Motorcycles

Can Dan Gurney’s Moment-Cancelling engine breathe new life into internal combustion?

Can Dan Gurney’s Moment-Cancel...
Dan Gurney's Moment-Cancelling Four-Stroke Engine attempts to re-invent the internal combustion engine
Dan Gurney's Moment-Cancelling Four-Stroke Engine attempts to re-invent the internal combustion engine
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Dan Gurney's Moment-Cancelling Four-Stroke Engine attempts to re-invent the internal combustion engine
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Dan Gurney's Moment-Cancelling Four-Stroke Engine attempts to re-invent the internal combustion engine
Dan Gurney's Moment-Cancelling Four-Stroke Engine viewed from different angles
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Dan Gurney's Moment-Cancelling Four-Stroke Engine viewed from different angles
Detailed view of the MC4S engine's internals
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Detailed view of the MC4S engine's internals
Engine cross-section from the right side showing timing chain, oil pump, camshaft, exhaust and transmission
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Engine cross-section from the right side showing timing chain, oil pump, camshaft, exhaust and transmission
Engine cross-section from the left side showing the end of the crankshafts
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Engine cross-section from the left side showing the end of the crankshafts
View of the MC4S engine's oil sump
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View of the MC4S engine's oil sump
Cross-section of the MC4S engine's valve train
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Cross-section of the MC4S engine's valve train
The illustration of the Otto cycle of the MC4S engine portrays the significant gains in power (shaded area) with the optimized porting configuration
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The illustration of the Otto cycle of the MC4S engine portrays the significant gains in power (shaded area) with the optimized porting configuration
One of the crankshafts of the twin-cylinder MC4S engine
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One of the crankshafts of the twin-cylinder MC4S engine
This graph from the MC4S engine simulations shows how the optimized porting configuration gives the best flow results as the valve lift increases
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This graph from the MC4S engine simulations shows how the optimized porting configuration gives the best flow results as the valve lift increases
Cross-section of the MC4S engine's valve train with a straight intake port
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Cross-section of the MC4S engine's valve train with a straight intake port
Cross-section of the MC4S engine's valve train with an improved taper intake porting, one of the layouts tested by Gurney
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Cross-section of the MC4S engine's valve train with an improved taper intake porting, one of the layouts tested by Gurney
Cross-section of the MC4S engine's valve train with the optimized taper intake porting
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Cross-section of the MC4S engine's valve train with the optimized taper intake porting
Cross-section of the MC4S engine's valve train displaying the valve seat angles in detail
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Cross-section of the MC4S engine's valve train displaying the valve seat angles in detail
Simulation graph of the Brake Mean Effective Pressure (BMEP) over engine rpm for several compression ratio values, showing peak power at the 8,000 rpm mark
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Simulation graph of the Brake Mean Effective Pressure (BMEP) over engine rpm for several compression ratio values, showing peak power at the 8,000 rpm mark
This simulation graph shows that compression ratios above 9.5 do not result in the linearly anticipated increase in power
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This simulation graph shows that compression ratios above 9.5 do not result in the linearly anticipated increase in power
Variation of the intake/exhaust flows over valve lift. Case 1 is the optimized taper configuration, Case 2 is the improved taper and Case 3 the straight intake configuration
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Variation of the intake/exhaust flows over valve lift. Case 1 is the optimized taper configuration, Case 2 is the improved taper and Case 3 the straight intake configuration
Peak horsepower over flow rate for the three intake configurations. Case 1 is the optimized, Case 2 the improved and Case 3 the straight intake. Note how Cases 1 and 2 produce similar outputs, considerably higher than that of Case 3
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Peak horsepower over flow rate for the three intake configurations. Case 1 is the optimized, Case 2 the improved and Case 3 the straight intake. Note how Cases 1 and 2 produce similar outputs, considerably higher than that of Case 3
View gallery - 18 images

American car racing legend Dan Gurney's patented Moment-Cancelling Four-Stroke (MC4S) engine features two counter-rotating crankshafts and an innovative intake system. With it, Gurney is looking to conquer the Holy Grail of internal combustion engines: reliability, efficiency and low emissions, all in a single design targeted at motorcycles, but which could also be used in cars, planes and boats.

The inventors of the new engine, Dan Gurney and his collaborator and formercompetitor Chuck Palmgren, believe that despite 120 years of development, the four-stroke engine hasn't been able to makesignificant advancements in addressing two fundamental problems: optimumcombustion and user-friendly operation.

"I'm notanti-electric automobiles," says 84 year-old Gurney. "The fact is that thereare global and US oil and gas fields available which should last for many,many decades, I want to have a go at making the internal combustion engine evenmore competitive with electric power for some of those decades."

Hispatented design stands out by incorporating a twin crankshaft configuration that we haven'tseen in the motorcycle industry for many years. Its roots reach as far back asthe 1910s, to Bugatti's airplane U-Engine. But in the motorcycling world its mostnotable early appearance would be in the Ariel Square Four from the 1930s, whileyounger generations probably remember Suzuki's RG500 and Kawasaki's KR250 and350 two-stroke racers from the late 1970s and early 1980s.

For Dan Gunrey, this layout is the best way to build a motor that self-cancels vibrations, which is astructural problem in every internal combustion engine.

"Without specialbalancing systems, vibration and reciprocating engines go together," heexplains. "My experience is that things vibrate for a while, then fatigue andfall off or fall apart."

