drilling airbox

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billo

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MGZS
hi bit of advice ive got a k&n panel filter in my airbox instead of spending money on other filters ive heard you can drill holes in your air box to give it a bit of a grunt i experimented this by just opening up the box by half inch and went for a drive the sound was very subtle and only grunted on hard acceleration which did sound very nice but im very unsure about drilling the air box cant afford upgrades but did like the sound , any advice ! cheers
 
It might make a bit more noise (a nice noise I might add) but I wouldn't do it myself. You run the risk of sucking in dirt and damaging your AFM or throttle body. You'll also be sucking in warm air from the engine bay rather than the cold air from the feed pipe which could slightly blunt engine performance.
 
Greetings billo and a Warm Welcome to our TorqueCars Forum my Friend!

Good to have you along with us :)
 
Im afraid just cos its on you tube doesnt make it so however..........

Changing just the filter wont make any noticeable difference unless the stock filter is restrictive, Neither will drilling holes anywhere .

The point of fitting a sports filter is when the engine performance has been enhanced to the extent that the filter is restrictive. Then there is a definate gain
 
Get a spare air box from the breakers yard and play with one to see if you like the difference.

If it has veins inside it can help a little smoothing this out. These are added to cut down induction noise and as a result can slow the air up a little but a good air box design should not really be restrictive in the first place.
 
Thanks for the replies guys i am really new to all this (and to the forums) but am willing to learn and take advice so probly gonna be bombing you lot with questions lol :blink1:
 
Just drilling holes doesn't work. You need to smooth any fins in the box. Get it as smooth as possible as this helps reduce air flow restrictions.

Edit* Sorry Waynne, I didnt see your post there!
 
After looking in the airbox there doesnt seem that much restricton tbh the veins to me dont seem that intrusive so would it really be worth all that work smoothing out ?
 
If you are convinced that the existing filter is restrictive, what's wrong with simply removing the filter from the box?

With the twin cam engine that used to be in the Elan and the Pinto in the Robin Hood, the twin Dell'ortos and Webers just had trumpets. No problem with this mythical dirt everyone talks about.

If you want the best N/A sound, you can't beat unfiltered webers/dell'ortos.
 
HDi fun said:
Hmmmm - not sure I'd want to risk that
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Think about it. How is this mythical dirt going to get up to the carbs? The gap between the end of the trumpets and the innner wing on the Elan was around 3". The gap betwen the sump and chassis sides was around the same. This dirt had to, therefore, make its way up approx 750mm from the road surface, between the sump and chassis and then do a 90 degree turn into the carbs. Even in heavy rain the area below the carbs stayed dry.

I drove this car for around 10 years without a filter and in all weathers as it was my daily driver. When I strpped the engine for EBay selling inspection (it had sat for 19 years) the bores still had the honing marks but no damage and this had seen quite a bit of action up the Pod.

On the Robin Hood the gaps are even smaller. As for modern cars, there are no gaps anywhere! If you leave the air box on the only way in is via the box inlet. Providing this isn't pointing to the ground, sticking out of the front panel or in an obvious dirty area I can't see a problem.

I know didlysquat about modern cars but I reckon removing the air filter will do no mechanical damage as nothing can get in. However, you may have to play with the map.

I would be interested in the counter argument :)
 
TommyTwinCams said:
Your age is showing. Who has a carburetor anymore? Everything's fuel injected.
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Yup, guilty as charged! Mind you, carbs are still popular with the V8 hot rod and drag boys (and girls).

Even so, I stick by my reasoning, whether carbs for FI is fitted.
 
How bout instead of drilling just holes in the box i drill one hole about 40 mm and put a duct pipe on it like the original one thats on it now but ill have 2 air flows into the box instead of one but no dirt
 
rmx-facepalm_fb_1072309.jpg
 
If the filter is restrictive, adding holes or extra pipes to the air intake side of the box (air intake-filter-engine) will make absolutely no difference as the filter will still be the limiting factor.

If the filter isn't restrictive, additional holes or pipes will still make FA difference as the engine is already getting all the air it needs as the filter box intake is plenty big enough.

