GDJT Allroad^2

two valves are for intake and three for exhaust, or three for intake and two for exhaust?

skiracer

on the intake stroke the engine is "sucking" the cold air/fuel mixture into the combustion chamber, whereas the exhaust stroke is venting hot exhaust products at considerable pressure. Thus, the three valves are for intake and two are exhaust.

Ross:D

<img src="http://www.robsaudiworld.com/5valve.jpg">

GDJT Allroad^2

That's... arousing.

Erik Hoffmann

you can get a lot of fuel and air into the cylinder without a lot of lift, this makes for cams that make the engine efficient and able to pass smog legislation. But still able to make Horsepower and Torque similar to a simple 2v overhead cam motor with radical cams