Following a recent major service i carried out on our car, (timing belt & aux, water pump etc), a pig of a job and i will document this in time, i decided to have a nose at the intake system and delve a bit deeper into the flow. First off, i felt the initial 90 degree bend that enters the air box from the from panel was a restriction, or rather, an interrupted path for air to flow efficiently, the offending suspect being the odd loop chamber which must be tuned to reduce induction noise. A simple solution to this occurred to me that i had, various pieces of material at my disposal and one of them being a sheet of aluminium from an old appliance. Not wanting to spend too long faffing around with this, i cut a piece from the sheet big enough to cover the loop chamber, forming it to a nice neat enough blanking plate, then with some of that carpet and vinyl adhesive (aerosol based), applied a little to the inside of the pipe and little again to the aluminium piece, once tacky, (anyone having used this stuff before knows, this don't take very long at all), slid the aluminium into position and also crushed the plate into the grooves at the start and end of the pipe inside. The result was very pleasing considering i wanted a quick fix solution, & not least as this has in effect cost me nothing & completed within 5 minutes


Next up, i thought while i had the air box removed i would delve into the air box & check the K&N panel filter that had been fitted about a couple of years ago, all good, surprisingly clean so i moved further on...
The trumpet shaped piece that is removable via two self tapping screws on the right hand side of the box has, a small but significant oval hole that leads to a massive air chamber to the rear of the box that effectively does nothing other than again, reduce induction noise by way of a measured volume. I removed this trumpet, cut another piece from the aluminium sheet to a decent oversized dimension, offered it up, trial fitted the trumpet, job was a good'un so refitted the screws, another void blanked off and even quicker than the first one that i did !


Not being happy with the poor fit of the induction pipes that enter and exit the box, i decided to seal these with a generous bead of silicone, waited for it to cure completely then, refit the entire air box in one piece. The result...? a nice improvement in air flow, noticeable increase in torque, slight increase in acceleration maybe (albeit a placebo effect) due to new found induction noise that essentially is for FREE !! This for me, begs the question why you you would want to throw any real money in this area because, as cheap mods go, the fundamentals are already there, its just a question of how you address it.
Thought i would share this with you all as, its something i wish i had done when i fitted the filter all that while ago, its quick, simple, effective, and free if you have the right stuff lying around but remember, this is just a suggestion as there is far more room for improvement as regards air flow, i may even get a tapered plate moulded up if i get really bored one day to, mask all those heat shrink type fins inside the box that are crude but, just part of the manufacturing process and aid some rigidity, just a thought for the future though...:idea:

Nice work.

I wonder if you got a stout piece of spring-steel and affixed it inside the elbow with a decent bolt and rubber washer assembly, you could achieve a pleasing kind of induction rasp/thrum. Like a fat, resonating tuning fork.

Obviously I lack the will to try.

Great post! I have done a intake pipe mod but I like what you have done on the air filter side of things as I did not even know that hole was there! I totally agree with you and think that standard air box if fine
with a few simple mods. Will take it apart next Wednesday and will post results!!

AB100 said:

Nice work.

I wonder if you got a stout piece of spring-steel and affixed it inside the elbow with a decent bolt and rubber washer assembly, you could achieve a pleasing kind of induction rasp/thrum. Like a fat, resonating tuning fork.

Obviously I lack the will to try.

Click to expand...

Thanks, like i said in the post, it has developed a pleasing & significant induction noise / roar, whatever you what to call it. No doubt there would be countless ways of achieving the same out come but, for the same outlay...? belt & braces me thinks. I was reluctant to butcher any parts to carry out what i intended so, this at least gave the option of reversing the mods and returning it all back to standard if i wish.

cooperman1 said:

Great post! I have done a intake pipe mod but I like what you have done on the air filter side of things as I did not even know that hole was there! I totally agree with you and think that standard air box if fine
with a few simple mods. Will take it apart next Wednesday and will post results!!

Click to expand...

