[urq] Re: Exhaust manifolds

[QSHIPQ at aol.com]

Collector is a heat/lean problem, #5 stud is a heat/lean problem as well, #1
is a heat problem as well, remember #1 is closest to the turbo, and has the
highest exhaust heat of the 5 runners (see Corky Bell fig 10-3, 10-13,10-15).
 Remember, #5 gets the most air, so if you are lean, it creates the most
heat.  Add to that a heavy WG right next to #5, you understand why it's
supported on the early urq's.  You have heat, and no support.  Crashing
mounts isn't the problem, it just adds to it.

Most coding for "chip" mods on pre Mac-14 do nothing with the FFV settings.
That means that most are hoping that the stock FFV settings is enough for all
the other mods folks do in their cars.  Sometimes it isn't, which creates
internal EM cracking.  Want to reduce cracking?  Get an EGT guage, and use it
for shutdown guidelines.  IME, most 10vt cars that are running Stoich or
better will see max 1300F at the turbo outlet, lean will run 1500, shutdown
should be at no more than 800F.

Don't forget that no support or motor mount can save a turbo owner's EM that
shuts down a car after a hot run.

My .02

Scott Justusson
In a message dated 1/9/02 9:44:40 PM Central Standard Time, JShadzi at aol.com
writes:


I have seen quite a few with the only crack being underneath the collector,
including the one I just took off my car.

Javad

<<
I've never seen a one-piece manifold cracked in only one place.  Every
one I've seen has been cracked in two places, and it's always the same
two places.  The configuration and loads on the thing make me happy
that the front crack is a direct and immediate result of engine mount
failure - but I wonder on occasons about the back one.
  >>