Ram Air intake modification
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bobby in Derby City
- Posts: 980
- Joined: Feb 12, 2006
- Location: Hidin' in a bowl of rice ready to put a cap in an a$$
I was wondering about the ram air intake modification. For those who do not know, it is when you replace the passenger side hi-beam with a fine mesh screen. I was wondering if one were to do this, should they be worried about water in the intake system when they are driving during the rain? I think I saw Raj with this set-up somewhere along the way. TIA
Many folks have done this, but what everyone fails to consider is that the screen takes a great deal of cross-sectional area away. Places like McMaster-Carr have "percent open area" data for screens and perforated plates -- you'd need to do a little PIxRsquared calculation to see if you don't end up creating a restriction.
Water from rain isn't a big deal when the engine is running -- it'll actually help clean the pistons & chambers. Water from sucking up a puddle is another matter (hydrolock), but as long as you're not moving the intake point, it won't happen.
Water from rain isn't a big deal when the engine is running -- it'll actually help clean the pistons & chambers. Water from sucking up a puddle is another matter (hydrolock), but as long as you're not moving the intake point, it won't happen.
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bobby in Derby City
- Posts: 980
- Joined: Feb 12, 2006
- Location: Hidin' in a bowl of rice ready to put a cap in an a$$
[QUOTE="Shawn D."]Many folks have done this, but what everyone fails to consider is that the screen takes a great deal of cross-sectional area away. [/QUOTE]
I must be ignorant 'cause I do not understand this statement. I am thinking that since I am removing the headlight and installing a screen, it will have more cross-sectional area since the headlight "totally" blocks the opening and the screen will allow alot more air in than than a headlight.
cheers!
I must be ignorant 'cause I do not understand this statement. I am thinking that since I am removing the headlight and installing a screen, it will have more cross-sectional area since the headlight "totally" blocks the opening and the screen will allow alot more air in than than a headlight.
cheers!
Bobby,
I think what Shawn is trying to explain is that even with screen, there is restriction caused by how fine the cross-hatches may be. If you are conserned about getting large items such as leaves, use chicken wire or the equivilant. All of the other stuff in the air will be filter out so, I would be more worried about restriction. Restriction I think here is your major consern, so more stuff in front of the light=restriction.
I think what Shawn is trying to explain is that even with screen, there is restriction caused by how fine the cross-hatches may be. If you are conserned about getting large items such as leaves, use chicken wire or the equivilant. All of the other stuff in the air will be filter out so, I would be more worried about restriction. Restriction I think here is your major consern, so more stuff in front of the light=restriction.
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C.R. Krieger
- Posts: 14507
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[QUOTE="bobby in Derby City"]I was wondering about the ram air intake modification. For those who do not know, it is when you replace the passenger side hi-beam with a fine mesh screen. [/QUOTE]
I think you might pick up almost as much 'ram effect' by simply removing the excess material between the grille bars around the right side headlights. I took off the grille and spent about a half hour with a Dremel and its cutoff wheel hacking out all the extraneous plastic in there. The best part is, it's still totally legal (Well, except that they're Euro lamps.
) and it looks perfectly stock. You'd have to be very observant to even notice the modification.
I think you might pick up almost as much 'ram effect' by simply removing the excess material between the grille bars around the right side headlights. I took off the grille and spent about a half hour with a Dremel and its cutoff wheel hacking out all the extraneous plastic in there. The best part is, it's still totally legal (Well, except that they're Euro lamps.
) and it looks perfectly stock. You'd have to be very observant to even notice the modification.OK, Bobby, let me explain:
Let's say the intake on a 535i is 3" diameter (I'm just eyeballin' my memory, it ain't a measurement). This means that it has about 7.1 square inches of open area.
A 5-3/4" headlight has an open area of about 26.0 square inches.
Thus, the stock intake has 27% of the area of the headlight hole, or in other words, the headlight hole is 3.7 times bigger.
Go to http://www.mcmaster.com/ and look down at the bottom right corner and click on "Perforated Materials," and then click on "Woven Wire Cloth" or "Perforated Metal." Drill down through the material types and grades and you'll find a selection for "Open Area (Percentage)" (this selection is at different levels for "Woven Wire Cloth" or "Perforated Metal" ).
"Woven Wire Cloth" has selections of: 14.5 | 19.4 | 21.2 | 24.6 | 25 | 25.4 | 26.6 | 28.1 | 29.2 | 29.3 | 29.8 | 30 | 30.3 | 30.5 | 30.7 | 31.4 | 33.2 | 33.6 | 33.8 | 36 | 37.1 | 37.4 | 37.5 | 37.9 | 38 | 38.4 | 38.9 | 39.9 | 40.8 | 41 | 41.1 | 41.5 | 42 | 42.3 | 42.4 | 43.6 | 44 | 44.2 | 45.2 | 45.7 | 46 | 46.2 | 48.3 | 50.7 | 50.8 | 51 | 51.8 | 55.4 | 56 | 56.3 | 56.7 | 57.6 | 57.8 | 58.5 | 59.1 | 60.2 | 62.4 | 62.7 | 62.9 | 63.2 | 64.3 | 64.8 | 65.6 | 65.9 | 70.5 | 70.6 | 72.3 | 73.6 | 76.4 | 77.4 | 79.8 | 82.1 | 84.6 percent open.
