We had a Cummins mech in the shop today and I jokingly said to him if he had a set of bigger injectors in his pocket he could put them in my 03. He said that I wouldn't see any advantages due to the stock computer limiting engine output.

I thought I'd stuff some injectors into the truck as the chances of the "***********" spotting them would be slim to none..

Any thoughts on this???


Blygy

 

IMO--Only having bigger injectors are not going to help because your computer is only sending a certain amount of fuel to them. get a fueling box 1st then when your used to the power switch to some bigger injectors then it'll be all new to you again .

there is a certain order in witch upgrades sould be installed IMO #1 gauges #2 drive train #3 make her breath some fresh air #4 throw some fuel to her #5 use your imagination so on and so forth usually people skip right to the chips/boxes and before they know it its time to get some trany work.$$$$

Use your head and it'll save you some dough

DM

 

I know on my 01, if I put just injectors in it (which I plan on doing soon), you'll gain more power.

 

Don't listen to him. Injectors alone will give you power, and it will be nearly impossible for the dealer to tell unless they have to tear things down for some reason. Of course, adding a box on top of injectors just compounds your gains. When my '05 finally gets here, I am contemplating the addition of DonM's EDM injectors and the new bullydog downloader. It appears that this would be undetectable to the dealer, since you just re-flash the stock program back on before you take it in for service.

 

I would think that if the injectors are bigger you would get more power. The computer fires each injector for a set amount of time. If the holes are bigger more fuel will be injected while the injector is open therefore more power. That is how I would asume it should work.

 

That's correct. The computer can't tell what size injector is in the engine. It just fires a given amount of duration. It's blind to what it's firing hence the overhead readout being off.

 

I thought the computer limited the injection at the maximum boost it wanted to see. Isn't that why a boost fooler is needed for higher power settings? If so larger injectors would not produce higher power without boost fooling. Am I missing something?

Wetspirit

 

Yes, with larger injectors you would need a boost fooler to get around defueling.

 

Um, no.

Well, only if your boost goes above the defueling setpoint as a result of the increased fuel.

Will "bigger" injectors increase power? Yes and No.

Bigger injectors will increase the MAXIMUM AVAILABLE power, by making more fuel available under max load conditions. Part-throttle fuel delivery is modulated by the driver's right foot, since the PCM delivers fuel according to driver demand under part-throttle conditions. Let's say, for the sake of argument, that 60 mph cruising takes 15 hp to keep that steady state 60 mph speed. Producing 15 hp requires the same amount of fuel whether that fuel comes through big or small holes. Big holes just inject it faster, meaning shorter pulse width for each injection event at part-throttle. PCM adjusts the fuel deliver to adapt to what you request with your right foot.

THe PCM has a set maximum pulse width- this does not change. WHat changes is the amount of fuel that can be injected duriing that duration of iinjection. More fuel available= more power available.

THe PCM does not have a "fuel flow meter" to tell it how much fuel is actually going in. It only knows what you are doing with the go pedal and adds more fuel or less fuel (by adjusting duration AKA pulse width) based on what you do with the pedal. Floor it, and you get all it can give- meaning maximum pulse width. Bigger holes flow more fuel- more power for same injection duration.

 

So, uh yes.

 

Should of made it a poll

I still say no ............

Its sort of like if you had a monster turbo it wouldnt increase the HP dramaticly untill you increase the fuel . you'd have plunty of air but its no big gain untill you give her some fuel. its the mixture that gives HP not one alone . the smokers are smokin because they have more fuel than air/boost . if they gained boost/air then all the wasted fuel would magically turn to power.

smoke's cool tho ,when you can control it.

with just bigger injectors i recken some fuel may slip by and get burnt up but not sure on how much power you'd gain.

DM

 

THat's gasser-think. Add fuel to a diesel, you will always make more power.
Gassers operate on stoichiometric ratio of about 14:1 air to fuel. Diesels will run anywhere from 100:1 to as low as 6:1, and that's a VERY wide range.

Of course you reach a point of diminishing returns, but generally speaking, more fuel= more power.

It's the EGT that gives the practical limit to the power. Adding air (boost) lowers the EGT, so you could say fuel is indirectly limited by air.

You WILL gain power with JUST bigger injectors. It's not subtle, either.

 

I am no expert on injectors, but if you could not get big HP gains with injectors alone than why would manufactures produce injectors that can up HP levels as high as 100 HP. Addtionally there is some what of a split in diesel folks on how to get more power. A lot of guy's like boxes and a lot of guy's like increasing injector size. Both will work and each has their own pro's and con's. Just my .02

 

You must exercise buyer beware when looking at products that promise you X HP gains. Do those products, by themselves, give that much power? Often, yes they do. But often, especially in the case of 80HP+ products, its not good or useable power.

Building reliable power in anything, whether its gas or diesel, is a balance between timing, air, and fuel (gas). With a diesel, you can often increase injector size and gain 100 ponies on a dyno, without any timing or air increases. But you try to use those 100 ponies on the street without timing or air, your EGTs will fire through the roof. So have you truly added 100 HP? I spose, but its not useable.

As a very general rule of thumb, and excluding the 600 Cummins, we've been able to safely add about 50 - 60 HP to any of the Dodges from 94 - 2004 with a set of injectors, and without boost fooling to increase boost. To prevent defueling, the wastegates sometimes needed to be setup to prevent overboost conditions.

Personally, I don't like injector-only power. I firmly believe you need a good box combined with good injectors and the right air to make good power.

Rod

 

I only said injectors can add power, not that the power gain is unlimited. Of course it is limited by smoke or EGT or other things.

Pushrod... what do you consider safe, and what are you using on the 2003-2004 dodges injectorwise? Some vendors claim to be able to get 105 hp safely without upgrading the turbo...

Maybe it's all how you define "safe"