Nuts About Bikes

New for 1974: Suzuki's Rotary RE5

If you're over 40, you probably remember the Wankel engine craze of the 1970s. The Big Three American automakers were churning out reams of publicity on the wave of the future in internal combustion: the amazing Wankel rotary engine.

m109rNamed for Felix Wankel, the brilliant German engineer who invented it, the rotary engine was going to overtake the auto industry and displace the reciprocating piston engine by the end of the decade.

Things didn't quite work out that way.

Detroit was salivating over the prospect of converting production for one big reason: dinero. Wankels are cheaper to build because they have so few moving parts – and they deliver more power in a smaller package. Just a combustion chamber, a few triangular rotors and a couple of gears. That's it. No valves, no cams, no connecting rods, no crankshaft. Detroit was seeing dollar signs through decreased manufacturing costs.

But it was a hard sell for a few reasons. First, Wankels drink gas faster than piston engines. They are dirtier because a lot of the gas you pour in goes out the tail pipe unburned. Performance is iffy. Comparable to piston engines at high revs but not so great a low revs. They run hot as all hell.

The one "benefit" the PR army could hang its hat on was the noise level. Wankels are quieter than piston engines. (As if mufflers hadn't been invented and cars were shattering windows everywhere they went.) Not exactly a compelling argument. And all this Wankel image-spinning occured just as the first big oil crisis hit. Overnight, gas prices skyrocketed, Joe Six Pack got passionate about fuel economy and Detroit had a fast change of heart.

By 1980, the Wankel was all but forgotten in passenger vehicles. Mazda beat the drum for years without success (to the puzzlement of its competitors). Today its RX-7 and RX-8 are the only Wankel-powered late model production cars, though old Felix's design has survived in aircraft, shipping and industrial applications.

Suzuki was the lone Japanese bike manufacturer to test the waters, with the first and only Japanese rotary motorcycle, the RE5. For a bike, a Wankel engine is theoretically a pretty good idea - almost no vibration and chatter. But the old problems of heat and fuel consumption were very much a part of 1970s technology and would not be tackled intil decades later with the Mazda RX-8. Like most Wankel-powered passenger vehicles, the RE5 died a fairly quick death. Read the whole story here.

Norton also experimented with the platform with a small run of production and race bikes and German moped maker Hercules released a full-size Wankel bike. (Note the heat shields on the pipes.)

If hydrogen becomes the fuel of choice for the future, we might see the Wankel make a comeback. Engineers have discovered that they are particularly well suited for burning hydrogen.

-Sal Emma
Editor