Opinion needed on raising fuel rail pressure

[JLinder]

What's the general opinion of boxes that raise fuel rail pressure -vs- those that acheive hp gains via timing and such? Is there a specific problem that can occur, or just being conservative?



I'm looking an an EZ, but it raises rail pressure and I've been cautioned against this. Is it a concern based on fact, or am I just worried that the sky is falling? What about the Bully box, does is also raise rail pressure? So far, a box that doesn't isn't on the market far as I know.



Comments?

 

[RSnaith]

When the Duramax first came out, Van Aaken released a fuel pressure box that raised horsepower about 120 ponies. It was amazing for its time, however they didn't test it well enough and they raised the rail pressures beyond what the Bosch CP3 (same injection pump as whats on the Cummins) could handle, as as such, they began blowing seals out. The current offerings from Edge and Bully Dog are much less aggressive than that early VA box, and as long as the companies can be believed (and I think we can trust them) they are not raising pressure beyond what Bosch tells us the CP3 is capable of handling.



As for which is preferable, a box that builds power through timing/injector pulse modification will always be preferable in my mind. Especially the timing optimization. The timing on the stock Dodge trucks is horrible, and the entire fuel map is seriously detuned to minimize particulate emissions.



Having said all this, when the first timing box comes out, I'll be the first to stack my fuel pressure box on top that critter

 

[Marco]

No No

As yuo know the common rail systems have been arround here in Europe for quiet a while now.



When they first came out several boxes that simply increased the rail pressure HAVE been on the market.



Experience has shown that raising the rail pressure leads to the failure of the high pressure pump.



It's true Bosch (and others ) claim the rail pressure "UP to 1600 bar" but that's an UP TO!!!



UP to 1600 bar for how long??? For a very short time! With a box that can change dramatically.



I can't say that brand X or brand Y box will shoot youre common rail pump but be advised.....

 

[David Muench]

This is why I've been forcing myself to wait on a box. . Otherwise, I'd have an EZ right now.

 

[bighammer]

I'm waiting too. Besides, I have a warranty to run out first.

 

[CATCRACKER]

the blue chip box claims not to raise the rail pressure according to our last tdr issue. i am not going to use a box that raises rail pressure. i am waiting.

 

[Swayse]

Ditto

I won't raise my fuel rail pressure either.

 

[Vaughn MacKenzie]

I emailed back and forth with Keith a bit at Diesel Dynamics. It appears all boxes right now only raise fuel pressure, including the TTPM, but he said timing is in the works however it's few months off. I would think there's two ways to achieve more power without raising pressure: Manipulate timing, and duration of injection (basically same principle used on VP-44 engines). I wonder instead of split shots they could engineer then for no more than two shots or maybe even 1 shot and not waste time turning them on/off? That should bring back some of the clatter some guys are looking for.



I don't want to raise my fuel pressures. If anything I'd see if they could be dropped a few lbs for longevity but that would of course reduce HP. Another concern with raised fuel pressure is certainly it would increase erosion/wear rate of the injector holes.



Vaughn

 

[d90boy]

Originally posted by Vaughn MacKenzie

Another concern with raised fuel pressure is certainly it would increase erosion/wear rate of the injector holes.

Sounds like a cheap and easy extrude hone your own injector process! Who needs Diesel Dynamics?

 

[Marco]

I wonder instead of split shots they could engineer then for no more than two shots or maybe even 1 shot and not waste time turning them on/off? That should bring back some of the clatter some guys are looking for.



It's true the small pre injection is meant mainly to lower the combustion noise of the engine.

It's also true that the "softer" combustion also lowers the peak pressure in the cylinder. Thus less stress on the engine as a whole.



That said...



The CR on the Cummins can't provide more than these two shots.

( OK a very late after injection is possible )

For more shots the new injectors with the piezo actuator are needed. These can provide up to 5 shots during the usefull injection time window.

 

[David Muench]

Originally posted by Vaughn MacKenzie

I wonder instead of split shots they could engineer then for no more than two shots or maybe even 1 shot and not waste time turning them on/off? That should bring back some of the clatter some guys are looking for.

I've noticed that it seems to do that from time to time anyway, and I believe Cummins has said that it will disable the pilot injection under some circumstances. I know that mine rattles every now and then, particularly when it's working hard.



I think it's very interesting to listen to the engine as the computer changes stuff around on the fly. .

 

[Marco]

Yep, the pilot injection is turned off above a certain RPM.

That's because ther's not enough time for the injector(s) to perform the two shots.

 

[4xquadrod]

Injection Pump

How much is a new injection pump and if these boxes are reducing the life of the pump, by how much? Would we be looking at replacing it at 20,000 miles 100,000 or when ?

Also, is the pressure raised all the time or just when you are on it?



Curious!



Steve

 

[Vaughn MacKenzie]

And related to Quad's question, if guys have been running boxes that raise pressure "and haven't had any problems" how many miles have they been on? They may be fine for 20K, but for those who want at least 100,000 miles of durability & reliability, what about that?



Marco, I have seen comments by someone the new Cummins HPCR injectors can do 3 shots, another place it said 5. Where I saw that I don't recall.



Vaughn

 

[CATCRACKER]

up to five.

 

[Marco]

3!

Where the third is a very late "after" injection meant to increase the cat and de-nox filter temperature in order to burn the particulates in the exhaust.



For five shoot's the CR third generation with piezo actuators in the injectors is needed.



How much is a new injection pump and if these boxes are reducing the life of the pump, by how much? Would we be looking at replacing it at 20,000 miles 100,000 or when ?



The pumps run in the 2K range here . Dunno in the States.

Most failures have been seen during the warranty. Ther's not a rule of thumb to determine how long a pump would last.



We've seen a lot of CR pumps fail on their own. But almost all pumps with increased rail pressure failed! I know a guy with a box, he's on his fourth pump in 80K kilometers...

 

[RSnaith]

Originally posted by Marco

We've seen a lot of CR pumps fail on their own. But almost all pumps with increased rail pressure failed! I know a guy with a box, he's on his fourth pump in 80K kilometers...

What sort of boxes, Marco? How much rail pressure increase? Bosch is telling me that the CP3 can handle a sustained 27,000 PSI. Neither the Edge box nor the Bully Dog box bring pressure up to that point.

 

[Marco]

27000???



No way the pump will stand that kinda pressure!

23200 Psi is the max pressure, for SHORT periods. That's what Bosch says about their systems.



Fact is most CR systems do not exceed 19500 Psi under normal working conditions.



There have been several boxes arround here, Koch, Dimensione Sport, Chiptuning,Tuningbox...

All with the same result...

 

[RSnaith]

Originally posted by Marco

27000???



No way the pump will stand that kinda pressure!

23200 Psi is the max pressure, for SHORT periods. That's what Bosch says about their systems.

It appears as though your Bosch guys overseas and ours here in North America are at odd with one another. There's a surprise



Is it possible you guys have a different injection pump in use, or that there has recently been a changeup?

 

[Vaughn MacKenzie]

If the common rail pressure is under 20K PSI then that really isn't any higher than the jerk-pump VP44 affair, isn't it? I though the VP44 were around 18,000psi or something.



Vaughn