Just stick your hand over the carb (I have to do that to prime my lawnmower all the time..)
Let us not get confusiated, there's two ways of running diesel... compression or spark ignition. With hot diesel and lower compression you can run it under spark ignition in a gasoline motor, or for compression ignition you need the compression higher. Retarding the cam enough so that the intake is open some time after TDC, reducing dynamic compression, might be a temporary measure to get a motor running on whatever the heck fuel you can find for it, veggie oil, kerosene, varsol, white gas, bunker fuel, jet fuel...
You might get compression ignition working by threading slugs into the plug holes, depending how much piston clearance you've got, M18x1.5 bolts might take up enough room in the chamber to let diesel go bang. Typically this would be in a head that was on the high compression side in the first place where losing about 3cc would make a difference. For instance a 1.6 motor with 11:1 compression might go up to 12:1 and just about make diesel bang with a slug in the plug hole.
The thing I'd like to try however, is compression ignition on gasoline with diesel to fire it... yeah, that's sounds wierd don't it. Well gas has low cetane rating, diesel high, now if you get some really good diesel, high cetane, then when a charge of gas is in the cylinder under compression and you just squirt an itsy bitsy bit of diesel in there... it will fire off... so instead of plugs you could have small diesel injectors, very small, and you barely need much diesel at all. I think this could fire far leaner mixtures (even accounting for the diesel use) than plugs could.
I remember The RoadWarrior..To understand who he was, you have to go back to another time..the world was powered by the black fuel & the desert sprouted great cities..Gone now, swept away..two mighty warrior tribes went to war & touched off a blaze which engulfed them all. Without fuel, they were nothing..thundering machines sputtered & stopped..Only those mobile enough to scavenge, brutal enough to pillage would survive. The gangs took over the highways, ready to wage war for a tank of juice
I've often wondered what it would take to get an engine to run backwards. I never put much thought in it, but at one time I had many Honda engines in my garage, and casually thought one day about trying to get one to run in the opposite direction.
I P'd-O my dad once when I was a kid. I took it upon myself, without his consent, to clean and gap all three sparkplugs in his, back then, nearly new 1965 SAAB. All was fine until I mixed the plug wires.
From being timed slightly advanced they were now significantly advanced, and although still in phase, were transposed by one cylinder. He cranked and cranked it finally backfired and ran, but the little two stroke was now running backward. Due to the freewheel mechanism there was no forward motion as the ratchet on the input shaft was spinning wrong way 'round. He locked out the freewheel for direct gearing and then found he had one gear to move forward (reverse) and four to move backward.
It was painful to sit in the next few hours after he figured out what had happened and found where I was hiding.
I cut my car teeth on a DKW (Deeke). It was manufactured by auto union in Germany (predecessor of Audi), and that 3 cylinder 2 stroke was a piece of work! Saab used that engine in some of their earlier cars. I would love to try converting that 2 stroke to diesel operation. I am a new member and have sure enjoyed this thread, every single contribution. I am the new proud owner of a 1990 carburetted Subaru Loyale that I am going to experiment with various fuels in. (Bad Grammer there, I know.) It cost me $51. It was originally offered to me for free but that offer was made at amnesia brewpub in NE Portland and then the scrap metal man offered $50 so I had to beat his price. If the experiment works, I'm going to try it in my '74 chev bread truck. Thanks guys (girls?) for the education and the entertainment.
Lasting 5 minutes would be a success in my book if I spent less than $50 doing it and could reuse the parts on another project
A TOTAL waste of time.
There are so many design aspects that clash that even a redesign of a gasser engine is a mistake, just ask GM!
You will never get the compression ratio you need without stretching the stroke beyond the limitations of the block because if you just dome the piston and fly-cut the heads enough to shrink the combustion chamber the deck will be too thin for even the stock compression ratio, and the valves will hit the piston when they start to open.
Originally Posted by Erik
I like the challenge of doing something new and different, learning from mistakes/failures and then trying to improve what went wrong (or deciding that its too much trouble to fool with).
Well, try something that has not been done before or a new technology, and save time by learning from the mistakes of others, not duplicating them.
There is a lot of work being done to produce "Browns gas" (Hydrogen and Oxygen split from water) and there is much more to be tested.
I recall back in the '70's a front-end loader I used to operate that a shop had converted to diesel. It used glow plugs drilled into the cylinders and was a ***** to start. It didn't have a ton of power either, but they used it every day, working hard. Only other thing I remember about it was it was a straight six.
$1000.00 in parts can save you HUNDREDS in gas!
Erik, where'd you go? I was thinking about the same exact thing. Starting small on a lawnmower engine is a good idea, but my main thought was to run indirect injection diesel (like an old Merc carb) for the main charg on the CVCC and then regular gasoline for the pre combustion chamber. I figure this should easily light off and work ok at the stockish 9.5:1 I'm shaved up to.
Of course I haven't really pulled the intake manifold but from looking at the head I can't really tell how the precombustion chamber gets it's charge and I'm not sure you can easily seperate this to a different runner for a gasoline carb. I would think if I could (or had any kind of welding fab skills) then a single side draft motorcycle carb should be enough for that chamber. The diesel with an old carb shouldn't be too hard, I'd really want a way to lean that out even more though. I mean I bet you could get to the point where the diesel would ignite at 50:1 and also at 25:1 or something so I could basically choose if I wanted half the diesel and half the power for cruise and idle.
Mostly I just want to start making biodiesel and any cheap old, crappy diesel car I look for is easily over $1000 which is too much.
The other thing I wanted to do, I have an old 4 cyl 550cc Suzuki engine doing nothing and would love to make it a 2 stroke turbo diesel. I have an old Turbo off a 2.2L Chrysler something and while that might be enough with some planning to get to good compression ignition, I'd like to go further and try to make it 2 stroke. That is, some kind of valve on the side of the cylinders for intake and same sealed oil as a 4 stroke and then EVERY cycle the intake opens at BDC or just before and closes a little ways up, maybe 45-60 ABDC and then compression, injection and ignition and about 45-60 BBDC we open exhaust. Close it 5-10 deg after intake opens for some scavenging (easy with a turbo pressurize intake). That way you get twice the power out of a smaller engine. Of course the main purpose in this was define some way for the engine to 'free wheel' or skip cycles if I chose. I like to be able to run 1 ignition even every 2 revs or every 3 revs or 1 rev (which is 2 stroke) on demand if I can. My main goal in either design is so I can more easily chose the amount of gas I'm giving and the amount of power I'm getting out so I can match it up to load for fuel savings. If possible I should be able to save a lot with either design.
The bonus with the motorcycle engine is that my CRX is an automatic and if I could somehow get the 2 stroke turbo diesel going and wedge it into the CRX I'd have a manual. Of course coasting would still be a pain because it'd be a sequential tranny . Of course either requires tons of fabrication skills which I don't have. I do have a welder I bought but can't find scrap metal and don't know how to start learning and don't have any time.