Originally Posted by
Krewat
Actually, the 3-valve configuration works well at low RPMs too, if you were to cut one intake runner at low RPMs. You'd get a lot more intake runner velocity at low end.
However, I don't think Ford does that
Yup, Subaru, in their basic 4 valve engine, has variable lift on one of the two intake valves. At low RPM, one intake valve opens much wider than the other, promoting swirl of the mixture; at high RPM, both intakes open fully.
You can do a lot of tricks with variable valve lifts and stuff. I recall reading that Ford is setting up the 6.2 to be able to shut off cylinders for cruising mpg.
It all adds complexity and cost, though.
George