Where boxer's really do seem to work is in air-cooled rear-engined cars (e.g., the VW Type-1 and Porsche 911) where width is less of a concern, the engine must be a short as possible to avoid a large mass behind the rear axle, and the banks of cylinders are easier to cool as they are more widely spaced from each other. Longitudinal mounted engines are preferred for front-engine, rear wheel drive, the boxer engine's lower mass probably does not provide enough advantage over the simpler straight-4 or V6. A straight-4 or a V6 are much more suitable that a flat-4 or flat-6 in this configuration. Many cars are now front wheel drive which work best with a compact, transversely mounted engine. The probable reason boxer or flat configurations are not used very often in modern cars is because a straight or V engines are almost always a better choice. True V's have pairs of rods sharing each crank throw. Like Vs boxers are more complex that straight engines, having 2 cylinder heads with associated head gaskets, exhaust manifolds etc., and double the number of camshafts, more complex camshaft chains or belts and more complex cooling.Ĭompared to Vs, boxer engines have a more complex crankshaft as they have a crank throw for each connecting rod. Compared to V engines boxers are not as tall, offering the ability to position mass lower in the vehicle's chassis, but are wider.Īll boxer engines feature low primary vibration as pairs of pistons are opposed and move in a way to cancel out each other's momentum. Like V configuration piston engines, boxer or flat configuration engines can be made approximately half the length of a straight configuration engines.
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