Although Gurney apparently developed this new type of ICE technology for motorcycles, he states that it could also be applied to cars. It should be interesting to see if any automakers purchase his new technology.
Looks intriguing. I would worry about all those gears lasting with the constant jarring inherent in ICEs.
Looks interesting. A different take than the counter-rotating balance shafts used for many years in big 4’s in cars. Less weight, lower parasitic drag. I have no doubt it produces good power from a 1.8 liter engine. That is fairly big for a motorcycle 4 cylinder but on the smaller side for a car. The crank axis is pointed in the wrong direction for cars as they are designed now. That can be fixed.
In a bike the engine could be mounted crossways for shaft drives avoiding 2 sets of bevel or hypoid gears or lengthwise with a chain or belt drive.
I don’t see the advantage here. Looks like he’s put two single cylinder engines together, connected them with a gear train. So what? They still have the primary imbalance of the cylinders, either both going up and down at the same time (like a 360 degree crank on an English twin) or opposite each other (like a 180 degree crank on a Honda twin). Either way, there’s a significant imbalance (especially with an 1800 cc engine).
What am I missing?
I don’t see an advantage here either. I’ve owned a few motorcycles and they have always had smooth and powerful engines.
I don't see the advantage here. Looks like he's put two single cylinder engines together, connected them with a gear train. So what? They still have the primary imbalance of the cylinders, either both going up and down at the same time (like a 360 degree crank on an English twin) or opposite each other (like a 180 degree crank on a Honda twin). Either way, there's a significant imbalance (especially with an 1800 cc engine).
What am I missing?
The primary imbalance is cancelled by the counter weights on the crank shafts. On a 360 degree design, the counterweights are up when the pistons are down and the counter weights are down when the pistons are up. When the pistons are half way up the bore, the counterweights are pulling in opposite directions and cancel each other’s force. Essentially, one crankshaft acts as a balance shaft for the other crankshaft.
Secondary imbalance will still be present however, but it could be cancelled by a pair of counter rotating balance shafts that spin a 2X crank rpm, similar to the balance shafts used in flat crank fours.
What I don’t get is how he was able to get a patent on something that Ariel was doing back in the 1950’s.
The patent office is operating in the mode of “grant the patent and let the courts sort it out” if anyone wants to contest it.
They recently granted a patent to Jeff Bezos’ (of Amazon.com fame) Blue Origin rocket company for landing a reusable rocket on an ocean barge downrange of the launch site, completely ignoring the fact that this recovery method had been described in earlier technical papers written by others. When Elon Musk’s SpaceX rocket company wanted to use this procedure, they challenged the Blue Origin patent on the basis that the method had already been described by others (“prior art”) and therefore could not be patented by Blue Origin. The patent office reviewed the patent and agreed that it should not have been granted.
I see what you mean, BLE - I wonder if the added gears, etc. is cheaper/more compact than a regular engine + balance shaft.
No doubt Dan Gurney knows more than me but isn’t the horizontally opposed engine (BMW) self balancing with considerably less Rube Goldberg engineering?
The BMW boxer still has a little added vibration from the offset of the cylinders that this avoids. And it’s not compact, something they push on this.
However the boxer twin naturally cancels out the secondary vibration due to the fact that the motion of the left piston is the exact mirror image of the motion of the right piston.
This is not true of inline engines. The motion of a piston at the top of the stroke is not a mirror image of the motion of a piston at the bottom of the stroke, and this gives rise to the secondary imbalance or the infamous four cylinder buzz.
I had a BMW R90/6 for a while and it’s hard to imagine a smoother twin. Unfortunately, it shifted like it had a tractor transmission.
The boxer’s not an exact mirror, the offset between the two cylinders creates a rocking motion. Only if both cylinders were on the same centerline would that vibration be eliminated.
The BMW opposed twins still have an imbalance due to the cylinders not firing at the same time and the fact that the cylinders are slightly offset so that one cylinder doesn’t need to have a split connecting rod.
