17 replies to this topic

[Asphalt]

Hi!

I'd like to hear some opinions about the Cooper RSP's snorkel fitted to the airbox.
I know the airbox is very good, but what's with the snorkel on it?

I mainly fitted it cause I'm thinking it's better to have the air not drwan direktely from the radiator's top.
BUT: the diameter were it fit's to the box is comparable smal...

What is more restrictive to the engine:
sucking in hot air or the smal diameter of the snorkel!?

 PICT7426.jpg   207.55K   18 downloads

cheers,
Jan

PS: engine is a 53hp SPI with HIF44, Maniflow LCB, twinbox RC40 and K&N inlet.

Edited by Asphalt, 20 June 2008 - 11:19 PM.

[Bungle]

i removed mine very quickly after buying my cooper

the air in the engine bay is almost as cool in the front of the grill as it is near the back with such a large grill

reading on the mainstream cooper forum the snorkel was fitted by rover to get the mini pass the drive by noise regulations

[THE ANORAK]

i would have to confirm what bungle said. but i can now explain why.

i have recently seen a photo of the engine bay for an MG metro. they have exactly the same air box but the trunk is a round tube that goes down towards the grille.

now the cooper engine is basically the MG one so my guess is that rather than redesign the air box they simply added the trunk to suck air from the usual position above the gear box and yes, the trunk also has an amazing ability to reduce the induction noise to a minimum. why did they not just make a new air box. probably cost but eventually they did use a new style but only on the later non coopers.

i have experimented with all variations of this air box on my car (this is why i have to keep buying new ones). in my opinion you get a marginal increase in power at the very top of the rev range (5000-6000rpm) without the trunk but you also get a hell of a lot more noise.

personally i prefer the car quiet. there is no reason why you cant just take the trunk of and try it.

two options i haven't tried, 1. get a later style air box (open classics are one model that uses them) 2. remove the trunk and add ram pipe to the end that doesnt have such a sharp bend, in a similar way to the MG metro, but you need to invest in the right type of pipe

EDIT: OK, this is the only pic i can find of an MG metro set up at the moment but you can just see that it has the same air box but with a pipe instead of the trunk....

Edited by THE ANORAK, 21 June 2008 - 09:34 AM.

[chairchild]

Another way that manufacturors use to reduce intake noise, is by introducing a restriction before the filter

sorry about the size of the pic - it's the only one I could find!



What happens is, when the engine is under what conditions, the sheer volume of air that the engine is trying to inhale, has to go through the ventuuri - when it does this, it speeds up to nearly mach 1 (or at least, they try to make it so it does) When it approaches this speed, no noise can escape from the intake - but obviously, it does create a hell of a restriction, which limits power output

Cars that use this system, are jag V12s (one either side) and I've seen it on a few suzukis aged from around 1995-2000





so yeah, if you want to reduce intake noise - find an airbox with a nice smooth ventuuri, and fit that to your standard airbox. But, you WILL lose power

[THE ANORAK]

aha, so would the design of the cooper snorkel actually give this ventuuri effect ????

pic added for clarity...



it seems to me that the far end of the tube, at the point it doubles back on itself, would have this effect as it actually goes very thin at that point as well.

this would explain its amazing ability to reduce noise and confirm the reason for the design of it. they did really struggle to get the car through the drive by noise test

[chairchild]

quite possibly! I've never really had the chance to have a good look at the cooper snorkel before, but I do remember it being VERY thin - and at that point, I didn't know about the ventuuri silencing effect


only downside is, as mentioned - you do lose top-end power

[THE ANORAK]

that's fascinating

thank chairchild, this has pointed me in the right direction to finally understanding the seemingly ludicrous design of the carb coopers air boxes.

i shall look into this further

[Asphalt]

Hmmm - honestly: I've just fitted the snorkel and didn't notice any reduction of any noise.

But possibly this could be due to the LCB and the missing sound insolation on either sides of the firewall.
So it's just so loud no matter what I do I can't hear less or more from the intake - know what Im trying to say?

Going to keep it - I'm too lazy to remove it now

Thanks for your awnsers!!

Cheers,
Jan

[edit]

Shot of the snorkel:

Edited by Asphalt, 21 June 2008 - 10:55 PM.

[Asphalt]

After some hundred miles of driving with that thing:
I need to contradict myself and claim the opposite: yes, it helps to quiten the engine
(Had the chance to run through some tunels ()).

But I didn't notice and change in power output or MPG.

Cheers,
Jan

[THE ANORAK]

in my opinion in only really makes a difference if you accelerate hard when at low revs, for example 70mph in 4th gear and you floor it to overtake something.

also, without it, when revving the car at standstill or pulling away, you seem to get more boom right at the point you start accelerating

as you are put in these situations quite a bit, i find the trunk to be a great benefit.

once your moving steady, it has no effect

I've only ever noticed extra power without it when passing through 5000-6000 rpm in third and then only slightly

to be honest, any type of induction noise just irritates me, it seems to be just at the right pitch to "buzz" my head, same a a boomy exhaust.

i like my cars to whizz and whistle not pop and boom

[taffy1967]

Well I switched mine to a cone K&N filter a decade ago which made things look a lot neater.

There is more induction noise when you're caning it, but I quite like it because it sort of adds to the excitement of driving my Mini.

I've removed the bulkhead soundproofing which didn't make a lot of difference anyway.

Edited by taffy1967, 30 June 2008 - 07:44 PM.

[Asphalt]

*Thread resurection*

Anyone ever tried this?



I'm bored of the 'snorkel' - and of the airbox sucking hot air directely from the radiator's surface. The snorkel is not ideal, nor is the position of the actual airbox inlet. So turning it by about 90° should give some improvements (if only illusive ones ). Anyone ever done it?

Cheers,
Jan

PS: remeber - on '59 Minis it was the same situation... The turned the airbox intake away from the rad - and all following airboxes did saty the same way, except the Cooper RSP 'box which came from the Metro - which had a front rad.

Edited by Asphalt, 04 June 2009 - 05:42 PM.

[Dusky]

*Thread resurection*

Anyone ever tried this?



I

Another thread resurection, how is it possible to turn it like this?

[THE ANORAK]

wow, old thread, cant remember any of it !!!!

 

dont know how thats been turned like that. not sure how its possible without serious mods. but it is now looking more like the standard 998box. that valve sticking out on the cooper box is just a really over engineered hot air valve and pointless. considering the price of these cooper boxes and trunks these days i would get one of the 998 ones and see if that fits. again, remove the silly hot air valve (bed pan thing)

 

Edited by THE ANORAK, 04 June 2016 - 08:22 AM.

[Dusky]

Haha
I bought a , indeed expensive, cooper rsp box because I hunt down every inch of sound deadning atm  

 

cheers