oceaneer77 wrote:
Erebus...
Some thing is very wrong with your EGT gauge.. Its reading very slowly.
EGT temps do not need time to cool down as they are a product of combustion not a byproduct of the heat of combustion.
True, but I don't think there is a significant difference for our purposes.
oceaneer77 wrote:
When you add fuel the EGTs go up when you back off they go down.. they are almost instant.
On acceleration max egts should be reached in less than 30seconds
(from normal driving with foot flat don on a grade). They should take the same time to come down.
No cooling period should be required.
My EGT gauge (post turbo) drops like a stone when i let off the throttle. i suspect that your gauge is holding heat some how.
Mine doesn't drop like a stone. Going down a long hill with foot off the pedal the needle takes about a minute to drop down to as low as 200F
oceaneer77 wrote:
Now a turbo temp gauge is a different story as the bearings compressor turbine and casing do take time to cool off and should be cooled before shut down as to reduce thermal fatigue. but i have never seen these fitted to a car and our style of driving should be sufficient to cool these parts without worrying. Unless you are full out down the road and hand brake side skid into your drive way shutting the engine down at the same time as applying the hand brake?
Well, I'm more interested in the temperature of the turbo than the temperature of the exhaust. And the turbo definitely takes time to cool down, all that metal has soaked up lots of heat. It sounds like my gauge (installed post-turbo) is acting more like a turbo temp gauge than an EGT gauge, but that's fine with me. Even if the exhaust gas temperature drops quickly, it will take a while for that gas to take the heat out of the exhaust manifold and turbo housing, especially at idle when there isn't a lot of airflow.
oceaneer77 wrote:
On the usefulness of a EGT gauge.. cannot be stressed enough as if your timing is out of adjustment or you are over boosted you will have no way of knowing until the death knock comes..
I try to keep mine under 1200F as thats what we do on the ships, i have seen lots of auto applications where they figure 1500F is ok.
Oceaneer
Mine normally shows 800-1100, and does reach 1300 on long uphill stretches into the wind on a hot summer day.