Air Intake Options

[tinkerbell]

resonant frequency where intake pulses are coliding or something?

why it occurs at 4000 is due to the specific lenght and diameter of the INJEN pipe...

i think if the pipe was longer or thinner, the point would be higher like 5000rpm,

and if the length was shorter or diameter larger , the point would be lower, like 3000 or below...


where is freakygeek!!!!!!!!!!!!!!!!!

[tinkerbell]

might be some theory here, but i dont understand it:

http://www.saltmine.org.uk/randy/airboxdesign.html

[00dc2]

they should make a pipe that varies in length as the revs change... so its always in resonance..

[Elwood]

My guess is that it happens at around 4000RPM because the engine starts preparing to engage vtec. Try driving your car a bit and slowly reving it up. You should notice a distinct noise change before the vtec engagement point then a further noise change when vtec fully engages.

before i engage vtec it makes a 'sucking' noise that i attributed to my airbox??????

and how does an engine 'prepare' to engage vtec? lol

[tinkerbell]

they should make a pipe that varies in length as the revs change... so its always in resonance..

hard to do,

but the concept is used in motorcycles a bit;

http://www.cycleworld.com/article.as...&page_number=3

it is also used in the dual runner Integra VTiR intake manifold but is only 2 stage...

[sinobi]

lol i got the same problem
injen cold air intake lol
it was F*%& when it rain the last couple of days when i was around livo dam i was scared to even drive the car cause the road was flooded and it was like 5 to 10cms deep...

[Elwood]

^lol are you stalking my threads sinobi? :P

[VTECMACHINE]

For a good - cost effective intake, Use a Trust filter in a Stock DC2R airbox, and get 4 inch air con piping, and duct it to the front bar from the air box! It's awsome...

Also heaps good for Civic Vti-R's...

[Elwood]

does anyone have any dyno sheets for all these? :P

[tinkerbell]

not "back to back" ones, which is the only way to compare.

[BlitZ]

For BFYB - egay 3" intake with velovity stacked air filter will net u more or same as injen.

[freakygeek]

they should make a pipe that varies in length as the revs change... so its always in resonance..

They do... many manufacturers have systems which vary the inlet tract volume. I will find some pictures of the BMW system to do this, quite groovy really...

Also on many cars you'll notice resonator boxes in strange shapes hanging off the inlet tube. These are for reducing resonances too, so they are there not only to remove the noise but also to smooth power delivery in many cases (remove unusual dips etc in power output).

Some K20A implementations come with this ... (not sure which variants)

see link

A Dual Intake Runner Manifold

Owners of 'regular' DC2s and DB8s will now know that their B18C intake manifold has dual intake runners and that a butterfly valve is used to disable/enable the shorter runner. This give the B18C a wide mid-range powerband. The K20A implements this as well but uses a newer rotary valve instead. The rotary valve is more like a ball-ish cylinder that can be rotated along its horizonal axis. Machined into this valve is a passage that matches the intake runners diameter. When aligned appropriately (by rotating the valve), this passage opens up a bypass path for the incoming air into the intake chamber. Otherwise the passage gets blocked by the body of the valve and air has to flow through the long runners. As Honda explained, the rotary valve implementation is superior to the traditional buttefly valve in that when properly aligned, there is no metal plate in the middle of the airflow path disrupting or restricting its flow.