large inlet valve size vs small port?

[tapkaJohnD]

Mignon said:

Physics isn't what needs refuting! What needs refuting is people latching onto something fancy sounding they came across on google, didn't understand in the first place and tried to apply it to a situation it's specifically not designed for.

If you'd done even the most miniscule amount of reading about Poiseuille's Law you'd have seen it's only applicable to 1) incompressible flow, 2) in thin tubes, 3) that are very long in proportion to their diameter and 4) where there is no acceleration of the fluid. So nothing remotely to do with gas flows in engines which as any fule do know always scale with cross sectional area.

All true, Mignon, but please, my training in physiology (so the blood analogy is true) was to post graduate level, and however inapplicable to the engine situation, when someone is trying to help, "bks" is unkind!
John

[Mignon]

tapkaJohnD said:

All true, Mignon, but please, my training in physiology (so the blood analogy is true) was to post graduate level, and however inapplicable to the engine situation, when someone is trying to help, "bks" is unkind!
John

You're not helping your case much. So you studied this to post grad level but still didn't understand that flow of liquids through tiny needles didn't apply to gases through big ports.

[Goldenballs13]

ampor said:

Hello

Trying to learn a bit more about head flow, and wondering what is the effect of installing a larger intake valve without enlarging the port. I'm aware of previous info posted here about having the valve throat end up at 86-88% of the inlet valve diameter, but what happens if there are constraints that prevent opening the throat? What to expect if your valve throat is only 80% of inlet valve?

Thanks

If the original set up is limited by the throat then increasing the valve size will have no effect, as will be choke limited at the throat anyway. if the valves are the limiting factor, then they can be increased in size until the the throat is the limit.