Building a Cold Air Intake for the ST

A cold air intake can be fabricated fairly easily for ST Celicas. This how-to will show you how.

You'll Need three 2.5" inch hose couplings. Rubber ones can be found at Lowes or Home Depot, and silicone ones can be found online for a little bit more money.

You'll also need one 180 degree mandrel bent aluminum pipe, 2.5" inches in diameter. I purchased mine from JC Whitney for around $30.00 shipped. You'll want the piping that has these specifications: 180° Mandel-bent Aluminized Tubing, (A/B)=24", (C)=5", ID=2-3/8", OD=2-1/2".

You'll also need six 2.5" inch hose clamps, which I got from Home Depot for $0.78 a piece. You can find them at AutoZone or Advance Auto Parts or any car part stores.

Finally, you'll need an air intake filter with a 2.5" inch inlet - Usually people get the K&N filter because it's reusable and it's a quality product. I am using a cheap one that I bought for $10 bucks. The K&N are usually $30-$40 bucks for the filter.

First, you'll need to take off your old intake box and the black box on the driver's side fender of your car. Taking the old intake box was the easy part, because all I did was loosen all the clamps and unscrew the bolts inside the box under the filter. You then unscrew the other bolts that were holding the intake box together. After taking off the intake box, you have to take off the box in the side of the fender. There were a total of three bolts that holds this black box inside the fender together. You'll see where it is, you just have to figure how to unbolt them. The size of the bolts is 10 mm, so use a ratchet set to do it. After taking that off, you have to literally jerk the thing as hard as you can for it to come off. I am weak, so it took me forever.

Next, you'll need to cut the pipes as needed. First, you want to take the U-shaped mandrel bent pipe and cut it in half, as in right where the middle of the curve is, not the other way around. Then you need to take one half of the pipe and cut that half way down. The other half of the pipe only needs about eighteen inches cut off of it. Remember to look at my pictures to see how I cut it. You have to measure the lengths you need, because you'll have to cut the pipe three times to make it fit. The reason for three hose couplings is because you'll have to connect three pipes.

You should have a total of four separate pipes after you finish cutting them. You only need three pipes though, and those are the short curved pipe, the long curved pipe, and the small straight pipe. You don't need the longer straight pipe.

Next, you'll need to drill a hole for the intake air temperature sensor. I drilled a hole the same diameter as the intake air temperature sensor. The hole I drilled was perfect, but the sensor wobbled too much when I put it in, so I just put a few pieces of masking tape around the O2 sensor and stuffed it back in there. Now it doesn't wobble anymore.

The next step is to put the pipes together and stuff the intake into your engine bay. First, put one hose coupling over the intake manifold and connect your small curved pipe with the hole for the intake air temperature sensor onto it. Put the intake air temperature sensor in before connecting the pipe, and remember to clamp the hose and pipes together with the hose clamps after each connection. Tighten the clamps tightly so that they don't loosen up.

Now you want to connect the small straight pipe to the small curved pipe. When doing this, make sure that the small straight pipe is away and under the battery so you can connect the last piece to it. Finally, connect the long curved pipe to the small straight pipe. The long curved pipe will be coming from the fender and up to the small straight pipe. When doing this, I jacked up my car, placed it on jackstands, and got under it to attach it from the bottom. I had another person help me out while I was doing this part. The very last step is to connect the intake filter to the end of the long curved pipe. You'll have to reconnect your splash guard, so that lots of rain can't get into the intake filter.

It might be a good idea to buy an AEM intake bypass valve for cheap and safe insurance from getting your car hydrolocked, which will happen if your filter gets completely submerged in water while the engine is running. The bypass valve usually costs around $30 bucks.

Once you're done, double check your connections, start your car, check for air leaks, and enjoy your new intake!