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I sit possible have a two cycle/stroke engine that has oil in its crankcase (and doesn't need to be mixed with the gas)? I was kind of thinking about it earlier. Could such an engine be used in a car? Why not?

When it comes to smaller engines like in my Jet Skis I like the performance and sound of two strokes :cool:
 

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That is how a diesel engine works...

2 stroke diesels were common for many years... Detroit Diesel built their business on them. 71 series etc

For a gasoline engine it is kind of difficult. There were prototypes with poppet valves (essentially like a 4 stroke physically) shown off by Toyota circa 1991. An Australian company called Orbital was pushing a 2 stroker hard too.

Now the emissions controls are killing them though.

The biggest issue is trying to both evacuate the exhaust and put in intake air at the same time... direct injection provides an interesting thing since you could theoretically do it like a 2-stroke diesel (scavenging with pure air)



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There have been many two stroke engines that had a separate tank for the gas and oil. The first motorcycle I ever got had a small oil tank with a big glass window on the side so you could just keep an eye on the oil. I don't know how the mixing event took place but I know the gas and oil were definitely in separate tanks. Unfortunately good emissions are very difficult to accomplish with the two stroke. Anyone that has ever had a chance to ride a fairly new 125cc or 250cc two stroke dirt bike knows the thrill of the two stoke.

It’s unfortunate that the emissions are such a problem because with a two stroke each stroke is a power stroke unlike the 4 stoke in which every other stroke is a power stoke. The two strokes are much smaller and lighter for the given power.
 

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When Orbital "revolutionized" the industry with their "clean" 2-stroke engines, the whole world jumped on the bandwagon. Chrysler and Toyota were among the biggies announcing engines and vehicles that were due to get their new 2-stroke engines. The problems came down to durability and emissions.

Modern direct injection and external scavenging to increase the compression were the puzzle pieces needed, and weight and power were the benefits, but keeping emissions low for over 100,000 miles was the tough part.
 

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There have been many two stroke engines that had a separate tank for the gas and oil. The first motorcycle I ever got had a small oil tank with a big glass window on the side so you could just keep an eye on the oil. I don't know how the mixing event took place but I know the gas and oil were definitely in separate tanks. Unfortunately good emissions are very difficult to accomplish with the two stroke. Anyone that has ever had a chance to ride a fairly new 125cc or 250cc two stroke dirt bike knows the thrill of the two stoke.

It’s unfortunate that the emissions are such a problem because with a two stroke each stroke is a power stroke unlike the 4 stoke in which every other stroke is a power stoke. The two strokes are much smaller and lighter for the given power.
Yeah, I had a 71 Kawasaki 3-cylinder that injected its own oil. I believe it put out 60 HP from 500 CC, not too shabby for those days.
A wee bit peaky, as in nothing until the tide comes in at 6000 RPM.

I thought Smokey Yunick was working on a two stroke adiabatic (physics of a process that occurs without loss or gain of heat) engine. http://schou.dk/hvce/

Don't know where it went, but the likes of Smokey will not be seen again soon. :yup:
 

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When Orbital "revolutionized" the industry with their "clean" 2-stroke engines, the whole world jumped on the bandwagon. Chrysler and Toyota were among the biggies announcing engines and vehicles that were due to get their new 2-stroke engines. The problems came down to durability and emissions.

Modern direct injection and external scavenging to increase the compression were the puzzle pieces needed, <at that time> and weight and power were the benefits, but keeping emissions low for over 100,000 miles was the tough part.
Correct (at acceptable cost) - good post - as far as we know.

'Air' or better O2 'enriched' injection combined with the above powered off a turb.... - wait, I'm sorry - musta' spent too much time in the hybrid today - either that or we're gonna' need to adjust my chemo again - {garbled sounds -of a man falling down** -Yes, you can keep the oil in the crank and out of the fuel -

Sometimes it positively depressing thinking on all that could be done thats not even considered feasible by flatlander people.
 

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Yeah, I had a 71 Kawasaki 3-cylinder that injected its own oil. I believe it put out 60 HP from 500 CC, not too shabby for those days.
A wee bit peaky, as in nothing until the tide comes in at 6000 RPM.

