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6-Stroke Engine (Seriously!)

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I wasn't sue where to post this, but since this is potentially applicable to dirtbikes, I put it here.  Feel free to move, if appropriate.

So, when I first heard about a 6-stroke engine (a few days ago), I thought it was a joke, but they really exist (at least in theory) and fascinate me.  I don't remember where I heard about it (hope it wasn't on TT).

Anyhow - here is a description (stolen from link):  https://en.wikipedia.org/wiki/Six-stroke_engine

The term six-stroke engine has been applied to a number of alternative internal combustion engine designs that attempt to improve on traditional two-stroke and four-stroke engines. Claimed advantages may include increased fuel-efficiency, reduced mechanical complexity and/or reduced emissions. These engines can be divided into two groups based on the number of pistons that contribute to the six strokes.

In the single-piston designs, the engine captures the heat lost from the four-stroke Otto cycle or Diesel cycle and uses it to drive an additional power and exhaust stroke of the piston in the same cylinder in an attempt to improve fuel-efficiency and/or assist with engine cooling. The pistons in this type of six-stroke engine go up and down three times for each injection of fuel. These designs use either steam or air as the working fluid for the additional power stroke.[1]

 

my-six-stroke-engine-14-638.jpg?cb=14280

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It needs to be hot enough to be "dry" steam or I think corrosion problems could be a issue.   If you get the water injected into a cylinder which does not have enough heat, such as a misfire or no fuel problem on the previous power stroke you could get a hydraulic lock and brake stuff.  I bet the reason they don't make it into productions is because the increased complexity does not produce enough increase in power to be cost effective.  

want to see something cool, with a high HP to weight ratio,  look into a  rotary vane engine

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I think the design intent is to reduce fuel consumption, as the steam cycle gives a partial power stroke with no gasoline being used.  I also imagine emissions to be a nightmare with this sort of engine. Keeping hydrocarbon output down with cylinder walls, piston crown, etc all running at a drastically lower temperature than a normal 4 stroke has got to be tough. 

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R2800 engine that was in WWII fighter planes 'later models' used turbocharger and water injection straight into cylinders for cooling purposes. 2800hp:ride: Just seems weird to put water or steam in a oil lubed cylinder.  Interesting tho :thumbsup:

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Not that some designs inject air instead of water.  The air also expands as it heats, but not as much as water.

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On 11/15/2017 at 3:47 PM, Dirt Hokie said:

It needs to be hot enough to be "dry" steam or I think corrosion problems could be a issue.   If you get the water injected into a cylinder which does not have enough heat, such as a misfire or no fuel problem on the previous power stroke you could get a hydraulic lock and brake stuff.  I bet the reason they don't make it into productions is because the increased complexity does not produce enough increase in power to be cost effective.  

want to see something cool, with a high HP to weight ratio,  look into a  rotary vane engine

I heard the Mazda rotary engines revved to the moon, always wondered if any of the dirtbike brands ever experimented with a rotary dirtbike engine. Would love to see that more than a 6 stroke, interesting though.

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1 hour ago, J-Biv said:

I heard the Mazda rotary engines revved to the moon, always wondered if any of the dirtbike brands ever experimented with a rotary dirtbike engine. Would love to see that more than a 6 stroke, interesting though.

Suzuki did a Wankel. But I wouldn't call it a "rev to the moon" engine. Accroding to Wikipedia it made max power at 6500 rpm. Even the cars that rev to the moon are usually make max hp before 8,000 rpm. Yea my buddy's bridge ported RX7 would rev to nearly 10,000 rpm, but after about 8,200 rpm you were just doing it for the noise. They earned a rep as insane screamers, as a mid 80's Wankel making peak power at 6500 rpm were other-worldly when V-8's of the time were redlining in the low 5,000 rpm range. A 1988 Fox-body Mustang with the 5.0 was rated at 225 hp at 4200 rpm.

 

In modern times that is nothing. My GM low budget family hauler (GMC Terrain, same as Equinox) makes max power at 6,700 rpm, and shifts around 7,000 rpm. Modern 250F's are making peak power at 12,000-14,000 rpm. So a Wankel isn't that much of a high reving engine anymore. 

Edited by adam728

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2 hours ago, adam728 said:

Suzuki did a Wankel. But I wouldn't call it a "rev to the moon" engine. Accroding to Wikipedia it made max power at 6500 rpm. Even the cars that rev to the moon are usually make max hp before 8,000 rpm. Yea my buddy's bridge ported RX7 would rev to nearly 10,000 rpm, but after about 8,200 rpm you were just doing it for the noise. They earned a rep as insane screamers, as a mid 80's Wankel making peak power at 6500 rpm were other-worldly when V-8's of the time were redlining in the low 5,000 rpm range. A 1988 Fox-body Mustang with the 5.0 was rated at 225 hp at 4200 rpm.

 

In modern times that is nothing. My GM low budget family hauler (GMC Terrain, same as Equinox) makes max power at 6,700 rpm, and shifts around 7,000 rpm. Modern 250F's are making peak power at 12,000-14,000 rpm. So a Wankel isn't that much of a high reving engine anymore. 

Do you think if the Wankel did get more R&D over decades time would it be possible to get it past the point of a modern 2T or 4T dirtbike engine?

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Do you think if the Wankel did get more R&D over decades time would it be possible to get it past the point of a modern 2T or 4T dirtbike engine?
For rpm? Definitely. For overall power level and characteristics? I'm not so sure.

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1 minute ago, adam728 said:
6 minutes ago, J-Biv said:



Do you think if the Wankel did get more R&D over decades time would it be possible to get it past the point of a modern 2T or 4T dirtbike engine?

For rpm? Definitely. For overall power level and characteristics? I'm not so sure.

Sucks that we'll probably never know either because most of the new innovators are looking into battery powered or just small advances into the existing motors. I doubt any of the big players are ever gonna spend that type of money on such a big risk.

I just read that Wikipedia on the 6 stroke, it was pretty cool reading all the different designs and the different methods they used to get that 3rd power stroke.

Also at the end it lists some opposed piston motor designs that I never knew existed.

Glad I stumbled upon this Forum category. Nice to read an interesting thread rather than the mindless 11 page bickering of my KTM is better than your YZ or vice-versa that I've been reading lately.

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