[ChrisH]

It has been pointed out many times that the aftermarket air intakes don't have any air vanes to ensure the air flow is straightened out before hitting the MAF, and that may cause some issues (such as CELs) because the air flow isn't the same over the MAF as it is with the stock air box. Some of the aftermarket filters even boast that they create a swirling action. The stock air box has a single vane (a miminal one), and there is nothing about the stock air filter design that would cause any kind of swirling action.

Rather than find a vane insert (such as a honeycomb that SweetDaddyD found, if I recall correctly) from another car at a junkyard, I decided to make my own simple vane insert. I basically did it with a single sheet of aluminimum, which I folded up, inserted into the air intake at the filter end, and secured with a single short sheet metal screw. The instructions are in the attached file. I have also attached some pictures.

The screw was also placed such that it forms a depth stop when putting on the filter, which makes putting the filter on a bit easier.

My aftermarket intake is a Fujita. I have been running this vane mod for about 6 months with no problems. However, I should note that I wasn't having problems before, once I started a slow learning method when changing air intakes, and cleaned the air filter every 10,000 miles. However, I added this mod for peace of mind. Other recommendations I have for the Fujita can be found here:
http://www.lotustalk.com/forums/f154/fujita-air-19014/index8.html#post1264307

Also, I recommend in your choice of aftermarket air intakes that you get one that has the same (or nearly so) inner diameter as the stock intake. I started a thread (link below) that has some real measurements of inner diameters.
http://www.lotustalk.com/forums/f154/air-intake-inner-diameters-52402/

 

[ChrisH]

One thing I forgot to mention in the instructions is related to the screw holes through the two flaps of the vane. The pipe and the flap closest to the wall should have a larger hole so that the screw can go through them without catching the threads. The interior flap should be small enough for the sheet metal screw threads to engage. It acts as a nut to pull both flaps tight. I have updated the instructions to say this.

 

[Seb]

You should check out the turbonator. They create a vortex and give you like 5whp or something like that.

 

[ChrisH]

You should check out the turbonator. They create a vortex and give you like 5whp or something like that.

You explicitly don't want that in the Elise intake. You want a straight flow, which is what the stock intake provides. Vortex flows mess up the MAF reading. The ECU relies on the MAF reading for proper fuel/air mixture. If the MAF reading is incorrectly low, then the engine would run lean, which would increase HP slightly, but cause other problems, including a CEL when the ECU notices it is running lean, and potentially damage your engine (gasses too hot, and possibly detonation).

 

[Seb]

I was ****ing with you.... but thanks for making my night

I would just find a honeycomb from an old MAF from what ever vehicle and cut it to fit. Would be a little more effective than what you have currently.

 

[ChrisH]

I was ****ing with you.... but thanks for making my night

...

I'm obviously too literal.

 

[ChrisH]

...I would just find a honeycomb from an old MAF from what ever vehicle and cut it to fit. Would be a little more effective than what you have currently.

I agree that a honeycomb could be more effective, but one of the points of doing it this way was to not go rooting around in a junk yard looking for something that would work. Also, the stock air box only has one short vane (short in the direction of the airflow). This method has two effective vanes, both of which are longer in the direction of the airflow than the stock one. So, I think it is probably good enough (as good as or better than stock).

 

[Frank Amoroso]

Does the stock piece fit into the Fujita?

I am one of the ones that used the black plastic mesh from a Porsche 968 / Audi RS2 MAF on my Turbo XS intake (which is FS btw, if anyone's interested) and I'm using stainless steel wire mesh in my Fujita (which is on the car), but I'm curious as to whether the stock piece wouldn't be the better solution? The Fujita has been on my car for 12,000+ miles and I've had a CEL pop-up 2-3 times earlier this past summer.

[Oy! I thought my 300th post would be more glamorous]

 

[ChrisH]

Does the stock piece fit into the Fujita?
...

No, I don't think you can use the stock piece.

I found that if I use the slow learning procedure (see link in post #1 in this thread) and keep the filter clean (I clean it every service interval now, every 7,500 miles), then I don't get any CELs, even before I put in the air vane. This ECU is very sensitive to dirty air filters (or even wet ones, say, if it got wet while washing the car). I just put in the air vanes for peace of mind, not because I was getting CELs.