The recent developments of the Collins Scotch Yoke technology embodied in an 8 cylinder, three litre (830), horizontally opposed, four stroke spark ignited demonstrator engine are summarised. In this representative engine, the Scotch yoke technology is seen to yield a far smaller and lighter engine than other design approaches, including some two stroke engines. Modular designs of 6 and 4 cylinders retain these advantages.
Internal losses (friction) are shown to have been progressively lowered until, today, the fMEP of the 830 engine is more than 14 percent lower than a recent production engine said to be a low friction target of the day (circa 1987). This achievement for a prototype engine with significantly more bearing surfaces than a conventional engine appears to be contrary to common wisdom, but has been verified by low BSFC, as well as numerous repeats of the friction tests.
The demonstration installation of the 830 engine in place of a production V6 in a Ford (UK) Granada, four door sedan provides obvious proof of the compactness, power and responsiveness of the Collins Scotch Yoke type 830 engine.