Duel fuel line mod M818 855 cummins

[patracy]

You should be able to use a billet fuel rail as long as it has enough ports. What is the PSI being supplied through those steel lines?

Maybe I should expand my last response. I *might* have added 10hp to the truck. For a cost of $40. Your idea might add 11hp for a cost of $400.

Cummins big cam trucks have a dual feed line setup like this that supports 400hp.

 

[FireFighterHill]

I guess it depends where you get your parts. except for some of the fitting I can scrounge most of it up for free or dirt cheap. Something Id have to think more about once I get my truck home. You are probably right on it not making much more of a difference.

 

[rangereter]

Common rail 5.9 fuel flow increase? How do you do that? (That's a real question, not sarcasm) 525 N14s do not have a fuel line "up-grades" to make more power. The pump pressures are the same for 100+ hp differentiation... injectors and timing change torque curves and hp ratings.
Regards, Bob

 

[patracy]

Common rail 5.9 fuel flow increase? How do you do that? (That's a real question, not sarcasm) 525 N14s do not have a fuel line "up-grades" to make more power. The pump pressures are the same for 100+ hp differentiation... injectors and timing change torque curves and hp ratings.
Regards, Bob

In the 5.9 performance world (and 6.7). It's very common for the "rail to drain". The solution is to plumb in dual CP3 pumps.

 

[350TacoZilla]

Common rail 5.9 fuel flow increase? How do you do that? (That's a real question, not sarcasm) 525 N14s do not have a fuel line "up-grades" to make more power. The pump pressures are the same for 100+ hp differentiation... injectors and timing change torque curves and hp ratings.
Regards, Bob

not just dual pumps you can keep 1 stock pump and put a fuel line into each end.

http://www.dieselpowerproducts.com/...ual-feed-cr-line-03-07-59l-dodge-cummins.aspx


patracy is correct that the higher HP rating motors had the dual feed from factory

 

[rangereter]

Patracy, That is very interesting about the dual high pressure pumps used to increase delivery in the smaller "non-stock" engines. I have been into these pumps (stock) before in order to id failures/cause of failures (amazingly engineered by the way), but with 24,000+ psi in the manifold (at rated power) I've never experienced a pressure/flow drop (fuel rail depletion) on a stock engine with a "healthy" low pressure side of the fuel system. Since the CP3 is actually two pumps (transfer and high-pressure), is a second HP side sistered/coupled to the existing pump, or is it otherwise remotely mounted? I think the high performance side of diesel engine building is very interesting now with respect to the way that the software has to be configured to operate the fueling (black smoke use to look "cool" to me...now just see it as wasteful).
As far as the 855 is concerned, it would be interesting to see if there is a rail delivery pressure change before and after this modification. I'm guessing there probably is based on the fact that surely along the way, someone has plumbed in a gauge and done a before and after measurement under load. I still tend to think that when these CPL's were put together for the variety of NH/NT configurations/applications over the years, there is usually more to it, with respect to performance and longevity, than slapping on a turbo or shoving more fuel into a hole. Experimenting with the diesel mods is a neat hobby in itself ($$$), I just think it's even cooler when you can capture some before and after numbers to base the findings on.
Regards, Bob
I should add however that a "little" black smoke does give me a warm fuzzy.

 

[patracy]

Some pics of my install. First the twisted up allen key. But notice the plug came out no problem. A dab of valve lapping compound saved me on that one. The doghouse has too large of an area cut into it. But I've since folded the "door" back down, put the foam/plastic insulation back on. And covered it with sheet metal I painted flat black.

 

[patracy]

Here's a video of it revving as well.

http://youtu.be/6QsAxvCRsvo

 

[350TacoZilla]

wow that really seemed to improve throttle response from what I have seen in these trucks (including mine)

 

[350TacoZilla]

only thing i am confused on is which port is the fuel inlet on heads... you say bottom post on front head but in pics of rear head its kinda hard to tell.

 

[patracy]

wow that really seemed to improve throttle response from what I have seen in these trucks (including mine)

I honestly never took a video of it before hand, but it's notably different/improved.

only thing i am confused on is which port is the fuel inlet on heads... you say bottom post on front head but in pics of rear head its kinda hard to tell.

The port on the bottom of the head is the supply port. If you look at the first pic, you'll see the second (return) port to the top left of the brass fitting.

