Basically what I was trying to mimic was the low-cam operation of the VTEC engine in the current Civic and the 1st gen Fit:
Quote:
|
Depending on engine load and rpm, an electronic controller determines which cam profile will be used and exactly how the intake valves will operate (usually around 3,400 rpm). At low revs, where low lift and shorter duration provide optimal operation, the timing of the two intake valves is staggered and the lift asymmetrically skewed in favor of the primary valve. This helps to create a swirl effect within the combustion chamber that increases the efficiency of the burn process. At higher rpm, a hydraulically actuated spool valve causes a locking pin to engage the secondary rocker arm with the primary one, transitioning the secondary valve into a long-duration mode that increases the volume of air/fuel mixture moving into the combustion chamber. The additional air/fuel mixture helps increase power at high rpms.
|
Since I never drive my car above 3400RPM, the swirl effect of the single intake valve seems ideal for torque and economy. Honda switched the current Fit to a full-time 4 valve operation, and while it gained 8 peak horsepower, it only gained 1lb-ft of peak torque, and fuel economy dropped by 1mpg.
So the theory is there, but obviously it's not as simple as deactivating one of the intake valves on any given engine without more of the supplemental factors, like specific cam lobe profiles, intake port design, etc. (At least on my OBDII, automatic sedan test car.) A VTEC cylinder head with cam and valvetrain (and ECU) would do the trick - complete with automated self-deactivation! There was one at the junkyard when I was there... but I'm not sure if I need another project just yet.