Engine Modifications

Learn what engine modifications are appropriate for your car, and what you can do to your car to generate extra performance.

Superchargers : A supercharger is an air compressor used to force air into the combustion chambers of your engine at pressures higher than would otherwise be the case. It increases atmospheric pressure in the engine to produce more horsepower.

Turbos : A turbo is used to increase the amount of oxygen blown into the engine by compressing air that is entering the engine. This process will provide an increase in the engines power.

Intercoolers : An intercooler is a radiator used to lower the temperature of air compressed by the turbo. Thus increasing density of the air so more can enter the cylinders, thereby increasing engine power.

Camshafts : A camshaft consists of a cylindrical rod running the length of the cylinder bank with a number of lobes (cams) protruding from it, one per valve. The lobes push on the valve lifters to cause the valves to open and close.

Nos - Nitrous Oxide Sysytems : Nitrous oxide is an oxidizer, not a fuel. It carries more oxygen to the engine, allowing for faster burning of the fuel and generating more power. At high temperatures, such as those found inside a firing cylinder, nitrous oxide breaks down into nitrogen and oxygen gas. This raises the partial pressure of oxygen in the gas mix above the level found in normal atmospheric air, and lets the fuel burn more efficiently.

Nitrous oxide is also incorrectly called 'NOS' among racers after one of the first companies to provide nitrous systems, Nitrous Oxide Systems. This is normally sounded out by letter ("en-oh-es") by pro mod drivers, although some pronounce it as a word (like "naws"). Today, there are several competing companies in the field, including BOSS NOSS, NOS, ZEX, Compucar, Top Gun, Nitrous Pro Flow, Nitrous Express, Nitrous Works, Cold Fusion, and Edelbrock.

Nitrous systems can increase power by 45% or more, depending on configuration, and are usually built in one or two stages. All Pro Mod cars and some Pro Steet cars use three stages, for additional power.

Fans can easily identify nitrous-equipped cars at the track by the fact that most will "purge" the delivery system prior to reaching the starting line. A separate electrically-operated valve is used to release air and gaseous nitrous oxide trapped in the delivery system. This brings liquid nitrous oxide all the way up through the plumbing from the storage tank to the solenoid valve or valves that will release it into the engine's intake tract. When the purge system is activated, one or more plumes of nitrous oxide will be visible for a moment as the liquid flashes to vapor as it is released. The purpose of a nitrous purge is to ensure that the correct amount of nitrous oxide is delivered the moment the system is activated - Air or gaseous nitrous oxide in the line will cause the car to "bog" for an instant until liquid nitrous oxide reaches the intake.

Air Filters : Two main types of air filters are used in automobiles: the combustion air filter, and the cabin air filter. The combustion air filter prevents particulate matter from entering the engine's combustion chambers. This filter is commonly changed at oil-change time, but may be changed at longer or shorter intervals, depending on operating conditions of the vehicle.

Most modern, fuel-injected vehicles use a flat panel filter. This filter is usually placed inside a plastic box connected to the throttle body with a large hose. Occasionally these are replaced with a conical filter and cold air intake which, in most cases, includes a heat shield to protect the intake air from under hood temperatures, along with tubing to improve airflow into the throttle body. In many cases an improved air-intake system can produce an increase in power and efficiency.

Older vehicles that use carburetors or throttle body fuel injection typically use a cylindrical air filter, usually a few inches high and approximately a foot in diameter (the most common version is 14 inches in diameter and 3 inches tall). This is positioned above the carburetor or throttle body and secured with a metal lid. Replacing this lid with a chrome-plated version is a common and simple modification among car enthusiasts.

The cabin air filter is typically a pleated-paper filter that is placed in the "outside-air" intake for the vehicle's passenger compartment. Some of these filters are rectangular and similar in shape to the combustion air filter. Others, such as in the Ford Taurus, are roughly triangular in shape, so as to fit in the narrow curving space of the outside-air intake. Cabin air filter replacement has recently become an opportunity for increased billings and profits at professional oil-change locations. Improper removal and reinstallation of this filter can lead to water leaks (by misalignment of the water diverter or seals) and in rare instances, a cracked windshield. This filter is often overlooked and clogged or dirty cabin air filters can significantly reduce airflow from the cabin vents, as well as introduce allergens into the cabin air stream. Periodic, proper replacement will increase cooling and heating efficiency. A filter should be replaced annually to ensure optimal efficiency. Drivers can change their own filters or have the service done for them at an automotive service center.