 

[350TacoZilla]

ahh yeah i can make it out now, do you think it would be worth while to split the return also? so there would be supply and return at each end? I cannot wait to do this mod along with little fuel adjustment .... then onto the turbo

 

[patracy]

The OP did, but honestly I think it works in your favor to leave it like I did. (Think about how the button works)

 

[73m819]

Here's a video of it revving as well.

http://youtu.be/6QsAxvCRsvo

A bit of over tack (showing 2450), 855s do not like over tack, something about valve floating, hitting pistons, ect.

There is a reason Cummins put squirters in the 290 and other higher hp motors, trying to pull 300 hp out of a non-squirter 250 (really a 240) plus over tack leads to cooked/broke motors.

A lot of the tricks ( the dime, duel fuel feed, a secondary fuel pump to raise the fuel pressure to the ip before it gets to the ip, trick injectors, springs ect.) to get more fuel to the motor is used on SQUIRTER motors

 

[patracy]

Thanks again Ron. I didn't hear you the second or third time.

 

[73m819]

Thanks again Ron. I didn't hear you the second or third time.

I was not attacking you, I know it is your truck and you have every right to do what you want with along with a great how to, I was trying to let others know the major problem of hopping up a 240 Cummins. You may get away with the hop up and the motor last for ever and that would be great, I hope it does.

I just want other to know and think about that when Cummins hoped up the 240 they added squirters, with CUMMINS not doing ANYTHING that cost an extra penny and has to have a VERY good reason for doing ANYTHING along with the RESEARCH to back up the EXSPENDITURE.

What ever you do to power up the 855, INSTALL A PYROMETER

The other thing I want others to KNOW is that the 855 is VERY RPM sensitive.

Once members realize the above, if they went to hop up their 240, fine, their motor, their decesion knowing the risk, I just want everybody to know the risk without finding it out AFTER the build, then it is to late.

A lot of us that have these trucks really don't have a lot of money, so if a hopped up motor takes a dump, that would be a BIG chunk of change to fix/replace which a lot of us do not have, this then would mean a dead truck for quite a bit of time, so in reality a slow/under powered truck is better then a non-powered dead truck, this is the message I am trying to get across.

 

[patracy]

I was not attacking you, I know it is your truck and you have every right to do what you want with along with a great how to, I was trying to let others know the major problem of hopping up a 240 Cummins. You may get away with the hop up and the motor last for ever and that would be great.

I just want other to know and think about that when Cummins hoped up the 240 they added squirters, with CUMMINS not doing ANYTHING that cost an extra penny and has to have a VERYgood reason for doing ANYTHING along with the RESEARCH to back up the EXSPENDITURE.

The other thing I want others to KNOW is that the 855 is VERY RPM sensitive.

Once members relize the above, if they went to hop up their 240, fine, their motor, their decesion knowing the risk, I just want everybody to know the risk without finding it out AFTER the build, then it is to late.

2400 is max governed RPM the military uses for testing purposes.

https://redriver.army.mil/contracti...ns/09T0012/OQEM939SeriesEngineDyno-NHC250.pdf

They also run the engine at full load 2150rpm for testing purposes as well. (2100rpm at 220hp for 15 minutes as well)

I agree that the lack of oil squirters means a safety net is gone for people. But as I mentioned previously, I drive by my gauges. I will not allow EGTs over 1100F.

 

[Cycletek]

While I agree with you to a certain extent Ron, a Multi-Billion dollar performance after market would not exist if experimentation with existing limits were not explored. I believe this modification is more evolutionary than revolutionary.........which is the smart move!

 

[Rkrug]

Got my second fuel line installed today , Makes a huge difference! Idles a lot smother and quieter,and has more power when driving also emits a nice smoke trail. Hardest part was getting the fuel rail plug out, tried the allen key but it stripped out so I had my uncle weld a nut on and it came right out.Will post more pics soon.Might get a video of it running to.
Going to go drive it some more now!

 

[quarkz]

Rkrug,
How difficult was it to remove the entire doghouse & gear shift column along with disconnecting the linkages?
I think I like that path better then cutting holes, plus there seems to be a lot more room to work.

Patracy & Rkrug thanx for the step by step pictures.

And for those who don't know, as I didn't before this thread, a JIC fitting is a 37 degree - flare fitting.
Some sort of industrial hydraulic fitting from Parker.