> On the lower end, it's constrained by sellability of a car Yes, as already said, I completely agree. > and on the upper end it's physically constrained by t

> On the lower end, it's constrained by sellability of a car Yes, as already said, I completely agree. > and on the upper end it's physically constrained by the size of car frame In theory yes, but in practice you don't really feel this limitation, that's my point. As I said, you can fit a K24 engine into a Honda Fit (B-segment supermini car) without modifying the frame or bodywork. A turbocharged K24 can put out 300 kilowatts without breaking a sweat.