What is the deal with injector upgrades with respect to the LLY motor. I was told that an injector change was worth 70 HP/160 ft.lbs on a stocker. As a "gas" guy, I am still trying to understand how these diesel motors make more power! If I am understanding this properly, the programmers control the injector duration, which would introduce more fuel into the cylinder. This in turn combined with the turbos ability to push more air is where the power is made. My question is; when these companies "balance and flow" your injectors I would think it was done to further increase the volume of fuel that they will flow. On a stock engine how does it know to increase the volume of air without some kind of boost increase with the turbo?? How can you do the injectors and the programmer and not over fuel the engine?? Just because they are diesels they still require a certain air/fuel ratio to make power just like a gas engine. I know when we build LSX gas motors and stuff larger injectors in, we need to control them with programming, why not the same with the turbo diesels?? I need some education on these diesels!!:lol:

Overfueling is fine in a diesel, much unlike gassers. If you really want to see overfueling, go find a hotrodded Cummins 12V, which can make legendary smoke.

If you turn up the fuel with existing turbocharger controls, you make more power because the extra burned fuel essentially generates more boost. For example, the Juice on my LB7 comes in in a series of steps according to the engine temperature. There is a long grade on my way to work, and I can easily feel the steps of added fuel by the seat of my pants. Also you can watch the pyro tick up a little bit and also the boost comes up 1-2 psi per step. And if you leave your foot in the same position, I also pick up speed.

There does become a point where the turbo is too small for the fuel you're feeding it. The LB7s seem to run out of air at about a +200HPish gain; the big VA, the big Quad, and the TTS Extreme all get you about 500 RWHP but to go higher, more air is needed. Thus, the dramatic performance gains of guys like SD, NLDP, BMDMAX, and a bunch of others well into the 700HP range on nitrous (which to a diesel is just more air).

Your truck comes tuned for low emissions, decent power, and high reliability. There is obviously a lot more to be had.

So, it's a balancing game the whole way up. Whether you use bigger holes in the injector, or hold it open longer, or both, you get more power. Then you get to a point of diminishing returns and the HP doesn't go up much more. Then you add a bigger single, or twin chargers, and now you back tobeaing able to burn more fuel. If you want to think of it in simple terms, when it smokes like a freight train, you need more air. When you're full on it and there's a bit of black haze, you're about on the money.

It's an endless cycle. Go watch some Super Stock diesel pulling tractors....1500+HP on 2 or 3 turbos, running almost 200 psi boost on a 6 cylinder stock-casting block, pouring coal black smoke.

Fuel + air + more fuel + more air + even more fuel + even more air = big time power.

The thing about "balancing" injectors sometimes refers to making sure they all match so that all cylinders get equal fuel. The holes are enlarged, and then they put the injector into a flow test to see if in fact they make the flow they're supposed to.

That's the "idiots guide to diesel power," I'm sure there are others who have more of the long story. Hope this helps.

Great explaination and very understood. Thats what I thought.. I understand about the "balanced and flowed" explaination as we have it done all the time on the gassers because the tolerance from one injector to another is quite different. I would think on diesel it would more critical, especially since I heard the GM injectors have quite a spectrum that they are off by. I would assume that anyone who is selling "ported" injectors will supply them balanced and flowed at that point.


Who is a reputable vendor for these injectors? Also what is involved with the swap? I just got all of the GM service manuals the other day and haven't had a chance to look at them yet to find where they are buried!

Anyone here done the swap?

You might want to PM McRat, one of the resident LLY pushers of the envelope. He may tell you that you can get all the fuel the LLY can take (with stock VV turbo) with simply a programmer.

As far as I know, the injectors have only been applied to the LB7 (I know BMDMAX has a set from www.kennedydiesel.com (http://www.kennedydiesel.com)), but I'm old skool and don't pay all that much attention to the brats with the newfangled version http://www.dieselplace.com/forum/images/smilies/biggrin.gif

I'm still toying with the idea of injectors. On a "bang-4-$" basis, they suck. Expect to spend $2000 to get that 70HP.

The most #2 power we are going to get right now is about 440rwhp, and at that level, your fuel system will prove inadequate. I'm fixing my fuel system in the next week. Without a good fuel system, the injectors will just agravate the fueling problem.

If you are looking for maximum #2 power with current off-the-shelf items, I'd suggest the Predator 100 + Van Aaken stack. With an exhaust, you should hit 430-440rwhp.

If you have deep pockets, do the injectors, then stack it. If you resolve the fueling problems, you will probably be in the 475HP range by my guestimate. Spray it and touch 600 at the tires.

