What you need to know about electronic fuel injectors.

What you need to know about electronic fuel injectors.

Ray T. Bohacz: EFI was adopted by the auto industry to comply with stricter emissions controls and fuel economy standards, and today many enthusiasts convert older engines to this modern design. Learn more about the fuel injector and how it operates, especially if you are planning to install a supercharger, and also recognize the injector requires service, even in naturally aspirated applications. Why EFI? Many believe that EFI improves an engine’s horsepower, but it does not. Rather it increases freedom for the intake manifold design as only air courses through it and not a mixture of fuel and air. The length of the runner that connects to the intake port in the cylinder head determines the torque output of the engine and the speed at which it will occur. The longer the runner, the more torque at a lower rpm will the engine produce. EFI allows the intake manifold runner to curve to achieve the desired length (resonant tuning) since there is no fuel present to drop out of suspension. The core component of the EFI system is the fuel injector. The injector is an electromagnet that controls a pintle that opens and closes against a seat. The engine controller (ECU) supplies 12 volts at all times when the ignition is on, and the injector is controlled by switching the ground circuit on and off. When the ground circuit is complete, the magnetic field is induced, and the pintle lifts against a spring, and fuel is passed. When the ground is turned off, the pintle is closed via spring pressure. The time in milliseconds (1/1,000) the ground is evoked,...
Supercharger blow-off valve explained.

Supercharger blow-off valve explained.

The key to proper operation of the BOV involves the pressure balance surrounding its piston. By Alfred Bilk On the left side of the picture (above), the piston encounters boost pressure from the charge pipe coming from the supercharger’s compressor. On the right side of the picture the piston senses pressure or vacuum from the intake manifold, which is positioned below the throttle body or carburetor, plus the pressure from the spring. With the engine stopped, there is atmospheric pressure on both sides of the piston and the spring holds the piston closed. At idle, the left side of the piston experiences atmospheric or slightly less pressure, as the supercharger’s compressor isn’t generating boost, and the right side of the piston is exposed to the idle vacuum in the intake manifold. At idle, the BOV will be closed; if it was open, it would introduce unfiltered air into the engine. So the spring must be sufficiently strong to hold the piston closed when there is idle vacuum in the manifold, but no boost in the charge air pipe. When driving normally the compressor builds boost in the charge pipe, which the left side of the piston experiences. Also, with the throttle open, boost is present in the intake manifold below the throttle body or carburetor. So, the right side of the piston will encounter boost in the intake manifold plus the spring pressure, which should hold the BOV closed. The critical operating point and principal purpose for having the BOV is to protect the supercharger under deceleration—the catalyst for vacuum. In addition to the vacuum occurring in the intake...
Superchargers for Fords: common questions and other comments.

Superchargers for Fords: common questions and other comments.

By Scott Brown: Superchargers have a fine sporting heritage, and you don’t need to be a genius to understand their perennial appeal. They are potent bolt-on concepts, and with hundreds of kits available for convenient installation, questions abound. Here are a few: Coyote power: Gen I (2011 to ‘14), Gen II (2015 to ’17), & Gen III What are TorqStorm’s plans for further development of the Coyote engines? – Bryan Debuting in 2011, Ford introduced Coyote power to the Mustang GT and to the F-150 pickup truck. To date, TorqStorm has developed supercharger systems for the Coyote Gen I and also the Gen II but with limitations. So far, the latter operates not in late-model Mustangs, but in repowering classic Ford vehicles such as the 1958 F100, the1984 Mustang SVO and others.  “Soon our focus will return to the first generation engines,” says the company’s Chris Beardsley, “as the sequential fuel injection—the multi-port system—was displaced by direct injection, which alters the supercharger’s configuration. TorqStorm aims to develop a supercharger for the Gen III engine but will follow its predecessors.” A twentieth century concept, electronic direct injection in gasoline engines was employed in production engines by Mitsubishi in 1996. Fox body without air conditioning or power steering “I need a blower kit for my Fox body Mustang no a/c no power steering pump either”–Charles The drive belt travels from the passenger side above the water pump to the a/c compressor, the power steering pump, and onward to the crank pulley. When air conditioning and power steering are omitted, a pulley must be substituted to facilitate the drive belt’s travel down...
Demolition Derby: how a special cylinder head survives when all coolant is lost.

Demolition Derby: how a special cylinder head survives when all coolant is lost.

