01-29-2018, 03:45 PM
Excerpt from from interview with engineer designing first gen CB1100 engine form Honda Worldwide site:
Sekiya:
On the hardware side, phased valve timing gives the engine its characteristic feel around the 3,000 rpm range. How did you create the engine's personality?
Minami:
Basically, straight-four engines run smooth as long as all four pistons move the same way. My initial thoughts were, to give the engine a deep rumble, we'd have to change the movement a bit.
We ended up shifting the valve timing of cylinders 1 and 2, compared to cylinders 3 and 4, and by continuing to change the gap, found the right combustion out-of-sync feel.
Sekiya:
Valve timing is usually changed or made variable to increase output, but your aim was completely different. Maybe the exact opposite of conventional wisdom.
Minami:
Precisely. We took the opposite approach to conventional thinking, so we weren't sure if it would work.
If the cam is the same across the board, then this must have went full circle and surfaced again when the '17 was introduced??? Regardless, I think it's pretty obvious this is a key reason why the CB's power output remains modest... Honda was clearly more concerned with feel and sound than HP (which is OK-fine by me!)
Sekiya:
On the hardware side, phased valve timing gives the engine its characteristic feel around the 3,000 rpm range. How did you create the engine's personality?
Minami:
Basically, straight-four engines run smooth as long as all four pistons move the same way. My initial thoughts were, to give the engine a deep rumble, we'd have to change the movement a bit.
We ended up shifting the valve timing of cylinders 1 and 2, compared to cylinders 3 and 4, and by continuing to change the gap, found the right combustion out-of-sync feel.
Sekiya:
Valve timing is usually changed or made variable to increase output, but your aim was completely different. Maybe the exact opposite of conventional wisdom.
Minami:
Precisely. We took the opposite approach to conventional thinking, so we weren't sure if it would work.
If the cam is the same across the board, then this must have went full circle and surfaced again when the '17 was introduced??? Regardless, I think it's pretty obvious this is a key reason why the CB's power output remains modest... Honda was clearly more concerned with feel and sound than HP (which is OK-fine by me!)