Stardard Airbox/Uprated replacement element.

[climbinghutch]

Hey, while recently working on the Micra i was looking at the standard airbox and thinking back to my Mini ownership days.

On the airbox the inlet is smaller in area than the inlet to the throttle body. On my old Mini the same was true. A tip from my Mini friends was to replace the element with a K&N or similar and then simply drill extra holes around the outer edge of the airbox so that the area was greater than that of the inlet to the carb. Then with hosing to direct cold air to the airbox you can then maintain the apperance of a standard car but have the benitfits of increased induction.

Does anyone know if the same will happen if the same principle is given to the throttle body of a Micra?

Looking at the Micra airbox i think it may be possible but the element is really small compared to a Mini for some reason. Anyway thought i'd ask before trying it..

 

[Titch]

You can get the K&N Panel filter, i belive Mike has one in the NME Micra, and he still thinks its the best setup. As for the drilling the box, i've heard it is actually better.

Titch

 

[user49484948488484]

So whereabouts do you drill into the airbox? I've heard this from some mates but seems a bit dodgy, would I notice improvement with drilled holes and standard air filter?

 

[Zephyr]

holes just take a look at the way the box filters air n then drill holes in the bit b4 the filter to tb that way it still filters air if u get what i mean n curdy u would hear basically more noise from ur box abit like an induction cone or something but performance i wouldnt count on it

 

[Craig]

You will suck in hot air if you just drill it.
The airbox is the best set-up, you can either run a larger duct to it (best option) or you can drill it and duct some air too it (not as good).
I keep meaning to have a play with airboxes as I am sure that there are gains to be found but am too lazy lol

 

[climbinghutch]

Just a little update, haven't been on for a while. I went to the scrapers and got an old airbox to experiment with and just in case it all went a bit pete tong...

If you look at the standard airbox, before the filter, there is just a single entry from the original ducting. To the side is a blank space big enough to drill a second entry hole of the same size. Then simply run ducting along the path of the original airhose from the front grill into the airbox. Jobs a good un'.

The area of the inlets is now greater than that of the inlet to the manifold and so more air can enter the airbox than is needed at any time.

As for induction noise increase, there is not a lot. But that's what i was aiming for. Exhaust note provides all the music i want and as for performance increase etc., not a clue. How much extra power does just a performance filter change make anyway.

Just eased up on the engine asthma a bit i guess! Kept a fairly standard looking engine bay aswell.

 

[Zephyr]

performance i say ur lookign at like 1/2bhp nothing much heh

 

[Hugh]

I drilled my K11 airbox when I had it. So did Norfolk. Both of us found it to help a little. I found that mine became a little more responsive, when testing with holes covered and uncovered.

Best setup may be drilled with aftermarket filter panel, but that's just my opinon.

 

[JayY]

I dont see how it can be more responsive or add BHP because your suckin in hot air through the holes. Micra's dont like hot air.....

 

[Hugh]

Mine ran better, and besides it wouldn't of been that much difference in air temp for the air brought in at the front.

It's time someone actually tested this with probes, as I doubt that there'd be alot of temp difference in the air box, from drilled and non drilled whilst moving.

 

[Dusk]

I dont see how it can be more responsive or add BHP because your suckin in hot air through the holes. Micra's dont like hot air.....

ie cream boxes with tinfoil are better ive heard

 

[goldstar0011]

Mine ran better, and besides it wouldn't of been that much difference in air temp for the air brought in at the front.

It's time someone actually tested this with probes, as I doubt that there'd be alot of temp difference in the air box, from drilled and non drilled whilst moving.

Wondered this myself.
If you're doing 50mph the airs moving that fast that there's barely anytime for it to sit around your manifold toasting marshmellows and getting nice and warm before vistiting the airbox!

I only notice differences on hot and cold days where the air is obvisously different

 

[Davey C]

this is the design i went for works quite nicely

 

[richmicratwista]

where is the extra piping from

what car?

 

[Davey C]

Mondeo front half and the back half is a sunny 1.6

 

[Fordy]

davey c heres a tip you might already know or you may not, to get a lil bit more responsiveness look in the attachment,

the part i have put a yellow line on cut it off where the red line is and block the hole, getting rid of the expansion chamber is what i did to a p11 gt which went i little better once the expansion chamber was taken off just an idea if your using a panel filter

 

[Davey C]

aye mate cheers, i'll have a bash at that. whats you theory for doing it or did you simply try it and it helped?

 

[Fordy]

the p11 was running like poo when the engine got hot due to the air in the expansion chamber getting hot from the heat of the gearbox then going into the engine, we were just trying things out on saturday as the expansion chamber is held on with a hose clip so if it didnt work we could always go back to standard, it helped improve the response of the engine but i dunno what gains you can get from doing it to a micra it can only bring good things to get rid of it in my opinion
the only bit you would have to be carefull of is where i have marked in blue in the attachment hopefully the pipes are seperate and not join all the way though the middle of the bit in blue overwise you will have to block it some how if you do this to it tell post up what gains you get from it as im interested in getting a k11