Upgraded Injectors?

linewarbr · **Posted:** Wed Dec 16, 2009 10:20 am

Has anyone upgraded their injectors? Diesel Power mag did a feature a few years ago, when the KJ CRD was still new in the US, but I don't have it any more and don't remember what injectors they installed.

Conversely, do you think upgrading the injectors is unnecessary?

patracy · **Joined:** Tue Apr 07, 2009 8:50 pm **Posts:** 115

I've wondered this as well. I know injectors in my cummins made a world of difference in power. I've got a Diablo power puck extreme. I know it's not dumping all the fuel it could handle. EGT's are only ~900F pre-turbo.

DarbyWalters · **Posted:** Wed Dec 16, 2009 1:46 pm

I don't think they changed the injectors...they just added a Dr. Performance "Box" and a Striker "Box" I believe.

I do think it would be interesting for GDE to change to Piezo Injectors and Reprogram the ECU to make them work...

patracy · **Joined:** Tue Apr 07, 2009 8:50 pm **Posts:** 115

DarbyWalters wrote:

I don't think they changed the injectors...they just added a Dr. Performance "Box" and a Striker "Box" I believe.

I do think it would be interesting for GDE to change to Piezo Injectors and Reprogram the ECU to make them work...

It's not really a matter of changing the electronics on a CRD injector. The electronics really only cause the "valve" to open and close. The real gains are to be had with opening up the injector ports or adding more of them. (There's a TON of injector port modifications for the cummins [5,6,7,8 hole injectors with .009 to .020 or larger diameters per hole])

If I could find a reasonable source for injectors I'd buy a set for our liberty and have them EDM'ed larger on the ports. On their own they wouldn't gain much power at all. (ECM wouldn't allow it since it'd monitor rail pressure and boost) But put them in with something like a rail pressure/boost fooling box like the Puck or MP8 and it'd be substantial.

What I'd like to know is the means in which inmotion/GDE/Kerma tune the ECM. If they're increasing power via timing, fuel, or a combination of both. In the cummins world, we commonly "stack" power adders. (Flash the ECM then add a "box" as well) If one of the tuner guys made their tunes to add power via extra fueling, one could stack it with a rail pressure box. (It adds timing) Then couple that with some custom injectors. You could possibly come up with a stout liberty then. (Transmission upgrades would be required of course!) I'd venture to guess with the right mods you could see 250ish hp out of it with 400ft-lbs. But one would have to watch EGTs, I'm sure the turbo's efficiency would be out of map by then. I wonder if there's any head studs we could get for these engines....

Glend · **Posted:** Wed Dec 16, 2009 4:12 pm

The injectors on the VM 2.8 changed from about early/mid 2007 (when the last of the Euro and Export KJ CRDs were built). The early 2008 build Wrangler CRDs carry the new VM injectors (these are the engines producing 460nm in stock tune as opposed to the latemodel KJs putting out 400nm). As the head seems to be the same (based on a comparison between my April 07 build KJ and my son's 2008 build JK) I would assume injector upgrades are possible but rail pressure and fuel mgt system would probably also require work. VM is probably the best source for how this could be done.

You might also ask these guys, who seem to be the UK VM specialists (and they could probably supply the hardware):

http://ccgi.vmspecialists.plus.com/rele ... 93ef8aaa4d

MrMopar64 · **Posted:** Wed Dec 16, 2009 11:34 pm

The cyl head on the new engine is completely different in design to the KJ head, on many different levels. The piezo injector bodies have a different dimension so they won't fit in the same hole. Additionally, an ECU specifically designed for piezo injectors is necessary since the operating voltage of the injector is different, plus they (in some cases) operate at higher max pressure.

If you were to install bigger injectors on any electrically controlled diesel engine, the injectors should be flowed to determine the correct energizing time for each given quantity and rail pressure to properly adjust the ECU. if you were to install bigger injectors in an engine without changing anything in the ECU calibration you would flow more fuel and likely make more power and probably a lot more smoke (hence why for like cummins, etc. the injectors are called '90hp', etc.). However, this approach isn't very robust because there would also be a change then to the start of energizing which would affect your overall timing, leading to a lot of hydrocarbon (blue smoke) on cold starts, combustion rattling, etc. Additionally, if the EDM process were to change the included spray angle and also the points where the spray is directed in the chamber it can in some cases have very negative effects on the combustion efficiency of the engine, leading to actually worse fuel economy and performance with lots of smoke, especially when cold since it could potentially impact the relationship of spray to the glow plug.

