,

And… straight shot into the snorkel of the stock air box.

Speaking of the stock air box, this is what it looks like on the inside.
Honda’s engineers attempted to create a seal between the intake tube and the two halves of the air box by creating the raised ribs and the central groove for the air box halves to slide into.
The upper half of the air box has an O-ring all around the perimeter to act as a seal. The lower half of the air box has a raised rib that butts up against the O-ring to create a seal. These small details are not cheap and it’s probably why the S2000 cost over \$30k new. It also shows Honda’s attention to detail and their efforts at trying to eke out as much power as possible. When the S2000 hit the market, it had the highest specific output of any naturally aspirated engine on the market, even outdoing those super expensive Italian and German makes.

Is the inlet to the duct big enough? Let’s do some quick math. The 2.2L engine spinning at 8000rpm will suck in about 147 liters (0.147 m^3) of air a second. The area of the duct is about 0.0075 m^2. Dividing the volume of air the engine sucks in at max power by the area of the duct gives 19.6 m/s velocity. The car has to be moving faster than this velocity (about 45mph) in order for more air to be pushed into the air box than the engine is sucking in at max power. On a race track, hopefully I’ll be doing more than 45mph.

As you might have noticed from the graph plotting pressure increase vs. speed, you have to be going pretty fast to get a measurable effect. So what better place to do it than Autoclub Speedway using the ROVAL configuration? Plus, it was going to be cooking Humpty Dumpty on asphalt hot allowing me to test the effectiveness of my newly vented track hood. Plus, MotoIQ Projects 370Z, G20 Racecar, Kojima’s Dog Car, and Girl Racer Annie with her NX2000 were all going to be in attendance. Plus, there are a lot of worse ways to spend a day than at the track with friends. Plus, I just wanted to say ‘plus’ again.

1. CHRISTOPHER M JIMENEZ says:

Hey Moto IQ , first thing you guys are the one of the best at building track cars and I love all of your upcoming projects. Im in need a a NACA vent for my 2011 BMW 335i and this vent looks perfect. By any chance can you guys get another one made and I will pay before its even made, really need this vent.

1. CHRISTOPHER M JIMENEZ says:

guys are one of***

2. Khiem Dinh says:

Appreciate the comment! This NACA duct was designed specifically for the S2000 hood shape and airbox location. For your needs, you can probably go with something generic? Pegasus Auto Racing Supplies has some NACA ducts that could work.

2. James Lee says:

Would the NACA duct have water issue when it rains? I’m also looking for a brake duct kit for an AP2 that comes with the dust shields already with the hole for easier installation. WASP Composite seems to be the only one that made such a kit with the hole directed towards the center of the rotor as it should be. Unfortunately it doesn’t seem like they sell the kit anymore. Any ideas/recommendations? Many thanks!

1. Khiem Dinh says:

Personally, I wouldn’t use the NACA duct in the rain. I’m not sure the stock airbox has any water drainage provision. It’s easy to swap hoods, so I only put on the track hood for the track.

As for brakes, if you track, I’m a huge proponent of going straight to the StopTech BBK. Of course, that means you need new wheels to clear the brakes. If you want to keep the stock brakes, you could just remove the dust shields. I haven’t had the dust shields o the S2k in ages and I went around 100k miles on my old Nissan without dust shields. You will need to figure out a way to mount the end of the hose. I just zip-tied it before.
https://motoiq.com/project-s2000-part-4-taking-it-to-the-track/3/

3. Jonathan says:

Are you selling these?

1. Khiem Dinh says:

No, I only made the one. If you decide to go this route, you should also stick a one-way check valve in the air hose going from the intake to the front breather on the valve cover. I was losing ram air boost through this flow path. I regained the lost boost after plugging it in later testing. A one-way valve is a more elegant solution.

https://motoiq.com/project-s2000-part-22-testing-new-goods-and-more-intake-mods/2/