1600F EGT's too high during high speed cruising?
 

Pretty much for as long as I've been turboed (and possibly even before that, as I never had an EGT gauge until I turboed). I've been seeing EGT's as high as 1600F when drivIng 80mph or so and up, or basically 4500 rpms and up. To me that seems a bit high, but for all I know it could be normal. I have AFR's about 13.5 in that area and I increased the timing from about 37 to about 41 in that area of the map to see if it changes. It might've gotten a little better, but not by much. I'm not worried so much about detonation since it's not in boost at that time, but I'm worried about burning/dropping valves, melting my turbo's turbine wheel, warping manifolds, etc.

Am I worrying for nothing?

FWIW, I cant really say for certain what it does under boost, say if I go WOT while cruising at that speed. My autometer EGT is pretty slow reacting, and I don't want to be doing 120mph staring at my EGT gauge waiting for it to move.

Yeah, that's too high. Are you sure the gauge is reading correctly? EGT that high with a non-retard spark table I'd guess the gauge is wrong.

That is too rich for cruising.
You should AT LEAST be stoich while cruising, but with good tweaking you should be able to run leaner than stoich in cruise.

Also, what kind of ignition advance are you running at cruise/decel

I tune my car into the 15s for cruise.

Also, what is the location of the EGT sensor?

Yeah i know 13.5 is too rich for cruising. I purposely made it that rich in an attempt to bring EGT's down. I have it at 14.7-15 in the lower rpms though.

The probe is mounted just before the turbine inlet.

EGTs can go up with fuel and up when lean. Its about finding the sweet spot between fuel and ignition.

I've seen more fuel make higher EGT temps. That position is wrong, its supposed to be 1.5x the port diamer from the head. Lean it out and play with spark. I bet a leaner mixture and more spark angle will reduce EGT.

I should have hooked-up my EGT a long time ago but I can't bring myself to drill into my manifold.

EGTs will go up from less fuel when there is detonation, which I dont think is the case.
My bet is that you dont have enough ignition advance in high vacuum combined with too much fuel.
Lean that shit out to 15.5:1 and advance ignition in that part of the map until it stops lugging

How much ignition advance is too much? How high can I go? 45 degrees? 50?

About as high as 45, dont give it more than it needs though, just bump it up a little at a time until it doesnt lug.
Ive seen people get it tuned right so that they can cruise at 16-17:1 AFR without lugging, and get epic mileage.

I'll have to give it a shot. Thanks.

so what are your EGTs under sustained boost?

In 2nd or 3rd gear pulls it maxes out around 1400 or so. On long 5th gear pulls it seems to stay around 1600, but like I said the gauge is a little slow. What's with the super sized text? :) Is where I put the probe that bad?

actually nevermind. mine's in the collector too. i was thinking of something else.

theres two things that primarily affect EGT: timing and air fuel ratio.

why:

retarding timing moves the ignition event later in the engine cycle. EGTs go up with retarding timing because the combustion event is still occurring as the exhaust valves are opening.

similarly, leaner AFRs tend to burn slower than stoich. as you go leaner, the burn is completing, again, after the exhaust valves are opening .. and more heat gest into the exhaust.

I suspect also that a relatively rich AFR may also be burning slowly or incompletely and carrying some heat out the exhaust valves.

The first thing I would do is correct your cruise fuel to something around 14.7 or 15.0 to 1 and re-check your cruise EGTs. I run 37-39 degrees of timing at 15:1 and my cruise EGT is closer to 1200. Advancing much beyond 45 degrees may not do much of anything.

I don't know how bad it is but some of your reading is from heat in the manifold rather than the actual exhaust gas temp. This is because the metal part of the manifold is hottest at and around the turbo, coolest at the head.

Next time you drive at night and cruise, pull over and quickly check to see if the manifold is glowing. This will tell you if the cast iron is above 700* or not. My cast iron manifold glowed at cruise and REALLY glowed on the dyno. My SS manifold only glows in boost; I'm not sure if this is due to the manifold or due to EGT.

-subscribing

steady cruise @ 80 mph = 1350* 14.9-15.1afr
wot at the track 80-140mph = 1550* - 1600* 11.5-11.7afr 10psi

my egt probe is installed right where yours is at, not sure what my timing is at in those cells but i'm sure it's mid-upper 30's

do what everyone else has said, set afr, then timing, and you should be good.

You also might want to verify that your base timing is correct.

Base timing is correct, verified with a timing light. Could the fact that my manifold is ceramic coated is what's making the EGT's at the turbo inlet higher? Does the coating work that well?

I've also wondered this considering my old ceramic manifold. It glowed all the damn time which didn't alarm me...until I let it idle for 10-minutes and it continued glowing.