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Model specific boards => Golf mk2 => Topic started by: DarnPB on 03 May 2007, 10:42

Title: Drilled airbox
Post by: DarnPB on 03 May 2007, 10:42
I have a '91 8v GTI and the other day in  a fit of boredom, I removed the airbox and drilled some ferkin great 'oles in it. Four to be exact, two of which I joined together to make an oval. 3 of the holes are 2.5'' with the other being 2''.
What a difference! Throttle is more responsive and acceleration is better. The only down side is that when I plant my foot, you need to turn up the radio as the induction roar is a little over powering. Its good fun off the lights though, although the fuel consumption is a bit more. But thats only my heavy right foot!!! :grin:
Title: Re: Drilled airbox
Post by: gibby on 03 May 2007, 14:46
I cleaned out my Rallye airbox the other week and I saw that the previous owner had drilled a good few holes in the airbox wing side. I thought the loudness of the car was due to my exhaust (g/f hates the noise it makes ! :grin: ) but I think it may well be the good few holes wing side of the airbox. :laugh: Oh well, fuel consumption is sh1te on it anyway ! :grin: 
Title: Re: Drilled airbox
Post by: cняis on 03 May 2007, 22:12
average 40mpg  :cool:

drilled airbox with K&N panel filter but i drilled lots of 5mm holes close together across the whole inner wing side
Title: Re: Drilled airbox
Post by: tom26 on 04 May 2007, 15:29
^ 40mpg?? driving miss daisey?
Title: Re: Drilled airbox
Post by: dabill on 04 May 2007, 17:32
40mpg?? best i have ever had outta it is 30. something... usually around 25 mpg. might be cos im always sat in traffic lol..
Title: Re: Drilled airbox
Post by: monzablue16v on 04 May 2007, 18:22
Average now is 37.9 better than the 18 I was getting before I rebuilt it and I don't drive like miss Daisy :D
Title: Re: Drilled airbox
Post by: vw-bob on 04 May 2007, 18:46
i recenly drilled my airbox, but since doing that i have had a popping on deceleration. is this ok or should i put a normal box back on?
Title: Re: Drilled airbox
Post by: T_J_G on 04 May 2007, 18:48
i recenly drilled my airbox, but since doing that i have had a popping on deceleration. is this ok or should i put a normal box back on?

yours is a Driver/Ryder ins't it?

I drilled the top bit of my carb cover when i had a Driver.....where volkswagen s written and sisn't have a problem....lol

bodged!
Title: Re: Drilled airbox
Post by: vw-bob on 04 May 2007, 18:52
yep its a driver. i drilled the underside and front of the front section of the air box. the bit that comes off easily when you undo the clips on the outside
Title: Re: Drilled airbox
Post by: dan7 on 04 May 2007, 20:06
Funnily enough, i drilled the underside of my airbox on my GTD the other sunday. Same again, even on a diesel! Much better acceleration and more responsive on the go pedal! And, induction roar at last! Thought I'd big up the diesel massive!!!!!  :smug:
Title: Re: Drilled airbox
Post by: cняis on 04 May 2007, 22:26
^ 40mpg?? driving miss daisey?

hardly, i often scare the missus and i break the speed limit all the way to work...  :undecided:

i rarely sit in traffic though (live in the country). even on the motorway it'll get 40mpg or thereabouts. its been tuned as per rubjonnies guide 2 week ago so its running fine  (ie not lean)

...oh and its chipped, 4 branch manifold, full stainless powerflow system and k&n panel filter... and 220k miles  :cool:
Title: Re: Drilled airbox
Post by: T_J_G on 04 May 2007, 23:13
^ 40mpg?? driving miss daisey?

hardly, i often scare the missus and i break the speed limit all the way to work...  :undecided:

i rarely sit in traffic though (live in the country). even on the motorway it'll get 40mpg or thereabouts. its been tuned as per rubjonnies guide 2 week ago so its running fine  (ie not lean)

...oh and its chipped, 4 branch manifold, full stainless powerflow system and k&n panel filter... and 220k miles  :cool:

on the way home from college i can get 45MPG out my 150K 8v GTi. :smiley:
Title: Re: Drilled airbox
Post by: owls88 on 05 May 2007, 14:06
i have a 1.3 , where on the airbox is probly best to drill it ?
Title: Re: Drilled airbox
Post by: DarnPB on 05 May 2007, 21:48
Anywhere upstream of the filter where there are no strengthning webs.
Title: Re: Drilled airbox
Post by: monzablue16v on 05 May 2007, 23:16
and make sure the air going in gets to go through the filter :laugh:
Title: Re: Drilled airbox
Post by: boneybradley on 07 May 2007, 12:47
I don't understand :shocked:...everybody quoting 38-45mpg with there mk2's..... Mk3's only seem to get 35-38mpg on a good run and down to 25-30 when driven hard....spose the mk3 is a lard ass!!! :grin: :grin:
Title: Re: Drilled airbox
Post by: Mew on 07 May 2007, 13:04
Or they're basing their figures on a 15-20 year old computer reading!  :wink:
Title: Re: Drilled airbox
Post by: cняis on 07 May 2007, 18:42
Or they're basing their figures on a 15-20 year old computer reading!  :wink:

lol you're probably right  :cool:
Title: Re: Drilled airbox
Post by: clipperjay on 07 May 2007, 20:52
Only drill on the wing side and along the bottom not above the filter as we all know the paper filter does a good job keeping the smaller particles out from a dirty box LOL!
Title: Re: Drilled airbox
Post by: tom26 on 08 May 2007, 15:22
^ 40mpg?? driving miss daisey?

hardly, i often scare the missus and i break the speed limit all the way to work...  :undecided:

i rarely sit in traffic though (live in the country). even on the motorway it'll get 40mpg or thereabouts. its been tuned as per rubjonnies guide 2 week ago so its running fine  (ie not lean)

