One of these days I'm going to take a 1st gen (all mechanical) 5.9, gear the camshaft the same speed as the crank, and add a supercharger for scavenging the cylinders. Then I will be making power on every upstroke, and because the fuel isn't introduced until TDC~ I won't have to worry about inlet charge dilution.
What a kick in the shorts that would be!!!! Initially the stock can phasing would due until I could get some dyno time. I would need better valve springs though....

I'll bet it would make an ungodly scream!

 

Good luck with that. Do most two strokes inject fuel at exactly top dead center? Why didn't Cummins ever make a 5.9 two stroke? (Did they ever make any two strokes?)

Will you let me mount it in a 1972 AMC Gremlin X?

 

Detroit made two stroke dieseld, but they were ported like a regular 2 stroke which made then sound and burn very nasty. Using the valves gives much more flexibility and is cleaner. Two stroke gassers are usually one cylinder jobs because they use the crankcase as a supercharger. When the piston goes up in it sucks the fuel mixture into the crancase from the carb. After the piston fires and it starts back down the piston first exposes the exhaust port, then a little further down it exposes the inlet port. Because the piston moved down it preasurized the crankcase (with the gas and air mix in it) so when the inlet port is exposed the pressurized mixture jams into the cylinder.
The problem is the inlet port and exhaust are exposed at the same time which dilutes the mixture and lets some raw fuel escape. That's why two strokes can't pass emissions. The Rotary engine has the same problem, although it is technically a 4 cycle.

 

I've rebuilt a few two stroke gassers, and dealt with a lot more, and I hate two-stroke gassers! I HATE THEM WITH THE FURY OF A THOUSAND SUNS! TWO-STROKES ARE THE BLOODY DEVIL INCARNATE!

I would clear three acres of thigh-high foilage with a hoe and no gloves, naked while wacking goat-heads with my [tongue], before I got annoyed enough to just try to start the two-stroke on a weed-wacker. God I hate two-strokes... :twitch:


I'm sorry, I just had to let that out.

Two-stroke Diesels, however, seem to be a lot better...

Do you actually think that you could do this if I dropped you a $20,000 check, or are you looking for theoretical discussion and advice?

 

They were a lot of big truck engines two stroke, but as was said emmisions problems not to mention the lack of power. two strokes generate all their power in a power band kinda hard to run a cummins at 7500 rpms all the time. might be fun to try though.

 

Beagle1, I know I could do it. And you are spot on, the cash is the issue. I have already done work on phasing the camshaft and am pretty sure I know where I want to degree it initially.

Loch, the big diesels out there are ported so they have a pipey power band. Using a cam and valves would generate a similar powerband as the 4 stroke counterpart.

In motocross, 4 strokes compete with two strokes, except they are allowed to be DOUBLE the displacement. Now extrapilate that up to a Cummins and you are looking at some serious power. I need funding!!!!!

 

So what will you do? pulse the intake and exhaust valves open at the same time while piston is at bottom center

 

The exhaust valve will open before BDC, then as it closes the intake will open and close. It will require a fair amount of pressure from a blower, but that's no problem.

 

Does the injector pump run off the cam gear? So it would be running at twice the speed at the same rpm as it does now? To get it to inject every stroke. Just wondering how you will get the pump to inject every stroke.

Are you still going to use a turbo? will you have any issues with really high exhaust temps as the exhaust valve is opening before BDC and possibly before all the fuel is done burning? Will the turbo be feeding the super charger?

The intake valve will have to open while the exhaust valve is open to help get the exhaust out and fresh air in. The problem I see is that they are right next to each other and the fresh air coming in will get pushed right out the exhaust valve so you are still going to have a bunch of exhaust left in the cylinder on top of the piston.
Gas two strokes usually have the intake port oposite the exhaust port and a special piston or some other method to facilitate total combustion chamber scavanging. to help keep fresh air shortcuting to the exhaust.

 

I know it is a little of subject but as we speak a swedish (i think) group is attempting to build a single stroke diesel engine. Yes, power on every stroke. I read this in the preface of an import magazine last month. If anyone has heard more about this can you start a new thread or PM me.

 

Single stroke diesel? Must be a double acting piston......Could be done as we done have single stroke compressers, but we'd need some type of scavenging going on. For this design you'd need a piston rod connected to a crosshead to transform the linear motion in to ratating motion.

Would be interesting to see the design.

Jeff

 

Scavenging happens during valve overlap by way of the boost provided by a positive displacement supercharger. I also would multi stage with a turbo.

 

Hey all come to New Jersey and drive my 74 Dodge CNT900 tractor 8V92Detroit diesel its a chain saw on steroids 2strke noise maker!

 

lucky for you (and us... ) Honda makes a 4 stroke weed eater

 

Is that a "Big Horn" Dodge tractor? Those are rare and worth $$$$