Custom intake manifold for Twin Carb / ITB

[82Alfetta]

Hi all

I am just wondering, before I go ahead and fabricate this, what do you guys think of this aluminium Airbox? (Pictures are on a Jappo FWD 4-cyl ITB but you get the idea)







All there is left to do, is stuck a K&N Cone filter at the front and mount it very near to the front/grill...

What you think?

Cheers

Syed

[scott.venables]

To my untrained eye,

There should be a bellmouth where the short runners meet the plenum chamber

The volume seems rather small

I doubt there is enough distance between the end of the short runners and the 'roof' of the plenum

The kink in the plenum seems rather sharp



Cheers, Scott

[82Alfetta]

Hi Syed
The airbox in your photos is actually a plenum chamber for fuel injection
it looks very well made, what is it that you plan on doing?
are you going to use the carbies as throttle bodies?
An airbox is usally a box with an opening to an area outside the engine bay to supply cold air to the induction and to separate it from heat generated under the bonnet
If you are going to use carbies and a plenum chamber, you have to make sure that the dimensions of the plenum is sufficient to supply air to both carbies at full throttle . If it to small it will act like a restrictor

Ok then pardon my English (especially on technical terms...) I'm from Malaysia.

Well, to answer your question(s) :

Yes I'm gonna use the existing twin DHLA40 carbies as throttle bodies. I just hate the existing black cylindrical "airbox" and when I saw the  plenum in these pictures above, it immediately caught my attention. The proton in the picture, being a FWD obviously had limitations as far as clearance is concern. I'm sure I will be able to enlarge the height of the "roof" of the plenum to suit my Alfetta.

Furthermore, this setup would allow me to choose different airfilter arrangements i.e. cone at the front, or use a standard "modern car"-type square airbox. I just love the sound of an "open-port" airfilter during wide open throttle... Oh just for the record, the engine is stock standard at the moment.

Cheers

Syed
Malaysia

[stradale]

Hi Syed

You don't have to apologize about your english I totally missed the TBI in your heading
I have to agree the standard airfilter housing is not very pleasing to look at.
you should use the standard housing dimensions as a starting point at least for your plenum.
A good induction sound is sadly missing from a lot of new fuel injected cars
As scott has mentioned try to avoid kinks or bends and If you can try to include velocity stacks [bellmouths or trumpets] in the plenum one for each throttle body, they increase the amount of air drawn into each throttle body [whole books have been written on this subject !!] so the diameter and length of any velocity stacks will depend on what power and torque you are aiming at
Good luck with your project

[stradale]

have a look at the velocity stacks on this 33/12
and also inside the airfilter housing of the montreal

[82Alfetta]

Look at what I just got in the mail...

Pictures speak better than words...







Cant wait to hear them tomorrow!!!

Cheers

Syed

[alfagtv152]

Hi Syed,
Is this for road or track?.Just for track use this is as big as an air box can get!.
Cheers
Andrew

[116gtv]

Hmm, interesting Andrew. Is there a gap near the carbs to allow for the engine to move? I know you said track use but I guess the engine isnt mounted solid?

[82Alfetta]

Hi Syed,
Is this for road or track?.Just for track use this is as big as an air box can get!.
Cheers
Andrew

Hi Andrew thanx.

Check out pictures of my engine in the "photos" section.

Cheers

Syed

[alfagtv152]

Hi Martin,
Yes there is a small section in the middle area where I have conveyor belt type material attached to the carbs and taped to the engine bay devider which lets things move around and keeps it sealed.My engines aren't solid mounted because I cant handle the noise and vibration through the chassis,what I do is use 3 chain links over the engine mount,1 bolted horizontal on the top of the mount-1 vertical down to the base of the mount and the third one bolted horizontal on the other bolt at the base of the mount.This allows a little movement withuot the noise.
Cheers
Andrew

[Storm_X]

That is a nice looking plenum. would suit a turbo/supercharged aplication very nice.
I my self used to have trumpets / verlocity stacks with a dividing plate mad by PACE  similar to andrews but his cuts off all the hot air of the engine. Anyway they sound nice when full throttle.

I have a stock 2.0 airbox here with another ally box welded on to the top to make a air tight plenum.Doesnt look the best but its very easy to make.