The BMW pistons reach top dead center together but one is firing while the other is reloading. Mine only had a single set of points and a single coil that fired both spark plugs simultaneously. Only one of the cylinders was on its power stroke, the other was at the end of the exhaust stroke and it got a waste spark.
Motorcycle inline fours do the same thing, cylinders 1 & 4 get the leads from one coil and cylinders 2 & 3 get the leads from the other coil. The plugs are fired every revolution instead of every other revolution, there is a waste spark at the end of the exhaust stroke.
Some of the newer boxer twins have a balance shaft to deal with the rocking couple caused by the offset cylinders.
Perhaps we are reinventing the wheel again?
There is also an increasing use of 270 degree cranks in inline two cylinder engines used in motorcycles. The Yamaha TDM, Honda CX700, cruiser and scrambler versions of the modern Triumph Bonneville, and more.
This puts the second harmonics of the two cylinders out of phase with each other for a potentially smoother engine, the primary imbalance being dealt with using balance shafts.
Also, Yamaha is using a cross plane crank on some of their inline fours, this has the second harmonic of the center cylinders out of phase with the second harmonic of the outer cylinders. These engines do not have an even firing interval though, they sort of have a V-8 sound to them.
Natural cancelation of second harmonic vibration is the reason nearly all V-8 engines have cross plane cranks instead of four cylinder style flat cranks, even though an even firing interval can be had with either crank on an 8 cylinder engine.
The only way to get rid of the second harmonic is to use infinitely long connecting rods or a Scotch yoke, however, the second harmonic, which causes a decreased dwell time at top dead center and an increased dwell time at bottom dead center is not necessarily a bad thing.
My engine has a counter-rotating “balance shaft” that helps offset the dynamic imbalances inherent in a crank-operated machine. Along with the harmonic balancer and the precision-done crankshaft balance weights, it runs great. And my car is 10 years old. I suspect all small engines now probably have counterbalance shafts. I know for a fact that they all have harmonic balancers and crankshaft counterbalances. Oh, and then there’s the damping effect of the flywheel mass.
It looks to be needlessly complex and the thought comes to mind of the old 500 CC BSA single cylinder thumpers which had vibration issues.
I don’t see 2 thumpers mated together eliminating vibration issues.
What Gurney should do is build a test mule, put it through the paces, and then announce the next big thing; or forget all about it all depending.
When BMW first introduced the 1000 CC models I bought one of the first 100/7s available and (unfortunately for me) discovered it had some inherent vibration issues right at my preferred cruising speed of 70-75 MPH. This meant either loitering at slower speeds or running 80+.
I expect all the low hanging fruit on the"reciporcating ICE" tree is gone,I saw a new L head motorcycle engine(made for some reason or the other)not so long ago,maybe one day we will get comfortable with something that is not powered by metal"slugs" that move back and forth(but the sound-what sounds better then silence?,nothing)
I don't see 2 thumpers mated together eliminating vibration issues.
Isn’t the BMW twin essentially two thumpers mated together in a way that they vibrate in opposite directions?
I have owned a few balance shaft singles and twins. I had a Suzuki DR650 single that was reasonably smooth, far smoother than a non balance shaft single, but the serpentine roller chain that drove the balance shafts had to be inspected and the chain tensioner had to be adjusted pretty often. This meant taking the left engine cover off and buying a new gasket for that cover. Later on Suzuki came out with a new DR650 that eliminated the roller chain drive.
My current bike, a Kawasaki Ninja 300, has a 180 degree crank and a single gear driven balance shaft in front of the crank. This bike is very smooth for a twin.
Yes, after riding for over 40 years and owning bikes up to a 1200cc four, I’m back to riding a small bike. I finally decided that I need to get 70+ mpg a lot worse than I need to be able to double the speed limit.
Plus, this nimble little 370 pound bike turned out to be so much fun to ride that I almost completely stopped riding the ZRX1200 that I owned. I finally sold the ZRX.
I dunno but when bikes start weighing over 600 lbs and only get 35-40 mpg, it sort of misses the whole point of a motorcycle, an economical alternative to a car that’s handy, easy to park, and fun to ride.