A question of degrees: Pyrometer

[gsanford]

I had a pyrometer installed in my '98 CC Allure because I heard that it's good to have. It is interesting to watch but I need some guidelines to know what I'm seeing. My coach has a 325hp 8.3L Cummins. Running on cruise at 65 it runs around 900, idles at 300-400 and will hit over 1400 accelerating up to speed on the on ramp and immediately drop to 1000 when I back off the throttle at cruising speed. i assume all this is normal and it will really be important when driving over something like Independence Pass while towing a vehicle. Previously on long grades when the coolant temperature started going up I would downshift to 3rd and maintain about 35mph to keep the temp down. I'm sure the pyro will show similar behavior but if someone could expound on the readings and what to expect I would appreciate it.
Thanks, gary

[HeapBigEngin]

I suggest you give the tech guys at Cummins a call....they are very helpful and should be able to answer your question. Your numbers don't appear unreasonable except for the 1400 reading. Usually anything over 1300 for any length of time should be avoided....our Banks system on our 8.3 ISC will begin to dial back boost at that point after a moment or two. Also, you may want to ensure that the person who installed the pyrometer did not "splice" any of the connecting wires, especially the thermocouple lead. As I recall, that may upset the gauge calibration. Also, air intake leaks and/or dirty air filter can raise the exhaust temps....that is per the Banks folks.

PLEASE let us know what you find out....Thanks!