Intake mods

alfamale

Member
Years ago I owned a part share in a race car, the rules were flexible but serious mods incurred weight Penalties, this meant the little tweaks that gained a few HP here and there were quite usefull, it's this aproach I like to apply to my road cars
I liked the look of the air scoop behind the grill it kind of makes sense, before spending time making a scoop I thought it best to test so ran a digital pressure gauge from the airbox pre filter
Looks like its a good design, I could get max 0.1 psi at full throttle at 8k rpm no restriction in the OEM design so nothing to do here
 
Ive got an RPI kit and its pretty good :thumbsup:

http://shoprpi.com/product_info.php?cPath=21_22_31_45&products_id=48&osCsid=2f21bd2a6d156a04051e9fccdc4c71f0
 
I'm saying I can't see any Improvement over OEM as the OEM gives no restriction to the supply of cold air to the filter, I doubt changing the filter will make much difference, I plan to test that next
Looking at the whole thing I would say the metal mesh in front of the air flow sensor is the bottle neck, I'm guessing it's there to smooth the airflow as it passes the sensor and should not be removed
All in all the OEM set up is a very good system
 
I'm not sure that the RPI scoop really makes any difference to the amount of air forced into the air box. There is a "charge" of pressurized air behind the kidney grill when the vehicle is in motion. This pressure acts in all directions, so the upward facing OEM scoop will "see" the same pressure as a forward facing RPI scoop - the open mouth of the air intake does not need to face the direction of travel, simply sit within the charge of pressurized air.

The only potential benefits I can see are as follows:

That the area of the opening with the the RPI scoop is larger than that with the OEM scoop by perhaps 50%, so may be more free flowing. That said, pressure drop is dependent on both the cross sectional area and length of a given conduit, and both the OEM and RPI scoops are very short when compared with the induction system as a whole, so the restrictive effect of the OEM scoop will be minimal if it really is the acting to limit flow rate in the system.

The RPI scoop entrains air from directly behind the kidney grill, not from high up next to the radiator, so the air might be just a little cooler.

The RPI scoop may increase induction noise as it points straight out of the grill, yielding a perceived benefit

RPI tells you it works, so it must give you a power gain, especially after parting with hard earned cash for it :D

Alphamale, I would love to see actual figures for air box pressure with the OEM scoop and RPI scoop to see if any benefits can be obtained
 
I've the RPI scoop. The car seemed no different when I fitted it but any gains would be so slight as to be undetectable I expect.
 
So if the standard box design is very good, would just putting a better quality filter in be the best bet? Like the K&N panel filters?
 
I run a K&N panel filter but only because i dont believe in the service intervals BMW suggest, surely if you live somewhere dusty its going to be clogged sooner, i clean mine once a year and re fit but you could just put a clean paper filter in more often, its not a matter of the filter flowing more air its a question of if the engine wants more air, if i can find a way to get a pressure tap in point on the clean side of the filter i can check the drop over the filter panel.

with just monitoring the dirty side of filter i can only check if the intake duct and upturned scoop are restrictive, it shows zero psi on hard accelleration but +0.1 psi when i take the foot off the accellerator, this is the ram effect from the front grill, im not convinced 0.1 psi will make a difference, i guess doing 3rd gear 3k to 8k timmed runs before and after scoop removal would show any real world gains.
 
M@r said:
{"]So if the standard box design is very good, would just putting a better quality filter in be the best bet? Like the K&N panel filters?

Ye i would say, or go the whole hog and get something like the group M but they are very expensive. talking £800 if my mind serves me right.
 
Forced induction is not required. As long as there is a constantly supply as the OP has assertained then it's all good.

IK's are for noise, not gains...I got one on the V6 and it lost me 1.4bhp actually, but the noise is epic and lets be honest you only notice a gain in performance above 10-15bhp!
 
tomscott said:
M@r said:
{"]So if the standard box design is very good, would just putting a better quality filter in be the best bet? Like the K&N panel filters?

Ye i would say, or go the whole hog and get something like the group M but they are very expensive. talking £800 if my mind serves me right.

Could be selling my Groupe-M soon if my M3-E90 comes to light! But the price would have to be right as its like new and only done a few hundred miles! boxed with instructions! Also my Eisenmann backboxes agin like new!! and my mint CSL's! Watch this space :roll:
 
Gruppe M noise is awesome, you'll get cold driving with the windows down all the time (Coupe owners).
 
BMWZ4MC said:
Deedub, Gruppe M would be awesome! Let us know if the day comes that you want to sell it :thumbsup:

Will do :thumbsup: I wish it would fit the M3 as i will miss the roar! But then again i'm looking forward to being back in a V8 :D
 
I have the RPI Scoop and a CSL Style airbox on my Z4M. Sounds amazing and gave more power.

engine_01.jpg


http://www.youtube.com/watch?v=ZRJyt10M4d0

Looking at an new airbox for my e92 M3, either a GruppeM, or AFE Stage 2 intake.
 
Z4M_CSL said:
I have the RPI Scoop and a CSL Style airbox on my Z4M. Sounds amazing and gave more power.
How much more power? Is this on a static dyno or measured in real world driving conditions from ECU datalogging?
 
daz05 said:
Gruppe M noise is awesome, you'll get cold driving with the windows down all the time (Coupe owners).
x2 :thumbsup:
I put one on last night and the noise around 6k rpm is truly addictive. Need to find a nice tunnel now! :D
 
Back
Top Bottom