Even though modular engines were delivered with mass air intake systems, you don’t have to stick with Ford’s design. The aftermarket intake manufacturers have offered a wide selection of units for modular engines over the years, so you should find an air delivery system that fits the look and feel of your conversion project.
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As mentioned in Chapter 2, “modular” doesn’t mean that lots of things crossover among engines, and intake manifolds are no exception. Just like the small-block Ford 351W and 302 manifolds, the 4.6 and 5.4 won’t interchange because of the difference in block deck height. The shape and size of the ports have changed over the years, even if they look the same. And, of course, the manifolds are designed to flow enough air to feed one or two intake valves per cylinder.
All Ford factory intake manifolds are made of composite plastic, aluminum, or a combination of both. Most of the early performance engines and 4V setups came with aluminum manifolds. The early 4.6 manifolds developed a problem with the coolant crossover, requiring a fix from Ford in the early 2000s (see Chapter 2). Starting with the 3V engines, Ford went back with an all-composite intake and continued with that material up through the 5.0 Coyote; factory supercharged engines required an aluminum manifold to handle the extra pressures.
The early 4.6 SOHC cylinder heads (pre-1999) were fine for street cars but started to run out of steam around 5,000 rpm. In 1999, Ford introduced the PI (Performance Improved) heads that work much better, and the intake port and intake manifold changed. Both intake ports have the injector mounted in the upper “corner,” but the port shape on the PI head was changed considerably. A head change requires a matching change to the intake manifold. Most aftermarket intake manifolds are designed for the later PI intake port. This design became the standard in the 2V engine through its production run.
The first 4V heads used a dual-port intake manifold that consisted of a square port primary intake runner and a round secondary port for use above 3,000 rpm. These heads work adequately, but have some issues with low rpm torque. In 1999, Ford redesigned the intake port into a Tumble Port design, which means that the air “tumbles” into the cylinder rather than swirls in. These oval ports have the injectors mounted in the middle of the port, and though they look the same, the size of the port varied through the engine’s revisions. A reminder about swapping heads and intakes: with a few exceptions (as when using adapter plates mentioned later in this chapter), when changing heads the intake manifold needs to be changed to match.
With the 4V heads still needing an increase in performance in the uses a manifold similar to the one sold by Ford Performance, and the entry to the manifold is on the back.
Engines that are supercharged or turbocharged have a constant pressure in the manifold that forces air into the cylinders, so the port runner design has less effect on air delivery. All the factory supercharger manifolds are aluminum.
A wide range of intake manifolds is available for the modular engine family, and you can find one to accommodate everything from carburetors to stack injection to compact supercharger applications. Ford Performance still carries a line of intakes for most of the modular engine applications. Through the years Ford Performance has also supplied many of the factory performance intakes through the parts catalog, so used manifolds are in good supply at the swap meets and online. Here are some of the manifolds currently available:
The term “original-style manifold” refers to a multi-port injection intake manifold similar to, or a duplicate of, the original style of intake manifolds found on the modular engines. These may or may not allow the use of factory components such as injectors and throttle bodies.
Trick Flow makes three intake manifold versions for the 4.6 2V engines. Similar to the manifold used on the 2001 Bullitt engines, the elbow comes off the rear of the manifold rather than the center. JPC Racing has an aluminum 4.6 3V manifold that incorporates a billet aluminum front throttle body mount that can be changed for different TB applications. Edelbrock’s Victor II manifold for the 5.0 is an aluminum construction, which allows it to be used with forced induction and nitrous.
Carburetors and Central Fuel Injection
It is possible to run a carburetor on a modular engine; there are both low-profile and tall-ram manifolds. These manifolds can also be adapted to run central fuel injection metering and even multi-port fuel injection.
Sullivan Performance has developed a high-rise single-plane manifold to fit the 4.6 and 5.4 DOHC engines. These manifolds are optimized for use between 2,500 and 7,500, and come with a standard Holley bolt pattern. They also come with plenty of material for mounting vacuum parts and nitrous ports, and come with or without fuel injector ports already machined. Bosses for fuel rails are cast in and they also work with aftermarket central fuel injection systems. (Photo Courtesy Sullivan Performance)
Probably the biggest advantage to the individual injection stacks is the fact that each port has its own throttle plate, and this can reduce the airflow losses associated with the bigger single or dual bore throttle bodies. Plus they just look fantastic. The downside to some of the systems is fitting the throttle-linkage-specific engine compartment configurations.
Sheet Metal and Custom
For the full-bore racing set, numerous manufacturers have developed a sheet-metal intake that can be designed for everything from old-fashioned GMC Roots blowers to modern fuel injection to tunnel rams with carburetors.
Most 2V manifolds used an intake elbow to direct the airflow to the manifold from one side of the engine compartment. The aftermarket designs have improved on the factory pieces and allow more combinations with the SOHC engines. Factory elbow design allows for cost and manufacturing concerns, noise reduction, and space restrictions, whereas aftermarket designs can concentrate on performance.
