What is the maximum valve lift?, Is 0.650" possible? Options

[Beebo Kanelle]

What is the most extreme valve lift you've seen on a Type 4 engine?

Thanks in advance.

[Beebo Kanelle]

Thanks for all the replies and help.

The extreme lift with short overlap and long duration seems to be the way to achieve the desired 100 hp /liter with a smooth idle.

But I didn't know if I was pushing the design beyond its capabilities.

I know these questions must sound silly to those who are familiar with the Type 4.

But, I do not have any reference point... hence the question.

Hang on, I'll have additional stupid questions in the future.

[jd74914]

Thanks for all the replies and help.

The extreme lift with short overlap and long duration seems to be the way to achieve the desired 100 hp /liter with a smooth idle.

But I didn't know if I was pushing the design beyond its capabilities.

I know these questions must sound silly to those who are familiar with the Type 4.

But, I do not have any reference point... hence the question.

Hang on, I'll have additional stupid questions in the future.

At what engine speed are you trying for 100 hp/L? In my relatively limited experience short overlap usual means you shy away from the exhaust scavenging gains you'd see at higher engine speeds.

Typically you don't gain very much flow-wise when your "valve shroud area" (I mean the effective outlet flow area-just drawing a blank on the correct term) is much larger than your valve/port area. Obviously, you need some room there for discharge losses, but just doing the simple calculation for a 42mm intake valve shows:

Valve area = 42^2*PI/4 = 1385 mm^2
Flow area @ 16.5mm lift = 42*PI*16.5 = 2177 mm^2

The 1.6x difference makes it seem like you have a ton of extra lift. Do the losses through the valve warrant that kind of lift?

I'm not attacking, just curious and asking questions. Engine modeling is awesome! (IMG:style_emoticons/default/smile.gif)