Drilled Air Box ?

[steveT5]

Evening all, I occasionally hear about drilled air boxes. Could anyone tell me what is this mod ? How is it done ? What are the benifits ? Is it worth doing ?
Thanks.

[glock19]

Personally, I would not do it because the heat from the engine bay would be higher than the air intake area before the radiator. I live in a hot and humid climate all year round, so in a colder one, maybe there's some advantage. Air flow and suction noise might be higher though.

[Bracer]

Some people Drill holes in the lower half of the air box to make more of a induction roar, and allow the CBV to be heard when lifting off the throttle

[Mrsmopp]

Like mine!!! My airbox has been drilled and whether it makes any difference to the performance or not I couldn't tell you BUT being able to hear my turbo whistle like a boiled kettle and the different tones of my engine at various points of boost means, that for me, it was a well worthwhile mod!!

x

[Wobbly Dave]

Surely glock the intake from the front is not radically different from the air coming over the back of the gearbox?

Anyway there was a substantial improvement in performance with the drilling of the airbox in mine. I did the mod 2 weeks back and particularly at the top end I found that the car is able to pick up speed. I am looking to source som pipe work to improve the cold air feed to the general area.

I also enjoy the noise from the CBV (does this make me a chav?)

[SaffronC70]

I've got a swis cheese airbox with KN panel sitting in the garden if you want to give it a try ?!

[glock19]

Surely glock the intake from the front is not radically different from the air coming over the back of the gearbox?

Anyway there was a substantial improvement in performance with the drilling of the airbox in mine. I did the mod 2 weeks back and particularly at the top end I found that the car is able to pick up speed. I am looking to source som pipe work to improve the cold air feed to the general area.

I also enjoy the noise from the CBV (does this make me a chav?)

Dave,
Is the air not hotter over the gearbox since part of it came through the fan after the radiator/intercooler/condensor coil (air-cond) ? With the airbox drilled, do you still retain the plastic ducting from the front ? Cool air can be directed by removing the left headlamp though

To the rest,
Are you still using the standard Recirculating Valve or aftermarket BOV for the 'music' to be more apparent ?

[Mrsmopp]

Standard recirc Giles!! I am blessed with a car that likes to make its presence known so no need to buy a BOV!!

x

[Wobbly Dave]

Dave,
Is the air not hotter over the gearbox since part of it came through the fan after the radiator/intercooler/condensor coil (air-cond) ? With the airbox drilled, do you still retain the plastic ducting from the front ? Cool air can be directed by removing the left headlamp though

Air will peal around the bottom and back of the gearbox as well as from the front.

[Justin]

The principal is this.....and i sell it on ebay and have for 2 years, i also have done several conditioned tests to which at least 2 people will verify if needed.

When travelling air is forced under the car, some gets fed up behind the turbo and some travels up from behind the gearbox and is sent directly to the bottom of the airbox, trust me, it does. So by drilling holes in the bottom you get ambient air into the bottom of the box, when stationary you will have warmer air from the engine bay, but you dont need cold air when your standing still anyway.

We carried out 2 tests, same car, same day, within 1 hour of each other, uphill climb on an open road in 5th gear, the car took well over a second less to pull from 70mph-110mph with the drilled box. (it was almost 2 secs)

Then on my car the same was done, it was 2 seconds quicker from 70mph-110mph, this i think is due to the flow rate being supplied to the engine, thus producing more power after taking its many readings from sensors, one being the MAF. My car at the time was an 855 T5, the other was an ex police S70 T5.

Also have a guy on this forum that uses a g-meter and the meter claimed he gained 17 bhp, same road, same car, same day within 1 hour, just by making holes in the box.

If you don't think it works, have doubts, are a skeptic etc, don't do it, i really don't care, but i know it does, and no one yet has proved me wrong.

Just my take on my mods

[adesou]

So wot size holes are we talking about and how many?

[Justin]

On the 2 tested cars we drilled 30 holes on the bottom using a 10mm bit

[lance]

Another job I will get round to doing when I finish the babys room!
Does the mod increase boost conciderably too?

[glock19]

On the 2 tested cars we drilled 30 holes on the bottom using a 10mm bit

Okay Justin, I'm sold. BTW what is the limit of the number of holes on the box, not breaking apart when we pull out the box when accessing the gearbox ? 30 here is 6 horizontal and 5 vertical (standing in front of the car), right ? How far apart will the holes be ? I think you try not to hit any ribs, right ?

[Giles]

Okay Justin, I'm sold. BTW what is the limit of the number of holes on the box, not breaking apart when we pull out the box when accessing the gearbox ? 30 here is 6 horizontal and 5 vertical (standing in front of the car), right ? How far apart will the holes be ? I think you try not to hit any ribs, right ?

i could be wrong, but do not think it matters - as long as you don't 'overdo' it - did mine last night. 10mm drill and as many as i could get in, leaving approx. 5-8mm between the holes. I too noticed pick-up from higher revs great!

[Justin]

Lance it will not increase the boost at all....

There is no limit to the amount of holes, just go for it, leave at least 5mm though between them to keep the structure, we hit a few ribs, but it wont matter, just make sure you clean out all of the debris after and smooth the edges off with a file.

[SaffronC70]

I'm sure you know, but only drill the bottom half of the airbox !

[glock19]

I'm sure you know, but only drill the bottom half of the airbox !

Yup, thanks.

[Wobbly Dave]

I used a 13mm wood drill bit - makes a nice hole which fits nicely into the squares formed by the latice in the bottom of the box.

Lance I can pop over and do yours sometime if you like?

[steveT5]

Seems like quite a debate i've stirred up ! Thanks for the offer of your air box to try Saffron, But i think with such a posotive response, i will go down the shed and get my drill out !!!
Thanks to all for the info !