What should EGT/pyrometer read on 10vT?

[Jorgen Karlsson]

Matt Kramer wrote:

> Just installed an EGT/pyrometer on a 10vT  and now I am wondering
> what a good
> heat range is?  What are common temps at idle, cruising, freeway, hard
> pulls??  I installed the EGT probe before the turbo in #1 exhaust
> runner to
> hopefully get the best reading since they are not really accurate
> after the
> turbo.  Hopefully I can use this to help tune after I figure out what it
> should read.

Make sure that your probe are rugged enough to be installed before the
turbo.

If your car is more or less stock you can probably accept most EGT's but as
you start to build real power you are better of not exceding 1500oF before
the turbo. If you don't go higher then that you will have some margin for
uneven mixtures between the cylinders. The engine will probably handle
1800oF for some time but that is begging for it.

EGT is hard to tune the mixture with, but you can see if you are running to
hot. That is often a result of a weak mixture, either by running hot because
of the lean mixture or because the lean mixture has resulted in knock. Knock
in it self does not increase EGT very much but if the car is knock
controlled the ignition will be retarded, that will increase EGT a lot.

EGT can also be used to find a good timing table, on my car I have seen a
250oF increase in temperature by retarding ignition three degrees. This will
vary from engine to engine but I have only seen it when the ignition table
is very close to optimal.

Jorgen Karlsson
Gothenburg, Sweden.