Rail pressure questions

[mfunderburgh]

Well i dont own a 3rd gen Cummins but i do have the same fuel injection system as you guys do (dmax) and was wondering if you guys are having any problems with the high performance side of the fuel system. On the duramax side of things were having rail pressure issues, buddies truck is dropping to 8,000psi full throttle with big injectors and big tunes. Is anyone working on a larger pump and what have you guys done on the supply side of things and what kinds of results did you have? I have a supply pump on my pulling truck that i would like to put on a dmax and see what kind of rail pressure gains i could achieve if any. I have a regulator and could supply anywhere from 1-85psi to the high pressure pump. I'm thinking that i should bypass the EDU and supply it fuel with some other system at like 5psi just to keep it cool. Whats the max psi anyone supplied to their pump? Or does anyone know what the safe level is? Thanks, Matt

 

[SRadke]

There are many pusher pump systems supplying 10-20 psi but the CP3 (high pressure pump) and rail seem to be only supportive of about 550 hp on fuel.



-Scott

 

[OT-OF-HERE!!]

Well i dont own a 3rd gen Cummins but i do have the same fuel injection system as you guys do (dmax) and was wondering if you guys are having any problems with the high performance side of the fuel system. On the duramax side of things were having rail pressure issues, buddies truck is dropping to 8,000psi full throttle with big injectors and big tunes. Is anyone working on a larger pump and what have you guys done on the supply side of things and what kinds of results did you have? I have a supply pump on my pulling truck that i would like to put on a dmax and see what kind of rail pressure gains i could achieve if any. I have a regulator and could supply anywhere from 1-85psi to the high pressure pump. I'm thinking that i should bypass the EDU and supply it fuel with some other system at like 5psi just to keep it cool. Whats the max psi anyone supplied to their pump? Or does anyone know what the safe level is? Thanks, Matt

You must be Irish!! A service mgr I know has told me that there is a fuel rail pressure thing-a-ma-jig that is there to keep us all honest on our 3rd gen CTD's. It is supposedly set at about 15psi, which is why I suppose pushers like FASS and Air Dog are set at that level. With the CTD if we would pop that pressure regulator by pushing our luck (no pund), then that part is a STAR regulated device which would get us Red Flagged on our warranty. Hope that helps you.

 

[lmills]

I've pushed mine 18 psi daily for the past 4 months. I've never heard anything about too much supply pressure. Now I do know the rail has a pressure pop off, but it is considerably higher. The rail pressure pop off is to keep us from blowing the rail out whille running higher pressures with power adders like EZ's.

 

[mfunderburgh]

I know all about the rail pressure relief valve. But when your at 8,000 psi at the rail at WOT then poping the relif is not an issue. I'm just trying to find out how much supply pressure to the high pressure pump we can supply with out damaging anything like seals and soforth. lmills supplied the kind of info i am looking for. Now how far i want to push past that is another thing. I will go map some rail pressures at WOT and then start supplying higher fuel pressures to the pump and see if i can gain some on that current 8,000psi. I have a feeling its going to take a lot more than supply pressure to solve the problem. I have a meeting with a couple common rail engineers in a couple weeks that should give me some more info. Thanks, Matt

 

[lmills]

your right Matt, it is going to take more than xtra delivery to the CP3. It is going to end up taking a modified pump. There are a couple vendors working on them as of right now.

 

[mfunderburgh]

lmills, any info on what vendors are working on a bigger pump. I would assume one of them would be Scheids. I know that Gale Banks is working on a duramax racing truck and that on their website they said bosch supplied them with a larger fuel system. Would be nice if this was comerically available but i doubt that we will see that. Some people have had the idea of adding a second pump but i think all the electronics would be a nightmare and maybe impossible. Matt

 

[DCasten]

From the Banks white pages. Banks white paper



"The common rail fuel pressure system on the Duramax operates at approximately 23,000 PSI. Operation in excess of 26,000 PSI may result in internal leakage of the seals, a highly undesirable situation. Any fuel enhancement device should maintain a maximum fuel pressure below this threshold. "



I would give their tech guys a call. They have always been very helpfull.

 

[DLeno]

I know all about the rail pressure relief valve. But when your at 8,000 psi at the rail at WOT then poping the relif is not an issue.

maybe, maybe not. The pressure relief valve may be the reason you can acheive only 8,000 PSI.

 

[mfunderburgh]

Failed relief valves usually show up as a 093 code on dmax trucks. Most cases of relief valves failing have the trucks shut down or just fall on their face. I know a couple people who had this problem when sled pulling. This truck still moves very nicely and i wouldnt think it had a fuel problem till you look at the rail pressure.

 

[wsteffes]

Probably the flow from the hpcr pump is max'ed.

But at what point do we start to look at the flow capacity of the singe line from the pump to the common rail?

Used to have 6 lines from the pump now only one.

 

[banshee]

mfunderburgh,



I push 26-29 psi at idle into my CP3... no problems with about 15k miles on that setup now.



John

 

[Big MAK]

I'm sure multiple vendors are working on a high pressure pump. Piers @ PDR http://www.piersdiesel.com is one of them. Sounds like you guys should talk; maybe share some info if you're hooking up with some CR fueling engineers.



Looks to me like between 550 and 600 hp is the limit for the current pump.