While the Crossrunner's V4 engine inherits the excellent high end performance of the VFR800F, the output characteristics of Honda's traditional V4 engine have been made even easier to handle by reducing the noise and harmful exhaust emissions and providing modified settings for more torque in the low/mid speed ranges.
The greatest feature of the Crossrunner engine is the V4 VTEC. This is a valve control system that operates only 2 (1 intake and 1 exhaust) of 4 valves at low revs and operates all 4 valves higher in the range, with the border between the two modes coming at around 6,400–6,800 rpm. The VTEC switches between open and idle by hydraulically stroking the slide pin inside the valve lifter. Finer control is now possible due to parameters such as detection/computation of gear position, throttle opening, and engine rpm to enable more accurate switching into VTEC mode.
Four-valve engines are designed to obtain high output by limiting intake flow velocity in the high rpm range, but have problems gaining charging efficiency in the low rpm range due to reduced intake flow velocity. Conversely, 2-valve engines can attain good intake flow velocity at low rpm, but cannot make enough output in the high rpm range, where the intake flow speed can become too high. Introducing V4 engine VTEC eliminates these problems and brings with it the advantage of incorporating the features of both the 2-valve and 4-valve engine. As a result, VTEC engines offer a linear acceleration that responds instantly to throttle operation in any rpm range.
As well as additional torque in low/mid speed ranges, other benefits include improved fuel efficiency while cruising on the highway and elsewhere as well as reduced running noise in the 2-valve range in particular. Furthermore, in the low rpm range, only one of the valves opens or closes for intake or exhaust. As a result, air enters and leaves the combustion chamber more slowly to improve quietness.
In sum, the adoption of the V4 VTEC engine perfects the engine as the true best fit for the Crossrunner, quiet and effective when cruising while delivering a powerful run on winding roads.