NHC 250 Turbo Conversion in M923

[red]

What type of gauge do you need and where the best place to install? Is it somethin you have to monitor all the time?

The others already answered. The nice thing about making the fuel gauge permanent (not necessary) is that you can find out if you are having a fuel delivery problem.

Whether or not these trucks were turned up before you bought the truck vary. On this forum people have found fuel buttons from a 20 to a 34, rail pressure from 220 down to 140, and shims to adjust redline from 2100 all the way up to 2500 (my m816 and no that is not a good rpm for these engines).

 

[CHAMPtd]

I recommend the dual fuel mod.

I don't recommend a turbo. The NH250 lacks the oils squirters needed for it.

That said, I've got an M818 with turbo, and I'll be driving it up I-35 sometime in the next few weeks. You're welcome to look and see how the turbo was added..

I'd definitely like to take a look sometime. Ever in KC?

 

[l3oss]

In another thread here on SS the following Turbos are recommended:
-Holset HT3B HT4B HX60

So far I’ve only noticed the HT3B being used. Maybe I will come across the other 2 in my further SS thread reads, but as of yet I havnt. That being said... Does anyone here have any first hand experience with HT4B or HX60? I came across this chart on a diesel bombers turbo thread(enjoy).
Turbo---CFM----Racing HP-----Daily HP inducerHX35----574------420----------330------ 56TP38 767HX40----763------560----------440------60T66-----800-------560----------440-----66GTP38R 897B1------900-------630----------495H2E-----868------700----------550HX50----1000-----700-----------550-----63,67HX55----1050------735----------578-----67HT3B----1085------770----------605-----76GT42----1302----------------------------75T76-----1350------945----------743------76 HT60----1400------980----------770B2,s400-1500------1050---------825-----75GT47------------------------------------80HX60----1550------1085---------853TV81----1600----------------------------85T88-----1750-------1225--------963-----88HT4B----1800------1260---------990Big Brother-1900----1330--------1045-----87T91------2000------1400--------1100-----91HC5A/HX82-2450----1715--------1348T100------2600-----1820--------1430-----100T105-----2900------2030--------1595------105

 

[gringeltaube]

... I came across this chart on a diesel bombers turbo thread(enjoy).....

Not much to enjoy... the way you posted that data...!

Please give us the link to that chart, so we can have it posted as such - (and readable, after all)

 

[Jakelc15]

I think this is close to what it should have looked like

Turbo---CFM----Racing HP-----Daily HP inducer
HX35----574------420----------330------ 56TP38 767
HX40----763------560----------440------60
T66-----800-------560----------440-----66
GTP38R 897B1------900-------630----------495
H2E-----868------700----------550
HX50----1000-----700-----------550-----63,67
HX55----1050------735----------578-----67
HT3B----1085------770----------605-----76
GT42----1302----------------------------75
T76-----1350------945----------743------76
HT60----1400------980----------770B2,
s400-1500------1050---------825-----75G
T47------------------------------------80
HX60----1550------1085---------853
TV81----1600----------------------------85
T88-----1750-------1225--------963-----88
HT4B----1800------1260---------990
Big Brother-1900----1330--------1045-----87
T91------2000------1400--------1100-----91
HC5A/HX82-2450----1715--------1348
T100------2600-----1820--------1430-----100
T105-----2900------2030--------1595------105

 

[l3oss]

Ha yes that’s a bit better

heres the link to the page:
https://www.dieselbombers.com/5-9l-12v-performance/67141-hx55-turbo.html

and also a screen shot








L

I think this is close to what it should have looked like

Turbo---CFM----Racing HP-----Daily HP inducer
HX35----574------420----------330------ 56TP38 767
HX40----763------560----------440

 

[162tcat]

You need to drill the ball out on the throttle linkage where it goes into the pump and turn it counter clock wise to adjust for the new button. it helps get more fuel but to not turn it too much.

So what if your PT pump doesn't have the ball to drill out? This one appears to be a solid shaft unless I'm missing something.

Sent from my iPhone using Tapatalk

 

[162tcat]

Went a little over board on the hose but I can hook it up and watch while driving then unhook it. You should be able to blip the throttle and see what the rail pressure is. It will go to set pressure then drop right off. The last 939 series truck 250 I checked already had the pressure turned up to 200 but no button change and came that way from GL. The older 809 series I have checked have had around 160 to 170 lbs.

What size is your hose on the pump end? I need to get one of those made up, would be very useful for tuning.


