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E90 M3 (Sedan) | E92 M3 (Coupe) | E93 M3 (Convertible) (2008-2013) {Engine: S65 - Max Hp: 414 hp (420 hp Euro) at 8,300 rpm / 295 lb/ft at 3,900 rpm}


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Old Tue, Oct-28-2008, 06:06:59 PM   #21
MarqE46
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Amazing drop and getting the car on the dyno as much as the power the car makes with the RPI scoops.
Getting me a pair soon when they're ready to ship..
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Old Wed, Oct-29-2008, 09:53:46 AM   #22
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Quote:
Originally Posted by tightie View Post
the fan gives a 60mph wind speed... thats enough just to show that it makes power over stock.. the real test is when you go on the freeway and your going more then 60... the faster you go, the more air .. more power.. makes sense?
I'll be honest... I may be with foolio on this one. I'm not skeptical of the ability for ram air to produce power.

But...

... I'm not convinced that that fan simulates a car travelling at 60mph. It's one thing to say the fan blows air at 60mph, and it's a different thing to say it simulates a car travelling at 60mph. Also, I'm not convinced that travelling faster than 60 mph will actually generate any significant gains.

This is how I see it...

Ram air is somewhat of a misnomer... you're not "ramming air", you're creating a zero-velocity region inside the duct entry, effectively keeping the air in the intake at atmospheric pressure. Normally, as the engine pulls air in, the air picks up velocity and the pressure decreases. The low pressure created effectively starts resisting the engine's ability to pull more air in. The point of the ram air system is to counter the pressure drop by creating a zero velocity region at the intake opening... but the pressure at this zero velocity region is only atmospheric pressure -- not more (as opposed what a blower or turbo do, which is actually create a *greater* than atmospheric pressure region at the intake).

Now, I have to say I may be a little rusty on my fluid dynamics, but I'm fairly certain the pressure inside the duct doesn't actually increase above atmospheric. If it does, it would be ever so minor. But I don't think it does. Anyone else knowledgeable on the subject please chime in.

Just in *front* of the duct is a high pressure region -- where the air "slams" into the front of the car. But when the car is moving through air, there are streams of air flowing towards the sides/back. These streams have lower pressure as a result of their velocity and the high pressure built up in front of the car get pulled in every direction to get beside/behind the car.

With a whole massive amount of air moving at velocity around the car (as would be the case if the car were moving at 60mph), you won't get more than atmospheric pressure inside the duct -- any additional air will take that path of least resistance, which is around the car.

At issue is that the actual volume of air that you're using is not high enough to simulate moving through fluid. The volume actually has a significant effect on the flow lines around the car and the pressure zones that are created as a result. Also, that relatively small fan's air stream is getting decimated by the car itself and I'd guess that the flow lines created above the car do not simulate the flow of air accurately enough.

You have a fan blowing air right at the middle of the car -- right where the ram air ducts are. The stream of air is roughly 1/2 (or less) the width of the car (estimating the size of the fan from the pictures). So you don't have enough air moving along side/above/below the car to "pull air" from the high pressure region in front of the car.

I believe by not having these flow lines going around the car, you're actually creating a *positive* pressure zone by pointing the fan at the intake like that -- something you wouldn't get if all the "real life" air flow was going around the car. As such, the numbers may be inflated.

In this case, in a way, I think of it as... the air to the sides of the fan's air stream is stationary, so it stays at a relatively high pressure and helps keep the air "in line". The air hits the front of the car and "splatters", but it doesn't really have anywhere to go (again, because there's a "wall of atmospheric pressurized air" around it), except over the hood of the car, where it eventually slows and, while still following the curve of the car, also "fires" off the top more, too. Whereas if it were moving through fluid there'd be streams moving all along the sides for the air to "join".

Also, I'm curious if the numbers were produced with that small metal fan on or off. I'm curious if the small fan could introduce turbulence to the air stream that might prevent the laminar flow of air moving over the hood of the car. This could reduce the speed of the air as it moves over the hood, and, as a result, artificially increase pressure at the duct openings.

- Som

Last edited by Som; Wed, Oct-29-2008 at 10:03:51 AM.
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Old Wed, Oct-29-2008, 05:47:37 PM   #23
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To me this mod is more a butt dyno - drag strip verified type mod. If I put the car in a wind tunnel it will make more power than with a lasko in front of it. If I see good reviews from butt dynos / drag strips I'll be picking one up for my e46.
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Old Wed, Oct-29-2008, 07:17:53 PM   #24
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Quote:
Originally Posted by Som View Post
I'll be honest... I may be with foolio on this one. I'm not skeptical of the ability for ram air to produce power.

But...

... I'm not convinced that that fan simulates a car travelling at 60mph. It's one thing to say the fan blows air at 60mph, and it's a different thing to say it simulates a car travelling at 60mph. Also, I'm not convinced that travelling faster than 60 mph will actually generate any significant gains.

This is how I see it...

Ram air is somewhat of a misnomer... you're not "ramming air", you're creating a zero-velocity region inside the duct entry, effectively keeping the air in the intake at atmospheric pressure. Normally, as the engine pulls air in, the air picks up velocity and the pressure decreases. The low pressure created effectively starts resisting the engine's ability to pull more air in. The point of the ram air system is to counter the pressure drop by creating a zero velocity region at the intake opening... but the pressure at this zero velocity region is only atmospheric pressure -- not more (as opposed what a blower or turbo do, which is actually create a *greater* than atmospheric pressure region at the intake).

Now, I have to say I may be a little rusty on my fluid dynamics, but I'm fairly certain the pressure inside the duct doesn't actually increase above atmospheric. If it does, it would be ever so minor. But I don't think it does. Anyone else knowledgeable on the subject please chime in.

