significant airflow
through the core?  I dont buy it.


>  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.

I disagree, but again, we need numbers here.  Just to make sure we're on
the same page, the bar and plate has the ability to STORE more heat
energy due to its mass, correct?  As a result, it needs to get rid of
MORE heat energy to reach a given temperature.  Granted, thats where the
higher efficiency comes in.

> 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.

Agreed, time to hit the dyno :)


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