J.DAVY

I was wondering if this can be done to the dodge cp3?I read in a different post that a guy shimmed his duramax one .060.I have looked at mine but not sure how to take it apart.It looks like they screw it together than helicoil another thread in there to lock it in place.

Dodgezilla

Why would you want to do this? The fuel rail can only handle so much pressure and that valve is there to keep it under control.


By the way, your Quadzilla isn't a downloader..

J.DAVY

How much can the rail handle?As long as the valve is working it should handle a little more.With the new cp3 mods coming out and the amount of guys poping and wrecking the valves it makes sense to do this ,at least for racing.

John Rodriguez

The valve looses strength with high rail pressures over time. Taking it apart then shimming it might make it as tight, if not a bit tighter than stock. Seems like a good idea, can you link us to the thread?

AK RAM

Have you thought about taking it off and finding a cap to fit that nipple? You would want to plug the fuel return line. The rail itself is designed to handle 29,000 psi all day, every day, so you would probably hurt your injectors (just assuming) before you hurt the rail. That darn relief valve is the weak link. Who needs it anyway!

Could be. Quad released his downloader right after BullyDog released the Pup, they just didn't stay in production for very long. You still see a used one pop up on E-Bay from time to time.

Dodgezilla

Man, I stand corrected. I apologize J.Davy!

king d

you are correct is is heli coiled and doesnt come apart well.i am getting one for a dmax and gonna see if it will cross over

J.DAVY

Dodgezilla,It is definatley a downloader.I knew they were getting them in ,and snagged one of the first ones.It can erase codes and has 3 settings 50-100-150.It seems to work really well with my t.s.t..AK RAM I thought about it but invisioned it exploding .Is this not possible?But if shimming helps stop them from popping and then getting etched I would be all over it.John R. I will find the link but it was a article about Cummins being the most reliable engine and I believe it was authored by Superduty.Then you click on his link to a article about Duramaxes over heating,and it is in one of the guys signatures.Can anyone tell me how do I post a link?

Superduty

"Cummins being the most reliable engine and I believe it was authored by Superduty."

I posted an opinion that the Cummins was the only engine without a major problem such as over heating or stretching head bolts.

Now as far as shimming something:

a) are you speaking of the pressure control valve on the CP3 (FCA) OR
b) are you speaking of the rail pressure relief valve ?

If you are speaking of the rail pressure relief valve, I recommend against it. I also recommend against running a program or box that significantly increases the fuel injection pressure above the maximum injection pressure:

a) increasing the injection pressure does not significantly increase the volume of fuel delivered. It might by 10-15%, but if you are looking for 50,100 or 150HP, I recommend increasing duration, not pressure.

b) the rail relief valve serves to keep things from over pressuring. Generally, it does NOT decrease in pressure a lot over time, unless it is continuously being exercised.

The common rail injection system is susceptible to pressure "issues" in two areas:

a) internally in the injectors
b) the injector connector tubes sealing to the injectors.

Significantly increasing the injection pressure puts both of these components under a lot of stress. A significant leak in either can result in a crankcase full of diesel fuel.

I'd leave the rail relief valve alone if I were you.

If you really have to fool with it, I'd test it to make sure it is leaking before I did anything to it. After I modified it, I'd test it again to see what pressure it actually operated at to make sure it still worked.

J.DAVY

Superduty,I was talking about the rail relief valve on top of the rail.I have read about a few guys double stacking boxes or running the edge ez on the secret 80 h.p. and having problems with the valve.I was interested in doing this in a racing application only.With the new geared up cp3's coming out we should have a lot more fuel at our disposal and what better way to take advantage of this.Injectors make sense but are way more money and I am still waiting for a proven set of edm's to come out.The t.s.t widens the pulse but there must be a point to where it is not effective anymore.More pressure is going to give the best atomization and power isn't it?I am learning more about these things all the time from guys like you so thanks for filling me in .I don.'t want to wreck anything in my truck as I like it way to much.

AK RAM

You never know. The cap maybe. That would suck if you launched it straight through the hood at 30,000psi. Would have to get one that is made for hydraulic systems from an industrial hardware store or something that can handle the pressure. The rail...probably not. If it can handle 29,000psi continuously, it can handle short duration spikes much higher than that. Like Superduty said, if you get pressures too high, you will probably develop some leaks at various joints first, creating its own pressure relief valve per say.

I don't know much about these modified CP3s, but stacking a pressure box with a duration box coupled with a CP3 that can keep up.....have you thought about the possible HP gains that can produce? Just thinking about it, with an aggressive pressure box like the Ramifier that is commanding pressures in the upper 27,000 psi region and a duration box like the TST, you can easily pull rail pressure down into the lower teens (lets say 12,000 psi) and still make 500+ hp. Imagine that stack with a CP3 that can keep up, duration stretched out to the max with 27,000 psi behind it the whole time! That would be a pressure increase of about 15,000 psi at WOT verses a stock CP3. In the early days, Quadzilla was able to make 140 extra hp with his first race pressure box just by increasing pressure by 5,000 psi. Theoretically, putting on a CP3 that can keep up (15,000 psi pressure increase at WOT) could possibly (realizing the increase is not linear) increase HP by an additional 400hp, and that is basing it off a stock pulse width. Take into account the compounding effect of the TST's stretched out duration....man at the possibilities. 800...900 hp? That would have to be a "Super CP3" to keep up though.

Who have you talked to that is re-gearing the pumps? PM me if you want. I don't know if I would go that extreme or not. I still need a reliable vehicle to pick up the groceries with, and with that kind of power, something is going to break and break often. I may go for a slight honing job myself, just enough to get this pig of an SO engine over 600hp on #2.

Dodgezilla

You guys are nuts!!!

J.DAVY

AK RAM,I am dragging my rail down to 9000psi,I can,t imagine the power with the same set up running 29000 or even 23000 psi.I Pm'd you the info on the cp3 pump.I use to run that 140 h.p. Quad race box stacked with my edge ez on my 03 ,lots of bottom end power but not as much topend as the tst/ez stack.

Superduty

"With the new geared up cp3's coming out we should have a lot more fuel at our disposal and what better way to take advantage of this."

All the new CP3s will do is increase their VOLUME, not pressure capabilities. The best way to take advantage of these pumps is to keep the maximum rail pressure the same, ie stock and changing the TIMING AND DURATION.

"Injectors make sense but are way more money and I am still waiting for a proven set of edm's to come out.The t.s.t widens the pulse but there must be a point to where it is not effective anymore.More pressure is going to give the best atomization and power isn't it?"

Fuel delivery volume DOES NOT go up linearly with injection pressure. It takes 21% more pressure to get a 10% increase in fuel delivery. Much easier to just add 10% to the pulse width than to increase injection pressure.

As far as atomization, there is plenty of it at the pressures we are talking about. Atomization is a problem at low pressures, ie idle, 3500 PSI, etc, not at the high end > 20,000 PSI.

re: rail pressure pulling down to 9000 PSI. This is a function of the programming asking for more fuel than what the CP3 can output, not anything to do with the rail relief valve. At low throttle settings you probably have lots of rail pressure.

My advice: don't touch the rail relief valve unless it is obviously defective.

abc4yew

Guys, The rail relief valve is a bosch part available as a Cummins part, it is relatively inexpensive, just replace it every three months.(saw one at my hot shop) From what I understand the 2006 Dmax is raising the limit on its rail max pressure to achieve power. This could be the same pop off with a stronger hold. ks