Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

   Interesting design at the link below of a 4 stroke engine without valves.  The valves are replaced with two pistons which act somewhat like reed gates to control input and exhaust flow to ports similart to a 2 stroke.

http://www.new4stroke.com/

It's unique but other than that, serves no useful purpose that I can think of. 

As per aa335's comment, a small rotary (Wankel) engine would be a great contribution to small hand held equipment.  Virtually no vibration, tons of power and likely very reliable.

Here's an interesting link to an outfit in Japan that builds small rotary engines:

  http://www.nitto-mfg.com/

This is a better link:

http://www.nitto-mfg.com/english/nrsyokaieng.htm

"No advantage," "no purpose".

Greater air volume.

Lower exhaust temperature.

Increased torque.

Increased efficiency as energy required to move the crank and main piston is the same as a standard engine but the output greater.

Capable of higher RPM @ greater torque.

 

He’s a guy working out of his garage and footing the bills.

 

    The engine reminds me of the early design phases of outboard engines where every few years there would be new entrants into the market with radical design changes to earlier engines.  Most of those makers would last for a few years then evaporate.  The established large companies also had radical changes every few years requiring expensive tooling and casting changes. 

 

   At one of the old time sporting lodges at the lake by my camp the owner liked and saved his old engines.  When people sold their camps and moved off he’d get their engines and built up an impressive collection over many years.  He had rows of them lined up under a huge barn.  Engine designs changes were radical and must have been extremely expensive.  

   I tried to buy one of his engines but he wouldn’t part with any.  He wanted give them to a museum. 

Borat,

    The second link to the big models flying around is great.  Those things look like the real deal. 

The simple matter of fact is that if that guy's engine had any clear advantages over existing technologies, the Germans or Japanese would be all over it. 

Trouts:

Those small rotary engines look pretty neat alright.  I bet they're expensive. 

One of those 20 cc engines would power a grass trimmer quite nicely.   Ramp the size up a bit and they'd be suitable for a chainsaw.  Lots of power.  Not so sure about fuel consumption.   I know the rotary engines used in the old Mazda RX sports cars of the  70s-80s was a guzzler.  

Quite inreresting.  Advantages ?

Greater air volume is not an advantage??

Lower exhaust temperature is not an advantage??

Increased torque is not an improvement??

Increased efficiency as energy required to move the crank and main piston is the same as a standard engine but the output greater.  Better efficiency isn't an improvement?

Capable of higher RPM @ greater torque.  More torque and higher rpm is not an improvement?

It's a concept engine in design.  Prototypes are never practical.  Design guys usually have no interest in marketing and are generally terrible at it.  No telling if he's ever presented it to Germany, Japan or anyone with some clout.

Just say the design is solid, it's being practical or implementable is another matter.   It's possible BMW loves it but finds it impossible to manufacture. 

Why would lower exhaust temps not be an improvement or advantage?

"Why would lower exhaust temps not be an improvement or advantage?"

Generally speaking higher exhaust gas temperatures increase exhaust gas speed.  Higher exhaust gas speed increases an engines breathing capability. Pprovided the intake is of sufficient size/efficiency to keep up with the exhaust. 

Have you ever noticed that certain high performance engines have a heat resistant material wound around the exhaust headers?  That's not to keep nearby stuff around them from being effected by the exhaust manifold heat.  It's to keep the exhaust gasses hot. 

   An irrelevant example.  Reducing the exhaust temp in any engine would be an advantage even funny car engines if they could maintain performance.  Since the funny car guys have not found a way so they run with the hot temps.

 

   Designing an engine with refrigeration coils around the exhaust valve in one sense would be a good thing to reduce heat as that’s always a good thing but to the point where it would negatively effect flow and impair performance would negate any advantage. 

 

  The guy has designed an engine and claims while improving performance he’s reduced exhaust temps, a good thing in his design and nice in any engine.  Pretty simple.  

>>>"Generally speaking........................" 

    That makes a general case that more heat is better which is silly.

 

Actually Trouts, generally speaking ,you're wrong.

Heat in the right places makes for higher performance, as in higher exhaust gas temps.  If you've never owned anything with high performance, you likely wouldn't be too familiar with the concept.  Do a bit of homework and you'll learn a bit about the subject.

All the advantage claims are generally hypothetical without hard data to back it up.  For a typical heat cycle, higher temperature means higher energy to do work, hence higher performance and efficiency.

If this guy really have something, he would keep it quiet and sell it to the highest bidder.  It just makes sense from a business standpoint.  :)  But it's not like engine builders haven't already tried to extract every bit of energy from a heat cycle.  It's fairly safe to say that all stones have been turned over. 

Higher compression, forced induction, less reciprocating mass, less parasitic drag.  The limiting factor is metallurgy that can withstand the heat.  The rest is just thermodynamics. 

aa335 wrote:
Very true. 

From what I see of this engine is an attempt to reinvent the wheel and ending up with one not quite as round as the wheels we already have.  Maybe I lack imagination.  I just don't see any potential for the design.  I wish him all the luck in the world because that's what he's going to need to see that concept go anywhere.