This is all we needed to build our own free-flowing intake tubing: an air filter, different-length, different-angled tubes, and some silicone sleeves. By rotating the angled tubing or cutting different lengths, any number of configurations can be created for any vehicle.

One of the quickest and cheapest ways to gain some performance for your racecar is by ensuring the engine gets as much cold, clean air as possible. A quick search on eBay or Amazon will net you hundreds of products for almost every car that claim horsepower gains from simple intake tubing. Admittedly, some of those stated horsepower gains from these products are a bit optimistic. However, from considerable chassis dyno sessions, our team has found success with different air intake pieces. Did we find 20 horsepower? No, but we did go in the correct direction toward finding power.

AEM makes a bolt-in piece for a 90-93 Acura Integra, but it is designed to miss things in the engine bay that we don’t have in our racecar anymore. We wanted to build our own system with fewer bends in the tubing and with some larger diameter tubing.

We have tried the high-end expensive products and the cheap Chinese made eBay pieces. What we discovered was that every piece had advantages and disadvantages. Namely, most over-the-counter pieces are designed for cars that still have most of the stock components under the hood. These are “bolt-in” parts for the import-tuning crowd. We realized that most of these pieces were designed with bends and tubing sizes trying to fit within all of the stock components under the hood. Since we were working on a true racecar, not hindered by emission laws, or attempts at reduced air-induction noise, we wanted something different. We wanted the intake tubing to go a different direction and have fewer bends in it. So instead of trying to make something somebody else built work for us, we chose to build our own system.

To make our custom intake tubing fit our vehicle, we measured the outside diameter of the intake manifold and the outside diameter of the intake tubing we were using. We used that data to order a reducer sleeve that had an inner diameter to match those measurements.
We wanted the smallest numerical angle possible for the intake tubing to bend before hitting the inner fender so it would not slow down the intake air. You can see here we used every centimeter possible under the hood for this design.

We were able to design our own bolt-in intake piece using simple hand tools and some inexpensive components from Summit Racing. Summit sells all sorts of different aluminum tubes and silicone sleeves to connect those tubes. For around $100 in parts, we were able to build whatever our imagination could create. We clicked “buy” and waited for the UPS man to show up at the shop.

A lot of people find horsepower with a short tube that pulls warm air from under the hood. However, dyno numbers in a shop with the hood open and a fan blowing on it, aren’t always what you see at the track during hot race conditions under the hood. We designed our system to pull cold air from the fender using the stock hole.

The aluminum tubes we ordered came in straight pieces and different angled bends. We mocked up what we thought would work and started cutting, twisting, and clamping until what we dreamed up started to come together. We designed a piece that was as free flowing as possible as it went from the intake manifold down into the fender well for some cold air. We used the largest K&N cone-style filter that would fit under the fender. We ensured the tubing we ordered had the correct outer diameter to go inside the inner diameter of the K&N filter.

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Once we determined how long each piece of tubing should be, we wrapped the tubing in painter’s tape and measured and marked all the way around the tube with a Sharpie. This ensured we were keeping the cut as straight as possible.
We used a large K&N air filter to pull cold air from the fender well. We removed the inner fender liner to ensure more air reached the filter. After we took this photo, we added wire mesh to keep race rubber from the front tire from gumming up the air filter.

We used a hacksaw to cut the different aluminum pieces to the correct length and then used a belt sander to clean up each cut. We mated the different pieces of tubing together using the silicone sleeves and clamped them together. The one piece we really had to ensure we ordered correctly from Summit was the final silicone sleeve that would connect our custom-built intake tube to our stock intake manifold. That required a reducing sleeve that matched the outer diameter of the intake tube and the intake manifold. Summit had tons of different options when ordering these pieces. As long as our measurements were right, everything would fit together perfectly.

We didn’t need expensive tools or high-end fabrication techniques to create our intake tubing. We simply made our cuts with a hacksaw and a bench vise. We used a towel to ensure the vise didn’t score the aluminum tubing.
We used a belt sander to clean and true the edges of the cuts, so when another piece of tubing was mated to it, that would be a seamless connection. We didn’t want any undulation for the air to endure between the two tubing pieces.
Once we cut each piece to the desired lengths, we mocked up what we wanted to ensure we had all the pieces we needed. We used a different angle for the middle tube to help turn the tubing down into the fender well to pick up cold air.
With all the pieces connected, you can see our intake tubing is much bigger and with fewer tight-radius bends compared with the AEM bolt-in piece. Our concept was to make the trip from the air filter to the intake manifold as free flowing as possible. And it worked.

Once we had the entire piece put together, we wrapped it in thermal tape to keep temperatures down for the air going to the engine. A quick trip to Performance In-Frame Tuning and some time on the dyno proved our theory was correct: Cold, unhindered air, equals more power. We made power for $100 with nothing more than a hacksaw to cut the tubes and a screwdriver to tighten the clamps. Not too shabby.

To keep the incoming air as cold as possible, we did two things. We wrapped our header in header wrap to keep heat out of the engine bay, and then wrapped our new custom intake with thermal tape to deflect under-hood heat.

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Image courtesy of Rob Krider

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