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/

"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.

borat wrote:
I don't see anything worthwhile on the design.  Claims without data is like a clown without a circus.  It catches your eyes quickly, but gets boring just as quick.

If the complexity of an extra piston and the extra space that it takes up, I'll keep my valves thank you.  Just run it at a reasonable RPM.    If I want crazy high RPM, I'd go with a Wankel rotary engine.

Internal combustion has reached its peak, limiting factor is man made materials.  Time for someone to design something besides the wheel.

 

>>Heat in the right places makes for higher performance, as in higher exhaust gas temps.

 

   Right, that’s a restatement of your first arg.   They even add components to shield the heat which they want to extract higher performance.  That’s desirable in their design but as irrelevant to the point as it was the first time.

 

   Reducing the exhaust temp in any engine would be an advantage even funny car engines if they could maintain performance.  They’d live to do it.   

Speaking of hot engines (good and bad) ... hot temps in turbine engines are great up till the point of what the burner can and turbine wheel can handle.... they push it to the limit...

even 5 degrees over temp for 30 secs can take years off the hot section of the engine..

As far as a 4 stroke motor "drinking gas"... the leaner you run the engine the hotter the exaust gets,   richen it up and it cools right down.... 

On my Cessna 170,   the Mixture is set by a knob in the cabin,  the mixture is leaned for cruise flight using a EGT guage,   not too hot (burn a hole in piston)--- and not too cold (foul out a plug)

The only thing I am trying to say is general statements can be worthless without context..  Every engine is diffrent as is its need for operation..

Friiy

   I think Borat has missed the qualifier in what I’ve said.

 

    “Reducing the exhaust temp in any engine would be an advantage even funny car engines”

 

this part…..

                            “if they could maintain performance”.

 

   The engine example Borat mentioned is a design where higher heat improves performance for that application.  Just magically lowering the exhaust temp in some way would impair performance and not what I qualified.

 

   I think Boarts understanding of what I said is that a lower exhaust temp would to be desirable because it would degrade performance and they want temps high for extra umph.  That’s not what I said at all.  That would be throwing a wrench into the design.

 

    What I’m saying is if they could maintain performance and lower temps they would do that as less heat would be a great benefit.  Borat might argue that can’t be done.  Possibly in current designs but I don’t think every design avenue is exhausted.  Either way, that’s irrelevant to a theoretical position that “if they could” they would go for it.  His case is obviously tangent to the qualifier and context.

Friiy,

    Found a nice Honda bucket to replace that one fixed up with your glue.  The glue held up fine to water and sub-zero temps.  A guy wants to buy it for $150 but I'm holding on to it as the chances of comming across another Honda with a bum bucket is pretty high.   Thanks. 

I do not like that design. My old Submarine had a Fairbanks engine. It had 2 cranks. The lower crank ran the generator and the upper crank drove the blower, water pump and stuff. It had 2 pistons for each cylinder. When the pistons come together it compresses the air and a injector the size of a 2 liter coke bottle injects fuel. Very reliable design. Tug boats use them too, they make about 4,000 Hp at about 50 gallons of fuel an hour. I do not think they will make a good snow blower engine though.