First I want to start out by saying I’m a chevy fan though when I first started contemplating buying a new diesel I was dead set on a dodge because of the Cummins. After driving both and researching I decided the chevy was the way to go FOR ME.

While doing research on mods for the Cummins there was always concern with increasing rail pressure. It seemed higher pressures would increase injector wear and decrease their life expectancy. I know the Dmax system has a similar common rail system with less max pressure but is there not the same concern?

I want to add a little boost just to make sure I at least equal the new Cummins and power strokes. I have read more than once about the 6.0 stock having considerably higher rw dyno numbers then the Dmax is putting out. Is everyone else seeing this as well?

Anyway I want to do a programmer in the 40-50 hp range but don’t want to worry about damaging anything over the long haul. I asked Diablo about increasing rail pressure and maybe I’m a little slow but could not figure out what the heck they were saying. Here it is-


This is a reply to your question from 2005-06-28 14:41

CATEGORY: Predator
QUESTION: [I am considering the LLY Predator for my 2005 Duramax Chevy.

How much if any of the additional horsepower is gained through increased rail pressure for each of the levels?

Thanks for your help,
James]

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ANSWER:
Dear James Phillips,

The tunes in the Predator do not make power by reaising the rail pressure. They simply add more fuel, which increases rail pressure- however rail pressure is not raised to squeeze extra fuel out.

Thank you for your interest in DiabloSport!
Stay tuned,
Dan, a proud member of the DiabloSport Support Team

GM looks like they are increasing rail pressure on the '06 models. Some programmers do increase rail pressure but they are the big tunes. I don't think the common programmers (Edge, Predator, Banks etc.) increase the actual rail pressure directly. I could be wrong.

Think of it as a garden hose. The stock truck has the faucet turned on half way, and lets say the pressure in the hose is 4psi. Then you try to spray a cat with the hose, and squeezing the trigger sprays out a short burst of 4psi water that quickly turns into a 1 psi dribble. The programmer just opens the faucet all the way. You still have 4 psi in the hose, but when you pull the trigger to spray the cat, you get a 4psi stream of water that stays that way, so you can really hose down that cat. Does this make sense?:help2:

One place were the chevy shows a less hp to the rears is the amount of drivetrain loss through the allison especially. It sucks a deccent amount of power. The newer programers mostly adjust how long and when the injector is opened. Programers are fine IMO in terms of injector life.....now trany life if you turn the box up too high is another story. Get one of the bigger names with the options that are important to you(each box has different bells and wistles with it) and dont set it to kill and drive sane and you will be fine IMO Welcome BTW :)

Judging by their response, the predator does not increase rail pressure above the stock pressures. It makes more power by holding the injectors open for a longer duration per shot. As such there should be no increased stress or wear beyond stock.

The predator 40 tune is nice. Some smoking, but not much, and is also quiet. If I were you I'd get the Predator for its diagnostics (nice bonus), ease of install, and "hide-ability" (it's easy to reinstall the stock tune). Don't forget an exhaust upgrade too.

If you increase the rail pressure on a stock truck very much, you will pop the relief valve, and throw P1093's.

Think of it as a garden hose. The stock truck has the faucet turned on half way, and lets say the pressure in the hose is 4psi. Then you try to spray a cat with the hose, and squeezing the trigger sprays out a short burst of 4psi water that quickly turns into a 1 psi dribble. The programmer just opens the faucet all the way. You still have 4 psi in the hose, but when you pull the trigger to spray the cat, you get a 4psi stream of water that stays that way, so you can really hose down that cat. Does this make sense?:help2:

Makes sense,

And...... If you take the sprayer and hold trigger down too far then you might see a pressure drop if your pump or line is too small, causing a loss in spray performance.....:)

But the main thing is that we got the cat wet:D

Thanks for the responses! From what I'm hearing I won't have to worry with the lower end tunes then.

Yep I hope to mod a little as my expenses allow. My plans are fingers stick, egr block, 4" exhaust w/ flange (so I can put the kitty back on when needed), and last but not least a 40-50hp tune, probably the Predator. Will be nice to be able to adjust for 265's and read codes.

Thanks for the responses! From what I'm hearing I won't have to worry with the lower end tunes then.

Yep I hope to mod a little as my expenses allow. My plans are fingers stick, egr block, 4" exhaust w/ flange (so I can put the kitty back on when needed), and last but not least a 40-50hp tune, probably the Predator. Will be nice to be able to adjust for 265's and read codes.

Good choices. Have fun.