Dan Gurney's Moment-Cancelling 4-Stroke tandem-twin engine
 

First saw this new engine (MC4S) spotlighted in Feb'16 issue of Car & Driver, then found this earlier on-line article:

Can Dan Gurney

The 'interesting' aspect (for me) was the leap from 141 hp to 262 hp with his change from straight intake to optimized tapering intake...that's an 85% increase in power...from 110 cid/1.8L and only 9.5:1 compression ratio!

This is his (Dan Gurney's) website on the MC4S engine with simulation data: http://www.momentcancelling.com/simulation-data.php

As far as "moments" go, they're generally not of any concern on anything but motorcycles and perhaps light aircraft or maybe the elitest of the elite racing machinery.

Perhaps I'm missing something, but tapered intake runners and carefully sized bowl volumes are nothing new. What is the new part of this... simulation? The text says a prototype should have been built by now...

The only enhanced combustion feature mentioned would be a supposedly high velocity charge penetration to the bottom of the cylinder. How that interacts with swirl and tumble the way we already know it I don't know, especially since they all end up at TDC anyway. And what happens when it's throttled? :confused:

They mentioned a "simpler structure with fewer moving parts". What? Twice the crankshafts and crank bearings AND a gear mesh between 'em. The counterweights better be perfect (how???) because both pistons rise and fall together. Power needs to be turned 90 degrees (bleah) for the cams... unless they got stubbified too.

Well, just because I don't get it doesn't mean there's nothing to it, but... I don't get it. I'll need to see a runner.

Some 'other' applications -- beyond motorcycles -- have been: planes, helicopters, EV-range-extender engines, boats, ie: just about anywhere where reduced vibration and increased engine reliability (MTBF) are important.