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Discussion Starter #1 (Edited)
I have received, but not yet installed the RPI scoops. I have read about some that have plugged some holes in the air intake with some benefits. Can someone explain this in some detail?

Rick

P.S. The sentence above contains an awful lot of "somes"!
 

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Rick:

Give Eloy a call. We actually manufacture the plugs as well. They're very inexpensive (currently $20).

Another way to go would be to make your own, and find a way to affix it to that location. Some people have used duct tape I believe.
 

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where are these holes??
The holes are at the bottom of the airbox. It leads under
the car. See these diagrams:

See part 16 from this diagram:
http://www.realoem.com/bmw/showparts.do?model=EH93&mospid=49343&btnr=13_1142&hg=13&fg=20

It seems reasonable to think that it's there to create airflow by
generating a pressure differential. This would pull air from the
intake ducts from the front (part 20 in the diagram). You can see
that something like this might be necessary as the direction of
the intake ducts are perpendicular to the air flow. So perhaps
as air flows past the "rubber buffer" it might create a lower
pressure region causing air to flow through the ducting. It's also
conceivable that because it's constantly flowing air it may tend
to keep the air in the airbox cooler?

By adding scoops to the front you are forcing air into the ducts
so air is already flowing into this area. Keeping the buffer open
at least gives good, repeatable results as seen in all the RPi Ram
Air threads. It seems like plugging up the "buffer" you could be
building up pressure in the airbox. What is the result of this? Well,
just from my dynos it appears to add a bit of midrange hp/tq.
But this is just one set of dynos. Until others try this and do before
and after dynos I don't think we can conclude anything. Deknight
was supposed to run a few tests but I'm not sure if he had
the opportunity to dyno yet.

I don't have access to CFD software anymore (different lifetime
it seems) so I can only speculate on any of this. Maybe someone out
there does? Perhaps they could throw a quick model together and
run a simulation to determine theoretically if there is any benefit.
Of course that would be pretty hardcore. :biggrin:
 

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Here's an additional mod that I've made - no idea if it has any benefit.

I noticed that after install, if you follow the airflow through the scoop, there is a small opening that looks to me like some of the air directed into the scoop would escape out this opening and not be forced into the intake. So I just took some aluminum tape, and covered this opening. It doesn't reduce any of the airflow to the intake, and may help build some pressure. I'll probably use the good old aluminum tape for to plug the hole as well.

If anyone is really interested, I can post some pic's.
 

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Here's an additional mod that I've made - no idea if it has any benefit.

I noticed that after install, if you follow the airflow through the scoop, there is a small opening that looks to me like some of the air directed into the scoop would escape out this opening and not be forced into the intake. So I just took some aluminum tape, and covered this opening. It doesn't reduce any of the airflow to the intake, and may help build some pressure. I'll probably use the good old aluminum tape for to plug the hole as well.

If anyone is really interested, I can post some pic's.
Pics please :biggrin: I think I know what you are referring to.
 

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Company Representative of RPI Power
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Here are installation instructions for our block off plates. We were originally going to make a larger plate so it completely sealed the bottom hole but we felt it would be safer with it slightly smaller plate so any moisture that finds its way in will come out of the sides.

http://www.raceprecision.com/forums/viewtopic.php?p=357#357
 

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I am a bit confused here.
First I see the claims of 17 rwhp gain from the RPI scoops. I have a hard time w/ that. There is noway the some fans blowing in front of the car can simulate the actual force of air rushing in thru the air boxes while driving at 100 mph. This applies as I see it, to air intake systems.
I use to have the Gruppe M intakes but I still have the CF piece which sits behind the Kidney grills which funnels air into the air boxes. This appears very similar to the RPI scoops.
Personally I would be somewhat concern blocking air ducts that BMW engineers had designed based on their R&D.

I do not mean to be dense but what is the anticipated benefit in air flow?

M5Ranger
 

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I am a bit confused here.
First I see the claims of 17 rwhp gain from the RPI scoops. I have a hard time w/ that. There is noway the some fans blowing in front of the car can simulate the actual force of air rushing in thru the air boxes while driving at 100 mph. This applies as I see it, to air intake systems.
I use to have the Gruppe M intakes but I still have the CF piece which sits behind the Kidney grills which funnels air into the air boxes. This appears very similar to the RPI scoops.
Personally I would be somewhat concern blocking air ducts that BMW engineers had designed based on their R&D.

I do not mean to be dense but what is the anticipated benefit in air flow?

M5Ranger
When we designed the scoops, we had no idea of how much hp we would gain. You can ask Deknight and Marshall about that as well. We normally do 3 runs to get an idea of power. We did several runs (18 on marshalls) just to confirm the results,...on several cars. Also, the air/fuel mixture changes instantly when the scoops are installed. Remember, we are changing a vacuum reliant intake system into a ram air set up. This will change the way it was designed.

Here is a graph (air fuel ratio / hp) with and without the ram air scoops.
 

