GolfGTIforum.co.uk
Model specific boards => Golf mk3 => Topic started by: whileoceanasleeps on 23 December 2012, 21:45
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thinking of modding my airbox soon, so just wondering what your setup is in regards to airbox mods? I know there's a few different ways.. cheers
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Once upon a time I though holes and cutting away sections was best, so my dyno graph said.
Then I cut away a little bit more, and my power was down.
After research and more research, and speaking to some people (people who actually know), I came to the conclusion that a sealed airbox, with the inside smoothed and the intake pipe on the inside rounded off and one or two sealed cold air intakes, giving the airbox more air than it's using, is the best method. It might not sound as loud as a drilled airbox but performance-wise it's the best setup.
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I got a 80mm hole saw and made the standard intake hole 80mm :grin:
Then got the trumpet from the top half of the air box and cut the trumpet end off. I then sealed the it in the 80mm hole with silicone and got a 80mm hose.
I need twin Hellas to make my second air box :wink:
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I need twin Hellas to make my second air box :wink:
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Elaborate.
Do you mean removing the offside spotlight and using that as a cold air intake? That's what I wanted to do, but I think it's illegal to remove one of the spot lamps.
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I need twin Hellas to make my second air box :wink:
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Elaborate.
Do you mean removing the offside spotlight and using that as a cold air intake? That's what I wanted to do, but I think it's illegal to remove one of the spot lamps.
That's exactly what I want to do. And I got a grill that takes hella lamps :wink: ugly as hell but will still have 4 lamps but 2 massive cold intake holes. I got 100mm trumpets that I got from empty electrical wire boxes from site. That I will mould/fibre glass in.
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I've got a garage full of air boxes and bits of tube, holes are deffo sh!te as is any unshielded filter in the engine bay.
The rest is a question of how much time and money you have vs what sort of power gains you want from the N/A abf.
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I've got a garage full of air boxes and bits of tube, holes are deffo sh!te as is any unshielded filter in the engine bay.
The rest is a question of how much time and money you have vs what sort of power gains you want from the N/A abf.
err not much money a lot of time. just want more power and efficiency and noise!
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I've got a garage full of air boxes and bits of tube, holes are deffo sh!te as is any unshielded filter in the engine bay.
The rest is a question of how much time and money you have vs what sort of power gains you want from the N/A abf.
err not much money a lot of time. just want more power and efficiency and noise!
Two of them words go together and one doesn't belong in that sentence.
Modified sealed box keeps efficiency and gains power but no noise.
Noise looses efficiency in case of cone filter, but drilled box will have no effect, but it will loose power.
You pick what you want.
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I've got a garage full of air boxes and bits of tube, holes are deffo sh!te as is any unshielded filter in the engine bay.
The rest is a question of how much time and money you have vs what sort of power gains you want from the N/A abf.
err not much money a lot of time. just want more power and efficiency and noise!
Two of them words go together and one doesn't belong in that sentence.
Modified sealed box keeps efficiency and gains power but no noise.
Noise looses efficiency in case of cone filter, but drilled box will have no effect, but it will loose power.
You pick what you want.
:grin:
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having a 1.4 i might aswell start blowing air in the intake myself but decided to get a cold intake pipe and smooth then drill my box it makes it sound louder but performance is none.
it all comes down to noise or performance.
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Iv ALWAYS said drilling holes in the standard box was daft....
Tweed, all that work man, just mount a cone outside behind bumper, works a charm, i know i have a big intercooler but its alwats best having cold air going into a Turbo rather than already warm air.. bit less work for intercooler to do :smiley:
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having a 1.4 i might aswell start blowing air in the intake myself but decided to get a cold intake pipe and smooth then drill my box it makes it sound louder but performance is none.
it all comes down to noise or performance.
So you put in a cold air feed and drilled the box, meh?
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Iv ALWAYS said drilling holes in the standard box was daft....
Tweed, all that work man, just mount a cone outside behind bumper, works a charm, i know i have a big intercooler but its alwats best having cold air going into a Turbo rather than already warm air.. bit less work for intercooler to do :smiley:
could you put up a pic or two of this? i'm quite interested..
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Iv ALWAYS said drilling holes in the standard box was daft....
