Basic explanations for some aftermarket parts & engine components. We are by no means an "actual" university, it's just a cool title. This section is intended to explain some terms used here at Mustangworld. We put it here to get beginners up to speed in Mustang lingo, but everyone is welcome here....
Written by Mustangworld
Listed in alphabetical (and grouped) order.
Recently Added: DOT.
This is a term that stands for "Brake Horse-Power". Which is basically the amount of horsepower present at the engine crank, and NOT at the rear wheels which is usually much less.
COLD AIR INDUCTION KIT
This is a kit that attempts to relocate the point where the air is sucked into the engine to a "colder" place (like into the fender well for example) for better performance. Cold air is more dense than hot air and produces a more violent explosion for better horsepower. Careful when choosing a cold air induction kit, some kits provide long lengths of tubing that will actually restrict air flow more than providing a benefit in performance.
COMPUTER SENSORS (in the Mustang, common ones but not all)
Oxygen Sensor(s) - These are two sensors (4 in '96 and newer stangs) that are located on the exhaust h-pipe. They measure the amount of oxygen and heat in the exhaust. They begin to work at high temperatures (over 300degrees C.) and are electrically heated on engine startup until exhaust temperatures reach proper operation levels. The sensors produce a voltage that is sent to the computer. Proper working oxygen sensors are essential for normal and performance engine operation.
Mass Air Flow Sensor - This measures the amount of air entering your engine. By using two wires a cold wire and hot wire, the air can be measured. The cold wire measures ambient air temperature, the hot wire measures the amount of air entering your engine. The hot wire is constantly being heated to 200 degrees Celsius by electric current (as it is naturally being cooled down from flowing air), the change in voltage from the electric current needed to heat the hot wire back up to 200c is measured by the computer. It is located just after your air filter, in-line with the large black rubber intake hose.
Throttle Position Sensor - This tells the computer how open the throttle is (how much you are pressing the gas pedal). It sends variable voltage signals to the computer depending on how open / closed your throttle is. The computer can also tell how "fast" the throttle is being opened / closed with this sensor. It is located on the throttle body.
Engine Coolant Temperature Sensor - This tells the computer how hot the engine is. At engine startup for example, more fuel is need to maintain a steady idle, as the engine heats up, different amounts fuel are required. Also as the engine heats up, the computer controls your smog equipment, spark retard, etc. A variable voltage signal is measured by the computer from this sensor. It is located on the engine block. Don't confuse this sensor with the engine's thermostat.
Manifold Absolute Pressure Sensor - This sensor measures the amount of air pressure in the manifold. It is used along with the Mass Air for accurate air flow measurements under different throttle positions (wide open, idle, etc.).
Throttle Bypass Air-Idle Speed Control - This senses if you have drastically lifted your foot from the gas pedal and if you did, it closes the throttle more slowly to improve emissions and to prevent the engine from potentially stalling out. It is located next to your throttlebody (like a small tube).
A catalytic converter is a small unit located on the stock h-pipe that heats up and burns off any remaining hydrocarbons that may be present in the exhaust. The inside of most catalytic converters are comprised of a heat catalyst called palladium. You will find 6 catalytic converters on a '96-'98 Mustang and 4 on most late model 5.0 stang h-pipes. Hi-performance or "high flow" catalytic converters are available as well.
This is a term often used to describe an exhaust system that replaces your stock exhaust system from the catalytic converters to the back of your mustang, hence the name "cat-back". A cat-back system includes the mufflers and all the pipes, hangers, and bolts needed to install. You can also just purchase the performance mufflers alone and have them welded into your stock exhaust system.
DOT (U.S. Department of Transportation (State) )
DOT is short for the Department of Transportation. It is a governing body that takes care transportation issues in your state. They grant permits, approve saftey equipment, etc. Find you states DOT here.
Detonation is when the air fuel mixture ignites before the spark plug has fired. Generally, this occurs in engines when the internal compression ratio in the chamber (above the piston) is too high. This will happen when the piston is still traveling up and can cause severe damage to your engine. People running superchargers, turbos, nitrous, and other forced induction systems have to watch out for this condition.
DOHC & SOHC
These are short terms used to describe different Mustang engines. DOHC stands for Double Over Head Cam engine, but a DOHC engine actually uses 4 cams total. SOHC stands for Single Over Head Cam, but a SOHC engine actually uses 2 cams total. The new Mustang GT uses a 4.6L SOHC 2 valve per cylinder engine. The Mustang Cobra uses a 4.6L DOHC 4 valve per cylinder engine. The Cobra needs the extra two cams to open and close the extra set of valves it has. These new 4.6L engines are also referred to as "Modular" or a "Mod" motor. The legendary 5.0 engine is a classic pushrod design, only one cam is used near the bottom of the engine to push "rods", that in turn push "rockers" that open and close the exhaust valves. The Corvette and Camaro LT1, LS1 engines are also of classic pushrod design. Both types of engine design Overhead Cam and Pushrod, are powerful.