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I am a bit confused here.
First I see the claims of 17 rwhp gain from the RPI scoops. I have a hard time w/ that. There is noway the some fans blowing in front of the car can simulate the actual force of air rushing in thru the air boxes while driving at 100 mph. This applies as I see it, to air intake systems.
I use to have the Gruppe M intakes but I still have the CF piece which sits behind the Kidney grills which funnels air into the air boxes. This appears very similar to the RPI scoops.
Personally I would be somewhat concern blocking air ducts that BMW engineers had designed based on their R&D.

I do not mean to be dense but what is the anticipated benefit in air flow?

M5Ranger

About the RPI scoops. They could be the same as the Gruppe. I haven't
seen those. There are a ton of dynos on the board showing the gains.
If you do a search you'll find them. True that a fan cannot reproduce
real world conditions. It would be interesting to see some 1/4 mile
runs before and after the scoops. They are so easy to install and remove
you could even do it on the same night. I'm not sure what a 10-20 hp
increase equates to in trap speed.

The plugs I'm not sure about. As far as I'm aware I'm the only one to
post pre/post dyno runs with the plugs. That's not enough to say whether
they are good or bad. As far as we know it could only be my car. I'm
not advocating this mod to anyone without further data. I think it's good
to be skeptical about it until the results are repeated. You can even
see in my past posts about it I've always been skeptical even in the
face of the dyno results. On top of all of this who knows the real world
gains with the plugs if any at all? We can only know with people posting
their results...without it all is pure speculation.
 

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Pics please :biggrin: I think I know what you are referring to.
Here's a pic through the grill. If you look closely through the second slat area on the left, you'll see the aluminum tape blocking the opening at the lower leg of the scoop. It's actually a pretty large area, and I can't imagine you wouldn't benefit by blocking it off.
 

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I guess I'm not understanding but why would you want to plug up air flow?
My position is not speculation but rather just want to understand the physics/dynamics of the mod.

M5Ranger
 

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I guess I'm not understanding but why would you want to plug up air flow?
My position is not speculation but rather just want to understand the physics/dynamics of the mod.

M5Ranger
It's a directionality issue.

With the scoops, you force enough airflow into the box that the air is forced downwards through the hole in the bottom of the airbox. Plugging this hole "pressurizes" the box more (in reality, it relieves the vacuum).

The difference is actually reasonably small at normal speeds, but we've found it does help.
 

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I guess I'm not understanding but why would you want to plug up air flow?
My position is not speculation but rather just want to understand the physics/dynamics of the mod.

M5Ranger
The only thing I can think of is by plugging the hole you are increasing
pressure. Given that the temperature hasn't changed this should result
in a higher air density.

http://en.wikipedia.org/wiki/Density_of_air

Higher air density should mean more oxygen to burn. It's not as extreme
as a NOS shot but it's something.

I know this is overly simplified but it seems reasonable.
 

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Okay you have my attention. What is the price of the mod?
 

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Here's a pic through the grill. If you look closely through the second slat area on the left, you'll see the aluminum tape blocking the opening at the lower leg of the scoop. It's actually a pretty large area, and I can't imagine you wouldn't benefit by blocking it off.
I see. The M6 scoops don't have as large a gap as that. Definitely it seems
like reducing that gap can only help. I believe one of the reasonings
behind that was to ensure water could drain if necessary. Somehow
I doubt that water would cause any issues in this case. Thanks for the
pic!
 

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Okay you have my attention. What is the price of the mod?
I wonder if your setup already accounts for all of this. You already
have the Gruppe scoops that come with their air system (BTW, do you
have any pics of this?). If they go behind the grills to force air into
the ducts then you are already set. Concerning the airbox plugs. Does
the ASR setup swap out the stock airboxes? If not then you could run
a test by just putting some tape in there (Deknight style). You can see
from Eloy's link in this thread what they are doing.

Edit:

Actually found this pic:

http://www.m5board.com/vbulletin/attachment.php?attachmentid=31292&d=1165606210

Pretty nice. If you have this you shouldn't need the RPi scoops
 

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Marshall you are correct, that is what I have right now. The Gruppe M carbon piece air funnel is present behind my grills.
I had dyno'ed the car after the Gruppe M air intakes and the Dinan TB's (all before the NOS install) and the car made no new hp. That was back when my complaints and issues w/ Dinan occurred. On motor I could not demonstrate any hp gains w/ dyno runs done on two different occasions.
 

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Marshall you are correct, that is what I have right now. The Gruppe M carbon piece air funnel is present behind my grills.
I had dyno'ed the car after the Gruppe M air intakes and the Dinan TB's (all before the NOS install) and the car made no new hp. That was back when my complaints and issues w/ Dinan occurred. On motor I could not demonstrate any hp gains w/ dyno runs done on two different occasions.
Yeah, I remember that. Real bummer. It's unfortunate that you went
through that hell but at the least you saved many of us from purchasing
that mod. A thing that keeps this board great is the dissemination of
information. At the expense of a few adventurous folk like yourself who
are willing to "take one for the team" we all learn and benefit.
 
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