I would say the KJ injectors are more than capable to support increased power levels with the proper adjustments - I would spend my money more wisely.

patracy · **Joined:** Tue Apr 07, 2009 8:50 pm **Posts:** 115

MrMopar64 wrote:

I would say the KJ injectors are more than capable to support increased power levels with the proper adjustments - I would spend my money more wisely.

I'd have to argue that with you. Although I'd like to have the ECU tuned on ours and see how it reacts with the puck. Electronic trickery only gets you so far on a diesel.

(BTW, my cummins put down 462hp/983ft-lbs on the dyno a month or so ago. I've still got some more tweaking to get those numbers to 500/1000. :wink:

)

kdlewis1975 · **Posted:** Thu Dec 17, 2009 10:07 pm

patracy wrote:

MrMopar64 wrote:

I would say the KJ injectors are more than capable to support increased power levels with the proper adjustments - I would spend my money more wisely.

I'd have to argue that with you. Although I'd like to have the ECU tuned on ours and see how it reacts with the puck. Electronic trickery only gets you so far on a diesel.

(BTW, my cummins put down 462hp/983ft-lbs on the dyno a month or so ago. I've still got some more tweaking to get those numbers to 500/1000. :wink:

)

I think GDE discussed this in one of their threads once. I think they get around 250 hp and 400 lbs of torque with there upgraded turbo/tune package. They very specifically said that they designed the tune to be at the engineering limits of the engine (the Al cylinder head being the deciding factor there). The also suggested they could go well past this with the tune+turbo combination, so hopping up the injectors may not be required at this point. They have the details of the various tunes on their site. I don't have one, but I've read that the Cummins is well over-engineered and permits one to mod it to get insane (read this as "really cool") performance numbers.

patracy · **Joined:** Tue Apr 07, 2009 8:50 pm **Posts:** 115

Yup, there's plenty of 600+ hp cummins engines who's internal components are stock. Heck mine is stock except for upgraded injectors and 110# valve springs. And to push past that 600hp barrier one only needs to swap the cam and a few fastener upgrades.

nursecosmo · **Posted:** Fri Dec 18, 2009 3:35 am

Ask GMCTD what happens to the KJ CRD when the IM stage II is stacked with a puck. Our injectors will handle WAY more fuel than this little aluminum headed-twin balance shafted-under cooled-4 banger can handle.
There is no way to compare this engine to the Cummins with a solid cylinder bore, naturally balanced damped crank, super deep throw, cast iron head, massive pistons and crank, great big turbo, and more than twice the displacement of the VM. If you compare the power to weight however, you will find that they show very well indeed. Cummins 5.9 = 519 Kg, the VM only weighs 205 Kg, yet at only 39% of the weight of the 5.9, it makes equal power to displacement, but 19% more power to weight (someone check my math). And these are stock numbers. When hoped up, the VM can do 218 HP 400 ftlb torque with the GDE turbo kit. somewhere I recall reading that they can get 250 hp out of the engine. A cummins can do up to 500 hp 1000 ftlb or maybe a little more before things like fire rings, studs, and welded heads start to become necessary, so they are about about even there, but the VM will never be able to get close on the torque numbers because those things can't be done to the VM. The aluminum head can just not handle low RPM, high pressure, high heat numbers required to get that level of torque. The short throw of our cranks can't compare to the Cummins either. Of course, our jeeps couldn't handle much more than 400 ftlb of torque anyway. Even if someone developed a cast Iron head for this little mule, the harmonics of this engine would cause it to tear itself apart.

Smoke doesn't equal power.

patracy · **Joined:** Tue Apr 07, 2009 8:50 pm **Posts:** 115

Interesting. But I'm willing to bet any issues GMCTD had were due to simply too much timing. I realize the 2.8VM to 5.9 cummins is an apple to oranges comparison. However, the fact the head is an aluminum alloy isn't the main concern. I'd imagine the stock head bolts simply can't handle the load. Remember the new powerstroke and duramax engines have aluminum heads as well. I know there's no way to get 500hp/1000ft-lbs out of these engines. But a reliable 250hp should be possible with studs, turbo, and a good tune.

