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re: intercooler ramblings

some time back, i discussed this topic with Ned.  general statement (i.e. 
lots of caveats, not sure where they all fit):  the more surface area you 
expose to the cooling airstream, the better the intercooler effect.  of 
course, as you increase the height and width of the intercooler, you'll 
need to make it thinner (another plus) so as not to go too big on i/c 
volume.  long story short:  the factory Volvo 740/940 turbo intercooler is 
exactly such a beast--about 2 ft high, 2 ft wide, only an inch thick, 
single pass.  scuttlebut is the Volvo intercooler is a great upgrade for 
SVO Mustangs.  Unfortunately for us, that would be a tough heat exchanger 
to mount under our hoods.

food for thought.


At 07:55 PM 12/9/99 -0500, C1J1Miller@aol.com wrote:
>As I understand it, a recommended upgrade for chipped 10v turbo 5000/200's is
>a better  (more efficient) intercooler than the stock 2-pass unit.  The
>factory upgrade is the single pass slightly longer length '91 200q20v
>intercooler, which requires a new cross-pipe and some metal work to fit into
>the 10vt cars (as I understand it).
>Another recommendation is to rework the factory 2-pass intercooler into a
>single pass intercooler, using new end tanks and some custom plumbing.  Any
>idea on why the factory used the 2-pass?  As I recall, it was used on the 10v
>turbo cars in USA/Canada through '91; the 10vt cars in europe got a single
>pass intercooler at some (earlier) point.
>Third option is to have a custom unit fabricated (Spearco etc.); however,
>there's not much room for a bigger system.  Listers have done this and
>reportedly got a larger more efficient system to fit in the stock location.
>Anyone considered adding a second intercooler into the system, rather than
>adding a larger unit?  Seems that the intercooler off an A4 1.8t or other
>small car, or an urS4/S6 unit could be plumbed in place prior to the stock
>10vt intercooler, perhaps placed down low like on the urS4/S6.  Or, if you're
>fabricating a custom cross-pipe from the turbo across the front of the car to
>the intercooler, perhaps that cross-pipe could be "finned" or designed to aid
>in cooling (might require slotting the bumper cover?).  Or placed down low
>where the auxiliary radiator is on the 200q20v.  Or perhaps a good place to
>add that air-to-water intercooling from a small radiator placed elsewhere...
>I would expect that the drawbacks would be: more drag from internal friction,
>and a higher volume of (pressurized) air in the system, leading to more
>perceived lag.  Isn't that why they moved the intake on the later 20vt cars
>to the front, to reduce the pipe lengths?  I would have swapped the radiator
>and air cleaner positions as well to isolate hot and cold sides of the engine.
>A second intercooler (i.e., larger system) should have the capacity to cool
>more air before heat soaking and reducing efficiency; a tradeoff against lag
>and pressure loss through friction.  On a track car, where the turbo is kept
>spooled up, this might be acceptable.
>chris miller, windham nh, c1j1miller@aol.com
>'91 200q20v ==> http://members.aol.com/c1j1miller/index.html
>The Audi 200 Quattro 20 Valve Mailing List

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