Drilled Airbox Mod - XUD9

birlengo · Unread post by **birlengo** » 02 Apr 2010, 00:06

I drilled the stock airbox with 6 holes that are about the size of a 2p coin. I noticed increase in torque throughout the rev range, and much more spirited drive from the engine, when downshifting and maintaining speed in high gears.

On the downside, it is not very economical now! I blocked 3 holes to increase economy and it seemed to have done the trick. I am suprised at how much extra power that gave the engine; thought I would share that with you lot.

BTW it is a non turbo XUD9 fitted to a Citroen Berlingo.

XantiaMan · Unread post by **XantiaMan** » 02 Apr 2010, 09:09

I very much doubt you gained anything but noise. Engines like cold air, and drilling the airbox will be some air will be drawn in from the engine bay.

Unread post by **CitroJim** » 02 Apr 2010, 09:11

Indeed, if anything was gained doing this mod then there is a serious underlying problem.

The air intake system generally does not flow badly at all in it's standard form.

Even the V6 has a nearly identical setup and that's perfectly good for near 200BHP....

DickieG · Unread post by **DickieG** » 02 Apr 2010, 13:40

CitroJim wrote:Even the V6 has a nearly identical setup and that's perfectly good for near 200BHP....

I've not had first hand experience of a V6 Berlingo, tell more Jim

Unread post by **CitroJim** » 02 Apr 2010, 13:51

DickieG wrote:
CitroJim wrote:Even the V6 has a nearly identical setup and that's perfectly good for near 200BHP....
I've not had first hand experience of a V6 Berlingo, tell more Jim

I'm sure one exists, somewhere...

It would be rather awesome, along the lines of Brigsy's Renault van

spider · Unread post by **spider** » 02 Apr 2010, 13:55

The only way I can think of that 'might' increase power (although it would increase noise) if the air box was drilled would be the entry of more cold air.

I'm just thinking along the lines that cold air = denser so the same principle the intercooler works in a way...

XantiaMan · Unread post by **XantiaMan** » 02 Apr 2010, 19:42

spider wrote:The only way I can think of that 'might' increase power (although it would increase noise) if the air box was drilled would be the entry of more cold air.

I'm just thinking along the lines that cold air = denser so the same principle the intercooler works in a way...

And where would this cold air come from? Last time i checked, engines generated heat and this heat sits in the engine bay, and even once moving, the heat will radiate around. Want cold air? Get it from outside the car, from the grille for example.

spider · Unread post by **spider** » 02 Apr 2010, 21:20

XantiaMan wrote:And where would this cold air come from? Last time i checked, engines generated heat and this heat sits in the engine bay, and even once moving, the heat will radiate around. Want cold air? Get it from outside the car, from the grille for example.

I have been mis-understood.

I just sort of meant that cold air = denser = more power same as an intercooler. That's the only possible explanation.

Top mounted intercoolers have the bonnet 'guides' anyway, but I know what you meant

No, I do not intend on drilling my airbox, although I keep thinking about popping an intercooler on (although space is a little tight for that on my 205)

birlengo · Unread post by **birlengo** » 02 Apr 2010, 22:07

LoL, ok people doubt me if you want.

I will have to take a pic tommorow morning so you get a better idea. It has improved performance and it had decreased economy I know that from driving it, and so would anyone else who drives the van.

I blocked three of the holes and got a nice balance now, believe me or not it does give the van some low end power. Even on any petrol car if you drill the airbox like I have it will increase performance, this is a common simple mod.

Xaccers · Unread post by **Xaccers** » 02 Apr 2010, 22:19

More air would improve economy wouldn't it?
You're getting more fuel burning as there is more oxygen available, so more power with less fuel.

XantiaMan · Unread post by **XantiaMan** » 02 Apr 2010, 22:41

This thread is silly. Warm air, less dense, less oxygen, less power. Fact.

This is a simple but badly thought out mod often carried out by chavs in Saxos wanting to sound like they have an induction kit on their 1 litre lawnmower engines.

Spider, if you didnt mean the entry of cold air and meant increase the volume of air then this is again unlikely, because the engine can only suck a certain volume of air, and if the airbox is good enough on a V6 it wont be causing ant degree of restriction on a 70bhp ATMO diesel.

Simple test to see if you have increased your performance to any degree.

Find a good clear stretch of road. Find a starting point, i.e a lamp post as a marker. Go along at 20mph in 2nd gear (as an example) when you pass the lamp post. Set another marker point 15 seconds or so ahead. When you have reached this end point, note the speedo reading.

Try with the holes sealed up, and try without. Then come back and say if your van IS actually faster or just sounds faster.

BTW, the increase in economy will be you putting your foot down more, and driving in a more spirited fashion. Its all a placebo effect. Atmospheric pressure has way more influence on day to day performance than people realise, especially on a non-turbocharged engine. Air pressure has gone up significantly in the past 48 hours and can account for a perceived increase in performance.

robert_e_smart · Unread post by **robert_e_smart** » 02 Apr 2010, 23:10

I've not had first hand experience of a V6 Berlingo, tell more Jim Laughing

It'll be this one then...

http://cgi.ebay.co.uk/2001-CITROEN-BERL ... 4a9fdcb8a6

birlengo · Unread post by **birlengo** » 02 Apr 2010, 23:29

you can sit here and discuss it all day, but you are not driving this particular van. I drive the van daily and I keep an eye on fuel economy whilst I have been testing the airbox by blocking holes etc; and I have seen an increase in acceleration.

LOL at everyone getting excited about the noise, as a matter of fact the noise as not increased, it it not noticable at all; even if it has got louder!

steelcityuk · Unread post by **steelcityuk** » 02 Apr 2010, 23:33

Try fitting a vortex induction ring.

They work like a charm - ie. Lucky charm if you believe it works then it must.

A set of those fuel magnets would really top off the job.

To really prove if it works as advertised an independent rolling road is best.

Steve

Toby_HDi · Unread post by **Toby_HDi** » 02 Apr 2010, 23:43

steelcityuk wrote:Try fitting a vortex induction ring.

They work like a charm - ie. Lucky charm if you believe it works then it must.

A set of those fuel magnets would really top off the job.

To really prove if it works as advertised an independent rolling road is best.

Steve

Don't forget the electric supercharger!...