wow thanks gorn, its the first time someone has explained that so it got through my thick scull. so the lt1s limiting factor is the size of the heads? ls1 head and intake design has higher capacity to move air?

 

When you talk about head design you really remove limits. The better they get at modeling air flow the better heads they can design heads. They allow for high flow without slowing down the air at lower RPMs. Also with better production systems inplace to make complicated designs in high volume (mass production) is a lot easier then it was even 10 years ago. So in most cases with heads that are design around preformance newer is better.

But when you are talking about changing existing design by increasing the size of the port as a general rule you increase air flow at high RPMs but you slow down the Air flow at low RPMs. If the prefect header changes length with RPM than the perfect head/intake port would change diameter. I like to explain it like this. Take a drink with a normal straw now imagine that straw 1" diameter. How hard would you have to suck to get a small sip?. People are different so there is no one perfect straw but if you drank at the same rate all the time there is a perfect size straw out there for you.