Just in *front* of the duct is a high pressure region -- where the air "slams" into the front of the car. But when the car is moving through air, there are streams of air flowing towards the sides/back. These streams have lower pressure as a result of their velocity and the high pressure built up in front of the car get pulled in every direction to get beside/behind the car.

With a whole massive amount of air moving at velocity around the car (as would be the case if the car were moving at 60mph), you won't get more than atmospheric pressure inside the duct -- any additional air will take that path of least resistance, which is around the car.

At issue is that the actual volume of air that you're using is not high enough to simulate moving through fluid. The volume actually has a significant effect on the flow lines around the car and the pressure zones that are created as a result. Also, that relatively small fan's air stream is getting decimated by the car itself and I'd guess that the flow lines created above the car do not simulate the flow of air accurately enough.

You have a fan blowing air right at the middle of the car -- right where the ram air ducts are. The stream of air is roughly 1/2 (or less) the width of the car (estimating the size of the fan from the pictures). So you don't have enough air moving along side/above/below the car to "pull air" from the high pressure region in front of the car.

I believe by not having these flow lines going around the car, you're actually creating a *positive* pressure zone by pointing the fan at the intake like that -- something you wouldn't get if all the "real life" air flow was going around the car. As such, the numbers may be inflated.

In this case, in a way, I think of it as... the air to the sides of the fan's air stream is stationary, so it stays at a relatively high pressure and helps keep the air "in line". The air hits the front of the car and "splatters", but it doesn't really have anywhere to go (again, because there's a "wall of atmospheric pressurized air" around it), except over the hood of the car, where it eventually slows and, while still following the curve of the car, also "fires" off the top more, too. Whereas if it were moving through fluid there'd be streams moving all along the sides for the air to "join".

Also, I'm curious if the numbers were produced with that small metal fan on or off. I'm curious if the small fan could introduce turbulence to the air stream that might prevent the laminar flow of air moving over the hood of the car. This could reduce the speed of the air as it moves over the hood, and, as a result, artificially increase pressure at the duct openings.

- Som
Great points...and I'll add, as I am a skeptic of these "designed for the 335 and mounted on the M3" scoops.

Do you all realize that there is a hole in the airbox going out the hood on the driver's side? It is against the law of physics that air would be able to be pressurized inside the airbox with a gaping hole in it. Have you noticed water droplets flying out the vent when you drive inthe rain? That's the ram-air effect being blown out the hood.
The 335, or the M5/M6, airboxes do not have this vent out the hood from the airbox. The product, designed for other cars, cannot build positive pressure due to the different M3's design. It stands to reason that a closed-airbox application...335/M5/M6/Z4...will see some type of change in "ram-effect", as they only draw air from the front kidney inlets and have no hole out their hoods. More power and MPG?...perhaps. But on the M3?...not going to happen...different airbox.

There is an interesting discussion on M3Post with the same heading in the "Engine" forum....very interesting statements, some blatantly contradictory, on the effectiveness of the 335scoops mounted on the M3.
Give it a read and make your own conclusions before you buy into the "butt-dyno"s and hype....

Last edited by ace996; Wed, Oct-29-2008 at 07:21:41 PM.
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Old Wed, Oct-29-2008, 08:12:38 PM   #25
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Why not (for those of us with csl bumpers or anyone with access to an auto parts store of home depot for that matter) just hook up front of the cai (for those of us that have one) directly to the port already there thus creating a RAM AIR EFFECT while not resticting the airflow to the radiator (which NEEDS ALL THE AIR IT COULD GET)? Don't get me wrong I like the idea (obviously since I have been driving around with my set up for SEVERAL YEARS NOW Thanks ROB) I just don't like the placing. Our cars suffer from high engine temps (ask anyone that has tracked thier cars or driven them hard) when pushed so why exaggerate the problem? Dyno's are nice but think about how long the car is actually is at those loads.
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Old Wed, Oct-29-2008, 10:26:24 PM   #26
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FYI - I remember from my sport bike days that when they did some real world testing on ram air intakes the results were only seen as the bike was traveling at 135 mph and up and even then it was barely 1whp.

I'm sure there is some gain but the 14whp is probably not the result of a fan blowing air at 60 mph.

The bike tests revealed that the entire front end of the bike needed to be hit with wind and static pressure tests were useless against a high velocity fan. They actually had to ride the bike on a closed circut with test gear affixed to pressurize the entire front end of the bike at xxxmph to get any ram air gain.
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Old Wed, Oct-29-2008, 11:51:07 PM   #27
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Hold the phone----14hp increase out of the V8 wouldn't changing the filter result in similar hp gains for less? I mean it is a V8 and TBH didn't people see similar results when switching to the streamline filter on the s54? If that's the case than this is another HUGE FAIL!!!!!!!!!!
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Old Wed, Oct-29-2008, 11:58:07 PM   #28
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Isn't this the company that used to be 1gracing. They should really stick to the rossion line (old M12 &M400 noble which they now bought the rights to since noble isn't noble anylonger). Never mind they are not them.
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Old Thu, Oct-30-2008, 01:31:22 AM   #29
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Are they the same as the 335 scoops? If not, how are they different?
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Old Thu, Oct-30-2008, 03:20:04 AM   #30
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All the numbers posted mean nothing if it cant be duplicated on several cars. Its why these things take time and for those who are waiting for our testing to be complete, we appreciate your patience. At this time, we are still looking for a few E92 M3's for testing in the So Cal area. Please call us if you are interested. Do not PM me. 562-630-5966
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