[Vwdiesel] EGT temps revisited

[dieseltdi at earthlink.net]

Just wanted to pass on some wisdom that I picked up today.  I went over to
Diesel Injection Service, the dieselpages people, they have an place over in
Dallas.  Anyway, I spent some time talking to the guys that actually work on
the engines and asked him what the difference in temperature one could
expect between preturbo and post turbo.  To answer the question, he handed
me two Isspro (sp?) pyrometers one to be installed post and one designed to
be installed pre turbo.  The caution zone on the post turbo one started at
900 degrees F and extended to 1150 degrees where it entered the red.
Preturbo had the yellow zone beginnig at around 1150 and the red at 1300.
He said that for the pickups that he mostly works on, they have found a
rather consistent 200-250 degree drop across the turbo.  However, after
looking at the tdi set up, commented that the drop could be much less
because the distances between head, manifold, turbo and downpipe are very
small.  I mean the total distance between the head and where my thermocouple
is located is not more that 12-16".  The same set up on a Ford Powerstroke
can be as far as 3 feet.  He also told me that the general rule of thumb in
automotive diesel engines for max preturbo temps is 1300 degrees.  I feel
better now that I am not horribly exceeding max temps when I have seen 1000
degrees post turbo only for a few seconds on a couple of times.
BTW while I was there, I had them check a bag full of turbo injectors to see
if I have 4 good ones for the turbo engine that I have in my garage.  No
charge for the testing.  hayden

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