If Honda's dual clutch, which will debut on the new VFR, got your attention, how about a V4 with unequal front and rear cylinder spacing plus cylinder deactivation? These Honda patent drawings show the layout of their new engine with the front cylinders widely spaced and the rear closer together. The connecting rods are mounted to the crankshaft with the rear cylinders both connected to the inner side of each throw, the front cylinders both mount on the outside.
According to the patent, turning cylinders on and off causes a number of problems with temperature cycling and engine vibration.
This part is a bit confusing, is there a space between the front cylinders?
When the cylinders in the front bank are arranged on the opposite end sides of the crankshaft, running wind can be made flowable rearwards from a central part of the front bank so that the running wind is also allowed to flow to the cylinders in the rear bank located rearward.
Say again? It seems there's a gap and they want the air to flow to the rear for cooling. Of course, I could be way off base, here, I'm just trying to understand what they said.
Update: Just found this:
Although the full-time operating cylinders are arranged in the rear bank Br in this embodiment, the arrangement of the opening 9 in the front bank Bf as in the first embodiment makes it possible to also feed cooling wind to the rear bank Br. It is, therefore, possible to reduce thermal loads on the full-time operating cylinders while keeping vibrations low. This embodiment is also advantageous in that, when the front bank Bf is provided with the opening 9 as in the first embodiment, running wind is allowed to flow from the opening 9 to the full-time operating cylinders located in the rear bank Br and to cool the rear bank Br.
Wow, got that? Who taught these guys to write?!!
The 2 rear cylinders are more easily balanced if inboard when running as a parallel twin, than if they tried to fire the 2 widely spaced fronts. The front cylinders are shut down by deactivating the valves.
According to the rpm map, it looks like the engine can run with 2, 3 or 4 cylinders depending on rpm and throttle opening. Running on partial throttle and 2 cylinders, fuel economy would certainly increase while all four cylinders are ready and waiting when needed or desired.
Honda certainly keeps their engineers busy. The new VFR is going to be a pretty impressive bit of high tech wizardry. This has the potential for high performance and high mileage. What's not to like?