Article by:GTRaptor Profile | E-Mail


This do it yourself article shows you how to install a home made cold air induction system.


Mustangs like cool weather, and the reason is that cold air is denser, which in increases combustion efficiency.

When you install your air filter inside the engine bay 2 things happen; the engine heats the inside air and the fan creates turbulence, both of which hurt performance.

There are several ways to eliminate those problems, one could be to install a RAM AIR hood which has openings at the front to draw cold air into the engine, or at the back to expel the heated air. But hoods are expensive and we think there's a better solution for the budget enthusiast.

RaptorGT our 1995 5.0 has a 9 inch conical K&N with a "home made" kit that removes the air filter housing completely, but the filter sits inside the engine compartment and draws mostly hot air.

We decided to make a COLD AIR setup that would relocate the filter to the fender well to draw cooler exterior air.

You will need to get a K&N Conical filter for this setup, part numbers are RE-9020 (9") and RU-3130 (7").

If you have a stock Air box in there, the first step is to remove it. Loosen all clamps and hoses, remove the IAT (temp sensor) and PCV hose from the passenger side cover, remove the MAf wiring harness, pull the air box, open it and remove the MAF.

To make the kit we used the very affordable PVC piping anyone can buy almost anywhere. Try to get the thickest and highest quality of PVC pipe, not all are created equal.

We went to Home Depot and bought a 3 inch PVC pipe, 2 45 angled elbows, two 3 inch rubber hoses, 4 clamps and PVC cement. (on left picture there's a 90 elbow. Use a 45)

Then we removed the filter, MAF and the intake hose. When everything was removed we decided to clean all the space beneath since it was VERY dirty.

After all the cleaning was done, we started measuring the TB to fender well opening distance to cut our PVC pipe.

The PVC pipe should measure 20 inches, plus the 45 elbow. Test try the pipe before you glue the parts.

Now you will need to reinforce 2 spots on the pipe, the TB side and sensor locations. To do this cut both ends of the 2nd elbow, you will then have two "rings", glue the first ring to the end of the pipe.

The second ring you should cut open on the side, add the glue to both ring and pipe and place it 3" inches after the first one. Drill 2 holes, one for the crankcase ventilation and the other for the Air Charge Temperature sensor (ACT/IAT).
To connect the Crankcase ventilation we used a copper hose connector and a 1" clamp we found at the plumbing section @ Home Depot. The ACT sensor is installed in the second hole, make the hole big enough for the sensor to screw into the pipe, enlarge it a bit at a time so the sensor is held tightly in place .

After this step, sand the Cold air pipe. Its very important to sand since the paint might not stick to it.

Now the difficult part, making the MAF ADAPTER. Here you have several choices, one would be to use a 4" to 3" Reducer such as we did first in our "No air box" article.

Your second "easy option" is to use a square flat piece of plastic and a two inches long 3" piece of pipe. You will have to measure the size of the square side of the MAF to cut the plastic piece, then you will have to make a 3" hole to place the piece of tube, and glue both pieces with EPOXY resin. Then drill the 4 holes to attach the MAF to Adapter.

The third option involves making it with steel or aluminum. A good muffler shop might be able to do it.

With the Adapter ready, assemble the FILTER + ADAPTER + MAF + HOSE.

Next is PAINT PREP TIME, we used 600 grit sandpaper to sand all pieces and then cleaned the pipe with a lint free cloth.

We used KRYLON enamel primer, Dull Aluminum paint and clear coated to give the finished piece a true metal look and to try to match the upper intake color.

It's time to install the Filter-MAF assembly inside the fender well, for that we just slide it from under the fender and then attached the MAF connector, the maf harness is long enough to move into the fender.

By now the job is almost finished, just a few things left to do like attaching the ACT sensor and CV hose and cleaning the inside of the pipe.

click to view larger imagePlace the other rubber hose at the throttle body, use some RTV sealant at each end of the Cold Air pipe, this will keep the setup from falling apart in case one of the clamps gets a bit loose with time.

We will suggest you erase the EEC stored memory tables, do this by disconnecting the battery for 20 minutes.

Now start the engine, and check for any possible problems, like air leaks or the hated "Check Engine" light.

Our overall impression of this setup is that it surely provides some more HP, but it is felt mostly at mid-to-upper RPM's, we still have to confirm this either at a dyno or using a G-Tech Pro

What we DID NOTICE was a tremendous increase in Miles per gallon, our GT was ingesting a fuel tank of 92 octane gas after only 170 miles. After we installed the Cold Air setup, the MPG's increased to 200-210 miles, this has been confirmed after 2 full tanks.

click to view larger imageProbably if you have stock air box and filter in place you wont notice this big MPG increase, we think our problem in the economy department was the use of an exposed K&N inside the engine.

As far as how the setup will perform on rainy conditions, we have no idea, no rain here yet, but the filter is shielded by the fender splash guard and we doubt much water will make it to the filter unless you get into a very deep waterhole.

On our GT we don't have the stock fog lights so some rain spray might get to it, we have plans to install some kinda shield to avoid ingesting water.