Hi Gang,

One of the Newsgroups had this reply to a fellow who asked about the difference in diesel engines in the big 3. It is so wonderful I am posting it here.

OK, let's see if we can sort out the what's and wherefore's.... Ford uses a diesel engine designed by Navistar (formerly called International). All these motors are V-8's and use glow plugs to aid in cold starting.
1. The 6.9L diesel was normally aspirated (no turbo) and did not have direct injection or intercooling. It is no longer being produced.
2. The early 7.3L diesel was an improvement over the 6.9L in displacement, but still did not have a turbo, intercooling or direct injection. It has been upgraded to #3.
3. The current 7.3L diesel, also called the PowerStroke, is turbo-charged, intercooled and uses direct electronic injection (HEUI).

Dodge uses a diesel engine designed and built by Cummins (the only one, there is no "Dodge" diesel although it is frequently referred to as such). It is an inline 6-cylinder motor and uses an intake heater grid to aid in starting. Displacement has remained constant at 5.9L and all are turbo-charged, intercooled and use direct injection.
1. The earliest models had 12 valves (two per cylinder, one intake and one exhaust) and mechanical fuel injection. Electronic injection was added later.
2. The newer models have 24 valves and electronic fuel injection, presumably for better power, fuel mileage and to meet stricter emissions standards. Both are currently still available.

Chevrolet's diesels were originally designed by Detroit Diesel. All are V-8's and use glow plugs to aid in cold starting.
1. The 6.2L was normally aspirated, not intercooled and did not have direct injection. The last year this motor was produced was '92-'93. This motor is not well thought of.
2. The current diesel is 6.5L and is turbo-charged, but still does not have direct injection or intercooling. This motor should be available thru the 2000 model year. The newest models have a twin thermostat setup.
3. The future motor will be a joint venture between GM and Isuzu. It will be a 6.6L V-8 with turbo-charging, an intercooler, electronic direct injection, and twin thermostats. It should make it's appearance for the 2001 model year.
4. GM's choice for it's proposed Heavy Duty series trucks should be the Caterpiller 3126B, a 7.3L inline 6-cylinder with a turbo charger and intercooling just like the Cummins, and the same electronic direct injection as the PowerStroke (HEUI). It will also use an intake heater grid instead of glow plugs to aid in cold starting. Expect to see it in the 2002 or later model year.

Banks is an aftermarket company which makes performance add-ons for these and many other motors, including turbo chargers, intake and exhaust systems and much more. Banks equipment does not come standard on any diesel motors I know of currently being used by the Big Three (but I may be wrong), therefore it will have been added on by a previous owner.

The basic difference between the motors lies in the cylinder layout (among other things, but this is the most basic). V-8's are commonly known as 'winders'. This is because they make usable power over a wide range of RPM's (wide for a diesel, narrow as compared to a gasser). Inline 6's are known as 'luggers', because they like to remain at one usually much lower RPM regardless of load. Inline 6's can get away with a lesser displacement and yet create excellent power, but V-8's will be better performers when unladen. Turbo chargers compress the incoming air to increase combustion efficiency. Intercooling cools the compressed air to make it more dense. Electronic direct injection precisely controls the amount of fuel sprayed directly into the combustion chamber, whereas indirect injection sprays the fuel into a pre-combustion chamber (not as efficient).

The automatics are generally considered more desirable for towing because of the internal strength. All tranny's have their share of problems regardless of maker.

As for choosing, I can only make personal recommendations but I'll forgo that for now because every one has their favorites. First and foremost, make sure any used diesel has complete maintanance records plus receipts. This is a good indicator of how well the motor was taken care of. Second, it is generally regarded that the longer the wheelbase, the better the tow vehicle will ride under load. Third, beware of aftermarket add-on's that were not professionally done. Forth, rear-end gearing is also important so make sure to look for a ratio that will keep you in the RPM range you want for the load and speed you will be towing (will be different for each motor).

Hunter
94 Sovereign
No diesels at the present