MC engine swap minutia

Marc Swanson marcswanson at
Wed Dec 13 19:39:34 EST 2000

> > Ha!  Come next summer, I may be asking how to add a second
> > a/c!  I'll definitely be trying to keep the a/c.
> that is gonna make the whole project a lot tougher.  I think Marc wanted
> AC and ended up giving up on it.

It's not impossible.. I was just in a "get the damn thing running!!" mode.
I may in the future decide to bring the AC back.  As I live in NH it isn't a
big area of concern.. although if I end up moving farther south it will
become more of a pressing issue.

The reason I gave up was because I was under the impression that the
radiator could easily swing (keeping everything else the way it is) enough
to allow room for the compressor.  It turns out that I would need to somehow
extend the bottom radiator support to allow enough room for the "swing".
The engine mount bracket gets in the way of the back of the radiator shroud.
I hammered away at it but still couldn't dent it enough to make room.  Maybe
while the car is in the garage this winter I'll play with extending the
lower support to make the compressor fit?  Did I mention how PAINFULL
storing this car is?  My NA 4kq feels dogish now that I know what ELSE I
could be driving...

> > I'm probably going to
> > have to have exceptional cooling capacity as well, so further down
> > the road I may be treading some new ground.  It get's hot here, and
> > I like to have plenty o' margin o' safety.

maybe you should try to fab up a custom aluminum radiator?  I wouldn't
suggest blowing $800 on the 2B unit but maybe something that a local race
shop could make up?  I think Nate Stuart had an all aluminum 2 row rad made
up for around $200 for one of his Renaults...  Although it should be noted
that I haven't had any problems with overheating... quite the contrary, my
car runs too cold! (stuck thermo I think)

> how about a giant expansion tank for greater overall coolant volume?

I'm not sure what that would do?  If I have my physics right that would only
keep your car cooler untill the coolant volume heated up to operating
temp... at which point it can only be cooled at the max cooling rate allowed
by the rad...

> > Cool, I'll check it out.  That reminds me of another series of
> > questions.  Is the autocheck stuff just lost in the swap?  Is the
> > check engine light the only thing that gets hooked up?

The autocheck doesn't HAVE to be lost.. but there is really a bunch of stuff
you don't need so why bother?  To see what the autocheck does, go here:

> I think we deleted the autocheck stuff - hard to tell how much, really,
> since I think some of it runs thru the ECU.  I really don't know.

the autocheck is completely gone on my car.  There is simply no need for it.
The check engine light is a feature wholly built into the ECU.. you just
need to connect the yellow wire to the ground of a light bulb with a fixed
+12 supply and then wire in a momentary ground switch to that yellow wire...
After pressing the switch for 4 seconds the ECU will start dumping codes to
the light (at least on my car).  The seatbelt warning light lends itself to
this nicely.. since it is always supplied with +12 and selectivly receives
ground by the seatbelt warning relay to turn it on... All the others in the
instrument cluster are switched +12 with ground supplied by the ground bus
in the pcb.

> I think as cool as the MC/4kq swap seems, it is really a tough kludge,
> due to the tendency of later Audis (type 44/89 etc) to combine far too
> many things in each individual harness, and the nightmare plumbing
> issues.  but it is still cool.  as cool as a supercharged small block
> V8? no, but cool in its own right.

No, not as cool as a supercharged V8.... but did I mention the MC 4ktq is
fast?  Even with STOCK boost!



/* +++++++++++++++++++++++++++++++++++++
+Marc Swanson                          +
+                                      +
+    +
+                                      +
+87 4kcstq                             +
+85 4ksq  "the spare"                  +
+87 5ktq   donor (Parting out)         +
+++++++++++++++++++++++++++++++++++++ */

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