[Vwdiesel] EGT temps and max temp for a TDI

[LBaird119 at aol.com]

>  about 4" below the turbo and have been told by many knowledgeable diesel
>  people that at highway driving speeds, the preturbo temps and the post
turbo
>  temps are almost equal.

  I'd heard 100 F drop across the turbine.  It seems it'd be closer to nada
than 100 but better safe.  It stands to reason there should be a temperature
drop across the turbine.  Laws of conservation of energy would dictate it.
I've just never looked up the formulas and done the math to see how many
degrees it would actually be.  The higher the boost the larger the drop,
would make sense.  So maybe it's ~100F max?

That being said, on two occasions on the last
>  trip, on a long and fairly steep hill, the EGT reached 900 and briefly
>  touched on 1000 degrees.

  Our 1.5 and 1.6 engines are listed at 1300 or 1350 as I recall so that's
good for almost 1200F downstream.  I'd expect the TDI to come in at the
same specs or slightly higher but not enough higher to count.  The only
reason I'd see it being lower is different metallurgy (doubtful it would be
of lower temperature tolerance) or if an IDI burns cooler in the cylinder
than a DI diesel.  I'd actually expect an IDI to have higher internal
temps than a DI.

I let up on the gas and downshifted to bring the
>  temp down and it immediately began to drop.  I would like to find a way to
>  keep the temps down without slowing well below highway speeds (I currently
>  drive around 60 with the trailer on).  I intend to do the following things
>  to help lower the EGT temps:  Monday a 2 1/4" exhaust system with a single
>  muffler will go on to increase flow

  Dude!  Go 3 inch!  At LEAST do 2 1/2 inch.  I've always said 2 1/2 for the
1.6 TD and Jake scoffed at the idea.  He had a 2 inch Techtonics system.
He finally did change it and could feel the difference.  He now agrees on
the 2 1/2 inch size.
  When my 5000TD is done it WILL HAVE a 3 inch system on it save for
a short exit piece from the turbo.  I have to be able to get to the flange
nuts.  Dad's pickup has a 3 inch "expansion chamber" between the turbo
and the steering rack with 2 1/2 inch the rest of the way.
  A bigger exhaust can make a HUGE difference in EGT.  My Dasher was
running along at about 1200 F when all of a sudden the pipe fell off at the
turbo.  EGT immediately dropped to about 800F.  The Dasher has the probe
upstream of the turbo with the BAE exhaust manifold.  :)

and I have installed a small fan to move
>  air over the exhaust manifold and turbo.  I also plan to remove both the
>  upper and lower engine covers as these seem to trap heat inside the engine
>  compartment.

  These might help underhood temperature but will do nothing for the EGT
unless you're sucking underhood air, which you shouldn't be.  If you were
then expect a 1:1 drop for intake to exhaust temperature.

Would rigging a water spray on the  intecooler help (cooler
>  intake air = cooler exhaust?) Or has anyone rigged a water injection rig
for
>  their diesels?  Any suggestions would be appreciated AND if anyone has the
>  max EGT temps for the TDI I would sure appreciate it.  TIA  Hayden
>
  My uncle always used water spray on his van.  You'll see a 1:1 drop in
temp from one.  Of course you want a fine nozzle or a BIG water supply.  ;-)
Checking your intercooler efficiency would be helpful here.  Compare
your ambient, pre intercooler and post intercooler temperatures.  If your
exit temp is still well above ambient, more intercooler would be the most
efficient step.  without VNT I'd guess 20psi would see CHT around 400
degrees or more!  Jake was seeing well into the 200's F with almost 10 psi
best as I can remember.  That was with mid 50 F ambient as I recall.
   More boost = more air = cooler EGT except for compression friction
of the air.  Get the biggest, most free flowing exhaust you can fit, up to
3 inch, and go from there
     Loren