M939A1 NHC Turbo

[simp5782]

Nhc250s do not have an aneroid. We block them off on the big cam pumps when they get rebuilt. It just limits fuel until boost pressure builds.

 

[Floridianson]

I only have a 17 fuel button but mine doesn’t smoke at all. By the time rail pressure gets up the turbo is spooled. I’m no pt pump expert but I don’t think an afc is needed without bigger injectors....

Yep no expert here myself but sounds like you got a good combination with correct turbo and fuel. Yes bigger injectors but that is where we are going to get the real power increase and all the other problems that come with it. Would seem like a well built higher HP / torque motor can be built and not smoke like a freight train on take off or under heavy load.

 

[Floridianson]

We block them off on the big cam pumps when they get rebuilt. It just limits fuel until boost pressure builds.

Why would you want to waist fuel and make the truck smoke like a freight train on take off or till the turbo spools up? It does not add HP / torque numbers on the top end. Yea it might take off a little quicker from the get go but guess I am getting older and worry about my carbon foot print. Also some people like myself live in a state that does not require emissions inspections but some states do. Even though my GMC 3500 can roll coal like a freight train when I use my EFI live I keep it turned down. Just saying there is more to making big HP / torque that blowing out black smoke and they can be built with big numbers and still get real close to emission numbers and also keep the AFC working as it should be working. Building a high HP gas engine is easy not so with a diesel and and old diesel even more so.

 

[simp5782]

Because the aneroid does stupid things. Like the thread posted this morning. 6 months on a new pump and it sticks closed and basically you are basically stranded. Or it sticks half closed and you can't move but at a snails pace.

The amount of smoke on takeoff depends on your foot as well. Not just the aneroid. It would be ignorant to not delete it and have to take a pump off every 6 months to unstick or rebuild the pump. Ive had one stick and it ran the truck at WOT from start up

 

[Floridianson]

One would think ignorant is an opinion not a fact. I do not know why you are having trouble with your PT AFC rebuilds or how long they last so I can not comment on that. I would bet many trucks ran many miles with no trouble with the AFC. My 915A1 with the 400 Cummins never gave me any trouble with the AFC diaphragm and it never gave Pete who I sold the truck to any problems that I know of and that is years of service. My 920 with the Cummins AFC never gave me any trouble for years and it sat around more than I like to say and more like a yard ornament once again that is years of service. I also did nothing to my PT's like raise the rail pressure / open the throttle screw or even do the duel fuel line. They seem to do any job I needed to do and never let me down. Did you happen see the article about the up grade seals and diaphragm. Maybe the fuel we get now. This is why I like the correct additives for the older trucks and try and keep the fuel moving through them as someone once told me the PT seem to go stale if they sit to long.

 

[Steve92307]

Because the aneroid does stupid things. Like the thread posted this morning. 6 months on a new pump and it sticks closed and basically you are basically stranded. Or it sticks half closed and you can't move but at a snails pace.

The amount of smoke on takeoff depends on your foot as well. Not just the aneroid. It would be ignorant to not delete it and have to take a pump off every 6 months to unstick or rebuild the pump. Ive had one stick and it ran the truck at WOT from start up

Ok, so I drilled the ball out on the pump shaft. I only turned it about an 1/8th of a turn. I'm still waiting on a guage I ordered so I didn't want to go to far. I also took the air cleaner off and I took it for a spin. Seemed to have a little bit better throttle response. I dial it in a bit more when I get the pressure guage. So i know these things are slow. My question is how slow. I can only get up to about 25 maybe 30mph going up a mild hill. Is that about right? Especially given the massive tires I have??

 

[Crf450x]

Ok, so I drilled the ball out on the pump shaft. I only turned it about an 1/8th of a turn. I'm still waiting on a guage I ordered so I didn't want to go to far. I also took the air cleaner off and I took it for a spin. Seemed to have a little bit better throttle response. I dial it in a bit more when I get the pressure guage. So i know these things are slow. My question is how slow. I can only get up to about 25 maybe 30mph going up a mild hill. Is that about right? Especially given the massive tires I have??