To those unfamiliar with the practice, Demolition Derby events provide handsome purses, especially at large fairs. At Yolo County in Northern California the promoters advertise a prize of $23,000 and rewards of $10,000 to $20,000 is often the standard at major fairs. Even more lucrative is the Topeka, Kansas, Blizzard Blast, which attracts 1,000 entries and offers $30,000 in prize money. Rewards at smaller county fairs, vary between $2,500 and $5,000, which appeals to a Derby class known as Limited Weld. But for the more seriously minded—those competing in the Modified and Pro Modified classes—car preparation consumes 120 to 150 hours of mostly reinforcing work. To assume that successful Derby contestants casually select their vehicles from junk yards, sally forth to the next event and conquer is an illusion.  Derby cars perform in an open pit, each one with an objective to be the last vehicle moving, disabling all others in the process. With vehicles built like tanks, some weighing 6,000 to 8,000lbs, it’s no surprise their engines need adequate low-end torque not only to move defiantly but also to generate sufficient bulldozing force to disable the others. Engines: Derby engines, unlike conventional competition power units, are obliged to survive without coolant because cooling systems are inevitably destroyed in the heat of battle–conditions so severe they devastate normal cylinder heads. “First and foremost”, says Indiana engine builder Lance Stillwell, “those engines need durability; they must have resilience to stand a chance of winning.” Stillwell’s Terra Haute operation serves a diverse racing market, including a dozen Derby contestants. To maintain valve train stability, they use specific camshaft contours to generate...
Injector sizing and boost-referencing the fuel injected engine for centrifugal supercharging.

Injector sizing and boost-referencing the fuel injected engine for centrifugal supercharging.

By Sam Logan: If larger injectors are installed—that is, injectors with a greater flow rate—an engine tuning shop is usually required to re-tune the map—the fuel curve—to achieve the correct air-fuel ratio. To acquire a safer tune in a supercharged engine, where cylinder heat increases with boost, tuning shops will often adjust the air-fuel ratio to 12.0:1 at full throttle as opposed to around 12.8:1 on a naturally aspirated engine. In cruising conditions, air-fuel ratios will remain at 14.7:1. The best way to give maintenance to your carburetor is by doing an ultrasonic carburettor cleaning. The size of the injector limits the amount of horsepower generated, and calculations are used to decide the appropriate injector for desired maximum rpm and horsepower. They are calculated in pounds-per-hour of fuel dispersed. For example, 25lbs-per-hr is sufficient to support 350hp; 45lbs-per-hr is sufficient for 500hp and so on. Here is a table with more particulars: FLOW RATE DEFINITION, CALCULATING HORSEPOWER RANGE. Horsepower is measured at crankshaft. Injector Flow RateNaturally Aspirated EngineEngine w/ Power Adder19 lbs./hr.225-290 hp185-240 hp24 lbs./hr.280-360 hp240-300 hp30 lbs./hr.350-450 hp300-375 hp36 lbs./hr.425-540 hp350-450 hp42 lbs./hr.500-625 hp410-525 hp46 lbs./hr.540-690 hp450-575 hp52 lbs./hr.610-775 hp510-650 hp60 lbs./hr710-900 hp590-750 hp Supporting a supercharged engine with sufficient fuel is a moving target—there are numerous factors to consider, even the model year of the same engine and vehicle brand. The route is determined by the amount of supercharge boost and the capacity of the fuel pump along with the flow capability of the fuel injectors. Avoid confusion: Injector flow capability is measured in lbs/hr—not psi. Supercharging with boost referencing or booster pump or larger fuel injectors:...
Superchargers and carbureted fuel system upgrades.

Superchargers and carbureted fuel system upgrades.

By V. Moore: Idle and cruise conditions don’t alter fuel consumption appreciably, but supercharge boost conditions do. Therefore, it’s sensible and probably necessary to increase fuel pressure relative to boost pressure, upgrading to a larger capacity electric fuel pump and bypass fuel pressure regulator. Bypassing fuel systems using a return-style regulator are the most efficient kind. They control fuel pressure constantly to the engine and return the surplus to the tank. The system is more responsive to fluctuating fuel demands, and as the fuel circulates from hot engine bays, it averts power losses and stalling from vapor locks. The advantage of the in-tank fuel pump is durability because it is submerged in cool fuel. Also, it is much easier to push fuel than to pull fuel. The disadvantage of the in-tank fuel pump, especially with high performance vehicles, is that if the fuel level in the tank is low, the fuel becomes warm because the pump is warm and the desired cooling effect is lost. Best practice is not to allow fuel level to fall below half tank or avoid driving with low fuel. The formula for upgrading a fuel system. The formula for determining a fuel system’s capability is based on a vehicle’s horsepower output. Typically, an engine consumes ½lb of fuel per horsepower per hour. Therefore, feeding 500hp requires 250lbs of fuel per hour. As 1 gallon of fuel weighs approximately 7lbs, simply divide 250 by 7 to find the answer, which is 35.7 gallons. Thus, a fuel pump is required that generates a minimum of 40 gallons (150 liters) per hour to feed the engine at...