b0mbrman

Wait a second...does this "filter" not really have a filter?

As in, is the horn just sucking air into the engine with nothing to block whatever bad stuff a standard filter keeps out?

Yellow Streak

I believe there is a K&N filter in the horn.

-YS

flyellow

That, my friend...........is CORRECT

b0mbrman

Ah...excellent

So what is the purpose of the horn then? Wouldn't more air get to it if the filter was exposed?

Yellow Streak

The purpose of the horn is to select where you are intaking air from. That design is intended to be pulling from a source of ambient air, not engine bay temperature air. I would think that an exposed filter would allow more flow, but it would be warmer air. In a naturally-aspirated car, my guess is that temperature of air has a larger impact than volume (and you certainly won't lose air volume with a K&N).

-YS

parkerdw

The filter is an inverted cone K&N located in the black plastic casing section of the intake. When you look into the horn it is like looking into the bottom of an orange street cone. The whole point of this design is to generate a Venturi effect.

"A venturi is a short, tapered tube or nozzle. The effect that a venturi or nozzle has on fluid flow is that it causes an increase in the velocity and a corresponding decrease in pressure and that is used especially in measuring fluid flow or for creating a suction."

"The increase in the velocity of a fluid stream as it passes through a constriction in a channel, pipe, or duct. Calculated by the Continuity Equation, or

Q = VA Q = VA

where Q is the volumetric flow rate, A is the Area of flow, and V is the fluid velocity. Because Q does not change, as A gets smaller then V must increase."

"Air flows from a region of higher total energy value E1 ( in fact ,total enegy per unit weight of air ) of pressure and velocity to another region of lower total energy value E2. In this air flow process, some energy is lost (E3) due to friction, and formation of eddy air currents. So air flowing into a conical form leading to an outlet of smaller area ( i.e like the Venturi tube ) will have a higher outlet velocity, but a LOWER outlet pressure than the inlet. Energy balance is E1 - E3 = E2. If well used, the Venturi principle can lead to effective natural ventilation and interesting architectural forms.
Venturi effect shows that energies for pressure and velocity are interchangeable "


The bottom line is that the PRM speeds up the air, lowers the pressure and lowers the temperature of the incoming air. It also creates a suction effect because of the high to low pressure flow.

The following is how the PRM lowers the temp of the air it brings in...

"In physics, the concept that as the speed of a moving fluid (liquid or gas) increases, the pressure within that fluid decreases.Originally formulated in 1738 by the Swiss mathematician and physicist Daniel Bernoulli, this principle states that the total energy in a steadily flowing fluid system is a constant along the flow path. An increase in the fluid's speed must therefore be matched by a decrease in its pressure. In other words, in regard to temperature, as pressure decreases gas expands and heat is dissipated temperature drops) because of lower pressure (less density) at greater volume dispersing the kinetic energy.

This is why air leaving a nozzle or discharge port of an air tool often feels cold"

dolebludger

TO: all above with installed PRM CAI's. In reading the above posts from S2k owners with these installed, I didn't find any discussion of the PRM's effect on performance. By that I mean acceleration mainly, and also gas mileage. As that is the only reason I would want to make any modification (not for sound), I'd appreciate all feedback. Doesn't have to be on a dyno, or timed runs at some official event. "Seat of Pants" opinions are also sought.

It looks to me that the theory of the PRM (along with "tuned intake pipes" and great looks) is that it pulls cool air out of the round hole in the passengers' side of the engine compartment that leads to a "cavity" between wheel well and front bumper. Is this true? To bring cool air into this cavity, was it also necessary to replace the fake bumper vent leading to this area with an operational one? (I strongly suspect it was, but just thought I'd ask.)

If a purpose of the PRM is to pull cool air from this cavity mentioned above, why then does it not incorporate a pipe running directly into this cavity?

Please excuse all my questions, but I am definitely on a "learning curve" about how to get more power out of an engine that already makes 120 crank hp per liter!

Thanks,
Richard

parkerdw

dolebludger,

the following link is what you are looking for.

Detailed PRM performance and design analysis

As for my drive a couple of nights ago with the PRM (on my way to to see the meteor shower) read on...

I take it easy off the line in first, but quickly find the courage that allows my right foot to mash the pedal to the floor. I note that throttle response is noticeably better, but you don't feel much faster at low rpm over stock. When you floor the throttle the power builds and the rush to 9000 feels faster. Under VTEC at WOT there is a deep growl that is brand new and after VTEC a vicious full-throated snarl that made my hair stand on end when I first heard it. The shift to second causes the car to squat and the wheels to break loose and spin way easier than stock. Floor it again in second and the car emits a frightening powerful growl and shoots forward with a purpose. The shift to third is upon you before you know it and once again the tires break loose. With yet another banshee howl you are now past 100 mph, and your heart is in your throat and a permanent smile on your face.

This is how it "feels". Check the above link for long winded discussussions on temperature, pressure, humidity, air horn placement, tube extensions and other boring facts. I also have a Mugen header, 94 octane gas and it was 37 degrees out, but you get the picture.

By the way, I waited 3 years to pick an intake to replace the stock airbox and really didn't care about sound improvement. I only wanted performance. I didn't think it mattered, just like you. I would bet money that you will change your "tune" so to speak if I could give you one ride in my car.

flyellow

Well said Parker ------------------>

ras2k

I talked with Jerry up in Toronto, and it is not a K&N filter, but a filter like K&N. You use a K&N cleaning kit to clean it though.

Also, he told me that Honda originally designed the S2000 to take in the cold air from the circular opening that the PRM takes it in from, but Mugen had them change it. Is this true - don't know. Does anyone have any input/information on this?

By the way, I did order a PRM intake. My decision was based on what I read on this board. Everyone that has one seems to like it. It should be here witin a week. I will post results after the install.