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

[4000GT]

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

Details pretty much in the last post. The inside of the intake is pretty well finished. I will try cutting off the plenum further up the neck and see what happens. I might then try one of those K&N setups with an flexible pipe to draw cold air in...

[Radar]

Just before you go and do anything to drastic, are you getting vacume during high RPM? If so, just add a second inlet for the plenum on a solenoid that opens at a certain RPM. Its not that you need larger dia runners, sometime the stock port dia size is best for port velocity (best for torque), its just the length of the runner and the plenum openings and size that give you the most improvement... Also it might pay to look up intake resonance tuning, your plenum is a good thing if you want more torque (lot easier to drive), if your chasing peak HP only though maybe just some shorter stacks without a plenum? Just my2c

[4000GT]

I didnt do the tuning, my flatmate did. Not sure if it was drawing a vacuum still. Yup very familiar with resonance tuning, The thing is, no one else has my combination of modifications, so there is a little bit of adjusting required clearly!

[Sam_Q]

have you considered angling your intake manifold up to overcome the factory design flaw of the intake manifold matching to the head?

[Radar]

Unqiue combo or not, do the maths for the resonance tuning and see what happens.. Also like Sam said, make sure your intake path is aligned otherwise you've made your self a anti-reverb step in the intake which will kill your intake resonace tuning. Also what percentage of size is the plenum compared to the L of the motor... I.E. 20% of 1.6L is 320mL plenum so 120% is 1.92L plenum.. (For the best resonance tuning I'm pretty sure the size of the plenum needs to be around 45% of the size of the motor.)
Also have you looked into putting anti-resonance chambers in the exhaust to stop exhaust reverbs yucking up your intake charge? Again just my2c

[takai]

Its not the 3" inlet, im making more power than that on a 3" inlet.

Excuse the dust:

[4000GT]

have you considered angling your intake manifold up to overcome the factory design flaw of the intake manifold matching to the head?

A friend made a plate to fix that issue, and had zero gains on the dyno, so probably wont be going down that path...

[4000GT]

Its not the 3" inlet, im making more power than that on a 3" inlet.

Excuse the dust:

Good to have some actual experience now, interesting how most people mentioned its the 3" inlet. I have a thought its the distance of the plenum to the trumpet. I am limited by the space with the master cylinders. I may go for a tilton pedal box eventually and build a more square plenum. I ran my design through EA, but the fact is you have space restrictions to make it impractical, often. I should have got bigger cams, I think the 288's are a bit tame! What are you making with the 308's?

[Sam_Q]

A friend made a plate to fix that issue, and had zero gains on the dyno, so probably wont be going down that path...

the guy from Yager performance thinks otherwise, he reports excellent gains. So just curious how did your buddy ger around the problem of being able to bolt the intake on? did he weld the spacer to the original intake?

[TERRA Operative]

What is this intake manifold angle issue?

[4000GT]

What is this intake manifold angle issue?

The angle on the short side of the port entry.

[Supra967]

how far do the trumpets go into the plenum? might be too tight around that #4 inlet? Takai's looks to have a fair bit of volume on yours as well

[4000GT]

how far do the trumpets go into the plenum? might be too tight around that #4 inlet? Takai's looks to have a fair bit of volume on yours as well

The trumpets go all the way into the plenum. Yes its tight at #4 but I cant do anything about that unless i change the pedal box. Not sure on the volume differences, mine is longer and thinner, his shorter and fatter by the looks.

[Sam_Q]

there's a sharp angle change from the intake manifold to head, if you open a throttle you should be able to look down and see the valve stems

[4000GT]

the guy from Yager performance thinks otherwise, he reports excellent gains. So just curious how did your buddy ger around the problem of being able to bolt the intake on? did he weld the spacer to the original intake?

From what I remember, a CNC'd plate with dowels, viton seal and studs. I never saw it in action as he took it off when there were no gains and binned it.