EGT and thermocouples

[Charles]

On Thu, 8 Mar 2001 01:00:10 -0800, you wrote:

>Most guys that drag race use EGT to tune. Most of us look for a max of about
>1200 to 1250 degrees F as the car crosses the finish line, i.e. max load max
>rpm.

	I have a thermocouple in the exit of my exhaust
manifold, just upstream of the turbo. (Engine is a BMW 3.5
liter factory turbo six cylinder, 8:1 forged pistons, 275
degree cam, "log" manifold). I am running 15 psi boost with
two large extra fuel injectors mounted upstream of the
throttle body (engine is normally port-injected) and an MSD
Boost Timing Master set to about 0.7 degree/lb boost. 35
degrees at the crank at 0 psi.

	Temps run about 950 F at idle (timing retarded for
emissions), cruise is about 1200-1250 and WOT is 1600-1650
at 15 psi boost. With a small squirt of nitrous (single
Fogger nozzle, 40 hp) it pegs the gauge which only has a
scale to 1600. I don't keep it on long!

	Problem is thermocouple life. I first tried an
open-junction (i.e.unprotected) and it lasted about 5
minutes. A 1/16" diameter Inconel sheathed unit worked for
about 2 months of vigorous street driving before the end
burned off. I'd love to find a fast K-type thermocouple that
will not require a $40 replacement six times a year...

-Charles
'81 BMW 745i
-------------------------------------------------
Tired of noise from Dulles Airport, BWI or National?
Check out www.caan.org and call your Congressman!
----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org