I have my pyro. Probe mounted in the manifold 2 in. Before the tubro mount . My EGT on a shot away from a redlight will climb to 1400 and a little better by time i reach 70 mph. I've had 16 semi's over my 51 yr. Career and all of them had the pyrometer prob mounted behind the tubro about 5 in. And we set our safety temp at around 1150 max on long pulls then we would back out of it some . How hot do we know to run with the prob infront ? The manifold had the probe hole already drilled and threaded when I got it ..Norval, 2002 3500 Ram 4x4 508354 miles .

 

My understanding that 1250°F max continuous at that location is a Cummins spec for the 6BT.

 

At 508K miles, I am wondering if you are getting an accurate reading. How could it make it that far hitting over 1400F regularly??

 

Gauges are great diagnostic tools and are relied on for accuracy. This is why its pointless to purchase cheap gauges. Why have ANY gauge which you're not sure if its telling you the truth. That said, a wise person would always second guess a gauge which is reading something NOT "normal". So if you think your pyrometer isnt accurate then test it. The thermocouple is subject to a constant barrage of extreme heat so they can wear out.

The reason we tap the thermocouple before the turbo is because you want the MOST accurate EGT reading possible. Reading the EGT's after a turbo could mean you're reading any dissipated heat temps dropping more than realized so the most accurate readings possible on this engine comes from the left side exhaust port about 2-3 inches before the turbo. The reason for the "left" side is because cylinder 5 and 6 are always the hottest.....and you care more about the hottest cylinders than the coolest. Post turbo can range anywhere from 300* to 400* (give or take) cooler than pre turbo temps.

The Cummins ISB will run all day long at 1300*. But.....this info is coming from Cummins who has immensely high dollar monitoring equipment which is as equally as accurate as it is expensive. So knowing that even the best stuff available (affordable) to the average everyday consumer is only so accurate and the difference between maintaining 1250* and 1350* is the difference between a running truck or a melted piston, its suggested to not maintain EGT's over 1250* at any time. Take note I said "maintain" too. That means that quick, few second, blips over 1250* is tolerable but holding that temp for any length of time isnt wise.

 

I took this exhaust manifold off a wrecked truck i bought for parts , my manifold was cracked BAD and this truck already had the pyro. In it. And yes i also am wondering about the accuracy. I have put about 1000 miles on sence instalation , and pulling loaded at 65 to 69 mph level ground and at sea level pyro shoes 900 maby 950 sometimes , but if i firewall it to pass it will kick up to 1400 to 1450 then drop back.. Norval. 510,500 and counting ...

 

I'd buy those numbers. What kind of boost is it running at, any idea?

 

Temps sound about right to me.

 

Sounds about right.
I see 700-800*F or so pulling 70MPH down the road on flat ground when empty.
Stomping on it for passing or pulling long hills loaded, I will see 1250-1400 too on most of my Cummins trucks.
A dirty air filter or restricted exhaust will make them run a little hotter as well.

 

You ask what i was showing in boost pressure . I have Not installed the boost gauge yet. Iam thinking about changing my waste gate unit out and installing a Gale Banks one , because i am starting to wonder if over 510,000 miles if the spring in the unit could be getting weak and opening a little two soon and robbing me of a little power , i am going to install the boost gauge first and see what i have .. I pull and run great but but i would get all i can get...I have the 275 hp injectors in this engine they been in the engine for about 105,000 miles...Norval over 511,000 miles and still counting...

 

You'd be well served to monitor your boost and elbow/fool it to 30+ psi.

I run pretty heavy (13k with a wind sail) and cruise at about 850 with 12 psi on level ground in calm conditions. Takes a long grade to make 1200.