While you should have balanced injectors, your motor will adjust each individual injector based on crankshaft acceleration. A benefit of OBDII technology.

I am definately not looking for every ounce out of this truck that I can. That's what the vettes are for!):h I was just interested on the mod and it's potential and why. I heard a price closer to $ 1200 for the injectors and was trying to justify there value. I am pretty impressed with the Predator at 65 until I yank the tranny in a couple weeks.


McRat, whats the Van Aaken stack?? Another programmer?

I finally landed a set of new LLY injectors. Will start working with these soon.

$1200 is for the exchange parts probably. Unless you do your own install, your total bill will come to about $2k.

The Van Aaken box is a harness box that plugs in under the hood in 5 minutes. By running an uploader with it, you can get gains. Warning - It is making more than 40PSI boost stacked and over 1400 EGT. Is that bad? We don't know yet.

$1200 is for the exchange parts probably. Unless you do your own install, your total bill will come to about $2k.

The Van Aaken box is a harness box that plugs in under the hood in 5 minutes. By running an uploader with it, you can get gains. Warning - It is making more than 40PSI boost stacked and over 1400 EGT. Is that bad? We don't know yet.
Yes that $ 1200 is parts only. I'll handle the install. Thats why I bought the truck!

How is the program uploaded? Credit Card style? Does the user have any control over the programming?

Is there a problem with these motors handling 40 PSI? As far as EGT's temps, it's up to the user to watch what they are doing!

I am not sure that I am sold on relying on EGT temps all the time. I have seen cars run real rich an make high EGT as well. Don't guys do any dyno testing with a wide band o2 to see how these setups are handling the fuel?

That being said, so how much hp can the stock engine take?

thanks

Yes that $ 1200 is parts only. I'll handle the install. Thats why I bought the truck!

How is the program uploaded? Credit Card style? Does the user have any control over the programming?

Is there a problem with these motors handling 40 PSI? As far as EGT's temps, it's up to the user to watch what they are doing!

I am not sure that I am sold on relying on EGT temps all the time. I have seen cars run real rich an make high EGT as well. Don't guys do any dyno testing with a wide band o2 to see how these setups are handling the fuel?

The LLY install is much simpler than the LB7, but care should be taken due to the 23000 PSI rail pressures.

You have an "uploader" - the Predator is an uploader. The VA box daisy chains into the 2 engine control bale harnesses on the drivers side top center of the engine. It intercepts the ECM signals and modifies them. It has 3 levels - Off, 70, 100? Not sure of the advertised numbers.

You WILL need a trans upgrade to consider stacks.

Wideband is pointless with a diesel, because it works at nearly all A/F ratios. At idle, you might be 200:1, and at full tilt with tuners, maybe 10:1. It just burns fuel no matter what ratio.

The problem with excessive boost is that the turbo might be spinning faster than it can handle. Nobody knows for sure, except too much turbo RPM will destroy the turbo,

That being said, so how much hp can the stock engine take?

thanks

At least 530! Got 30,000mi most of them with "tuners" installed.

THANKS McRat. What do you stack with and at what levels?
thanks

Stoichiometric for different fuels:

CNG 17.2
LPG (Propane) 15.5
Gasoline 14.7
Diesel 14.6
Ethanol 9.0
Methanol 6.4
Nitromethane 1.7

THANKS McRat. What do you stack with and at what levels?
thanks

Running the TTS #2 LLY + VA set to kill, and clean it up with a small shot (.070") of N2O. Also have run other stacks. The Predator+VA works good also.

MrMagu is currently the LLY HP King in our area at nearly 600, running the Predator+VA+N2O+Propane, IIRC.

Where can a person get the VA lly box? I have been unable to find anyone who carries the lly version.

nwpadmax,
Very well said post.

Where can a person get the VA lly box? I have been unable to find anyone who carries the lly version.
I have a few of them on hand and available, but haven't really had a chance to evaluate the production version. Sounds like it's doing well and making about 110RWHP from what I am told. Snow storm due in here today so I probably won't get much eval time.

Stoichiometric for different fuels:

CNG 17.2
LPG (Propane) 15.5
Gasoline 14.7
Diesel 14.6
Ethanol 9.0
Methanol 6.4
Nitromethane 1.7
This was my point about air/fuel ratios. Even though it's a diesel it still has a range of A/F where it makes peak power. Just feeding it fuel and not supplying the proportionate air has got to make it to rich. The Stioch #'s above are for complete combustion not for peak power. I think that the diesels make peak somewhere around 11.0:1 (guesstimate)