RPI Scoop

P

pilchardthecat

Active member
So i'm thinging of getting one of these - is it worth getting the "BMC Performance Air Filter" that they optionally sell along with it?

My instinct is not to bother as i'll have a new OEM filter at inspection 2 next month
 
stick with the ome filter,oiled filters can cause problems with the maf sensor,also imo i would have a go at fabricating one yourself and save your money :thumbsup:
 
The filter comes for free if you buy from CA Automotive. PVR has the RPI scoop and used the BMC filter and I don't think he's had problems. The filter may contribute to the increase in induction noise...

May be of interest to you:

http://www.z4-forum.com/forum/viewtopic.php?f=2&t=38073
 
The scoop alone is £129 from CA, it's £200ish with the filter

Is there extra noise? with/without the filter.... i wasn't expecting any
 
pilchardthecat said:
The scoop alone is £129 from CA, it's £200ish with the filter

Is there extra noise? with/without the filter.... i wasn't expecting any
Click to expand...

I didn't realise they now charged for the filter. I bought mine a few years ago for much less and with the filter for free. At that price, I would make a scoop and buy a new filter!
 
Save your money the scoop does nothing, I have tested the oem standard intake box with a manometer and it never goes negative on dirty side of filter, remember the whole area in front of the radiator is positively pressurised
Oiled filter is ok as long as you don't over oil it but it's not better than a clean oem filter
 
How does that correlate with the testing result as per that link to the US forum?
 
Do you believe a scoop without the ram effect of the car moving forward will add 12 hp
A fan could not generate enough pressure over that small amount of surface area the scoop has
I'm happy to be wrong but after testing the air pressure and seing a slight over pressure over 60 mph I can't see it giving much
If I could get hold of a used set of intake pipes I would drill test holes at several points and test the bottleneck in the system, my gut tells me it's the mesh panel just before the maf, so biggest gain would be to go for alfa N tune and do away with the maf and screen
 
As others have said... It's rubbish. I had it on mine, and it makes no difference. A complete waste of money with negligible benefits, if any.
 
alfamale said:
Save your money the scoop does nothing, I have tested the oem standard intake box with a manometer and it never goes negative on dirty side of filter, remember the whole area in front of the radiator is positively pressurised
Click to expand...

You tested it at full throttle/engine load at say 40mph, and it never went negative? Or you did a static test?
 
Had mine for a few years. Changed the BMC filter for a K&N this year. No problems but can't say it makes much difference.
 
pilchardthecat said:
alfamale said:
Save your money the scoop does nothing, I have tested the oem standard intake box with a manometer and it never goes negative on dirty side of filter, remember the whole area in front of the radiator is positively pressurised
Click to expand...

You tested it at full throttle/engine load at say 40mph, and it never went negative? Or you did a static test?
Click to expand...
Yes ran the sensor through passenger window and under the bonnet and up into the dirty side of the filter box
Took the car on the dual carnage way and gave it some stick in different gears, rev range and throttle position only time it changed was when the car was travelling at high speed with the throttle closed, under those conditions I saw a slight over pressure, it's a very good design
 
alfamale said:
pilchardthecat said:
alfamale said:
Save your money the scoop does nothing, I have tested the oem standard intake box with a manometer and it never goes negative on dirty side of filter, remember the whole area in front of the radiator is positively pressurised
Click to expand...

You tested it at full throttle/engine load at say 40mph, and it never went negative? Or you did a static test?
Click to expand...
Yes ran the sensor through passenger window and under the bonnet and up into the dirty side of the filter box
Took the car on the dual carnage way and gave it some stick in different gears, rev range and throttle position only time it changed was when the car was travelling at high speed with the throttle closed, under those conditions I saw a slight over pressure, it's a very good design
Click to expand...

I would love to see a direct comparison with/without aftermarket scoop.

Pressure and flow are different, but all things being equal the aftermarket scoop only has to increase pressure to have a positive effect. It doesn't require that the OEM design goes negative. Did you test an aftermarket ram with the manometer too?
 
I'm intrigued that some say it makes no difference yet it was fitted to their car from before the time they acquired it - I bet they haven't removed it and made back to back comparisons :poke: :poke: ...there's at least two of you that I know of :wink:
That said, I have only found a subjective change at very high RPM (and stupid speeds)
 
The one factor posters are ignoring, is required air flow and assuming more air is better, more air is better when the timing is advanced to make use of the extra flow and thus produce a bigger bang, which it isn't.
I find it unlikely BMW would design an air intake that doesn't supply enough air and it's the limiting factoring in the engines performance.

If the car was remapped with the scoop then it could make a difference

I did back to back tests and it made no difference, see below

http://www.z4-forum.com/forum/viewtopic.php?f=9&t=37872&p=521689#p521689
 
the original cup thing is designed for all road conditions as it reduces the amount of dirt getting to the filter, just like the ecu is tuned the same for everyone around the world to account for all manner of variables. and to a certain extent the ecu will adjust itself to the increased air flow. you get a yellow light on your dash when the engine gets too much. might get the laptop out in the next few days and get a reading from the engines sensors while driving and test it against the old readouts i have saved somewhere.
 
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