Best to not mess with the screw.

 

[simp5782]

Backing the screw out is how you get more boost.

If it has a steel ball in it then its set at stock. Rebuild places tend to use a nylon ball. 1/8" turn at a time till you get your gauge then you can back it however much you want and drive with your foot to control rail pressure

 

[Steve92307]

Backing the screw out is how you get more boost.

If it has a steel ball in it then its set at stock. Rebuild places tend to use a nylon ball. 1/8" turn at a time till you get your gauge then you can back it however much you want and drive with your foot to control rail pressure

Did you happen to see my question about the mph of our trucks

 

[simp5782]

Did you happen to see my question about the mph of our trucks

They are slow up hill. Even with a turbo.

 

[simp5782]

You could drive it to Barstow tomorrow and I could look at it. Will be there from 10am on

 

[Steve92307]

You could drive it to Barstow tomorrow and I could look at it. Will be there from 10am on

I would love to but I have to work tomorrow. I also just noticed an oil leak at the front of the engine....yay!!

 

[Steve92307]

You could drive it to Barstow tomorrow and I could look at it. Will be there from 10am on

How long are you gonna be out in barstow?

 

[Floridianson]

Ok, so I drilled the ball out on the pump shaft. I only turned it about an 1/8th of a turn. I'm still waiting on a guage I ordered so I didn't want to go to far. I also took the air cleaner off and I took it for a spin. Seemed to have a little bit better throttle response. I dial it in a bit more when I get the pressure guage. So i know these things are slow. My question is how slow. I can only get up to about 25 maybe 30mph going up a mild hill. Is that about right? Especially given the massive tires I have??

Still believe to see top end gains one needs to get the air fuel mixture right at all RPM ranges so injector work when adding a turbo. As for the 200 psi rail pressure I have increased in a couple of mine to I crossed my fingers that I did not flatten my cam. Yes you must be care full with that throttle screw. Now I do not know if they did it to all the 939 series 250 but when I checked a truck for a friend his rail pressure was already turned up to real close to 195 psi. Now we always turn the throttle screw counter clock wise to increase. I have not seen the one PT throttle screw that you have to add shims buy backing out the screw and adding shims but they could be out there.

 

[simp5782]

So after looking at the setup. The turbo is equal to an HX80. Which is double the volume of the HT3B most folks use.. The small cam doesn't have the air or ability to even spool it up. Its stupid overkill. Intercooler serves no purpose as no air can get across it. It probably builds 4lbs of boost but loses most with the Intercooler.

They installed a rear fuel line feed but simply capped it off without completing it.

they Used a small cam manifold and piped it to the turbo and made their own flange. Alot of stupid work done to it when a big cam manifold would have allowed for a 1 hour installation and put the turbo in the same spot

 

[Steve92307]

So after looking at the setup. The turbo is equal to an HX80. Which is double the volume of the HT3B most folks use.. The small cam doesn't have the air or ability to even spool it up. Its stupid overkill. Intercooler serves no purpose as no air can get across it. It probably builds 4lbs of boost but loses most with the Intercooler.

They installed a rear fuel line feed but simply capped it off without completing it.

they Used a small cam manifold and piped it to the turbo and made their own flange. Alot of stupid work done to it when a big cam manifold would have allowed for a 1 hour installation and put the turbo in the same spot

I'll have to take some more pics so everyone can see what the guy did to my truck. Thanks again for the help!

 

[Superthermal]

Primer isn't needed. It just fails and sucks air

Solenoid has a plug like shown below. Remove it and use hydraulic fittings. And hose and a liquid filled gauge

Simp, with the primer, how can I test if it is leaking? I live in a winter cold climate. Is the primer not needed in a cold start? Is there a thread for "primer delete steps". Would it be better to add an ether injection for cold starts? This is for an M813.