Official Downforce - Stack Intake System

[Exiled]

... well if you think about it and looking at the pictures, the stack intake fits into that velocity stack right? same as how the df snorkel also fits into the stack intake that some of us have already. So if you don't have the df snorkel, then I would guess that the velocity stack would go in place of it. Maybe i don't understand but looking at the pictures it appears the stack intake just plugs into the velocity stack. that would mean the velocity stack would go on the other side of the wall where your stock intake tube or the df snorkel goes?

Look at this picture:

see where the stock tube is? the stack intake would stick out of that hole and you just attach the velocity stack to the end?

 

[Dhalsim]

...
see where the stock tube is? the stack intake would stick out of that hole and you just attach the velocity stack to the end?

Well OK I was thinking that might be the way it works so does that mean I would have to remove the plastic part that the end of the intake goes into now? I circled the part I'm talking about in the pic below.

 

[YTRY]

I believe the CF piece that attaches to the end of the intake is supposed to fit over the rubber piece. I'm not using mine since I have the DF intake scoop.

 

[nsxpowered]

The little funnel replaces the factory air resonator setup. To install you push into the rubber boot where the air resonator used to be. There is a cut out on the funnel and that is where the wheel well curves up to the funnel.

 

[Dhalsim]

The little funnel replaces the factory air resonator setup. To install you push into the rubber boot where the air resonator used to be. There is a cut out on the funnel and that is where the wheel well curves up to the funnel.

OK so push into the rubber boot from inside the engine bay? Do you have a pic of this?

Or do you mean I should remove the whole factory air scoop and resonator and just use this?? A picture would sure be helpful.

I'm beginning to suspect you are making this difficult so I will just break down and buy your AIS.

 

[nsxpowered]

Sorry for making it difficult, I was looking all over and I can't find the pictures I had taken during the DYNO. You have to remove all of the factory resonator as you will not need it anymore. And yes you just push it into that rubber boot. I'll post a picture when I can.

 

[Dhalsim]

Sorry for making it difficult, I was looking all over and I can't find the pictures I had taken during the DYNO. You have to remove all of the factory resonator as you will not need it anymore. And yes you just push it into that rubber boot. I'll post a picture when I can.

OK I understand then. So now with just the funnel in there is it efficient since it deosnt reach all the way down to the air intake scoop?

 

[nsxpowered]

Band update. The factory has confirmed our 1000 piece production yesterday. They should be done in about 3 days and QC within 1 day. Ground shipping to us in about 5 days, so that's about 2 weeks out. We'll ship them right away as we get them.

 

[nsxpowered]

Dhalsim: Yes it is efficient and that is what I will be running on all of my NSXs. The best air to draw is steady air, when you have high and low pressure air buffering near the inlet, it creates surges and draws of air.

My example for those of you who've cleaned fish tanks. If you move the vacuum hose around violently you'll notice the flow is slightly decreased, the slower you move the vacuum hose around, the faster the flow becomes. Once the vacuum hose is sitting stationary, that is when you'll experience the best flow. The only way to beat it is to actually force pump water through the vacuum which can be done with either a power pump or if you move the vacuum tube in a way that it is acting like an air ram. However you can't keep going forever as you will need to stop and change directions, this is where you'll exprience the draw. Flame me if I'm wrong, because I'll deserve it.

 

[Gansan]

Sorry for making it difficult, I was looking all over and I can't find the pictures I had taken during the DYNO. You have to remove all of the factory resonator as you will not need it anymore. And yes you just push it into that rubber boot. I'll post a picture when I can.

Hi guys,

I'm trying to install the last flared piece inside the fender. I removed my factory intake tube and it's just the rubber grommet. The small funnel does not want to go into the rubber piece, as the diameter is just a little too big. I tried very hard to work it in by flexing the grommet and getting the end in a little at a time, but it's a no go. There is a ridge in the inner surface of the grommet that blocks it. Has anyone else done this successfully?

*edit
I took a few pics. If the funnel had a flange the same size as the stock tube, it would press-fit quite nicely. Currently, it is too small to be snug in the outer part of the grommet, too large to fit into the narrow center portion of the grommet.

 

[YTRY]

I believe the large end should go over the rubber grommet and the small end fits into the stack.

 

[Gansan]

I believe the large end should go over the rubber grommet and the small end fits into the stack.

No, that would negate the benefit of the funnel. The reason the end of the tube is radiused is that it allows the air to accelerate smoothly as it enters the tube--otherwise, a vortex forms around the rim of the tube that constricts the flow of air and you get reduced flow as if the tube were narrower. If you stick the funnel's flared end onto the rubber grommet, you don't get that benefit. The filter is completely snug against the grommet without the funnel, as you can see in the picture that looks down at the blue filter. You can see the textured surface reaching right up against the center ridge. That's the filter housing inserted all the way into the engine compartment side of the grommet and bolted into place. There's no way anything else would ever fit in between.

 

[YTRY]

I'm not using the flange because I have the DF Air Intake Scoop, but from the DF site it shows the stack like this.

 

[Dhalsim]

I'm not using the flange because I have the DF Air Intake Scoop, but from the DF site it shows the stack like this.

View attachment 62490

Lol...its not as simple as that picture would suggest. Have you installed it yourself?

 

[YTRY]

Lol...its not as simple as that picture would suggest. Have you installed it yourself?

I installed mine myself, but like I said I'm not using the last flared piece because it isn't used with the Intake Scoop, without the flared piece the installation was fairly simple.
Now I'm just waiting for the Silicone clamp to get it sealed up properly.

