Diesel Bombers - new to the site, need some help

All of the Cummins engines are great in their own way.

Starting with the 89-93 first gen dodges.

PROS:

Very reliable, super easy to work on due to the fact that there is no body cowl hanging over the back two cylinders. So injector installs, aftermarket head studs and valve train maintenance are much easier to perform. The injection pump is simple and easy to modify for noticeable power gains. Transmission are easy and cheap to beef up.

CONS:

The VE injection pump is only good for roughly 500 horse power fully maxed out, The cylinder head does not flow air very well at all, in fact it is the worst out of all of the Cummins engines. It can be ported and polished to flow plenty though but this is an added expense. The turbo is junk you will want to replace it with an HX35 if you are going to leave the truck stock or an aftermarket turbo if you want to soup it up. Those are the most important things I can think of right off the top of my head.

94-98 12 Valve equipped with P7100 series injection pump.

PROS:

Very easy and very affordable to double the stock power output.
Stronger front and rear axles than the first gens.
The manual transmissions are stronger to start out and the 47RH and 47RE transmissions can be built to hold over 1000 horse power.
The factory lift pump is good for over 600 horse power before it needs to be upgraded.
This is by far the most sought after of all of the Cummins engines due to it's simplicity.

Cons:

Again the 12 valve cylinder head just doesn't flow very well, they run much hotter with after market injectors than the newer 24 valve and common rail heads.
So porting and polishing the head is a good idea.
Stock exhaust manifolds like to crack so plan on replacing it as the factory cast manifold is a horrible design and retains a lot of heat.
The NV4500 manual transmission is kind of a crap shoot, I have had a few that stayed together for years without any problems all they required when I started uping the power was a clutch upgrade. But many of them have the 5th gear retainer nut issues were the nut backs off and destroys the trans. They also like to snap input shafts with an upgraded clutch. So if you plan on making power with a manual think about getting the upgraded 1 3/8" input shaft and keying the 5th gear nut.

98.5-2002 Cummins equipped with the VP44 injection pump.

PROS:

This is the first year that the cummins engine came with electronically controlled injection system. This was a huge plus because you could simply install a programmer and increase your horse power at the touch of a button! The injectors are still a very simple low pressure design so injector failure is very rare on the early 24 valve trucks.
Another bonus is the fact that the 24 valve head flows better and overall stock horsepower is higher than that of the stock 12 valve engine. They also released the 6 speed manual transmission for these trucks. This transmission did away with the 5th gear nut problem found in the NV4500 but the early 98.5-2001 6 speeds still have the 1 1/4" shaft which needs to be upgraded. 2001 and above NV5600's have a stock 1 3/8" input shaft.

CONS:

The biggest downside to the VP44 trucks was the VP44 it's self. The injection pump is very likely to die due to poor fuel supply from the new electronic lift pump mounted at the rear of the engine block. When the lift pump dies it stresses out the injection pump to the point of failure. The injection pump will cost over $1000 to replace.
This problem can be solved by installing an aftermarket heavy duty lift pump.
Another problem commonly found in this line of Cummins engines was a casting flaw on the engine blocks stamped with a 53. The blocks will crack on the passengers side right bellow the exhaust manifold. Again this is a 6 in one hand half dozen in the other kind of scenario.

2003-2004 Common Rail Injected Enigines.

PROS:

This is obviously the first year that Cummins went to the high pressure common rail injection system used my European automakers and designed by Bosch. This system runs on very high pressures up to 30,000 PSI. This allowed Cummins to make much more power and still maintain good fuel atomization keeping their mileage up.
They also did away with the 53 block castings.
On these newer trucks the no longer use a Dana 70 or Dana 80 in the rear, Dodge switched out to the AAM 11.5" rearend. This axle is virtually indestructible.
All of the front end poor steering issues were resolved by beefing up the front ends on the new trucks.
This is also the first year the dodge was available with four doors.

CONS:

The common rail injection was new to Cummins at this time so the issues we have run into is they still use a pathetic little lift pump that simple does not last. The dealership fix for this was to relocate the lift pump into the tank because they thought the pumps were just overheating and they thought the fuel would help keep the pump cool. They still continue to fail. When the pumps fail on the common rails it does not damage the injection pumps like it did on the VP44 trucks because the CP3 injection pump used on a common rail can create suction as well as supply. So when the lift pump fails the truck will still run fine but the injection pump will falter under heavy load situations. when this happens the pump will create a pressure spike trying to keep up. This pressure spike can exceed the pressure ratting of the injector bodies and nozzles causing them to crack. When this happens if it is not caught right away you run the risk of torching a hole right through the top of the piston.
Again the fix is to get yourself an upgraded aftermarket lift pump, like an Air Dog 150.
Poor fuel filtration is another issue. Bosch requires the common rail injectors to be filtered at 2 microns. The holes in the nozzles are tiny and require this level of filtration to function without clogging. Dodge used an 8-12 micron filter depending on the truck and this will cause injectors to become jammed and will result in hard starts, or no start.
The Air Dog lift pump comes with a 2 micron filter so it will kill two birds with one stone for you.
Injectors are expensive. Over $2500 for a full set. If you get a Common rail truck take the time to do these fixes and you will save a small fortune in the long run.

2004.5-2006 Common rail injected Cummins.

PROS:

Very similar to the 03-04 cummins, they went to a multi pulse injection system on these trucks, there really isn't much different in these years except that in 2006 you could get the MEGA Cab option which made the back seat much larger than the 4 door.

Cons:

Same as the 2003-04 trucks except that the multi pulse injection on the 04.5-05 trucks had more problems with injectors going out due to the fact that they were trying to work the same injectors from the early common rail trucks twice as hard. This was resolved in 2006 when the implemented a new injector design that could handle the multi pulse injection.
A new problem for 2006 though was the change in the design of the injector wiring harness. They built the wiring harness into the valve cover gasket. Wires can become pinched causing dead injector symptoms. It is a simple fix if you know that is what it truelly is. but many people get raped by a local mechanic for injector repairs and then they find that it is the harness.

2007.5-2011 6.7L Common rail injected Cummins.

Pros:

Nothing really changed here as far as power out put or anything.

CONS:

EMISSIONS. The EPA really screwed use on these trucks. Cummins had to completely redesign their engines to meet Californias retarded emissions standards. You will find an EGR (exhaust gas recirculation) system and a DPF (diesel particulate filter) on these trucks. This will end up costing you a fortune in repairs or a lot of time without your truck if it is still under warranty.
The upside to this is it can all be deleted. There are a tons of sensors monitoring the two systems. So you can not just simply remove the DPF or the EGR, you will have to buy a programmer that clears all of the codes that will come up when the systems are deleted. Or better yet, a programmer that turns the two systems off through the ECM.
H&S performance offers the Mini Maxx which will turn both systems off without any future codes as well as an EGR delete kit. At that point you can buy any aftermarket turbo back exhaust and you will have an excellent running truck. The deletes will cost you right around $1200.
The lift pumps are still an issue on these trucks as well, so plan on getting an aftermarket one.

I hope this helps. I'm sure I missed a bunch or info here but read through and ask questions about what I wrote and myself and other mambers will do our best to answer them!