Mate, if you think you have a nice induction roar now from your mod, wait until you blank that rear part of the air box off !! :devil: I don't doubt it sounds nice now but, i will be interested to see the difference it makes to your car drive ability / torque wise. A good test to notice a difference in pre & post mod would be to maybe, pick a long hill you can take at a reasonable speed and see if you can hold it in the highest gear possible, without putting your throttle to the floor whilst keeping the lightest throttle. This sounds a bit daft but honestly, i noticed a long hill that i take fairly regularly and found that i was on light throttle whereas before it would be on the floor in sixth gear !! What i also noticed on the motorway was a sharper throttle response, and the car picking up better than before, but not forgetting the 0 degree temperature outside, that in itself makes for good performance. I hope you find a good solution to blanking that rear hole off in the rear of the air box, and maybe have the oval hole flush with the intake pipe...?

Defo noticed it top end pulling on the motorway when the mod was done, had 3 up last week with a full tank and it would still pull good at 70 (officer!!).
Really keen to open it up and see what I can come up with, got some carbon kicking around so will see what I can do with that! But just got to be careful as if something comes away that side of the air filter it won't stop till it hits something expensive!!!

As an aside, it would be really good to rolling road it. I did a project on a Range Rover Sport, and it has a 'bagpipes' style entry. To open up the system we bypassed it with a larger diameter, gently radiused, pipe. Whilst we got a very small peak increase, we then discovered that the bagpipes quite cleverly filled in the torque curve by tuning the induction more effectively at a range of RPM. The really interesting thing was that by removing them the car felt quicker (with a peakier delivery and surge), but was actually a slower package overall as we lost more useable power across the range. I'm not saying that is what's happening here, but it may be worth consideration if you rolling road it.

I went to a rolling road day on sunday and was tempted to put my 100HP on but a) i was testing my track car so it was at home & b) I was worried what it might have lost in 6 years! lol!
Would it still be a 100HP or a 90HP

Van Diemen said:

As an aside, it would be really good to rolling road it. I did a project on a Range Rover Sport, and it has a 'bagpipes' style entry. To open up the system we bypassed it with a larger diameter, gently radiused, pipe. Whilst we got a very small peak increase, we then discovered that the bagpipes quite cleverly filled in the torque curve by tuning the induction more effectively at a range of RPM. The really interesting thing was that by removing them the car felt quicker (with a peakier delivery and surge), but was actually a slower package overall as we lost more useable power across the range. I'm not saying that is what's happening here, but it may be worth consideration if you rolling road it.

Click to expand...

That is a great point, I replaced the Air intake pipe as the original just looks rubbish (a few of them have been known to fall off!) It has the extra square chambers on the side for reducing intake noise and collection of heavy dirt/water before it gets to the air filter (so I believe reading the posts on this forum).
The chamber in the air filter itself I agree will more then likely play a more important role in the torque curve and smoothing out the air delivery throughout the rev range (the Ferrari 2011 F1 car ran a added chamber pipe on its exhaust system during the 'blown' diffuser era to help smooth out the pressure). I may leave it as I am still worried about putting parts that 'could' fly into the engine! Still would love to try both on a rolling road as would be really interesting to see what option works best!! sods law it will be the completely standard system and the rest is in our heads!!

Cheap air box mod.

After looking at the mod above I thought " hang on - that looks like PVC guttering would fit. " And it does !
Replaced last section of air intake with black plastic guttering elbow. £ 4 .
Engine sounds better.

Re: Cheap air box mod.

xatabay said:

Engine sounds better

Click to expand...

Hehe of all things, a drain pipe, looks factory lol ! Nice to see you have gone this route, another simple mod and you can still easily return it back to standard too

I know this is a really old thread,but i read it the other day,i took the pipe off to measure it, and decided to try simply filling in the holes in the old pipe,i stuck some old work gloves in the holes and taped over them,i believe the car picks up a little better at low revs and there is more induction noise,i imagine a straight through pipe without the holes gives a cleaner passage of air,so a free upgrade and in my mind it seems to improve performance.