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[simp5782]

The rail pressure gauge setup is a 1/8th inch pipe fitting and you can use any hose you want. I have a 1/4" 3200psi hydraulic line to a liquid filled gauge.

The hose for the fuel feed on the pump is half inch. The bigger the better. You would have to upgrade the tank feed line to benefit from it at all.

 

[162tcat]

So what if your PT pump doesn't have the ball to drill out? This one appears to be a solid shaft unless I'm missing something.

Sent from my iPhone using Tapatalk

Hoping Will will see this. Curious how to adjust fuel on this one, throttle shaft doesn't have the tamper proof ball. This one looks solid.


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[PyroJoe]

This many of you have turbo'd your 250's and no videos to be shown!?!? Y'all need to grow up!

What is the consensus on numerically-lowest fuel button to run? #15 ?

 

[74M35A2]

This many of you have turbo'd your 250's and no videos to be shown!?!? Y'all need to grow up!

What is the consensus on numerically-lowest fuel button to run? #15 ?

That might not get people to help you.

 

[WillWagner]

Might. And there are plenty on threads on it. With pictures.

@162tcat, I just saw this thread. That would I believe, be a PTR style fuel punp. The ones with the ball in the shaft are PTG. PTR were used early on, and had external aneroid on turbo applications. PTG was later and incorporated the AFC or aneroid, into the pump. There is a plug in the pump body where the AFC assy would be if used on a non turbo application. No easily accessed rail adjustment on PTR style pumps. Sorry I was late to the game. And it has been a long time since I messed with fuel systems.

 

[PyroJoe]

That might not get people to help you.

I realize it's 2022 and everyone gets offended by anything, but take it easy - it's a joke

 

[PyroJoe]

I got the gauge mounted in the new pod on the column with the pyro, it's hooked up but the light is not wired in yet. I will shoot a pic tomorrow and post it. They both look good mounted there, are easy to see, and I did not have to cut any holes to mount them.

I just got my hands on a cummins pt pump rebuilding and calibration instruction book from a truck shop so I'm doing some reading on pump setup before I get into it any more.

I just ordered a number 12 and number 10 button.

For anyone that's interested the cummins part numbers for the fuel buttons (Idle spring plunger) are as follows:

#5 cummins 141623
#7 cummins 141624
#10 cummins 141625
#12 cummins 141626
#15 cummins 139894
#17 cummins 140417

To summarize everything in this thread to this point:


Plumbingbuddy claims he’s running cool with a #5 and no turbo – this is hard to believe.

Jdknech says he is running a #15 with turbo and can get things warm sometimes.

162tcat is running a #20 and turbo and had no complaints of heat but has enough power on hills to keep up.

Patracy is running a #17, 200psi fuel pressure, 15psi boost, max of 900° EGT.

Bjmca ordered #12 and #10 after not being able to get over 1050° EGT with #15.

So, Bjmca, that was 10 years ago. Where did you end up? I'm guessing the #10 is too hot and #12 is probably borderline where you'd have to drive by your Pyro, while the #15 is probably the safest in case your buddy is going to possibly borrow your truck.

I'm also noticing a variance on here of people running air/water aftercoolers vs. no aftercooler at all. That can certainly make a significant difference. I just bought an NTC-290 to rob all my parts off of and it doesn't have the A/W AC, so I'm somewhat expecting to have results similar to Jdknech.

 

[PyroJoe]

And for anyone wanting video (because this isn't a thread without video!), here are some of the best links I've found:

 

[Jbulach]

To summarize everything in this thread to this point:


Plumbingbuddy claims he’s running cool with a #5 and no turbo – this is hard to believe.

Jdknech says he is running a #15 with turbo and can get things warm sometimes.

162tcat is running a #20 and turbo and had no complaints of heat but has enough power on hills to keep up.

Bjmca ordered #12 and #10 after not being able to get over 1050° EGT with #15.

So, Bjmca, that was 10 years ago. Where did you end up? I'm guessing the #10 is too hot and #12 is probably borderline where you'd have to drive by your Pyro, while the #15 is probably the safest in case your buddy is going to possibly borrow your truck.

I'm also noticing a variance on here of people running air/water aftercoolers vs. no aftercooler at all. That can certainly make a significant difference. I just bought an NTC-290 to rob all my parts off of and it doesn't have the A/W AC, so I'm somewhat expecting to have results similar to Jdknech.

Might just want to throw the 290 in the truck, I think it should have the piston squirters.

