Mustang Cold-Air Induction

The factory dual-inlet air...        read full caption The factory dual-inlet air cleaner looked like a prime candidate for a homemade cold-air system. We picked this one up from the yard for $11, including all the factory plastic tubing that vents the air through the inner fenderwells. If you can’t find one of these, the single-inlet air cleaner from any mid-’70s Ford 460 is virtually identical. All you need to do is take the snorkel from a second air cleaner, cut a hole in the base, and bolt on the extra inlet. If you’re looking for a readily available system to fit different makes and models, contact Air Inlet Systems, which makes most any part you’ll need to build a custom ram-air system for most cars.

To quantify on-track temperature...        read full caption To quantify on-track temperature gains or losses with the cold-air system, we used a Craftsman multimeter with a K-type thermo- couple wire to read the ambient air temperature going into the carburetor during the pass.

To duct the cold air into...        read full caption To duct the cold air into the carb, we routed the inlet tubes through the opening for the side marker lights in the ’87-and-up fascia we swapped on. We can easily mount the corner lights back on within minutes and no one would ever know about the system.

Giving our ’86 Mustang...        read full caption Giving our ’86 Mustang a facelift only required the removal of eight nuts from behind the front fascia.

While we had the fascia apart...        read full caption While we had the fascia apart we also removed the front bumper support (don’t do this on a streetcar) to shed a few pounds and aid in weight transfer.

To monitor underhood temperatures...        read full caption To monitor underhood temperatures on the track, we used a Craftsman Professional Multimeter with a built-in temperature probe. With either cold-air induction setup, we noticed about a 20-degree drop in temperature between the start and end of a pass. Without cold air, inlet temperature increased by about 20 degrees down the track.

So far we’ve managed to get our ’86 Mustang project car to muster a decent 12.73 at 108.5 mph. In our pursuit of even quicker e.t.’s before we hit it with nitrous, we decided to try our luck with a home-brewed cold-air induction system using the theory that colder air equals more horsepower.

The cold-air kit we fabricated consisted of a factory dual-snorkel air- filter box that came standard on ’83-’85 5.0L Mustangs, which we picked up at the junkyard for just $11. The factory air box mounts to a plastic tube that’s normally directed towards the ground and features dual inlets that extend to already existing fenderwell holes. We also gave the coupe a facelift due to the terrific deal we got on an ’87-and-up–style front clip. As an added bonus, we later found that the corner light-mounting area had an enlarged opening that could be used to route air directly into our air inlets. In addition to the new fascia, we ordered a 4-inch cowl hood from Cervini’s to get the extra clearance we needed for the air box.

During our track outing we weren’t quite sure what to expect with the nearly 20-mph headwind we encountered on our test day at Los Angeles County Raceway. The track temperature was less than optimal, and with sand drifting across the track, it made for a difficult day to get good traction. Our initial pass with the cold air produced a 12.83 at 108.23 mph with a 1.86 60-foot. Our air inlet temperature (AIT) read 79 degrees at the line and 69 degrees through the traps. That wasn’t bad considering the conditions; we were right where we left off from the previous outing. For the next pass, we blocked off the cold air and removed the air-box assembly, leaving the carburetor open to the atmosphere.

The results were 12.73 at 108.32 mph with a 1.77 60-foot. The AIT read 87 degrees at the line and 69 degrees at the traps. Interesting, isn’t it? It seems the Cervini’s hood was ducting an incredible amount of air through the rear of the 4-inch cowl! To test that theory, on the next run we used a liberal amount of duct tape to seal off any air from entering the engine compartment through the cowl area. This time, with both the cold-air system and the cowl sealed, the coupe ran a 13.02 at 104.87 mph, with the AIT reading 85 degrees on the launch pad and 95 degrees through the traps! That’s a loss of 4 miles per hour based on an increase in air temperature of about 26 degrees (see sidebar).

To double-check the results, we made a pass with the rear cowl open and the front ducts taped closed, followed by another with the ducts open—the results were identical 12.67s at 108 mph.

Although the track conditions varied considerably from our previous outing, the results during this session proved the worth of the cold-air system. And if our NOVA weather station is accurate, it means a sea-level corrected time of 12.29 at 111.80 mph. Another interesting point is that we did get one great launch with an awesome 1.70-second 60-foot time. Unfortunately we lifted and scratched the pass because the coupe slid all over the track and headed towards the wall, which makes us wonder why we’re still running two different size tires on the front of the car. But hey, when we learn, you learn, and we’re just getting started!