new australian intake manifold for the 4g63

[npaulseth]

I guess AMS fucked up with their VSR intake manifold.

Those AMS guys are just a bunch of ignorant noobs, obviously.

[rst95eclipse]

My question would be: Why create turbulance before the air enters the desired tract? So why not just add a ton of raised petrutions into the plenum in addition to the raised stacks? You'd be slowing down the flow, since there is something for the incoming flow to hit. The theory behind a velocity stack is to create turbulance as it enters the runner, not before. If I am incorrect in saying this, please correct me. Examples would be excellent to highlight the information.

BTW: Thanks for stating what should have been obvious to the previous poster to your comment, Pimpin DSM. I just love how people are using their Jump to Conclusions mat in this board. Apparently a Fluid Dynamics course is required to join this board and post.

[JET]

But you don't want anything protruding into the plenum...

Me thinks you better do some more book learnin'!

A velocity stack is used to minimize turbulance going into the runner. Then you start getting into laminar flow (which is why they have it protrude) and all that fancy jazz.

[npaulseth]

http://www.grapeaperacing.com/GrapeApeRacing/tech/inductionsystems.pdf

[Shane@DBPerformance]

I don't know. Things that often look like the way to do things or look better or smoother don't always end up making the most power. The same thing goes for head porting, lowering an intake port floor to do a gasket match, over porting with the bigger is better mentality, knife edging dividers, port matching the exhaust side, valve guide boss removal, etc can make a head produce less HP. I know AMS spent a long time dyno testing their intake manifold and wen't through many different versions before they settled on releasing that design.

Maybe if you think of the intake manifold plenum as a waiting area for ready to use pressurized air. A reservoir for air for the piston to suck in air when it wants it, not as something to direct the air right in from the turbo. You want the insides of the plenum to be somewhat rounded or have angled walls when needed to avoid 90 degree corners to not cause too much major disturbance when the air comes hurtling in past the throttle body to slow down and get ready to make the journey down a port with an open valve. Too big of a plenum and the turbo can't keep it full, too small and there isn't enough air ready to fill the motor at high rpms. You don't want air coming in a favoring one cylinder, maybe the raised ports cause a little turbulence to keep an air flowing along the walls from being directed right into a specific port constantly. Or it might allow the port to suck from a less turbulent area of the plenum away from the walls. Another possibility would depend on how air flows around the radiused inlet, one that sticks up into the plenum would have more of the radiused inlet which might give it more directions to be able to suck in air than just directly infront of the port.

[rst95eclipse]

That paints a clearer picture for me. And I understand why they would want a velocity stack, since the port can pull air from a larger area. But why create turbulance. The velocity stack "compresses (for lack of a better term)" air from a larger area while the stack pulls it in. Why "rough up" the air? Why not streamline it so that it flows better/evenly? The more air you pull in, the better. So why slow the air down in the plenum for it to just wait? I've got gas to burn, let's move it.

[Shane@DBPerformance]

The intake valves aren't always open to pull in air.

[Super Bleeder!!]

if you really want to know, here is a good place to ask just about anything:

http://www.eng-tips.com/threadcategory.cfm?lev2=6