 

[hethead]

I haven’t added my turbo yet so this may not be beneficial, but I did put a #15 button in and while my EGTs didn’t go over 950 on hills ( I also had no load), my rail pressure would go up to 270 if I let it. I kept it at 210 or less which is where I want it.

Based on that alone, I ordered a #20 button, so its one less gauge to watch. I’m hoping that keeps it in the 210-215 area. I have only done the button and a straight pipe so far. It made a big difference. Much more responsive to rev up and pulled hills way better already.

Again, that’s just a 20,000 lb truck with no trailer though. My opinion for a small cam that will be pulling loads is to keep it under 220 psi if it has stock injectors, but there are far more experienced guys on here than me.

 

[PyroJoe]

I spent all of last night reading thru 4 very long threads, and have them jumbled, so I'm not sure if it was written in this one or not but...
DO NOT RUN OVER 200 PSI FUEL PRESSURE as anything more than 200 will shear off the cam lobes on the Small Cams.

The 290 I bought is locked up, hence why it was cheap. Cheaper than just a new turbo even. The only parts of it I'm not sure about messing with are the injectors or pump. I would actually expect these NA pumps to produce a lot of black smoke off idle since they lack any type of AFC/ALDA to limit fuel till boost arrives.

After watching several videos of 800's and 900's, it appears to me that the 800's with the Deuce-like stack in front of the window makes for a very loud, obnoxious truck. I straight-piped my 923A2 with a straight piece of 4" and rain cap on top. The 8.3 is quiet enough that I don't mind it. Definitely have to keep the rear window closed if you want to have a conversation. The 855 is the one and only engine in my life I ever put a muffler back on! Holy loud, Batman! I don't imagine the turbo is going to quiet it down enough that I'll want to keep the stack behind my head. I'm thinking of either dumping it out the side behind the first mud flap, or running it all the way to the back and dumping it down. I saw a picture on here with someone who ran it all the way to the back with a muffler. I would sure like to hear a video of it driving/walk-around etc.

As for the intake, you pull a lot of vacuum with all that snorkel tubing. The 800's certainly have the better setup with the fender-mounted air cleaner. Unfortunately, our 900 fenders are just too narrow for the Ø16" housing. Plus, you'd have to make some type of grommet coupler like the heater air intake uses, and I just don't trust that as much as these hoods can move side-to-side. Either way, I'm going to experiment with relocating the air intake to the RH side somewhere. I'm not driving this off a ship, thru the sea, onto the beach, and I doubt any of you are either. Only things I see it being a benefit for are mud bogs and hurricanes.

 

[simp5782]

Anything under

I spent all of last night reading thru 4 very long threads, and have them jumbled, so I'm not sure if it was written in this one or not but...
DO NOT RUN OVER 200 PSI FUEL PRESSURE as anything more than 200 will shear off the cam lobes on the Small Cams.

The 290 I bought is locked up, hence why it was cheap. Cheaper than just a new turbo even. The only parts of it I'm not sure about messing with are the injectors or pump. I would actually expect these NA pumps to produce a lot of black smoke off idle since they lack any type of AFC/ALDA to limit fuel till boost arrives.

After watching several videos of 800's and 900's, it appears to me that the 800's with the Deuce-like stack in front of the window makes for a very loud, obnoxious truck. I straight-piped my 923A2 with a straight piece of 4" and rain cap on top. The 8.3 is quiet enough that I don't mind it. Definitely have to keep the rear window closed if you want to have a conversation. The 855 is the one and only engine in my life I ever put a muffler back on! Holy loud, Batman! I don't imagine the turbo is going to quiet it down enough that I'll want to keep the stack behind my head. I'm thinking of either dumping it out the side behind the first mud flap, or running it all the way to the back and dumping it down. I saw a picture on here with someone who ran it all the way to the back with a muffler. I would sure like to hear a video of it driving/walk-around etc.

As for the intake, you pull a lot of vacuum with all that snorkel tubing. The 800's certainly have the better setup with the fender-mounted air cleaner. Unfortunately, our 900 fenders are just too narrow for the Ø16" housing. Plus, you'd have to make some type of grommet coupler like the heater air intake uses, and I just don't trust that as much as these hoods can move side-to-side. Either way, I'm going to experiment with relocating the air intake to the RH side somewhere. I'm not driving this off a ship, thru the sea, onto the beach, and I doubt any of you are either. Only things I see it being a benefit for are mud bogs and hurricanes.

You can run 215 to 220 injector pressure on a small cam