NHC250 EGT pyrometer and gauge install finished

[sed6]

To complement my dual fuel line mod and to prep for turning up the fuel some more I installed a EGT probe and gauge in my truck. Lots of other threads out there but I took lots of pics so here goes.

I choose a Hewitt Industries gauge and custom ordered one direct from them with 0-1600° range, 250° needle sweep and red led back light. You have your choice of needle, face, numeral and bezel color as well. All for $85.




I had dreams of squeezing the gauge in below the ABS light but no joy. I instead fabbed up this mount of wood and a hose clamp. I figure such and important gauge deserves to be front and center. And yes it dims with the dash lights too!




I also ordered their 90° K probe and a 7' extension wire. I prolly should have ordered a 1/8 to 1/8 adapter as opposed to the 1/4 to 1/8 that came standard. No biggie, just a bigger hole to drill.




I moved the trans filter out of the way to give me easy access to the manifold for drilling.




The manifold was thicker than I'd have guessed and it tapped well with a 1/4 NPT tap.




Ready to install.




I sprung for a new drill bit to make it easier. Did I mention I was nervous as **** drilling into my exhaust?

 

[sed6]

Moving back inside, I used a 6' fiberglass fish pole thru the washer fluid line hole in the firewall to get the probe wire fished.




I tapped power off one of the dash lights using a y-splitter I fabbed up with Packard connectors. I ground it at the bottom of the steering wheel and tidied it up with heat shrink and zip ties.




Here's a closer up of the mount. I'll disassemble and paint it all green tomorrow. Worked out real well!



Hope you like!


ETA- Oh, so, she runs hotter than expected. 600-1000° unloaded driving in town and up to 1200° with it floored going up the highway on ramp. When I had the PT repaired last year the diesel tech said it was turned up or flowing extra well, I forget which. Guess he wasn't kidding. Doesn't seem I should turn it up any nor mess with the button. Opinions?

 

[wrenchturner6238]

That looks really nice! Good job!

 

[my blood flows OD]

That is really nice!
what was the total dollar figure?
do you have a link to the parts source?

 

[Floridianson]

Myself yea I say stick you with a fork cause your done.

 

[Jakelc15]

Nice setup. I use Hewitt on mine too. They make nice stuff. I'm not sure if they still do but they use to make gauges for Caterpillar.
You should put a gauge on the pt pump pressure. Anything over 225 to 250 psi wears the cam.

Time to turbo that motor!

 

[sed6]

Nice setup. I use Hewitt on mine too. They make nice stuff. I'm not sure if they still do but they use to make gauges for Caterpillar.
You should put a gauge on the pt pump pressure. Anything over 225 to 250 psi wears the cam.

Time to turbo that motor!

So affix the gauge to the pump or run a hose up thru my window so I can watch it while driving? I ask because i dont know if max pressure is achieved under load during driving or if it be checked with a fast idle while parked?

 

[Jakelc15]

Max psi is under load. You'll be able to see the rpm the pump is set to defuel at also.

 

[Floridianson]

If I was to turbo a non turbo motor I think I would look for a different PT. Ours does not have a A/F fuel adjustment for the lower end. I also would shim the RPM to 2350 so it would not defuel so early. You don't ever have to run the rpm that high though. Myself I try and stay around 200psi. I bet your fuel is running around 195psi. The older 809 series I have check have been around 172psi. When I checked Petes 939 series it was running 195psi.

 

[sed6]

That is really nice!
what was the total dollar figure?
do you have a link to the parts source?

Thanks everyone!

You bet. Attached. The only other part is the generic 2" gauge bracket from Amazon for $7.

View attachment Hewitt_Industries_3700.pdf

 

[73m819]

If I was to turbo a non turbo motor I think I would look for a different PT. Ours does not have a A/F fuel adjustment for the lower end. I also would shim the RPM to 2350 so it would not defuel so early. You don't ever have to run the rpm that high though. Myself I try and stay around 200psi. I bet your fuel is running around 195psi. The older 809 series I have check have been around 172psi. When I checked Petes 939 series it was running 195psi.

I would be REAL CAREFUL going to 2350 rpm, this is getting REAL close to valve float and valve kiss which starts at 2400, The 855 series is not designed as a hi rpm engine, it has fairly long rods, valves that WILL start to float at about 2400, to make a high rpm 855, it gets different valves, valve spring, trick rods, trick push rods, ect., ect., I have seen some high rpm 855s (4000 or a touch over ) in some race trucks, If they get the run, great, sometimes yes, sometimes no, not a big deal, there are 3 or 4 more in the trailer, BUT we are talking $50000 to $100000 a engine, so if you want a high rpm 855, only lack of money will stop you, if you DO NOT have the money for ANOTHER engine, watch how high you bump the rpm, at 2350, you just a bit under floating rpm, going down hill will bring up the rpm , which in this case will put you IN valve float zone.

 

[Floridianson]

I said you do not need run that high as you have a tac and a foot. From what I understand it pushes the derail point higher so it will pull harder. Most people don't run the motors to the Gov. to shift anyway.
Everybody wants more performance but with that comes responsibility.

 

[73m819]

Everybody wants more performance but with that comes responsibility.

Yes SIR, THAT is the key word.

 

[simp5782]

Nice job on the pyro install. Just get some more air to the puppy and those EGT's will drop a good bit. People always say more fuel, then add a turbo. Natural air can cool down that engine just as well as a turbo at a fraction of the cost. Not as much of an EGT drop but you would be surprised.