I thought Smokey Yunick was working on a two stroke adiabatic (physics of a process that occurs without loss or gain of heat) engine. http://schou.dk/hvce/

Don't know where it went, but the likes of Smokey will not be seen again soon. :yup:
Yes - and notice you can't really get on the net the best of what sir Harry was up to - before of course, he was knighted.
 

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As stated the issue is the emissions.
Now it isn't necessary to pull the intake charge through the crankcase, as stated before, diesels used a charging device to pressurize the intake side and force the exhaust gas out. With a DI method the drawback would be controlling EGR either actively or passively. Cam overlap is generally regarded as passive EGR while manifold introduced would be active. Because intake pressure and velocity would alter the EGR amount, a truely clean modern 2-stroke would require very precise fuel/air adjustments.

Even taking all that into account, the benefits of a 2-stroke engine, especially a small displacement engine, are worth the needed development in engine controls.
 

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Pnuematic (sp?) controlled valves would solve most of the problems, and be infinitely variable with respect to lift, duration, and overlap.
Valves not controlled directly from the crankshaft (pushrod or camshaft) have been talked about for years. It would definitely help with intake and exhaust by allowing them to be infinitely and continuously variable. The problem remains speed and cost. Opening and closing valves at 50 times (in a 4-stroke) or 100 times (in a 2-stroke) a second (at 6,000 rpm) is a tough hurdle to overcome...especially when the car has to last 150,000-200,000 miles without a rebuild. I'm anxiously waiting for the day when these valvetrains are available...BMW and Mercedes-Benz have been teasing us for years.

It may be one of the last great advances in internal combustion technology.
 

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It’s unfortunate that the emissions are such a problem because with a two stroke each stroke is a power stroke unlike the 4 stoke in which every other stroke is a power stoke. The two strokes are much smaller and lighter for the given power.
I think you meant revolution. Every revolution has a power stroke in a 2-stroke, but a 4-stroke only has one every other revolution. There was a thread I read (wasn't it here?) that talked about an engine design that used both a supercharger on the intake and a scavenging pump on the exhaust with OHVs as opposed to normal 2-strokes that use ports at the bottom of the cylinder.
 

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The emissions problem with 2 smokers is that a large percentage of the intake charge comes directly out of the upper transfers and simply blows right out the exhaust port.

The newest designs incorporate an extra set of transfers to blow a shot of air only into the cylinder at near BDC. This greatly improves fuel economy, decreases emissions and can produce the same power. Some of the OPE manufacturers are using this now. It's call strato-charge. I've got a Stihl MS441 chainsaw with just this tech. It works great.:)
 

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Of course, most snowmobiles have had separate oil takes for years. It wouldn't happen because 1: would pass enviro nazi emission tests and 2: with gas this expensive, adding more cost doesn't seem like something most people want to do.
 

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Of course, most snowmobiles have had separate oil takes for years. It wouldn't happen because 1: would pass enviro nazi emission tests and 2: with gas this expensive, adding more cost doesn't seem like something most people want to do.
The oil issue really isn't anything. The only thing is that you don't have to drain on 2stroke.

2 stroke engine in the classic sense is much cheaper to make. The piston is really freakish to make (it is like a pyramid) but the rest... bone simple.

Emissions control is killer! Huge amounts of CO and HC emissions, but virtually no NOx. Emissions from oil also...

The biggest issue is that a 2 stroke burns a lot more fuel.



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Emissions control is killer! Huge amounts of CO and HC emissions, but virtually no NOx. Emissions from oil also...

The biggest issue is that a 2 stroke burns a lot more fuel.
Not necessarily so anymore, actually some Direct Injected outboards have cleaner emissions that their 4 stroke equivalents. They have also matched the 4 strokes fuel mileage, mainly because of the weight savings.

Now outboards are somewhat different than cars, outboards generally run at ¾-full throttle all the time, where as cars generally need 1/8th-1/2 throttle always fluctuating.
4 strokes tend to have more torque than 2 strokes, making them better matched for this purpose.
 
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