Clutches : A clutch is a mechanism for transmitting rotation, which can be engaged and disengaged. In everyday use, the term clutch refers to a subcomponent of motor vehicle engine's transmission designed to allow engagement or disengagement of the engine to the gearbox or whatever apparatus is being driven. Invention of the clutch is attributed to Karl Benz.

There are many different vehicle clutch designs, but most are based on one or more friction discs, pressed tightly together or against a flywheel using springs. The friction material is very similar to the material used in brake shoes and pads and used to contain asbestos. Also, clutches found in heavy duty applications such as trucks and competition cars use ceramic clutches that have a greatly increased friction coefficient, however these have a "grabby" action and are unsuitable for road cars. The spring pressure is released when the clutch pedal is depressed thus either pushing or pulling the diaphragm of the pressure plate, depending on type, and the friction plate is released and allowed to rotate freely.

A wet clutch is immersed in a cooling lubricating fluid, which also keeps the surfaces clean and gives improved performance and longer life. A dry clutch, as the name implies, uses no fluid. Since the surfaces of a wet clutch can be slippery (as with a motorcycle clutch bathed in engine oil), stacking multiple clutch disks can compensate for slippage. Most Moto Guzzi and BMW motorcycles use a single plate clutch like a car.

In a car it is operated by the left-most pedal using hydraulics or a cable connection from the pedal to the clutch mechanism. No pressure on the pedal means that the clutch plates are engaged (driving), while depressing the pedal will disengage the clutch plates, allowing the driver to shift gears.

ECU An Engine Control Unit (ECU), also known as Engine Management System (EMS) is an electronic device, fundamentally a computer, that is part of an internal combustion engine, which reads several sensors in the engine and uses the information to control the ignition systems of the engine. This approach allows an engine's operation to be controlled in great detail, allowing greater fuel efficiency, better power and responsiveness, and much lower pollution levels than earlier generations of engines. Because the ECU is dealing with actual measured engine performance from millisecond to millisecond, it can compensate for many variables that traditional systems cannot, such as ambient temperature, humidity, altitude (air density), fuel octane rating, as well as the demands made on it by the driver. In addition, to a large degree it is able to compensate for the gradual wearing of the engine as it ages, which in practice allows it to extend engine life to two or three times that of engines of twenty years ago.

Fuel Pumps : A fuel pump is an essential component on a car or other internal combustion engined device. Fuel has to be pumped from the fuel tank to the engine and delivered under low pressure to the carburetor or under high pressure to the fuel injection system. Some fuel injected engines have two fuel pumps for this purpose: one low pressure/high volume supply pump in the tank and one high pressure/low volume pump on or near the engine.

Forged Pistons In general, a piston is a sliding plug that fits closely inside the bore of a cylinder. Its purpose is either to change the volume enclosed by the cylinder, or to exert a force on a fluid inside the cylinder. Forge your pistons to make them stronger.

Fuel Injectors In trying to keep up with emissions and fuel efficiency laws, the fuel system used in modern cars has changed a lot over the years. The 1990 Subaru Justy was the last car sold in the United States to have a carburettor; the following model year, the Justy had fuel injection. But fuel injection has been around since the 1950s, and electronic fuel injection was used widely on European cars starting around 1980. Now, all cars sold in the United States have fuel injection systems.

Cam Gears Before adjustable Crane cam gears came around, it took hours to make a cam timing change. Adjustable cam gears are reliable, precise and affordable.

Forged Rods Urban legends abound in the gearhead community. One is: aluminum connecting rods don't work in street engines. Prior to the mid-'70s, that might have been true, however, introduction of the Bill Miller Engineering Forged Aluminum Connecting Rod in 1975 provided a glaring exception to that myth.

Pulley Kits Lighter pulleys increase horsepower by decreasing the parasitic effects that factory accessory pulleys have on a vehicles engine. The pulleys lightweight 6061 T-6 billet aluminum construction reduces rotating weight and increases efficiency. All pulleys have a tooth profile that is guaranteed to match Original Equipment (O.E.) specifications, elimination the chances of premature comprehensive instructions, performance belts and AEM decals. ¡VRemoval of torsional vibration damper NOT necessary.

Valve Springs Single and double updated valve spring sets are available for various applications.