Attempt to quieten TB'd valver

Hi

NOISE - a growing issue, and its only going to get worse with more and more trackdays getting restricted. When the measurement is by driveby, its a massive issue with throttle bodied valvers so I have been trying for ages to get an airbox setup that would fit under the bonnet of my Ibiza, which is worse than a golf as the bonnet slopes more. Anyhow, I think I've got there using a modified PX600 airbox from pipercross. I say modified as it comes with a pathetically small cone filter inside the neck of the inlet - when questioned about the capacity of this, pipercross admitted to only testing it to 160hp.......which isn't enough lads. So, this was removed with a stanley knife and stored in the bin. The box comes with either 80mm or 100mm intake, so I got 100mm. Except that its restricted to 85mm as it goes through the neck of the intake......not very good again lads. So sanded this out to nearly 90mm. Fitted to car with 100mm trunking and got a 350hp capacity jetex filter for the end. And it all just about fits - 10mm or so underbonnet clearance...phew. Have a short rad in the car so filter sits above and gets cold air direct from high pressure area behind front grill. From A/F ratio guage it looks like its running a touch richer than it was when stationary but fine when cars moving - will stick it on rollers just to check map in next couple weeks but hopefully the setup wont be too restrictive









the silver stuff is heat reflective sound deadening that I have added to the outside of the box which was fairly thin plastic.

interesting stuff found out when reading around what size intakes you need for engines of x power, a 2L engine running at 8000rpm needs 133L of air / second - 100mm diameter intake has area of 78.55cm2 and thus the airspeed in the intake would be 0.49mach. Now this sounds ok but its important that this does not approach mach 1 as apparently the air just stops moving......and is very restrictive.

I wonder how things like R32's manage on 85mm intakes....(or they may be even smaller than that ?)

We'll see exactly how restrictive the box is when it gets on the rollers

Ave it

Rob

 

nice job rob reckon could loose a few pony,s on the rollers, but once your on the road might have a gain , faster air speed . noticed high spec m3s , and rally cars got realed air box,s around the trottle bodies , then ducted to a air box and ,or cone filter , just make sure its nice and strong , would imagine ther a fair bi t of suck at 9 k,

 

Rob do you have any sound proofing in the engine bay mate?

 

none - it is the devil (fibreglass bonnet for lightness) and doesn't do much to quietening TB's - tried it already

 

cheers - if there is little restriction in the filter and ducting, there should be little or no vacuum in the airbox itself so it 'shouldn't' need to be that strong......we will see

 

Nice work.

Interesting about the air flow - so the point is that the air needs to be unable to flow enough... to create airbox pressure?

Re the silver stuff, is it akin to 'brown bread'? - what dem MaxP boys fit to reduce their ICE resonation.

 

Shoot me down in flames, but...

How about getting an airbox the oppersite hand and clamping the filter directly to that and duct air from the grill to the filter - you might have to move the PAS resovoir and thread it through pipes/clutch cable, but would do away with all that 100mm trunking.

 

I can hear a gun being loaded....

 

My original aim was to create a pukka 'ram air' airbox system - forward facing a-la

http://www.motorsportfilters.com/casestudy_touringcar.asp

but

(a) I wonder how well this would work on a car that does get driven on the road, and sometimes in the rain
(b) it will take a lot of work to achieve this and there isn't much room to play with anyhow

These setups do try to have the airbox under positive pressure so when those throttles are opened, instant air, (kind of very mild turbocharging). Top sports bikes use this effect as do F1 cars and the like. But....the jury is out about what speed you have to be doing to actually have this have any appreciable benefit, I have found lots of conflicting data from 'experts'.

Taking these factors into account, I figured I could get a lot of the way there easier than fabricating a ram air system - the system I have will not have a positive pressure element (unless I box the filter into the slam panel....which may yet happen) but it will have a very good supply of cold air from a high pressure zone on the car and if it rains, it can draw air from the back, engine side, of the filter

Re 'brown bread', certainly not.

 

Meh, occupational hazzard pour moi

 

I did consider this believe it or not , the clutch cable is the issue and its not easy to negotiate 100mm pipe, and thats a big filter you have to mount somehow

hence this solution and silicone ducting weighs naff all

 

Yep, useful to be able to close off the filter for wet weather. I remember Sollis trying ram air with the Miglias in CCC - again, playing around, trying to turbocharge N/A stuff, with feel good factor, but no clear results.

Pickle end result is pretty much the same as where I got to with the Jetta - airbox, round filter, minus low rad - and tbh, the Golf will reappear like that. Haven't figured out a better way, whilst keeping the thing shut up.

[I wasn't joking re: the brown bread btw -IIRC is v. similar (albeit with a far too stupid a trade name):

http://www.caraudio.com.cy/images/BB-small-L.gif]

 

The trunking double backing on itself shouldn't cuase to much of a restriction regarding air velocity - ie minimal effect?

Take it sounds (alot?) quieter.

 

so 'not much' = 'minimal'......well ok, but thats a new concept for me and perhaps others

yes its a lot quieter but it still has its teeth

 

Good work Rob, I have to careful around puddles in mine as the filter is behind the bumper, it's sheilded by the wing but in deep water I suppose it could still get submerged.

Glug,glug,glug..

 

Nice air but then the sound gets out:

 

I was looking into this for my 2.0l on carbs, what size trumpers are you running Rob? says that you cant run anymore than 45mm in the Demon tweeks catalogue? Heat proofing is a good idea though.. top job!.

 

Thats to let hot air out from the backside of the rad and it must be an 8V, no room to do this on a 16v

 

Guessed that after seeing the front of the block, just thought it may have had other applications/variations.

edit:I noticed some of the bergcup cars have it boxed off & draw air into the front of the box.

 

Hi
40mm trumpets inside the box and 40mm spacers between end of throttle body and the backplate (basically as much as would fit) - and these are direct-to-head TB's so total induction legth to back of valve = 270mm - so theoretically resonant tuned for 8300rpm - could do with being a bit longer to bring this into play in normal use rpm ranges, say 5000rpm, but that means the length would have to be 450mm - no chance, not enough room, not without some serious fabrication with bends or fancy touring car-like carbon creation
Rob