...oh and its chipped, 4 branch manifold, full stainless powerflow system and k&n panel filter... and 220k miles  :cool:

on the way home from college i can get 45MPG out my 150K 8v GTi. :smiley:

This is nuts. My car was only recently tuned by john mitchell of JMR racing and when MOT'd the emissions were almost perfect. I can't understand how some of us struggle to reach 28-30mpg while others are returning 40+ from their cars??
i usually get 25-28 (sometimes 30-31 when stupidly careful IE not revving above 2500 etc)
Title: Re: Drilled airbox
Post by: Mew on 08 May 2007, 15:36

This is nuts. My car was only recently tuned by john mitchell of JMR racing and when MOT'd the emissions were almost perfect. I can't understand how some of us struggle to reach 28-30mpg while others are returning 40+ from their cars??
i usually get 25-28 (sometimes 30-31 when stupidly careful IE not revving above 2500 etc)


Or they're basing their figures on a 15-20 year old computer reading!  :wink:
Title: Re: Drilled airbox
Post by: tom26 on 08 May 2007, 15:38
^ :grin:
Title: Re: Drilled airbox
Post by: kyle on 08 May 2007, 16:19
hmmm well i struggle to get 24mpg out of mine - was doing 15.5 down the motorway the other day :shocked: :shocked: :evil:
Title: Re: Drilled airbox
Post by: vw-bob on 08 May 2007, 17:18
how to you guys get a mpg reading? is it something on the gti that i dont have on the driver?
Title: Re: Drilled airbox
Post by: cняis on 08 May 2007, 18:27
yes, we have the (now not so) trusty MFA onboard computer  :cool:
Title: Re: Drilled airbox
Post by: monzablue16v on 08 May 2007, 18:55
I worked mine out the proper way because my 20 year old computer is fubared :D my timing was one tooth out when I stripped the engine down timed it properly and it's back to where it was when I bought it and the MFA worked to .3 of an mpg. Need to fix that next :) on a valver the mpg should stay the same as the same amount of air passes the metering head so it will still inject the same amount of fuel on an 8v witchraft electric thing the maf will see all this new air and ramp up the fuel to match.  :nerd:
Title: Re: Drilled airbox
Post by: Ben Lessani on 08 May 2007, 19:46
My fuel consumption goes a bit all over, I managed about 40 going to manchester, went about 60 the whole way, then on my recent trip down, I did about 230 miles in 2:27 and being diffcult to judge because the fuel needle only ever goes 3/4 up and the MFA says I'm doing 65mph @ 12mpg. Next time I fill the tank I can say...but 40 is a dream for me - I think I enjoy driving too much to try and hit the dizzy heights of 30+ mpg.
Title: Re: Drilled airbox
Post by: tom26 on 09 May 2007, 13:13
enough of this talk of 'miles to the gallon' anyway, if we were that concerned, diesels or 1.0L petrols would be a wiser choice??!  running old expensive cars is more about SMILES per gallon.
Title: Re: Drilled airbox
Post by: T_J_G on 09 May 2007, 13:38
enough of this talk of 'miles to the gallon' anyway, if we were that concerned, diesels or 1.0L petrols would be a wiser choice??!  running old expensive cars is more about SMILES per gallon.

but when you can't afford the money to get smiles per gallon,it's a bit of a problem...ican't afford any petrol to stick in my car  at the moment:sad:
Title: Re: Drilled airbox
Post by: Simpson on 16 May 2007, 18:20
so how is it that we get more than the book figure, i can honestly say with average driving on b roads i can get 36 mpg, and that is worked out from tank to tank but 40 mpg, i cant believe that. as the book figure is only 29.6 or something.
Title: Re: Drilled airbox
Post by: Dougie_91 8v GTi on 16 May 2007, 19:15
I reset the MFA on position 2 when I bought the car just over 1000 miles ago, (2-3 wks ago), by accident, pushing and poking things, but since then, and thrashing it occasionally, an average MPG of 37.

Did get it up to 50.1 doing about 45mph on a slowish drive to work (10 miles), but on an average dual carriageway trip about 34-37 MPG.

Interestingly, (he says!) doing 70MPH or 90MPH produces the same MPG 34-37 depending on the length of the drive.

Very interested in the whole drilling the holes idea, as mine is orignal throughout, and is typically sluggish, very deep accelerator pedal, feels like a two different engines almost. There is also a semi disturbubing, although probably normal dip/near stall in the revs if you tap/rev quickly up to about 2,500RPM before it settles again around (according to the MFA) 780/840 RPM.  Would be interested to see other peoples figures on the MFA's to compare.  I also have, although I thought it is an exhaust problem, a blow back, popping type noise occasionally when decelerating from high revs.  Replaced the two middle parts of the exhaust, but not sure what causes it.  Wrong mixture air/fuel?

If I wasn't desperate for a beer and running late I'd post them here now, but will do later. 
Title: Re: Drilled airbox
Post by: cняis on 16 May 2007, 19:44
get your timing and CO mixture sorted!! should run fine then with no popping:

http://www.golfgtiforum.co.uk/index.php?topic=33253.0

works a treat
Title: Re: Drilled airbox
Post by: Ben Lessani on 18 May 2007, 09:39
Any guides to set up a K-Jet or is all hope lost. I get popping on deceleration, but I am running the car without a backbox, so its probably why.
Title: Re: Drilled airbox
Post by: tom26 on 18 May 2007, 17:10
^ no back box? thats going to be noisey!
Title: Re: Drilled airbox
Post by: kagero465 on 24 May 2007, 17:28
fantastic! this site is really addictive. i'm away to go and drill some holes in my '88 8v. cheers guys :smiley: