Tech | Cold Air Induction System Install
It's no secret that on our classic Ford cars the factory passenger car air cleaner assembly wasn't designed for maximum horsepower. Rather, a major consideration in the factory design was intake noise suppression. Some factory designed air cleaners came with an open element to reduce intake restriction, but this still doesn't address the issue of engine-heated air being drawn into the carburetor. An open element design will draw the same hot air that the factory enclosed unit will (just more of it) and for this story we wanted to know if getting colder air into our engine would make a difference on a popular classic small-block Ford. Our '68 Torino GT is an original F-code 302 2V-equipped vehicle with a factory style air cleaner, stock exhaust manifolds, and single exhaust; a good representative of a basic Ford small-block project car. It has a C4 three-speed automatic transmission and an 8-inch axle with 2.79 gears. Other than a 500 cfm Edelbrock four-barrel carb and Performer 302 intake manifold, the engine is completely stock. The cam is so mild that it noses over at 4,200 rpm, but the car idles in gear like a sewing machine. With the mild cam and single exhaust it's difficult to hear the engine running inside the car. It's the perfect passenger car engine found in many Ford cars of the era. It was made to idle for hours in Manhattan traffic if need be. Our car was factory rated at 200 horsepower at the engine.
We've run plenty of stock 289 and 302 two-barrel-powered classic Fords in the past on a chassis dynamometer and we usually see between 120 and 140 horsepower at the tire, so we know going in that our Torino is no screamer. However, it's an appropriate car to begin with for baseline testing because it's a good representation of the factory power offering found on many of our favorite classic Ford cars, including Mustangs, Falcons, Fairlanes, and more. For purposes of testing, Spectre was interested in a mostly stock vehicle to eliminate as many variables as possible. A baseline using a stock example would provide the best understanding of the starting point that the factory gave all of us who are beginning from scratch in the upgrading of our engine's performance.
Spectre Performance specializes in automotive fresh air induction systems. We were happy to visit Spectre and have it test the Torino for a baseline and then see what improvement might be realized with one of its dual snorkel cold air kits using flexible ducting. Further, we wanted to see what arrangements the company offered for a solid inlet arrangement for our Torino via its build-your-own-cold-air-intake program. With the build-your-own program you can choose from hundreds of aluminum tubing lengths, angles, and diameters to custom design your own cold air induction for a one of a kind show-ready look. The tubing can be welded or clamped together and Spectre offers several filter housings to ensure you have enough filter area for your engine. For evaluation of road horsepower Spectre has an in-house Mustang chassis dynamometer. We know from past experience and were advised by Spectre technicians that readings on a Mustang dyno run between 15 and 20 percent less than the readings seen for the same vehicle measured on a Dyno Jet. Let's see if the concept of getting cooler air into the carburetor really makes a difference at the rear wheels.
On the Mustang chassis dyno...
On the Mustang chassis dyno the Torino makes its baseline pull with the factory air cleaner housing in place. The car registered 99 hp and 156 lb-ft of torque. The torque curve was flat from 2,000 rpm and it began to drop off at 3,200. As we noted earlier, the cam nosed over at 4,200 rpm at right around 100 horsepower. We would have guessed this car at 120 hp on a Dyno Jet so it seems the 20 percent drop in readings, as predicted by the Spectre technicians for the Mustang dyno, was in the ballpark.
The stock air cleaner housing...
The stock air cleaner housing is set aside and a dual-snorkel unit from Spectre is installed. First the baseplate was tried by itself, checking for interference with the throttle linkage and other fittings. None was found. Here, the filter element is fit onto the top of the new baseplate.
Next the dual-snorkel housing...
Next the dual-snorkel housing is dropped into position. It's a tight fit and a snug seal once the housing is fastened down in place. Because it's an enclosed unit, it offers the same intake noise deadening properties as the factory air cleaner but it offers a much taller filter element for more filtered area.
The dual snorkel installation...
The dual snorkel installation can be completed using Spectre's flexible air ducting, shown here being mocked up as a temporary installation just to prove the contention that a cooler air charge means more horsepower at the wheels. If it works on this 100hp powder puff think of what it might do on a livelier engine.
Here's a look at the Spectre...
Here's a look at the Spectre flexible air duct system ready to go on the dyno. The ducts extend forward and down and pick up air from near the bottom of the radiator core support, well forward of any engine heat and more exposed to the vehicle slipstream. These air duct kits are available in black, red, blue, and chrome and in 3- and 4-inch diameters. The anodized airbox kit with black ducting is available as part number 711 at a cost of $222.
A closer examination of the...
A closer examination of the dyno information shows a gain of 9 hp at certain points along the power curve, while the disparity in the torque curve was as much as 13 lb-ft at certain times. Clearly there's merit in getting a cooler intake charge to the carburetor no matter how mild or wild your engine may be.
We were intrigued by the wide...
We were intrigued by the wide selection of air intake boxes available at Spectre for a custom or low-profile installation. For our low-profile mock up we selected one made to fit the low hood clearance found on a Mustang.
Likewise a wide variety of...
Likewise a wide variety of custom junction fittings are offered. Using these smooth-flowing connectors ensures a free flowing induction system as well as a wild look.
This rack shows all of the...
This rack shows all of the various angled connection fittings available for system fabrication as well as the different styles of air filter elements available. Spectre has literally hundreds of part numbers in tubing, filter housings, fittings, filters, and more to make a one-off induction setup no matter the classic Ford, engine compartment configuration, engine size, or induction type.
Here we see how the various...
Here we see how the various straight and curved pieces can be configured to almost any desired shape. Styrofoam plugs are used to help mock up the connections until they can be welded. These build-it-yourself kits can be welded locally, or you can mark the tubing orientation and send everything back to Spectre to be welded and polished and returned to you.
When the design calls for...
When the design calls for a direct connection to the core support and a filter element at the end isn't desired or can't be fitted, this inline cone filter can be used. It's sized to fit inside the 4-inch tubing and yet still flows more than 450 cfm.
Here we try on a Spectre low-profile...
Here we try on a Spectre low-profile enclosure. Although our Torino has plenty of hood clearance we still liked the look of this enclosure and wanted to mock up a system similar to one that might be used on a Mustang or a Torino with a larger engine.
Using the Styrofoam plugs...
Using the Styrofoam plugs to mock up the connections, the passenger side inlet is configured. For this scenario the battery would be relocated to the trunk.
Before this straight section...
Before this straight section going to the core support is installed an inline filter is placed into the tube. A pair of these will flow more than 900 cfm, more than enough capacity for most street engines.
With the inline filter in...
With the inline filter in place, the final section for the righthand side is installed. To prevent sagging and get an accurate mock up, tape was used over the section joints. The end flange would be attached directly to the core support over a 4-inch hole cut into the support.
Likewise, a similar duct is...
Likewise, a similar duct is constructed on the driver side, leading directly to the core support. On this side there is no battery and plenty of space to locate a new inlet. The net effect would be a ram air system exposed directly to the vehicle slipstream and completely hidden from view.
Here's our solid tube system...
Here's our solid tube system mocked up. Spectre offers a service where you can use a selection of its ducting components to create your own custom system. Simply mark the connections, A to A and B to B for example, and send it in to the company. Spectre will weld all of the connections and then polish the complete system. Of course, the cost varies with the components used and the complexity of the system.
Here's a view of a similar...
Here's a view of a similar Spectre cold-air system installed on a '68 Mustang. Here, the low-profile airbox is really needed because of the limited hood clearance available on Mustangs. This low-profile cleaner should work on big-block-equipped cars as well. Cone filters were installed onto the inlet ends and isolated from engine heat by fabricated steel enclosures with rubber edging designed to seal the area from engine heat. Custom enclosures like this are easily made with some 0.040-inch aluminum sheet and can be designed to work with hoodscoops, headlight openings, and so forth.
Since hood clearance isn't...
Since hood clearance isn't an issue on our Torino we decided to also mock up a system using Spectre's 120-degree dual snorkel enclosure. Instead of the flexible black ducting, we wanted to see what such an arrangement using the steel tubing might look like on our engine. Here the enclosure is in place and the Styrofoam plugs added to allow for experimental connections.
Just like with the low-profile...
Just like with the low-profile system, the ducting connections were created to fit and then locked into the correct orientation using tape. Because we're using the enclosure that has the filter element in it, we don't have to be concerned with a filter either at the ends or inline.
On the passenger side the...
On the passenger side the same procedure holds true. As we have mentioned, this type of system often requires relocating the battery to the trunk, which is a good idea for weight transfer and to clean up the engine compartment's overall look.
The completed mock up in place...
The completed mock up in place on our Torino's small-block certainly has a nice show worthy look to it and it'll make some additional power to boot. Once the welding is completed we'd have a solid cold air system that fit the same way every time. Because of the air inlet location being directly exposed to the slipstream, we suspect that this arrangement would make even more power than the isolated filters inside their own individual airboxes because cold air is, in effect, being force fed to the engine. Judging from the results on the chassis dyno and after looking at these different cold air system alternatives, we think that the Spectre systems offer a great bang for the buck across the board when it comes to improving horsepower. Spectre offers application specific kits for GM vehicles, but as yet no complete kit is offered for classic Mustangs or other classic Ford, but these kits are coming.