As with the pushrod small-block, more intake manifolds are available for the lower deck height engines than the taller engines. Modular Motorsports Racing and Professional Products make adapter plates to retrofit a 5.4 engine with 4.6 intakes. They are application specific and have to keep within the “family” of cylinder heads (e.g., 5.4 DOHC to 4.6 DOHC of the same year).
IMRC Eliminator Plates
While the IMRC (Manifold Runner Control) is good on a stock engine for helping with low-RPM torque, it creates a restriction for high-revving engines. Steeda and Modular Motorsports Racing make eliminator plates that remove these restrictions on high-horsepower engines and maintain factory intake manifold height and geometry.
Intake Tubing and Components
Factory Ford intake systems use a throttle body, an IAT sensor (intake air temperature), an MAF (mass airflow meter), a length of tubing to draw the air from a remote location, and an air filter/filter box. Speed density systems use a similar setup without the MAF; instead, they use a manifold absolute pressure sensor or MAP. Some supercharged or turbocharged setups may use both. The engine build determines the choice of components.
The throttle body meters the amount of airflow into the engine by using a blade or blades to meter airflow. The throttle body needs to match the airflow requirements of the engine. If the throttle body is too small, the engine can’t get enough air and loses performance. If the throttle body is too big, the speed of the air coming into the engine is too slow and the engine loses horsepower and throttle response.
Cable versus Drive-by-Wire
Prior to 2005 Ford used a mechanical throttle cable to open the throttle body. In 2005 Ford began using drive-by-wire on modular engines. This consisted of a sensor mounted on the accelerator pedal and an electric motor mounted on the throttle body. If you’re buying an engine and harness from a donor car, you need to get the pedal and the under dash harness, so you have the equipment to properly run the engine. Aftermarket pedals are available, but some pedals don’t work well in some vehicles, such as the Crown Victoria pedal. Ford has kept the connector fairly consistent, so swapping a pedal from different vehicles is not a big problem. (See Chapter 6 for more information.) Some aftermarket PCM systems do not work with drive-by-wire and require a conversion back to a cable-style throttle body.
Single- versus Dual-Bore
Ford has used both single and dual-bore throttle bodies on its factory engines. Why a particular style was chosen goes along with the overall engineering of the engine. A 4.6 3V has a dual-bore throttle body and a 5.0 Coyote has a single bore. Most of the supercharged engines have an oval dual-bore setup.
While a large single-blade throttle body allows greater amounts of airflow, the engine can be sluggish at low RPM. One way to improve engine response is to have the same air volume run through two bores to increase the air velocity. However, the dual-bore throttle bodies have a “splitter” in the middle, which restricts airflow at higher RPM. At high RPM, the single-blade throttle body may move more air without the restriction between the bores.
Intake Air Temperature Sensor
The Intake Air Temperature (IAT) sensor works similar to the coolant temperature sensor: as the air heats up, it changes the resistance in the IAT and the computer can change the amount of fuel delivered to the engine. Later mass air systems integrated the IAT into the mass airflow meter. Both mass air and speed density systems use an IAT.
The location of the IAT is usually close to the inlet of the air intake system. Supercharged or turbocharged engines use a secondary IAT sensor mounted in the intake manifold to measure the temperature of the air after it has been compressed. When a supercharger or turbocharger compresses air, the air temperature is increased.
An IAT sensor must have the correct resistance range for the PCM being used and should be mounted away from heat sources, such as the engine or radiator.
Mass Airflow Meter
Engines equipped with a mass airflow system use a small wire in the MAF, which is electrically heated, and as air flows past the wire the air cools the wire and changes the resistance of the wire. The resulting change of resistance is sent to the PCM to determine the amount of air that is flowing into the engine. This information, along with the IAT, tells the engine the volume and density of the air entering the engine.
Remembering the analogy that the size of the “straw” used determines the volume and speed of the air passing through the MAF, it is important to match the size of the mass air meter to the required volume of air entering the engine. This is one of the advantages of the speed density system; no MAF to change out when changes to the engine are made. Matching the MAF, the throttle body, and the tubing are all important when designing the intake system.
There are two basic types of MAF meters: blow-through and draw-through. Normally aspirated engines use a draw-through meter and some supercharged and turbo applications use a blow-through MAF. These are exactly as named: a naturally aspirated (non-super or -turbocharged) engine uses a draw-through system. Forced air systems can be equipped with either, but the routing of the blow off valve and tubing is different for each application.
