Carbureted I6 turbo-diesel...?

[SuperMag]

Used to be years ago you could get a 'multi-fuel' tractor to run on carbureted diesel fuel. Old timey generators were sometimes like this as well. Typical compression ratios were about 6.0:1 (or lower). You would start the engine on gasoline, and when things got warm enough, you turned the valve on the tanks and you'd be burning diesel.

Fast forward to modern times.... What would happen if you took a modern motor like a Ford 300, built it to 6:1 compression, and burned carbureted diesel fuel? Anybody have any idea whether or not decent power could be made? By 'decent' I mean 100HP or so...

Now let's take this mental exercise a step further... What if we took this same motor and hung a turbo charger on it? Would we experience the same kind of power and economy gains we are used to seeing in 'normal' turbo diesels? Or are we just raising the effective compression ratio and opening ourselves up to detonation problems? Or would we even care about detonation? I'm wondering if diesel detonation at low compression ratios would even be as destructive as gasoline detonation...

 

[StrangeRanger]

Injected Diesels canot "detonate" in the sense of Otto cycle engines. They have all their fuel injected during the power stroke, not during the intake stroke. How do you handle the business of getting fuel into a Diesel with a carb? The line between compression-ignition and massive detonation has got to be a very fine one, if it even exists. I think you might be able to build a 2 stroke carbed Diesel, but you'd never be able to convert a 4 stroke engine from Otto to Diesel.

I'm guesing that these older engines were really Otto cycle engines simply running on the lower heat content kerosene/Diesel fuel with very conservative valve timing. So they'd have throttled intakes and all sorts of other un-Diesel-like features. I think what you'd have is an extremely low efficiency Otto engine running crappy fuel. Adding a turbo would raise the performance from dismal to merely sub-standard.

does anyone know how the military multi-fuel engines work? They might provide a clue.

 

[SuperMag]

Military multi-fuel engines are essentially diesels equipped with a fuel density compensator. In other words, all the fuels are injected in the fasion of a 'normal' diesel engine...

http://www.jed.simonides.org/transport/ ... eries.html

 

[Lazy JW]

I suspect that if any modern engine could be adapted for this conversion, it would be a 300-6. I do believe that 6.0:1 compression is probably too high, but you could try it and see. I base this on my old tractors, a John Deere Model A and an Allis-Chalmers Model C. According to my shop manuals, the AC's that were set up for "Low octane fuel" used a 4.7:1 ratio, and the JD used 4.45:1. The gasoline versions were up around 6.0:1 and an LPG version of the AC model WD-45 was a whopping 7.2:1. Keep in mind that these engines were designed as "Heavy-duty" units and were intended to be operated at or near maximum power outputs for extended periods of time, so an automotive application with a lower duty cycle could possibly get away with a bit more compression. A turbo version would need to start out pretty low for compression. I wonder if a variable wastegate could be used here? One key feature on all of these engines is the use of a heated intake manifold. My dad once told me about running a Ford Model A on kerosene during the early part of WW11 (before he was drafted). He said they used two head gaskets to reduce compression and wrapped the fuel line around the exhaust manifold. I like this idea, but I think 100hp will be tough to get.
Joe