1970 Mercedes-Benz C111-II Wankel(!) by Norev

Here's what Supercar Nostalgia has to say about the Mercedes C111-II:

The C111-I first appeared in public at the Frankfurt Motor Show in September 1969.

But it wasn’t long before Mercedes-Benz unveiled an uprated version. The appropriately named C111-II arrived at the Geneva Motor Show in March 1970. It incorporated a series of modifications that yielded more power, extra torque below 4500rpm, better driver visibility and improved aerodynamics. Like its predecessor, the C111-II attracted an enormous level of attention. However, Mercedes were unwavering in their commitment not to produce it for public sale. Instead, the firm would use the C111-II exclusively for research and development. The R&D programme was two fold; establish whether Felix Wankel’s rotary engine had a future and experiment with bodyshells manufactured from glass-reinforced-plastic (GRP).

Whereas the C111-I had a three-rotor Wankel engine mounted transversely in the chassis, the C111-II was equipped with a four-rotor unit. Each of the piston chambers once again displaced 600cc, which meant overall displacement rose from 1800cc to 2400cc. Like the three-rotor M950F unit, the new Type M950 KE409 engine ran a 9.3:1 compression ratio with mechanical Bosch fuel-injection. Whereas some C111-Is had used dual ignition, which proved difficult to adjust, the C111-II was fitted exclusively with single ignition. Peak power rose from 280bhp to 350bhp at an unchanged 7000rpm. The torque rating was also improved; the C111-II produced 289lb-ft between 4000rpm and 5500rpm compared to 217lb-ft at between 5000rpm and 6000rpm. Transmission was once again via a five-speed ZF 5DS-25/1 gearbox with triple-plate clutch and limited-slip differential. Bodywork modifications resulted in a drag coefficient of 0.325 compared to 0.35 for the C111-I.

The four-rotor Type M950 KE409 was the most advanced of the Wankel engines created at Mercedes-Benz. Many of the engineering problems involved in the rotary-piston principle, especially in engine mechanics, had been solved. However, the Wankel engine’s poor efficiency owing to the elongated, variable combustion chambers of the rotary-piston principle could not be overcome by technical modification. Inherent design problems meant a Wankel engine would always require more fuel for the same power output as a conventional reciprocating-piston engine. Furthermore, with high pollutant content and more stringent emissions legislation on the horizon, Mercedes-Benz chose to discontinue work on rotary engines in 1971. However, that was not quite the end of the story. The fuel crisis of 1973-1974 saw Mercedes-Benz turn their attention to diesel. As a way to improve the image of the compression-ignition engine, they used a diesel-powered C111-IID as a record setting test bed…but that's a story for another time.

This would have been a Holy Grail item if I'd ever dreamed that someone would make it. Guiloy had a 1/18 version a few years ago, but the little tray in the back covered up half of the engine, which for me defeated the purpose of making the model. Luckily Norev has come to the rescue, and it is worth the wait. Everything opens, and the model is an absolute delight to hold and manipulate.