First of all, Im not trying to step on any toes because I know of some beautiful Bronco's in here that owners are doing this and I commend you. Im all for making a car/truck/Bronco YOUR ride, to be different.
I am just trying to understand the positives vs the negatives about it. Aren't the diesel engines heavier than a small block V8? I haven't done much mudding with my '76 but my first Bronco I had back in the 80's I did ALOT of hunting/mudding in it and one of the greatest things about it was that it was light and was smaller than normal trucks and wouldn't get stuck in the 'ruts' that a heavy chevy would make.
Is the power/weight ratio better with a diesel??
Good questions. I feel much of the attitude towards diesels has been shaped by 2 things:
1) terrible 70s-80s diesels. Slow, loud, smelly, etc
2) Coal-rolling brodozers with deleted emissions equipment and poor aftermarket tunes.
Diesel are really split between the older mechanically injected units and the new computer-controlled common-rail engines. Mechanically injected engines are dead reliable, require no electricity, but lack the fuel control or high pressure ability to meet modern emissions. Newer diesels are complex like any modern engine, but still very reliable and much cleaner, efficient and power dense.
Others have made valid points, but I'll speak from my perspective of owning a modern common-rail diesel in a Bronco. (Cummins R2.8)
PROs:
- Weight: Same as a 302 or aluminum-headed 351. 503 lbs. I did not change springs or shocks. My truck sits at the exact same ride height as it did with the 351W
- RPM Band: The R2.8 de-fuels at 4200 rpm, so it is considered high-revving by diesel standards. I stuck with my 4.56 gears and 37" tires. The engine could tolerance 4.88s if I needed more torque at the axle. Overall it works great. I rarely took the 351W over 4500 rpm.
- Mileage: HUGH PLUS here. My Bronco started at 9 mpg when I bought it. I made it heavier (cage, back seat,etc,) and put taller tires on it (33s vs 37s). After fuel injecting the V8, I could get 13mpg. With the diesel, I jumped straight to a consistent 23 mpg, tracking mileage with a GPS verified Dakota Digital gauge set. I took my hardside camper out and still achieved 17 mpg. For comparison, my camper behind an F-150 would get ~8mpg or 13 mpg behind an OBS 7.3l PowerStroke.
- Reliability: Subjective, but I was constantly fixing little things on the 351, either from old architecture/design issues or aftermarket parts not working as advertised. The R2.8 is set-it-and-forget-it.
- Noise: The R2.8 is pretty quiet. You can tell its a diesel because it clatters a little, but not because its loud.
- Smell: The R2.8 with a diesel cat just doesn't smell like a diesel. I've been wheeling with 2 groups this summer, leading both times. Neither group noticed a smell from my truck and had no issues being behind me.
- Torquey: Good low-end torque, especially towing. Makes over 300 lb-ft @1800 rpm
- Cool factor: I get stopped all the time by people wanting to check out the engine. Many comments on how clean the install looks with a modern engine.
CONs:
- Complexity: The R2.8 fits easy in the engine bay, but the ancillary equipment was a tough squeeze. Wiring however was dead simple.
- Conversion parts: If you're installing a diesel, you better have fab skills or a knowledgeable shop. No one makes a drop-in kit.
- Emission laws: Not every state will let you drop in a diesel in place of the OEM engine.
- Power: Only 161 HP. It's slower merging into traffic, but still cruises at 75-80 mph. The 351W could take the Bronco to 100 mph, but that's pretty fast for a Bronco.
ADDITIONAL THOUGHTS:
- On paper the engine has 1/2 the HP of my 351, but driving it, you would swear it has 80% or more of the power. Diesels just drive different. They are great for climbing steep grades, towing or crawling. Just don't expect to be doing tons of burnouts unless you have an 8-speed trans.
- Turbo-diesels are great if you live in mountainous areas. Even though my 351 made 440 lb-ft of torque, if you took it to 10,000 ft, it only made 308lb-ft. Less than the little R2.8's 310 lb-ft.
If you only drive your Bronco on the weekend to the car show, the diesel will probably not appeal to you. If you daily drive, tow or off-road, the diesel is a game changer.