"Perforated Metal" has selections of: 20 | 21 | 22 | 23 | 26 | 28 | 29 | 30 | 31 | 33 | 34 | 36 | 37 | 40 | 41 | 43 | 45 | 46 | 47 | 48 | 49 | 51 | 58 | 63 | 79 percent open.
You'd need to select one that's 27% or greater in open area or else your headlight hole will effectively be smaller than the stock air tube. Of course, unless you have the stock tube sealed to the headlight hole, it won't choke it off, but you won't be getting the full ram effect you seek.
[Edit by Shawn D. on [TIME]1112217094[/TIME]]
Let's say the intake on a 535i is 3" diameter (I'm just eyeballin' my memory, it ain't a measurement). This means that it has about 7.1 square inches of open area.
A 5-3/4" headlight has an open area of about 26.0 square inches.
Thus, the stock intake has 27% of the area of the headlight hole, or in other words, the headlight hole is 3.7 times bigger.
Go to http://www.mcmaster.com/ and look down at the bottom right corner and click on "Perforated Materials," and then click on "Woven Wire Cloth" or "Perforated Metal." Drill down through the material types and grades and you'll find a selection for "Open Area (Percentage)" (this selection is at different levels for "Woven Wire Cloth" or "Perforated Metal" ).
"Woven Wire Cloth" has selections of: 14.5 | 19.4 | 21.2 | 24.6 | 25 | 25.4 | 26.6 | 28.1 | 29.2 | 29.3 | 29.8 | 30 | 30.3 | 30.5 | 30.7 | 31.4 | 33.2 | 33.6 | 33.8 | 36 | 37.1 | 37.4 | 37.5 | 37.9 | 38 | 38.4 | 38.9 | 39.9 | 40.8 | 41 | 41.1 | 41.5 | 42 | 42.3 | 42.4 | 43.6 | 44 | 44.2 | 45.2 | 45.7 | 46 | 46.2 | 48.3 | 50.7 | 50.8 | 51 | 51.8 | 55.4 | 56 | 56.3 | 56.7 | 57.6 | 57.8 | 58.5 | 59.1 | 60.2 | 62.4 | 62.7 | 62.9 | 63.2 | 64.3 | 64.8 | 65.6 | 65.9 | 70.5 | 70.6 | 72.3 | 73.6 | 76.4 | 77.4 | 79.8 | 82.1 | 84.6 percent open.
"Perforated Metal" has selections of: 20 | 21 | 22 | 23 | 26 | 28 | 29 | 30 | 31 | 33 | 34 | 36 | 37 | 40 | 41 | 43 | 45 | 46 | 47 | 48 | 49 | 51 | 58 | 63 | 79 percent open.
You'd need to select one that's 27% or greater in open area or else your headlight hole will effectively be smaller than the stock air tube. Of course, unless you have the stock tube sealed to the headlight hole, it won't choke it off, but you won't be getting the full ram effect you seek.
[Edit by Shawn D. on [TIME]1112217094[/TIME]]
The "ram air" screen with K&N cone was actually the first "modification" I ever did to my car, back when it was just a beater to get me through college. Simply removing the highbeam on the right side does not offer any performance improvement for two reasons:
1. The AFM is the limiting factor in our intake
2. The factory airbox is pretty good about pulling in cold air
The only real benefit I can think of is it helps keep warm exhaust-manifold air off the intake, if you have a cone w/o heatshield. I had planned on putting the high beam back in place, but never did because the highbeams work fine without it. That, and people get a bit intimidated when they see a cock-eyed black BMW approaching at 90+ and get out of my way.
1. The AFM is the limiting factor in our intake
2. The factory airbox is pretty good about pulling in cold air
The only real benefit I can think of is it helps keep warm exhaust-manifold air off the intake, if you have a cone w/o heatshield. I had planned on putting the high beam back in place, but never did because the highbeams work fine without it. That, and people get a bit intimidated when they see a cock-eyed black BMW approaching at 90+ and get out of my way.
I don't think any of those things make any differance on a street car. The cone filter may add a sound you like, but if you put one on extend it up to the headlight area and build a heat sheild. I put foam pipe insulation on my extender pipe as well. Just removing that cover behind the lights will give all the air that will flow past the AFM, as already pointed out. There seems to be some argument if K&N filters better or worse. People I trust have taken both sides of the issue.
It is now in my son's car, when he comes back to town I'll see what I can do. I just have the stock one in my M535 pressently. When I had the Cone in my car I extended it with 3" exhaust pipe, covered in pipe insulation and a heat shield I made out of aluminum to keep the heat from the manifolds away from it. Pretty easy really.