Went on the dyno, now I need a velocity stack and filter solution

[4000GT]

4AGE 20v, some mods...

Made 169WHP with a full plenum with velocity stacks, and with the plenum removed and velocity stacks in place, it made 175WHP. So assuming the plenum has some kind of restriction in it somewhere, either the volume or length of intake pipe etc.

So just wondering what the best (non restrictive) velocity stack and filter solution might be? Pipercross foam? K&N system? Uni foam with springs? Just wondering about peoples experiences testing these if any data is out there!

[CrUZida]

Those are just peak HP figures, and tell about 1% of the story.
What does the rest of the curve look like?

[Celica RA45]

what size air hose to the air box and what size is the air box ,the best way to find out if its 2 small is set the map sensor up for atmosphere put the hose into the air box do a duno run and see if the map stays steady its ok if it falls way lower than what you started with 1 you will need a bigger pipe to fill the air box or your ram tubes are to close to the back of the box ,so need to make bigger
3sge motor 12 litres in size and dia of pipe .air hose is 150mm dia

[4000GT]

The shape of the plenum is not easily calculated, I just made it as big as the space allowed. It reduces to a 3" intake pipe then a big K&N filter. If I had a tilton pedal box or similar I would have more room, but I might do that down the track. So I really just want to look at doing the velocity stack thing and filters in the short term, then do the E85 tune...

I would also be interested in hearing what guys making 180WHP+ are doing for intakes on the 20v.

[4000GT]

[Celica RA45]

the pipe going into the plenum is the restricter it would be better if it were the size 100 mm dia ,that looks smaller as i use 150mm dia

[TERRA Operative]

You can calculate volume with foam peanuts and a large measuring jug etc stolen from the kitchen.
It's a trick the audio guys use to calculate the volume of their oddly shaped fibreglass subwoofer boxes.

[Sam_Q]

hey I got your email, silly question but did you do a retune when you took the plenum off?

[4000GT]

Yes Sam, it used more fuel to make more power... so needed a retune.

Celica RA45, how did you determine that the pipe (3") going into the plenum is the restriction and not the plenum volume or the distance from the bellmouths to the plenum wall?

[Celica RA45]

well it looks like 50mm at the air filter then slowly gets bigger ,at a minium it should be 100mm

[Celica RA45]

also what size ram tube are you running as i have black top 1s here that are 30mm

[4000GT]

The air filter is 3", to put the rest into perspective.

The ram tubes are about 50mm.

[mattysshop]

pics of tubes inside the box? i would also suggest 4" (100mm) filter and intake as a minimum... it's an odd thing as the CFM through 3" tube would most definitly be 'enough' for the engine... but intakes sometimes do not work that way at all, had twin 45mm webbers on a 2L pinto (escort) that when boxed with a 3" filter made less hp than a 4" filter/pipe... torque was slightly better with the 3" though..

is the inside of the box linished like the outside??
angle of the stacks??

p.s. nice power figure

[Bazda]

I assume the base of this plenum is what I madeyou?
If so i cant remember if I supplied him the velocity stacks. If I did they are wide mouth 40mm long stacks inside. Mouth of the velocity stacks are 82mm tapering down to 50mm. Very nicely formed mouths and very smooth.

If you put any filters over velocity stacks you will loose alot of power as it disturbs the air flow.

Possibly the air filter your using is too restrictive? Did you try remove this?
I would try it without the filter and possibly even make the entry alot bigger at 4".

Inside of the plenum should look like this:

[4000GT]

Hey Barry, yes it is your plenum, and you included the velocity stacks so will be the specs you provided. I might try cutting the plenum off at a point where its 4"or larger and see how that goes. But I will have some velocity stacks and filters handy to try at the same time when Im on the dyno next to do the E85 tune. Im pretty confident a 185-190WHP is possible with some intake work and E85 to crank up the timing. Not sure where this sits with other 20v NA's here?