Saturday, June 15, 2019
The New (for 1983) Honda V45 Engine
More than power makes the V45 engine better than other street engines.
The objective: a new street bike engine with improved performance.
The technology: the V45 engine. A liquid-cooled, 90-degree V-4 displacing 45 cubic inches (748 cc). The first V-4 engine in a modern production street bike. Designed by Honda R&D and built for the V45 Magna™ and V45 Sabre™.
The bottom line to the V45 is easy to understand: the best power characteristics in the 750 class. But more than power distinguishes the V45 engine from its competition. Because the V45 engine is a breakthrough in motorcycle engine design as well as in performance.
The vee configuration makes the V45 extraordinarily narrow-just 16.3 inches from sidecover to sidecover. So it can be mounted low in the Magna and Sabre for more responsive handling and still provide outstanding cornering clearance. It also permits a low seat height as well.
The 90-degree angle between the V45's cylinders gives the V45 perfect primary balance, minimizing engine vibration. Link-type rubber engine mounts eliminate secondary vibrations for even smoother running, but without sacrificing frame rigidity.
The four-cylinder layout makes the V45 engine more powerful than a V-twin because it can pump a larger amount of fuel-air mixture through the engine in a given amount of time. Furthermore, the four-valve cylinder head with a narrow included valve angle improves combustion efficiency and permits high rpm operation for even more power.
Thermostatically controlled liquid-cooling narrows the range of the V45's operating temperatures. And uniform engine temperatures contribute to outstanding long-term reliability. Even so, the liquid-cooled V45 is lighter than a comparable air-cooled four-cylinder engine.
A unique powertrain design enables the transverse rotation of The V-4's crankshaft to be efficiently converted to the longitudinal rotation of the shaft drive system. The rotation of the crankshaft is simply reversed compared to a conventional engine. So no extra power robbing crossover shaft is required in the gearbox. The transmission is further simplified by locating the driveshaft's shock absorber inside the swing arm.
There are many things that make the V45 engine the strongest in its class. A 90-degree vee configuration for smooth running, a low center of gravity and outstanding cornering clearance. A four-cylinder layout with a four-valve cylinder head for increased power. Transistorized ignition, automatic cam-chain tensioners and screw-type valve adjusters for easy maintenance. A hydraulically actuated clutch and simplified powertrain to transmit the engine's power to the rear wheel efficiently yet the new V45 is more than just a powerful engine.
It's a better engine, too.
(text and image taken from here ... reformatted).