Converting a gasoline engine to diesel power. (Page 1 of 2)

I think the key is items 1-3.  I would change your answers from "probably yes" to "probably no".  Cylinder pressure in diesels is about double of gasoline engines.

#5:  Don't think a custom cam would be needed.

#6:  If for non-every day use, then glow plugs aren't needed.  You want the combustion chamber and piston head to be as smooth as possible, though.  You want to avoid hot spots.

#7:  This would probably work fine.

I will say the 273 Mopar engine is the way to go.  It is the thickest walled LA engine and has closed chamber heads. 

I LOVE THIS IDEA!!! 

The 273 has a natural stroke of 3.31 but can be increased to 4.00 as easy as tying your velcro shoes.  The intake will match up after you match cut the angle to the heads, whatever you decide to take off.  The 318-360 intakes can be used if you notch where the intake is bolted to the head.   The 273 have a straight cut the 318-360's are angled where the bolts go through. 

Now how to get the injection pump to the exact timing - This is critical.  Nothing...

 
Go ahead and sell your soul to the devil.  You don't need it anyway.

It can work, but cutting too much off the block and head deck surfaces will make them weak and less capable of holding a head gasket.  Add stroke to increase displacement + piston domes + tight deck clearance and you might get enough compression.  You must inject into the chamber through the plug hole as already stated.  Longevity will be determined by how much power you try to make...if you don't put in much fuel, it will last.

Yeah, but the GM diesel had stupidly high compression (so the thing'd start in frigid Midwest weather) of 22.5:1 and not-really-up-for-it head bolts. My crazed GM Powertrain pal had an idea along these lines for an Olds diesel: 262 iron heads with tiny combustion chambers taking the compression down to 17.5/18:1 then modern electronic 'pilot' multi event injection and an intake heater grid and there you go...

To me, this idea strikes me as something you'd see out of the whole DIY/MAKER movement which expouses the idea of taking a perfectly good scarf, deconstructing it, and knitting your own sweater from the remains. The goal is NOT a useful sweater (which probably could have been bought for less than the cost of the scarves) but to see if it can be made.

Amiright?

Or, is there still an advantage to running diesel vs. gasoline even at super low compression?
Apparently, Mazda's Skyactiv-D diesel is designed to run at 14.1:1 compression and still nets a 20% better fuel economy (than what -- I'm assuming its' gas counterpart). If you could allegedly get better fuel economy, which would translate to fewer fuel stops, well, that might be a cool goal (and not just a cool journey).

-g

I hate to poop at your party, but keep in mind,diesels have a slightly different ideal combustion chamber than your average gasser. best case: it'll start if you crank it fast enough to overcome the inefficient design. worst case: it'll burn a hole in the piston tops before it gets that far.

gunn, you've hit it on the head. This isn't a good idea, just a thing that would be cool to make work.

Stroking the 225 is definitely doable, but it would require a custom or welded/reground crank (expensive) if you wanted to go far enough to be worth it. This is actually a reason why it might make more sense to go with the low-deck 170 block. With the right pistons, you can install a 198 crank in a 170 block to get considerably higher compression before milling anything. Unfortunately, you now have a shorter-stroke, lower-displacement engine. It would also have a rod ratio lower than a stock 225, but I'm not sure how much that matters. These are typically built to be high-revving drag engines, not low-end torque monsters.

You'd definitely need pistons designed for a diesel. I'm not sure there's anything out there that would be in the right bore neighborhood (3.4-3.5") and also have a prechamber and valve reliefs in a spot that makes sense for a slant six head design.

Big block Cadillac; the motors are build like a brick outhouse. Boring .080" over is common and is only considered the maximum because parts for larger bores aren't readily available. Late heads on an early motor gets 14:1 without even decking them. There's a guy who used to shave 17 lbs off the crank for drag motors, so there ought to be plenty of meat. You have to grind the crank journals down to fit BBC rods.

The mercedes om603 has a bore of about 3.43". Just fyi.

you could probably use a toothed belt, or rig up a chain drive for the injection pump.  if you converted a v8, you could get two 4-cyl pumps...
setting the timing of the injection pumps is pretty easy.

I wouldnt stress too much about getting the shape of the piston to line up with anything in the head, as long as there is no mechanical interference, and the compression ratio is high enough to start it

I say go for it!

I'm thinking going to longer, more spindly rods is probably a bad idea.  Diesel rods look like dumbbells, and pistons look like coffee cans.  I'm thinking that the injector timing and injector pressure are going to be tough also.  The injectors typically have their own cam lobe to control timing and give the required pressures to crack the injectors.  S/F....Ken M

When Phil pipes in to promote an idea, I say it's time to run. Exhibit One: K Car.

Prosecution rests, yer honor.

Yeah, but which one of those is a Slant Six? ^_^