Detailed view of the MC4S engine's internals
Detailed view of the MC4S engine's internals

The MC4Sengine is a tandem twin – the two cylinders are positioned along the axis of theframe – with a different crankshaft for each cylinder. As the two shafts rotatein opposite directions, their moments balance each other out, thus eliminating theneed for balance shafts and making for a simpler structure with fewer movingparts.

Each crankshaft is shorter and sturdier and allows the engine to be more compact. Weight-wise, the second crank more or less evens out the balancinggear that has been removed. This design should benefit the bike's handling as themoment-cancelling nature of the engine promises a completely neutral feeling whenthe motorcycle tips into a corner.

But that'snot all. As we delve deeper into the patent description, things get even moreinteresting. Gurney ventures into the world of optimal combustion by designing the intake system with an oversquarecylinder (piston bore larger than its stroke) and a meticulously calculatedrelationship of the intake valve area to the bore area.

The intake port has a "doubletapered" cross section, as its diameter gets thinner in the middle section,forcing the flow to accelerate, before gradually expanding to meet the exactvalve seat size. Playing around with small variations in intake port diameterand inclination, as well as valve seat angles, results in what Gurney calls the "optimized taper configuration" and some astonishing output results.

Cross-section of the MC4S engine's valve train
Cross-section of the MC4S engine's valve train

The firstprototype engine to be built will be the liquid-cooled tandem twin (pictured above),with a displacement of 110 cubic inches (1,800 cc), two overhead camshafts andfour valve heads. According to the simulations that Gurney has run, the MC4S enginewith a standard straight intake port will produce 141 hp (105 kW), while the output of the verysame engine with the special porting system skyrocketed to 262 hp (195.4 kW);that'd be an 85 percent increase, from a naturally aspirated engine burningnormal pump fuel. According to the patent text, this is simply the result ofdelivering the air deeply and efficiently into the bore to enable a more efficient combustion process.

But the simulations produced even more surprising results.Measurements of the Brake Mean Effective Pressure (BMEP) in the cylinder – aneffective indicator of engine performance – showed that peak output can beachieved at just 8,000 rpm with a relatively low 9.5:1 compression ratio.

Thispractically means that the MC4S engine should produce vast amounts of power workingat a level that doesn't place significant load on pistons, piston rods,bearings and valve springs. The effectiveness of the combustion process canallow for a lean mixture, resulting in good fuel economy and equally lowemissions.

Dan Gurneyplans to build several different engines using this design principle. His patentrefers to the twin cylinder engine that is illustrated in the patent drawings,as well as four, six and eight cylinder variations. He plans to have a twin-cylinderworking prototype on his test bench by the end of 2015, so hopefully we willsoon know if the revolution of the internal combustion engine is imminent ornot; because, as much as we want to believe, it still sounds too good to betrue. But that's how progress is made, by people who take on those challenges thateveryone else considers to be impossible.

Source: All American Racers via USPTO

View gallery - 18 images
25 comments
Tom Benson
Dan seems to be talking about cars, the writer about motorcycles. In a motor cycle "just 8000 rpm" might be a likely output but in a car it would be a screamer. On the other had an 1800 cc, 262 hp engine would seem quite lovely in an automobile but a 1800 cc, 262 hp bike a bit of an overkill regardless of how smooth running the motor might be.
max2tall
Yeah, despite some of the crazy hp bikes coming out lately. The engine is interesting though, the port design power improvements are impressive. The gearbox possibilities with the engines intrinsic 2 output shafts get interesting as well.
Gavin Roe
the idea of duel crankshafts is not new, it was done in the 1940's I remember reading about a car built with 2 4cylinder engines mounted horizontally opposed to form a flat 8 due to the design, it was used in a hill climb vehicle I believe there was a square 4 built by a motor cycle company
Brendan Dunphy
'The fact is that there are global and US oil and gas fields available which should last for many, many decades' Indeed, but I would suggest it should be used for more important purposes than powering transportation....
Freyr Gunnar
> "I’m not anti-electric automobiles," says 84 year-old Gurney. "The fact is that there are global and US oil and gas fields available which should last for many, many decades … provided we totally ignore minor issues such as EROI or CAPEX. Peak oil is already here: The very fact that we had to move to non-conventional oil starting in the 70's is a symptom. Actually, there will still be oil in the ground in thousands of years. We'll just have given up on oil a long time before that.
Jay Gatto
Geared crank connections are sloppy and inefficient, Phil Erving's 76° parallel twin offset crank are relatively expensive to make, compared to a 180°, but are compact and effective.
Buellrider
I hope he succeeds. Thing is, an electric motor is so much less complicated in comparison. Maybe this would lend itself to a gas/electric hybrid bike.
Martin Leitner
I hope the day will come soon, when the last fool will recognise that it's time to abandon the combustion engine completely.
Mirmillion
OK, I really like the idea of venturi technology being used to make combustion more efficient. That could work with other engine designs as well, one presumes. Its a hell of a lot better than the complicated and slow to spool-up turbo-charger and, I would guess, less expensive than the super-charger. 260 peak HP is a nice step up from todays 190hp bikes cause there is nothing worse than pretending you have 190HP on tap only to find out that 140-150 was the usable limit. If the design is sufficiently compact, it could be shoehorned into a sport bike...right?
steveraxx
Another article, another group of naysayers. Good for you Mr. Gurney. Thing is, these people commenting do not even know who you are, and what you have done. People on the internet are in greatest majority going to post a negative comment, it is how people work. Good thing people pay no attention to all of the complainers and move projects forward all the same!