Tweed, all that work man, just mount a cone outside behind bumper, works a charm, i know i have a big intercooler but its alwats best having cold air going into a Turbo rather than already warm air.. bit less work for intercooler to do :smiley:
We don't have turbos and inter coolers. Just mounting a cone filter behind the bumper is pointless for N/A engines. Or have I missed something?
Having two 100mm holes forcing air into a sealed air box at 70mph is much better. The faster you go the more air being forced in that box. It has no where to go other than in the inlet. (Forced induction) that's why you fit a turbo right? You get your forced induction from the turbo, I get my forced induction from cold air feeds at speed.
You won't get that from just sticking a cone behind the filter.
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We don't have turbos and inter coolers. Just mounting a cone filter behind the bumper is pointless for N/A engines. Or have I missed something?
Having two 100mm holes forcing air into a sealed air box at 70mph is much better. The faster you go the more air being forced in that box. It has no where to go other than in the inlet. (Forced induction) that's why you fit a turbo right? You get your forced induction from the turbo, I get my forced induction from cold air feeds at speed.
You won't get that from just sticking a cone behind the filter.
what tests are these based on ??
yeah you have missed something, basically id would think you will be able to get much more air to a Cone behine the lower bumper, a cone is a bigger area than the standard box filter and also much easier to get more cold air feeds to - at low speeds too.. you would have to drive at 100mph to see any real benefit with it the way you describe..
will also look alot better than lamps missing and stupid square lamps in grill, however thats just my opinion
You way seems a lot of more for about a 1 BHP (if you are very lucky) gain...
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We don't have turbos and inter coolers. Just mounting a cone filter behind the bumper is pointless for N/A engines. Or have I missed something?
Having two 100mm holes forcing air into a sealed air box at 70mph is much better. The faster you go the more air being forced in that box. It has no where to go other than in the inlet. (Forced induction) that's why you fit a turbo right? You get your forced induction from the turbo, I get my forced induction from cold air feeds at speed.
You won't get that from just sticking a cone behind the filter.
what tests are these based on ??
yeah you have missed something, basically id would think you will be able to get much more air to a Cone behine the lower bumper, a cone is a bigger area than the standard box filter and also much easier to get more cold air feeds to - at low speeds too.. you would have to drive at 100mph to see any real benefit with it the way you describe..
will also look alot better than lamps missing and stupid square lamps in grill, however thats just my opinion
You way seems a lot of more for about a 1 BHP (if you are very lucky) gain...
Got my info from the rr test day trying cone filters and modified air box.
Also I have a 10mph gain down a 1.1 mile straight from a drilled box to a sealed box with 80mm cold air feed.
You have missed something! No matter how much cold air feeds you run to a cone filter it will be wasted as there is nothing to contain the unused air. Air will be escaping in all direction.
With a sealed unit you capture every last bit of air that you can get.
You will have twice as much air at 100mph with two 100mm feeds to a sealed unit than a open cone filter.
Christ the standard box has a 50mm opening that goes to the wing. And that copes just fine at low speed. So why would you have to go 100mph to see any gain from my air box?
What gain do you get from a cone filter? From all the research I've done I haven't seen any on a N/A motor.
I truly am surprised at you to think a cone filter behind the bumper is a good idea.
Just to add even though if you read properly I wouldn't have to, I have a grill that uses round hella lamps. Not the square fog grill your on about.
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And I also called it ugly as hell. I agree with you on that.
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The only problem of having the cone mounted so low is water intake. With the number of streams that cross the road I've had to cross in the last week I would have had to call the AA a few times. I can see the benefit in a turbo car, as the bay is a hell of a lot hotter than on an NA car, but once the air is in the engine and out of the exhaust it's going to come out piping hot anyway, so it's not really worth risking a few degrees cooler if it means there's a chance of sucking in water.
I'm sure tweed hasn't had his airbox on a CFD program but if I blow into my cold air intake (fog lamp housing) and put my hand over the other side that feeds the box, I can feel the air going through, and that's out of my lungs, I can image a hell of a lot of air going in when travelling at speed.
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In the rr air box thread the open filter has a massive fan blowing on it and with a open bonnet so no hot air is around the filter.
It then gives better torque than a standard box, but the torque is matched by a modified top half air box. I can't see the cone filter getting any more gains than that on the road.
Why even waste money on a cone filter? When you get same results as a modified top half air box.
I'm then adding two 100mm cold feeds to that box. You telling me I won't see any gains?
I think someone has had a heavy Xmas and is not thinking things through.