Manifold Absolute Pressure Sensor
Most speed density systems and some mass air systems use a Manifold Absolute Pressure (MAP) sensor. The computer needs to have three pieces of information to command the proper amount of fuel: the pressure of the air inside the intake manifold, the density of the air, and the load that the engine is working under. The MAP sensor measures the pressure in the manifold relative to a perfect vacuum; that is, no pressure from the outside air. Barometric pressure (the air pressure around you right now) is greater at sea level than up in the mountains, and barometric pressure can change with the weather. The MAP measures pressure from absolute vacuum (no pressure; outer space) up to 1 bar (around 14.7 psi, 29.9 inches of mercury or 101 kPa). Aftermarket MAP sensors can measure up to 5 bars, or approximately four times atmospheric pressure.
The speed density system uses the speed of the engine (RPM) and the density of the air going into the engine to determine how much fuel to supply at any given time. The speed density system uses a series of internal fuel curve maps to calculate this fuel/air ratio.
Intake Tubing and Filters
Matching the intake tubing to the rest of the components in the intake system is also critical when designing the system and tuning the computer. As noted in Chapter 4, the Ford Control Packs come with a preselected intake system and the PCM is programmed for this specific tubing set.
One of the cheaper horsepower add-ons is a cold air kit. Well-designed cold air tubing systems do two things: they draw air from an area away from the engine and radiator flow to equalize the intake air temperature to the outside air, and by reducing unneeded bends and silencers, they can reduce restrictions, increasing airflow to the engine to make more power. They also typically use a low restriction air filter to further increase airflow.
JLT Performance, Ford Performance, Western Motorsports, K&N, and others offer cold air intake for the modular engine. Because there is a wide range of modular engines, there is also a wide range of cold air intakes to fit them, and each engine type has its unique flow requirements. While most cold air kits are designed for a specific late-model application, some might work in a different engine compartment. Some aftermarket tubes do not have a provision for an aspirator tube, which allows for power brake operations in automatic-equipped vehicles.
Swap Spotlight: Double Trouble
Before he gave the world the Equadroline, master fabricator Gordon Tronson built Double Trouble, a built-from-scratch 1927 T that proved that a modular engine masterpiece can blend new technology with old school chassis, and do so seamlessly.
Double Trouble was built with no plans, from scratch. The plan was to build something that nobody else had. Gordon had seen dragsters and custom cars with engines inline, but Gordon wanted to build a car with engines side by side. Some serious engineering would need to be worked out to make everything work.
You would think that a side-by-side engine build would have you searching for a pair of narrow engines, but Gordon established the bar by starting with a pair of wide-bodied, all-aluminum 4.6 DOHC engines and a fiberglass 1927 T body, then he went to work. Almost everything on the car is hand fabricated by Gordon. The chassis was built out of 1.5-inch tubing custom bent by Gordon to accommodate the modular engines. The entire frame was then powder-coated for durability because his creations are driven. Gordon then custom-fabricated the front suspension using an unequal-length double A-arm design using coil-over shocks. The rear axle is a Jaguar independent unit with inboard brakes. Rear brakes are matched with a pair of Corvette spindles and brakes on the front. The rack-and-pinion steering unit is similar to ones used on sandrails. The brake booster is mounted under the floor.
A custom fuel tank was fabricated and works in conjunction with a Procomp high-flow electric fuel pump. Griffin Thermal Products made the custom radiator for cooling the dual engines. The headers and side exhaust were made from a street rod kit then custom bent to fit the engines.
Even though the engines are new with overhead-cam technology, Gordon went old school for the look on this ride. Its engines are not only carbureted with Holley 4150s, but they run through several (yeah, I said several) Weiand Roots superchargers. The original combination used two superchargers and was good for around 1,000 hp. But with Gordon, more is better, so he fabricated new intake manifolds to allow twin superchargers and carburetors per engine. Now Double Trouble puts out around 1,200 streetable horsepower.
Other improvements to the engines include a conversion back to distributors run off the back end of the camshafts. The Procomp CDI systems are reminiscent of the flathead designs of the late-1930s Fords. Twin starters work in tandem to start both engines at once.
The transmission is an unassuming Ford C5 automatic worked over to handle the horsepower. A custom transfer case was engineered and built, and it transfers power to the transmission via a pair of steel sprockets and a jackshaft that drives a Gates 90-mm poly chain belt. Micar Fab did the heavy machine work.
With the drivetrain in place, Gordon then fabricated everything else in the car (windshield screen, seat pans, dash, wiring, plumbing). The body was painted a beautiful Candy Apple Blue. Billet Specialties 15 x 14–inch wheels went on the rear with 15 x 7–inch wheels on the front with Mickey Thompson tires.
You would think that a car with that much horsepower would be a beast to drive, but in fact it has very accommodating road manners. Seeing around all those superchargers can be a challenge, and hold on if you decide to light up the Mickey Thompson tires.
Gordon Tronson comes to the United States via his home in Napier, New Zealand, where he developed his hot rod building skills. With Double Trouble and Equadroline under his belt, I can’t wait to see the next project to come from the master builder.
Written by Dave Stribling and Posted with Permission of CarTechBooks
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