GEARS (Ring & Pinion)
"Gears" is the common term used to refer to the gears in the rear end axle at the back of your stang. These gears consist of a ring and pinion. A complete "Gear kit" would include: Ring and pinion, gear oil and a new speedometer gear that matches your new gear set. Some popular ratios for aftermarket gears are 3.55, 3.73, and 4.10 ratios. The GT and Cobra use 8.8 inch rear ends. The base model Mustang uses a 7.5 inch rear end.
0-60 TEST -This is a test that is basically the time it takes for a car to reach 60 miles per hour from a standing start. IN THE PAST (the early automobile era) at the time when speed tests were beginning to take place, 60mph was the fastest a car could go, so this test was actually how fast a car could reach it's top speed! Today, the 60mph standard still stands, but cars today are capable of much higher top speeds. Mustangs can do 0-60mph in the 5-7 second range (depending on the model).
ENGINE DYNO -This is a test machine that measures horsepower and other data about your engine. Most performance shops have a dyno so they can see how modifications affect the performance of an engine. It uses a multitude of sensors including a "rolling log" under the rear wheels, to calculate data about your Mustang. People will say for example: "I dyno'ed my stang at 250 rear wheel horsepower man....". There is a difference between "rear wheel" horse power and "crank" horsepower. Most of the horsepower numbers that are published and reported, is how much horsepower is present at the crank. Horsepower is lost in the drivetrain. By the time it reaches your rear wheels you've lost at least 15% .
SKIDPAD TEST -This is a test used to determine the lateral gravitational forces (or G's) a car, tires, and it's suspension can handle before the car skids out. This test was created to have a way to inform consumers about a car's handling attributes. Depending on the test, a circle is drawn out with a diameter of 90 - 900ft. The size must be mentioned in the test, the most common size is 300ft. On a flat level surface, a car is then driven along the outer diameter line of this circle. The driver of the car continues to accelerate the car in this circle pattern until the car's tires "brake loose" and the car skids out. While the car is flying "round and round" in this circle pattern, the driver (and car) is being thrown outwards because of lateral "G's". This outward force is measured and recorded just before the car spins out. A lateral value of 1G (outward force), is equal to the force of the earth's gravity (a natural downward force). The stock Mustang can handle about .85 G's (approaching 1 G) of lateral force before it skids out. Lowering your Mustang and using larger aftermarket tires improves the lateral G figure. A lowered Mustang will have it's center of gravity closer to it's tires for better weight distribution to the tires in turns.
The Fuel Pump is an electrical pump located inside your Mustang's gas tank that pumps fuel through your mustang's fuel lines and then into your injectors. Like a balloon has air pressure, the fuel pump must maintain a minimum "fuel pressure" to ensure that your Mustang's engine gets enough fuel. Every time a fuel injector squirts fuel, the fuel pressure is affected. Your fuel pump is always running while your engine is running to always maintain a constant fuel pressure. You can even hear the fuel pump when you first start your stang. That little "buzzzz" coming from the back of your stang when you put the key in and are about to start is your fuel pump. Your Mustang also has a remote fuel pump cutoff switch that turns off the fuel pump in case of a bad accident. Your electric fuel pump does not ignite the gas in the tank (even though it's completely submerged in gas) because an open spark or flame is required to ignite gasoline. You can purchase high performance aftermarket fuel pumps that replace your stock pump OR purchase an "in-line" fuel pump that is placed just outside your gas tank, this means that you have two fuel pumps pumping, your stock one AND the aftermarket one. Aftermarket fuel pumps are required when you start to heavily mod your mustang to ensure proper fuel delivery and fuel pressure.
The h-pipe is the term used to describe the pipes that connect the engine's headers to the mufflers. It is 2 pipes joined together by a section of small pipe or a "blow by" section. The whole pipe assembly looks like the letter "H" on it's side, hence the name, "h-pipe". The stock h-pipe has several catalytic converters on it to reduce smog emissions. An off-road h-pipe does not have any catalytic converters on them, improving exhaust flow, but it's technically illegal for street use in most states.
Headers are the individual pipes that come from each exhaust port (from the heads) and then route exhaust gases to the h-pipe, then out through your mufflers. The stock engine has headers (sometimes referred to as "exhaust manifolds") already installed. Aftermarket headers are usually of a larger diameter than stock and provide better exhaust flow. Aftermarket headers are also available in "Shorty" (un-equal length) and "equal length" design. The difference in both designs is that an equal length header will have each tube of equal length, to provide a timely and slightly better exhaust flow from your heads. Equal length headers usually look like twisted pretzels because each exhaust tube must be made equal length.
