Safe pyro temps for 7.3 psd

m67tang

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I put pyro thermocouple into the manifold on drivers side. What is the safe max temp for this engine?
I set my IDI alarm at 1100*F. Not sure what to expect with this truck. 1997 PSD
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greenskeeper

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sustained 1200 is ok

short burst to 1400 is ok

I have a pyro on my 97 and it's almost worthless. I'll run out of road if pulling empty, and if it starts to creep up just drop down a gear and let it breathe.
 

m67tang

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On my way home I gave it a decent run empty. Uphill at 80mph I hit 1155*F and ran outta road before getting higher.
I know it’s a different world than IDI, just hard to see so much more heat and not feel concerned.
My old IDI turbo could barely hit 1100+*f with a loaded trailer and 1 mile 7% grade hill AND pedal to the floor!

This is a new world to me!
 

m67tang

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On the flat interstate at 70-75mph I was running 600-680*f.
The old IDI would be about 400-600 at that same drive.
 

greenskeeper

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A good rule of thumb for any diesel is mph x 10 for level steady state driving expected temp on the pyro

(example 65mph = 650 F)
 

FarmerFrank

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This is my way of thinking, and I have been wrong before.

A direct injection diesel will run cooler and have a higher safe manifold EGT than an IDI.

The heat from the combustion cycle on an idi is easily heat soaked into the head from the precup and also heat soaks everything around it.

Since DI engines' combustion happens in the piston it gets pushed out the valves sooner and has less time to soak into the head. Therefor giving you a higher reading in the manifold and less water temp.....


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m67tang

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This is my way of thinking, and I have been wrong before.

A direct injection diesel will run cooler and have a higher safe manifold EGT than an IDI.

The heat from the combustion cycle on an idi is easily heat soaked into the head from the precup and also heat soaks everything around it.

Since DI engines' combustion happens in the piston it gets pushed out the valves sooner and has less time to soak into the head. Therefor giving you a higher reading in the manifold and less water temp.....


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If I’m understanding your thought process, sounds like me seeing a higher pyro temp doesn’t mean it’s actually running hotter. Just the exhaust gas gets out quicker to the thermometer.?
 

greenskeeper

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This is my way of thinking, and I have been wrong before.

A direct injection diesel will run cooler and have a higher safe manifold EGT than an IDI.

The heat from the combustion cycle on an idi is easily heat soaked into the head from the precup and also heat soaks everything around it.

Since DI engines' combustion happens in the piston it gets pushed out the valves sooner and has less time to soak into the head. Therefor giving you a higher reading in the manifold and less water temp.....


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More fuel in a PSD = more heat
 

FarmerFrank

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Yes, and also that heat escapes the cylinder faster than an Idi and has less contact surfaces to soak the heat into.

How's come my idiT truck wouldn't stay cool with both the factory 7.3 or an 87 6.9 but never gets the slightest bit hot pulling a heavy trailer at 60 mph with a power stroke in it and the same radiator??

I know I know, apples to baseballs... but still. I'm making gobs more power and I don't have to keep my eyes glued to the temperature gauges.


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m67tang

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Yes, and also that heat escapes the cylinder faster than an Idi and has less contact surfaces to soak the heat into.

How's come my idiT truck wouldn't stay cool with both the factory 7.3 or an 87 6.9 but never gets the slightest bit hot pulling a heavy trailer at 60 mph with a power stroke in it and the same radiator??

I know I know, apples to baseballs... but still. I'm making gobs more power and I don't have to keep my eyes glued to the temperature gauges.


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So you’re saying that your powerstroke pulls and remains cooler temps under load??
 

Thewespaul

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Pre chamber exposed like double the surface area to the heat of combustion compared to direct injection. And all 7.3 IDIs has blocked off coolant passages in the cylinder heads which made them overheating prone.
 

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