View Full Version : Innovation series, episode 6: boxer engine

07-09-2010, 09:25 PM
Note that this is episode 6 so you might find it helpful to read episode 1 for some background.

Don't get me wrong here, I love an American V8. For goodness sakes, I've got the LT-1 in my boat. So, don't think I'm un-American or that I don't understand history, displacement, or torque. That being said, I think there are some applications where a horizontally opposed (boxer) engine would be great for an inboard boat.

Ideally (dream world) the engine would be flat enough that it would fit under the floor without needing space for the engine compartment typical of an inboard. Again, I agree that there are some very cool aspects to having a small block smack obvious in the middle of the boat - I get that. All I'm saying is that there might be some customers or configurations that would really benefit from the flexibility and extra space. In the real world, I'd expect the engine to protrude some but I'd expect it to be low enough profile that you could easily have a properly proportioned seat on top of the engine and/or serious storage space. It's likely that the engine would need to be dry sump (oil collection located remote from the bottom of the engine) to allow the engine to be placed a low as possible in the hull.

Beyond the benefit of additional space and configuration flexibility, a boxer would offer greater refinement due to the smoothness of the engine layout. There would also be a slight stability and maneuverability benefit to having the weight of the engine low and in-line with the roll center of the hull.

There are several obstacles that would need to be overcome for this to ever become a reality including marinizing a boxer engine, finding a boxer engine with a torque curve we spoiled boat owners would accept/love (The Subaru H6 is 3.6 liter and makes 256hp in stock trim - well short of modern expectations. An H8 would be better.), adapting a hull/boat to deliver the benefits. Customer acceptance/demand would be critical too.

Both Porsche and Subaru make frequent use of boxer engines. I've included a photo of a Subaru car engine for reference. Note that this engine is wet sump (with the oil pan directly below the engine). Again, dry sump would allow the engine to be installed as low as possible. I figure this idea is likely to spark the most criticism because it's so counter the established norms but I'd still like to hear your perspective (on either side). Thanks for the input.

07-09-2010, 10:04 PM
Could be a great idea. Love the little boxers but for a ski boat application they would need some more torque than what is currently available. For what it's worth I'm on my second Subaru with the H4 boxer. They have quite a bit of torque for their size but as is often said there is no replacement for displacement.

07-10-2010, 04:56 AM
Ideally (dream world) the engine would be flat enough that it would fit under the floor without needing space for the engine compartment typical of an inboard.

What is a typical height of the engine pictured, including the intake and exhaust systems, and how does this compare to the typical V8? I understand the two designs, but dont have a feel for the numbers...