I reckon that any effects felt (other than noise) on a standardish car are purely wishful thinking. However, it is a phase we all have to go through when starting out on this wonderful journey called car modding :)

The above is based on 43 years of playing with cars, reading about cars and listening to people far cleverer than me. However, I may still be wrong.
 
old-git said:
If the filter is restrictive, adding holes or extra pipes to the air intake side of the box (air intake-filter-engine) will make absolutely no difference as the filter will still be the limiting factor.

If the filter isn't restrictive, additional holes or pipes will still make FA difference as the engine is already getting all the air it needs as the filter box intake is plenty big enough.

I reckon that any effects felt (other than noise) on a standardish car are purely wishful thinking. However, it is a phase we all have to go through when starting out on this wonderful journey called car modding :)

The above is based on 43 years of playing with cars, reading about cars and listening to people far cleverer than me. However, I may still be wrong.
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But thats my point i dont want it to go much faster as havent got the money to spend but have just had a remap and wanting to know how to make a bit of a growl under the bonnet without spending money like i said opened up the air box by bout an inch just as an experiment and on accelarating hard there was a nice growl to it all i want to know now is how do i keep that sound doing it safely just with what ive got
 
Without spending money, messing with the airbox isn't going to do squat. You want the car to growl, pay for a cold air intake and a full exhaust (from the header to the tip). That'll give you the noise you're after. Nothing in the car world is cheap or free.
 
TommyTwinCams said:
Without spending money, messing with the airbox isn't going to do squat. You want the car to growl, pay for a cold air intake and a full exhaust (from the header to the tip). That'll give you the noise you're after. Nothing in the car world is cheap or free.
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But with the k&n panel filter ive got in when i opened up the airbox by an inch it gave me the sound that i want so now how do i mod the airbox to still give me that sound but safely
 
Problem with the K series engines Tommy, is the air box is tiny. To ideally get the most of it, a BMC CDA enclosed induction kit has proven to give fair gains with these engines. Now... I cannot remember if the 1.8 120 version has the 52mm throttle body attatched. If you find a BMC CDA to expsensive new, find a used one on Ebay or something.
 
I'm with OG on this.
When I go to marshal for the vintage bikes, most of them if not all use open ended trumpets on the bike carbs with no problems at all. Even in rain they don't add anything.
 
I thought dust etc caused pitting in the piston chambers and scarred sleeves and all that? I'd imagine driving in hot countries you'd want a filter shurely?
 
filters are a safeguard for modern engine

vintage engines dont need them as the tolerances they run are nothing like nowadays

i had a 650 single side valve bike that maxed at around 4500 rpm and ticked over so low you could count the rpm

TBH you could probably have put a stone in the carb and it would have spat it out the exhaust without a problem
 
Yugguy said:
I thought dust etc caused pitting in the piston chambers and scarred sleeves and all that? I'd imagine driving in hot countries you'd want a filter shurely?
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Define dust? Most dust is organic so will simply burn. If you are running offroad then a filter would be sensible.

Hot country? California if hot but not dusty unless you go out into the desert. If driving in the Middle East a filter would be a must, IMO.

I am talking about the UK road network which, although it has lots of potholes, isn't dusty due to the amount of vehicles using it and the rain we have.
 
davalav said:
Problem with the K series engines Tommy, is the air box is tiny. To ideally get the most of it, a BMC CDA enclosed induction kit has proven to give fair gains with these engines. Now... I cannot remember if the 1.8 120 version has the 52mm throttle body attatched. If you find a BMC CDA to expsensive new, find a used one on Ebay or something.
Click to expand...

Thanks for clarifying. We don't have those engines over here, so I'm out of my element a bit.
 
Maybe you can remove the lid of the air box and lie a cone filter in there. That's what I've done. The filter doesnt't get wet. Sound is great and the air is the same temperature than inside the closed box. I' ve done a lot of testing of temperatures inside the engine bay through all driving conditions. I wouldn't say I'm an expert now but one thing is for sure. "Cold" air intakes or not alway designed to take colder air in. You must try and work out yourself the coldest point inside the engine bay and go from there.
 
Am i right in saying that the more air that goes into the engine then the quicker the fuel will burn, or has my memory of 70's diy totaly gone ?
 
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