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multi port fuel injection changed somewhat the idea of having intake velocity.
Once the air is past the intake valve, what happens inside the combustion chamber is pretty much a different subject.
I'm most familiar with the progression of the chevy v8's but other series are similar. With the new chevies, they have a huge squish area creating large turbulence inside the combustion chamber.
They also have HUGE intake runners to let lots of air into the chamber. And they have large lift, but traditional short OEM duration. For a given duration, if you add lift you get more rpm range without sacrificing anything. Obviously there is a limit in camshaft profile, which can be added to by going to roller rockers.
For aftermarket, add more duration for even more RPM. With more duration, you can get even more lift keeping ramp accelerations within reason.
But this will only work if you have the port flows to support the cam.
lets talk MPG for a second.
What do you do for max MPG?
crank the compression WAAAAAAAY up, . Then run too much duration especially letting the intake run long, so at low RPM's you don't get detonation as you get reversion lowering.
then watch your igniton timing curve, reducing timing at peak torque to prevent pre ignition.
all of which is pretty turbo friendly.
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