AE92 Air Intake Restriction. Alternative Systems / Solutions?

[GeeEss]

I have an '88 AE92 FXGT Bigport with Quads which I recently had re-dynoed by Adam @ JEM (+1 to these guys; finally got the car running like it should have).

The car dynoed 86FWKW @ 7700rpm but was pulling vacuum at higher RPM because of my restrictive inlet configuration*

* I am running a modified OEM AE101 Levin Plenum on the ST QUADS running into an OEM AE92 45⁰ duct & AirBox.

There are a lot of aftermarket Intake Systems out there but (for Street use at least); I would like to keep a Factory looking Intake arrangement but would obviously like better flow so was wondering the available options are.

My first thoughts were that I should firstly replace the Filter with an Apexi / TRD item and cut a 2nd hole in the base of the Factory Airbox & run a second Cold Air duct to a meshed inlet.

Another alternative is a Fibreglass TRD (according to advertisement**) replica Airbox with dual feeds @ photo. AFAIK this would utilise an 8" < Cone / Mushroom ? > filter; but I'm not sure about it; mainly because I have my doubts about its LT durability (i.e. OEM unit is a tough Plastic Moulding with lots of strenghtening ribs while this is just a Fibreglass shell - wouldn't be surprised if it started cracking after 2-3 months). The other issue I have (apart from what type of Filter it takes) is how this Filter would seal properly against the casing (I don't see any stepped flange etc, unless you can buy sealing flanges).

I'd welcome comments from anyone that's buggered around with standard / modified Airboxes.

** Actually a TOMs pattern Airbox @ advised by Poster below < Thank You >

PS: Not interested in comments suggesting I just run a Pipe & Pod Filter as I want to keep OEM look for Street.

[oldeskewltoy]

jmho....

move the battery to the back and that way you don't have to have such an odd shape to the intake

[TERRA Operative]

I did this with my 4AGZE. It wasn't a restriction after I finished.
Also, that item is actually a copy of a Tom's super air intake. The original is top-notch gear (but completely NLA from Tom's these days), but I can't speak for the copy.



Silicone bend sizing up to a 3" alloy pipe with an Apex'i filter in it's own little box where the battery used to be, then there's a duct leading from the 2.5" hole where the resonator used to sit, down to the front bar for cold air.

[GeeEss]

Thanks for the heads-up re. the item being a Toms (Vs TRD) knock-off. Those items had a pretty good rep & I would be inclined to wager the money & give it a shot; but the thing holding me back is that the Foam-type mushroom filters (which, correct me if I'm wrong - are the only type that works with this thing) don't exactly get a ringing endorsement on various Forums. The general consensus is that their small particle filtration is noticeably inferior to that of a good dry / paper type Pod / Panel Filter.

I think I'll take a look at the OEM air box tomorrow & see if I can cut another hole in the base & run a CAI duct to it from a square / rectangular mesh inlet in the front bar. I think that this; together with a TRD / Apexi Panel Filter might help matters. I might even plonk $40-50 down on a Manometer so I'm not just throwing darts. . .

[TERRA Operative]

True re. the foam 'mushroom' filters, although it shouldn't be too hard to adapt the intake to work with a pod filter, they are a similar shape.

Before you drop the cash on a panel filter, do some tests with a manometer first. I think you might be a little surprised just how little restriction a standard paper filter actually poses.
Check out Autospeed as they did some extensive manometer testing on intakes and the like. Could provide some interesting info.

[George]

I use subaru legacy b4 airbox + apexi power intake filter inside it, engine is supposed to deliver ~150kw at crank (1jz vvti close to stock) , MAP reads ~100kPa , exactly the same value as when engine is off. Chosen the subaru airbox for its compact size. There was quite a choice of them at wrecker.



I run 76mm inlet/outlet with it. The subaru wrecker also had sort of the same filter but with outlet directed in the opposite side.

[BLSTIC]

You can just make a manometer. I made one for about $10 in materials (I think, but it was definately cheap). Buy a length of whatever wood at bunnings, a large length of clear ~8mm hose, 8-10 U shaped nails and some food colouring (blue is good). The most restrictive intake I have heard of was on a stock RS Liberty (around 32 inches of water, or a bit over 1psi) so if you have a piece of wood that length it will probably measure anything.

find the mid point of your hose and nail it just enough to clamp (not enough to choke the hose) to the bottom of your wood. Then nail the two halves of the hose parallel (and close) to each other. Fill the hose to the half way point with coloured water. Mark off lines half an inch apart as whole inches of water (because the each side only moves half an inch for each true inch of water column height) and use it as a normal gauge type manometer. It won't be as easy to read at very low pressures like half an inch of water but a good point to look for is 5-10 inches of water total restriction.


Incidentally if you *do* move the battery you may be able to fit a larger air box out of something like a falcon (which also sit in that corner of the car and has been proven to flow very well with a decent inlet and outlet pipe, standard filter, up to around 160-170 flywheel kw).

If you're at all worried about filter flow just find a pod that has a bell-mouth built into it (as many supercheap ones do) and hide it inside the shell of a factory box that you can then hack up as much as you want (when there's no more requirement for it to seal around a filter).

[BLSTIC]

Oh and PVC/ABS pipe can easily be heated, molded, stretched, bent, plastic welded and sanded to make all kinds of cool shapes. Then painted. Don't under-estimate $30 worth of plumbing when it comes to making complex looking patterns.

[jondee86]

Apexi filter in TERRA's pic is a pleated paper type, and has pretty good flow and filtration performance. Put one on the end of a nice free-flowing intake pipe, and you will see some gain, especially at higher revs. Paint the alloy tube matt black for more of a "factory" look.

Cheers... jondee86