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i think i remember tht grill yeah (dont do it tho :sick:)
Anyhow - Space in the airbox to capture air.. haha.. serious ?
(cone filters need not do this. should see the size of mine its farkin HUGE :evil:
the hole in the wing for standard box is not very good at all IMO, if i was to keep a standard box id junk that for a better location of feed, i found brake dust in my box along with leaves and sh!t
Lastly have you ever had a issue with heat soak ? i haven't ever... wouldnt get too hung up on all this filter bollox.. more stuff to worry about. especially if its on the 8v (not a joka against the engine as i dont mind it, just this whole heat soak thing is a bit over hyped)
Khare the filters is monted at a height so that water is not a issue, iv had mine on over a year with a big ass direct feed to my bumber grill, i use the car every day, rain or snow and never no issues. i dont think Tweed ever uses his as his mileage never goes up :laugh:
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In the rr air box thread the open filter has a massive fan blowing on it and with a open bonnet so no hot air is around the filter.
It then gives better torque than a standard box, but the torque is matched by a modified top half air box. I can't see the cone filter getting any more gains than that on the road.
Why even waste money on a cone filter? When you get same results as a modified top half air box.
I'm then adding two 100mm cold feeds to that box. You telling me I won't see any gains?
I think someone has had a heavy Xmas and is not thinking things through.
i would bet you that u see no gians nor feel any gains
id agree i wouldnt spend money on a cone if i dint have to, but somethimes its the only route to take
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I doubt ill do it in all honestly as I'm still gonna vr it, but if the Hellas come up cheap ill give it a go.
And yeah that grill :sick: what a joker :grin: only opened the box two weeks ago.
When I vr mine I want it loud and already got a simota carbon loud box on it only like vr6's for the noise so its got to be loud. :grin:
But I do stand by what I say! I do think it will give more than 1bhp and that's slower than 100mph.
If I had a turbo yes I would go out and buy a cone filter because that is the only way to go. But certainly isn't on a N/A
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I've done 10,000 in 2 years and 3 months :grin:
And I think that's to much.
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Reckon a 16v needs about .92 Cubic m/s at full chat, VW must have made it at least 90% efficient in the factory.
To increase intake pressure (without going on about bernoulli) a turbo needs to pump more than this figure.
What hope does an 80mm bit of pipe have?
To put it into perspective .92 CmP/S is about 5500 lts per min, the engine is drawing this in on its own.....
My maffs is a bit out granted as im suffering a port headache but you get the picture
I think the OP would be happiest with a cone filter or a giant hole, just for the sound and the backfire on engine breaking, did me for years :grin:
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Have you read this thread?
I'm on about two 100mm feeds.
And why work cubic m/s at fall chat?
Why not work it out in litres at 4000rpm?
To get boost you need to go from 1 atmospheric pressure to 1.01
1 atmosphere is 14.6 psi
Most standard turbos are 7psi. I'm sure most people are running 12psi.
So you only need 1 psi to get air inlet pressure.
What bhp gains do you recon you would get from say 0.5psi to 1psi
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To make it easy for you a 4 cylinder 2.0 engine will use 1 litre of air every 1rpm.
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3373 lpm at 4000 rpm with an efficiency of .85........
Why not try four 20 cm pipes, you may need a dump valve with all that boost your building
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N/A engine at 4000rpm will have minus - pressure, a vacuum because its sucking air.
Lets just say it -7psi at 4000rpm. Now I ain't believing that I will get boost, that's just plain stupid.
Why you are thinking that is beyond me?
I do think that I can lower the vacuum inside the air box with a big cold air feed. So the engine doesn't have to suck in as much air.
And at 4000rpm the engine will be sucking 4000 litres of air. That's 66.6 litres a second.
How are you working your math out?
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N/A engine at 4000rpm will have minus - pressure, a vacuum because its sucking air.
Lets just say it -7psi at 4000rpm. Now I ain't believing that I will get boost, that's just plain stupid.
Why you are thinking that is beyond me?
I do think that I can lower the vacuum inside the air box with a big cold air feed. So the engine doesn't have to suck in as much air.
And at 4000rpm the engine will be sucking 4000 litres of air. That's 66.6 litres a second.
How are you working your math out?
Volumetric efficiency of 85%, just one of many variables when calculating air flow and fluid dynamics.
The one of the variables you are playing around with by flowing an air box or intake manifold.