Converting to diesel

[rongoodlad]

I have a 51 Willys that currently has a Chev 350/T400 4x4 setup. I am doing a frame up rebuild on it with many mods. In fact the body is the only part from the original car. I have purchased a new 40 gal fuel tank for it.

I plan on using the Willys as a daily driver. I'm very concerned about the cost of running this beast. It seems to me that a diesel engine will give me the low-end torque & fuel efficiency that I want. I have little experience working with diesels.

Can any one direct me through the conversion process? Also, what engines do you recommend. I will be using a 700R4 trans in it.

Any info will be appreaciated.

Ron

[curtis73]

I suggest using one of the Chevy diesels prior to the Duramax. 6.2/6.5/6.5T. They were made for chevy to their specs. The Ford and Dodge diesels were pretty much carry-overs from their Navistar and Cummins production, so they required SAE transmissions to go behind them. I suggest staying away from the Duramax since it is installed to a Chevy truck like Brain Cancer in a frontal lobe. You can't really separate it without damaging both The Chevy 6.2/6.5 family uses standard motor mounts and tranny bolt patterns, so they are bolt-ups.

Probably the wiser choice of the chevy diesel family I listed above is the old 6.2. They were pretty bulletproof and entirely mechanical. The newer 6.5 and 6.5T were electronically controlled. Not that its a bad thing, but its a much tougher swap with more to potentially go wrong. The trannys used behind the later 6.5Ts were also controlled by the computer, so using a 700r4 would possibly confuse the computer further. I might also consider getting a whole kit and caboodle 6.5T and 4L80E tranny. The benefits are that performance upgrades can be had both electronically and mechanically (an easy 100hp can be had with just a chip) and the tranny will be able to handle the torque you give it. If you're really going to stick with the 700, the 6.2 is probably the wiser choice.

The 6.2 can be rebuilt with a little more displacement and aftermarket or GM turbos can be added. Standard mechanical upgrades can be applied like fuel injectors, fuel pressure increases, compression changes, propane. It will never be a screamer like a new Powerstroke, but it will be a good torquey engine with tons of life to it.

Swap requirements would probably include an aluminum radiator (since they're a little more stable with the coolant additives diesels require), bigger fuel lines along with the matching fuel pump, and a huge exhaust. For reliability's sake I would go with two batteries and some huge cable. The amp draw it takes to crank over one of those things is pretty stiff.

You might also consider some sound deadening. Dynamat on the metal panels like the firewall and under the hood help tons, and so does carpet padding glued to firewalls and other low-heat places.

[MagicRat]

Excellent reply, curtis.

I would add that using an older entirely mechanical diesel is the way to go. They are remarkable in that all they need is power to the starter motor and a 12 volt hot wire to the fuel cut off switch. This switch will cut off the fuel to the engine when the 12 volts is switched off. Otherwise, there is no other way to shut off the engine.

Do you have a vacuum power booster for the brakes? If yes, you need the vacuum pump mounted to the engine. Most small GM diesels have this.
The GM 6.2 and 6.5 diesels are not very good engines, as diesels go. They are not particularly durable, and are good for about 120 - 150,000 miles or so. I know from much personal experience. The Ford 6.9/7.3 and the Dodge straight 6 diesels are MUCH more durable and longer lasting.
Also the injector pumps often last a bit less mileage and are expensive to rebuild.
So if you get a diesel, be sure to get a low mileage/rebuilt example, regardless of brand. Be prepared to spend about double the cost for a comparable Chevy gas V8, in the same condition.

Also these engines are much heavier then the 350 you have. The stock '51 Willys axle may be overloaded.

[curtis73]

Good catch on the vacuum pump, MagicRat. I forgot that one. Weren't the 6.2/ 6.5 diesels produced by Detroit? I had heard they were pretty bulletproof, but I've not had the direct experience with them that you have. I had a 6.5T that I only took to 100k.

I do know a guy who put 350k on a Navistar 6.9 in an 83 F250. He had to replace an injector pump, but that was it. I had a 7.3 'stroke that I would have transplanted in a heartbeat, but their shortcoming is their height/width. I think even for a Willys hood it would be a very serious clearance issue.

You bring up an excellent point, though with the Cummins suggestion. The Willys hood is tall but not very wide. Maybe the I-6 is the way to go for the Willys. I don't really recommend any of the automatics that Dodge offers for the sake of reliability, but its something to consider. The biggest obstacle with the Cummins is the oil pan. Some were cast aluminum and difficult to modify. Not impossible to overcome, but not exactly a bolt-in.

[MagicRat]

I am not sure who made the 6.2/6.5. GM did own detroit for a few years, but I think the engine was a GM design, not a Detroit one. I know 4 people with those engines, about 180,000 to 200,000 km is about maximum for them, whether they are old or new. They don't seem to just wear out, they either snap a crank or blow a hole in a piston.

I know that those older Dodge/Cummins engines can easily be modified for more power. The non-electronic ones just need the fuel pressure regulator adjustment turned up and the waste gate adjusted; and they produce good power. However, you are correct, those Dodge transmissions cannot take the extra power.
It seems as if the factory has deliberatly restricted power output to preserve the transmission. But those engines will easily go 1 million km between rebuilds.

Personally, if I were building this Willys, I would keep the gas 350 and just install a 4 speed auto overdrive trans (700R4) for better gas mileage and save the $6000 conversion cost.

[RandomTask]

I just have to add,
Define fuel efficiency of a diesel? We had a F-350 dually diesel that we drove from Norfolk VA to Pontiac Michigan. I think the best fuel mileage we achieved (with trailer off) was 12 MPG. But then again, we are the same people who had the truck bouncing off the rev limiter the whole way up W/ the trailer (90mph on downhills ) so I don't think we took it easy.

I always wanted to take a completely mechanical diesel, put a huge snorkel on it, and just put it halfway up the windshield in water. Stupid college mentality...

[benchtest]

Fuel efficiency of a diesel...'97 F250 powerstroke: 70 miles a day and about 20 mpg average. Pulling 5500 lbs of trailer 200 miles - 17 mpg. I'm pretty happy with it, for 3 tons of rolling brick.

[curtis73]

I had a 95 Powerstroke, auto tranny, 4.10 rear, all day empty 22 mpg any speed. Towing 10,000 at 70 mph, 12 mpg. Twice the towable power of its gas counterpart and twice the fuel economy.