 

[greenberet]

Just for reference, could any of you guys installing the Downforce intake measure the:

• outer diameter of the air filter at its widest point (closest to the throttle body)
• outer diameter of the air filter at its narrowest point (furthest from the throttle body)
• length of the air filter (distance between the wide and narrow ends)

With that, we could see what has more surface area – a flat foam filter in the stock airbox or the conical foam filter in the Downforce airbox.


Also, it would be interesting to see how much larger the intake and exit of the Downforce airbox are than of the stock airbox. If it’s easy for anyone, could you measure the:

• cross section of the Downforce airbox at its narrowest point on the intake side
• cross section of the Downforce airbox at its exit towards the throttle body

 

[greenberet]

Anybody? It would be good to know whether the Downforce intake has a bigger bore / larger filter than the OEM intake.

Here are the cross sections of a stock NSX intake:

• Intake end of OEM snorkel in fender at smallest point: 50.6 cm2 (7.84 in2)
• Exit end of OEM snorkel towards airbox: 65.1 cm2 (10.10 in2)
• Foam portion of Unifilter flat foam air filter for OEM airbox: 496.9 cm2 (77.02 in2) and 2.0 cm (0.79 in) thick
• Exit of OEM airbox towards throttle body at smallest point: 59.1 cm2 (9.16 in2)
• OEM throttle body: 29.6 cm2 (4.59 in2) - assuming a 6.2mm thick spindle

How does the Downforce airbox compare? Does it have larger openings or a larger filter?

 

[BATMANs]

.......

What is that "appendix" to the right of it that is a dead end?

I've seen that on my brother's Impreza and a few other cars.

is that some sorta muffler for the intake?

 

[greenberet]

What is that "appendix" to the right of it that is a dead end?

I've seen that on my brother's Impreza and a few other cars.

is that some sorta muffler for the intake?

Yeah, that "appendix" is a sort of muffler. As the intake air flows past it, the air in there resonates and makes a sound. Kind of like when you blow over a coke bottle. The sound it makes is tuned to cancel out engine noise. If you want to hear the engine more - get rid of the resonator.

Come to think of it, getting rid of the resonator will also create a second opening in the intake snorkel with a cross section of 19.6 cm2 (3.04 in2) that inhales cold air from the fender. The primary and the secondary (formerly resonator) openings have a combined cross section of 70.2 cm2 (10.89 in2), which is larger than the exit towards the airbox.

 

[Gansan]

Just to give people a follow up on my fitment issue: I talked to Downforce (Peter) and explained my problem. He sent me a roll of cloth tape to build up the thickness of the funnel. I wrapped the funnel's end until about 3-4mm thickness had built up. That means about 6-8mm increase in total diameter. This made the funnel wedge nice and tight into the rubber grommet.

I think ultimately, the funnel should have a mounting tab on it which lets it use one of the stock mounting bolts to positively locate it. I would not trust the funnel to stay in there based on friction for the life of the vehicle like you would a bolted part.

I took a pic which I'll add when I get it off the camera.

 

[Dhalsim]

Just to give people a follow up on my fitment issue: I talked to Downforce (Peter) and explained my problem. He sent me a roll of cloth tape to build up the thickness of the funnel. I wrapped the funnel's end until about 3-4mm thickness had built up. That means about 6-8mm increase in total diameter. This made the funnel wedge nice and tight into the rubber grommet.

I think ultimately, the funnel should have a mounting tab on it which lets it use one of the stock mounting bolts to positively locate it. I would not trust the funnel to stay in there based on friction for the life of the vehicle like you would a bolted part.

I took a pic which I'll add when I get it off the camera.

Wait I thought previously the proble,m was the funnel diameter was too large and would not fit into the rubber grommet. Now you say you needed to add girth to the funnel by warpping it with tape so it will fit? Im confused.

I haven't tried putting the funnel in so I am very interested in how you get this done before trying myself.

 

[Gansan]

Wait I thought previously the proble,m was the funnel diameter was too large and would not fit into the rubber grommet. Now you say you needed to add girth to the funnel by warpping it with tape so it will fit? Im confused.

I haven't tried putting the funnel in so I am very interested in how you get this done before trying myself.

Oh, sorry about the confusion. The grommet has an outer part that is too large and an inner part that is too small. I made the funnel larger so that it fits tightly in the larger outer part. It butts up against the smaller section and stops there. There is no way it will ever fit in the smaller part.

I should also mention that I pulled out an old 2001 Mugen catalog and right there is the original Mugen NSX intake system. It comes with its OWN GROMMET. Ah ha! I bet that grommet is meant to fit the funnel correctly.

 

[Dhalsim]

Oh, sorry about the confusion. The grommet has an outer part that is too large and an inner part that is too small. I made the funnel larger so that it fits tightly in the larger outer part. It butts up against the smaller section and stops there. There is no way it will ever fit in the smaller part.

I should also mention that I pulled out an old 2001 Mugen catalog and right there is the original Mugen NSX intake system. It comes with its OWN GROMMET. Ah ha! I bet that grommet is meant to fit the funnel correctly.

Thank you for the clarification. And nice find on the Mugen grommet. I wonder if we could get that. DF should include it with the kit!

 

[Gansan]

Here's a pic of the amount of tape I applied. I want to thank Peter@Downforce for promptly addressing my issue. I gave him my feedback on altering the funnel for future revisions--but I think my bracket idea would be the ideal solution.

 

[mdcfab]

Hello guys just wanted to offer 2 more intakes at the sale price I am over stocked. I will do the sale price on these. And to update you Chris From Science of speed ran a few dyno runs and got 3 to 4 horsepower across the power band and 5 horsepower peek . keep in mind this is in Arizona. first come first serve.