Tinman · **Joined:** Mon Apr 10, 2006 10:45 am **Posts:** 308

Back to the original question. KAX (out of Italy I think) had some performance injectors for the libby. I haven't seen anything about them in a while though. Also, Dynomite Diesel in Washington has their own honing machine and could probably hone some stock nozzles of one wanted them to. They know their stuff.

Larger injectors are a nice way to add power but they do cause other changes such as timing and spray angle which have to be considered. The best advantages of honed or performance EDM injectors is the holes are much smoother and cleaner which leads to better spray patterns and atomization. Some of DDPs low hp injectors smoke less than stock. It's not really necessary to get power from bigger injectors as optimizing timing and extending duration can give a lot of power (way more than the light duty VM can take). Bigger injectors are for big power, not something the VM can do. But used correctly could give a nice performance gain in power and mileage.

GDE uses timing and duration (maybe a different pressure curve) to get the improved power.

patracy · **Joined:** Tue Apr 07, 2009 8:50 pm **Posts:** 115

Tinman wrote:

Back to the original question. KAX (out of Italy I think) had some performance injectors for the libby. I haven't seen anything about them in a while though. Also, Dynomite Diesel in Washington has their own honing machine and could probably hone some stock nozzles of one wanted them to. They know their stuff.

Larger injectors are a nice way to add power but they do cause other changes such as timing and spray angle which have to be considered. The best advantages of honed or performance EDM injectors is the holes are much smoother and cleaner which leads to better spray patterns and atomization. Some of DDPs low hp injectors smoke less than stock. It's not really necessary to get power from bigger injectors as optimizing timing and extending duration can give a lot of power (way more than the light duty VM can take). Bigger injectors are for big power, not something the VM can do. But used correctly could give a nice performance gain in power and mileage.

GDE uses timing and duration (maybe a different pressure curve) to get the improved power.

Thanks for confirming my suspicions. In that case stacking a ECM tune with a rail pressure box would lead to excessive timing.

UFO · **Posted:** Fri Dec 18, 2009 5:39 pm

patracy wrote:

Interesting. But I'm willing to bet any issues GMCTD had were due to simply too much timing. I realize the 2.8VM to 5.9 cummins is an apple to oranges comparison. However, the fact the head is an aluminum alloy isn't the main concern. I'd imagine the stock head bolts simply can't handle the load. Remember the new powerstroke and duramax engines have aluminum heads as well. I know there's no way to get 500hp/1000ft-lbs out of these engines. But a reliable 250hp should be possible with studs, turbo, and a good tune.

Even without I would think you could get 250hp. The VW TDI 1.9 liter is constructed similarly to the VM, and can make 200hp without internal mods. Injectors, turbo, and maybe an injector pump.

nursecosmo · **Posted:** Fri Dec 18, 2009 6:51 pm

patracy wrote:

Thanks for confirming my suspicions. In that case stacking a ECM tune with a rail pressure box would lead to excessive timing.

Just to clarify, pressure boxes do not affect timing. Timing is controlled by the ECM and the ECM only. Fooling the rail pressure sensors or boost sensors just causes the computer to add more boost or more fuel via a wider pulse width. This is not timing. The computer bases injection timing mainly on throttle position and RPM. Timing can be affected somewhat by changing the fuel temperature reading, but as far as I know, no puck alters this parameter.

patracy · **Joined:** Tue Apr 07, 2009 8:50 pm **Posts:** 115

nursecosmo wrote:

patracy wrote:

Thanks for confirming my suspicions. In that case stacking a ECM tune with a rail pressure box would lead to excessive timing.

Just to clarify, pressure boxes do not affect timing. Timing is controlled by the ECM and the ECM only. Fooling the rail pressure sensors or boost sensors just causes the computer to add more boost or more fuel via a wider pulse width. This is not timing. The computer bases injection timing mainly on throttle position and RPM. Timing can be affected somewhat by changing the fuel temperature reading, but as far as I know, no puck alters this parameter.

Actually boxes like the MP-8 and Puck do change timing. Since it fools the MAP sensor it adds injection timing. It's a scaling advancement of timing though. Not X* advanced in a linear motion. The other portion of MAP trickery is not allowing the ECM to see that boost has exceeded the factory thresholds. That's the boost fooling portion. But capping the levels being fed to the ECM, it stays happy and doesn't try to defuel. Then the rail pressure is pretty straightforward. It allows the rail pressure to be increased allowing more fuel to flow during the injection event.

Upgraded Injectors?

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