Quote:
Originally Posted by Nissanboy
I agree but one thing that people seem to misunderstand around here is just because something is used to provide better emissions and gas mileage doesn't mean it has been made only for that. Think about it; if the hydrocarbons in the air-fuel mixture is burned better or more complete, it will give us better gas mileage, emissions AND power. Just simply increasing the efficiency of the motor.
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Yeah... in theory that is true (although with a few more mm of valve lift, that means a greater volume of air is sucked in!), but the reality is you can rarely obtain all three in practice without the risk of jeopardizing two other factors: Driveability and longevity.
For example, many OEM tunes run much richer than necessary under high load, and high engine (air, water, and or oil) temps and or dial back ignition advance, resulting in a less efficient burn and wasted power -- but it substantially reduces the likelihood of ping under extreme conditions.
Also, in general, peak torque tends to be made with a richer than stoichiometric mixture anyway... that might not be true with a good DI system on the same motor (or, I dunno, with water injection), but it's pretty tough to gain power AND use less fuel or produce fewer hydrocarbons in practice on a typical port injection engine.
As to valve lift and overlap on this particular motor -- it's all an empirical question. We simply need more data.