Changing out rails

Gibson

Gibson

There's no love in diesel
Joined
Oct 11, 2008
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Can the rail from an 8.3 or simalar displacement cummins be swapped in on a 5.9? I think in all theory a larger rail equals more volume which means harder to drain under heavy load. Is it doable? Anyone done it or thoght of it?
 
Gibson said:
Can the rail from an 8.3 or simalar displacement cummins be swapped in on a 5.9? I think in all theory a larger rail equals more volume which means harder to drain under heavy load. Is it doable? Anyone done it or thoght of it?
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I think the 6.7 rail is bigger too.
 
The 6.7 Rail is bigger along with the 8.3 But I don't know if they can match up. Don't quote me on that.

Why don't you look up TC Rails they extrude and hone them make them hold more volume and flow better. Supposed to have a HP increase also.
 
My point exactly. If A 5.9 and be honed. An 8.3 can be aswell. So go big with a honed 5.9 rail or go over board with a stock/honed 8.3 rail. Have y'all seen an 8.3 rail? That thing dworfs the 5.9! And y upgrade a very expensive cp3 when I can just maje it more free flowing with a larger rail? It like when you have a water tower that hold 1000 gallons and a 10hp engine feeding it. And the motor can't keep up. But you double the tank to 2000 gallons and it never goes empty so the little 10hp engine doesn't have to directly feed and compensate fir loss of volume. That's what I'm trying to achieve now. I'm not looking for horse power just better efficiancy the capacity for big fuel down the road. Savvy? So got anyone that can directly see if injector lines mate up and corresponding parts? I belive new or bending of the lines will be required. The distance between each port on the rail is like 2"
 
The gain / stock cp3 would be next to nothing, just look at a rail, the port going IN....is the same size as all the ports going out.

Take a air compressor and blow through the feed line to the rail, and you will feel a pressure build, but still good flow through the line.

NOW take that same air nozzle and blow through the input line to the rail and the air just fog's out of the rail through all the ports like crazy.

The rail is no restriction.

Put some BIG injectors in your truck and you'll find out quick the rail ain't holding you back.
 
look at some of the upper HP engines out there. I don't think any of them are running a modded rail. I have a modded rail and drilled connector tubes that I will NOT be using. I was told second hand that Don M. said it is not needed with the Flux 5.1's and that the filters in the connector tubes should be left in place. If they dont hurt flow to the injectors I can't see a modded rail ever being needed. The interiors of those modded rails look so rough I would never run it, at least the 1 I was sold.
 
The rail is no restriction thatswhy it drains under heavy load with big fuel. I'm not wanting less restriction or tryingto get that. I'm wanting higher volume so it'll be harder to drain. And the feed line will be up enlarged definately.
 
Woah woah woah. How can air be used to compare fuel flow? Air and liquids have way differant properties. Correct me if I am wrong. This is just a thought
 
5 times the rail volume isn't going to make any difference. You could put a 55 gallon drum in there if the pump can't maintain the pressure needed all the fuel in the world isn't going to help that.
 
Ok I'm
Starting to see. Would an 8.3 rail be worth it? Even with twin cp3's?
 
the larger rail helps the psi pulse coming from the CP3 at very high psi. It's like a dampner absorbing the shock of the pulse. The bigger the tank, the more dampening... that's one benefit. It help prevent the injectors from taking the brunt of the psi

You guys see the 6.7 and 8.3 have larger rails. There's obviously something to it if they felt the need to enlarge them from the 5.9's rail. I agree the tubes make no difference... been there, done that and I have no proof the larger rail makes a difference but, the theory behind it makes sense.

The bigger the tank, the more fuel can be dumped. look at it like this....

an air tank fills up to it's set psi.... say 150psi. You can run say a air tool for so long before it's power is diminished from lack of psi behind it. Yes, the tank still has air in it but, the compressor has to kick on to get it back to optimal psi. If the air tank was say 250psi ( a larger rail ), it would be able to run the air tool for a longer period before needing the compressor. I know you can't compare air to fluid but, you can get the idea.

The modded rail is like oil..... no one can or will ever agree on it.
 
The reason I even thought of this because I've takin the 7.3 HPOP off a dt466 and put on reg truck engne. Same thing baicky but the dt466 HPOP has higher volume and pressure. It was more efficiant on the reg truck engine than on the big truck engine. Again I know a ford HPOP don't compare but in theory it's the same. I'm gunna try to hit up the cummins instructor at school and see if he can help. They have every cummins modle known to man there and the capabililties to program them. I wanna talk him into letting me use the programmin on my ECM :) oh yeah!
 
Your looking at it wrong. The higher pressure would be from the PUMP. A larger tank at the same PSI would still exhibit the same pressure drop as a smaller tank at said psi. Simple fluid dynamics. Look at it this way. A furnace needs 10 CFH. at 10psi. but your line will only supply 5 CFH. You can have 100,000 CF storage tank but as soon as the control valve opens and the pressure drops below needed you have a tank full of unusable fuel. FYI it takes 9 OUNCES of water to raise the pressure in a 1000 gal. tank 40 psi, so in this system we are talking very small amounts of fuel. The lack of pressure is from lack of volume from the pump, so the bigger rail MAY help for a few thousanth's of a second.
 
The6.7 Has Different Lines, I Have Bore Out One To 14mm, I Have Ran A 12mm With Big Injectors But It Never Quit Hazin, The Factory Is 10mm,the 14mm I Am Gonna Run Twin Pumps And I Am Gonna Try 4 Feed Lines Or Just 3
 
triton said:
an air tank fills up to it's set psi.... say 150psi. You can run say a air tool for so long before it's power is diminished from lack of psi behind it. Yes, the tank still has air in it but, the compressor has to kick on to get it back to optimal psi. If the air tank was say 250psi ( a larger rail ), it would be able to run the air tool for a longer period before needing the compressor. I know you can't compare air to fluid but, you can get the idea.

The modded rail is like oil..... no one can or will ever agree on it.
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I think 150psi in both tanks would make more since.
 
not enoughsmoke said:
The6.7 Has Different Lines, I Have Bore Out One To 14mm, I Have Ran A 12mm With Big Injectors But It Never Quit Hazin, The Factory Is 10mm,the 14mm I Am Gonna Run Twin Pumps And I Am Gonna Try 4 Feed Lines Or Just 3
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Lemme ask this. What are you trying to achieve by having a bored out rail? Flow? Volume? Pressure? Etc?
 
I understand what Triton was tryingto say but it came out wrong I think. Say one tank is 2 gal. and one is 50gal. put 50psi in both and see which one runs dry first. Although it seems that injector size would have alot to do with it and how fast your rail would bleed down. On the other hand it will take longer to have the rail recover to or reach a higher psi which would ultimately come from flow of cp-3.
 
A 2 Gal Tank Filled To 110psi Would Need The Pump To Kick On Earlier Than A 50 Gal Tank Filled To 110psi Using The Same Tool For The Same Amount Of Time. The Catcher Is The If They Ahve The Same Size Pump The Pump On The 50 Gal Tank Would Have To Run Alot Longer To Get It Back To 110 Psi. This Is Where A Larger Rail With A Modded Pump Or Twin Pumps Would So The Advantage. Over The Stock Rail And Stock Pump.

Since The Cp3 Is A Variable Volume Pump To A Limit Unless You Were Running Full Out The Cp3 Would Not Have To Work As Hard To Maintain The Rail Pressure In A Modded Rail.
 
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