The heads are where all the exhaust valves, springs, and rockers (5.0) are located. Aftermarket heads are usually made of aluminum and offer larger intake and exhaust ports for greater performance with larger valves for greater combustion. Heads are bolted to the engine block, one on each side with a gasket between to ensure a proper seal.
The throttle body houses a large circular valve that opens and closes depending on how much you are stepping on the gas pedal. There is also a TPS (Throttle position sensor) located on the side of the throttle body that tells the Mustangs ECC computer how open the valve is. This valve regulates the air flow into your engine. Aftermarket throttle bodies offer a larger opening to allow a greater flow of air into your engine. The throttle body is bolted to the upper intake manifold with a gasket in between to ensure a proper seal.
Valve covers do just that, cover the valves, rockers and springs to prevent them from getting dirty and to prevent oil from splashing all over your engine. Aftermarket valve covers offer you a chance to improve the "look" of your engine. They come in chrome, brushed aluminum, etc...
This the core of your engine. It is what the transmission is bolted to and it is also where all other engine parts, heads, crank, upper & lower intake manifolds, headers, throttle body, etc... is bolted. It needs to be strong and is usually made of cast iron.
NORMALLY ASPIRATED ENGINE
This is a term used to describe an engine that has NO blower, supercharger, turbo or any type of forced air induction system installed on it. An engine that runs via normal induction.
A supercharger is a unit that "blows" air into your engine. It looks like a big alternator. Like a vacuum cleaner an impeller (driven by your crank) draws air into your engine. Normally, your engine would have to "suck up" air as needed on it's own. Because a supercharger "forces" air into your engine, your engine creates more horsepower. A supercharger is another engine accessory that is powered by the crank, like your alternator or water pump is. A little HP is lost at the crank to drive the supercharger, but the horsepower gained from the forced induction more than compensates for this.
When you are driving down the road at 50MPH and you stick your hand out the window, you can really feel the wind resistance blowing your hand backward. What if you could take this air and RAM it into your intake? Well, with the right tubing or hood you can do it. When your car flies down the road, air is blown or "rammed" into your intake, hence the name "RAM AIR". The only problem is, a ram air system must be very direct. If air has to travel through 4 ft. of tubing before it reaches your intake then you'll have to be going 60MPH before you feel the benefits of a RAM air.
A turbo is very similar to a supercharger but a turbo is powered by your exhaust system. A special header is fitted to your engine that blows exhaust gases past an impeller and drives air through the turbo and into your intake. Some problems with a turbo charger is that heat generated by your exhaust, heats up the air that is forced into your intake. Intercoolers were created to control this problem. Also, because turbos are powered by your exhaust system, at low RPM's you don't get the full benefit of the turbo, to get the turbo spinning up to speed you need to really be "flowing" exhaust gases through the turbo, which does happen at higher RPM's. This is often referred to as "turbo lag". The benefits of a turbo is getting high levels of boost is no problem. A "twin turbo" is a car which has a turbo blower fitted to both exhaust sides (in a V type engine).
Oversteer is a term used to describe a car's handling characteristics. Oversteer is basically when a car's rear end swings out in a tight turn. If you "loose it" in a turn, swing around, etc... your car is oversteering, a spinning sensation. Oversteer tends to act up in long sweeping small turns taken a little too fast. Cars with engines mounted in the rear tend to suffer from this problem. The rear engine weight wants to swing the tail out in tight turns. Cars with rear mounted engines achieve their optimum weight transfer ratio (from braking) at the beginning of the turn.
This is when you turn your wheel to go right or left and your car just keeps going straight. A loss of steering control sensation. Understeer usually happens if you approach a hairpin turn a little too fast. After braking, a little throttle usually brakes the rear tires loose and you start to get into an "oversteer" situation. At Mustangworld we call this the "haystacker syndrome". Cars with engines mounted in the front tend to suffer from this problem, because when braking in a tight turn too much weight is transferred to the front of the car and the front tires begin to slide / skid. Cars with front mounted engines achieve their optimum weight transfer ratio (from accelerating) toward the end of a turn.
This is what a racer does when he or she gets into an "oversteer" situation in a turn. Corrective steering is when a driver turns in the same direction as the tail is sliding. If your tail is sliding right you turn right, if it's sliding left you turn left. This will prevent the car from "spinning like a top" on a race course. When corrective steering your car will slide sideways instead of sliding into a 180 degree position. Corrective steering is held in place for the duration of the sliding motion, if it is held in place too long, the car can "hook up" and slingshot it spinning in the opposite direction. Sometimes this duration is only a fraction of a second when racing. Corrective steering is used in conjunction with throttle and brake control.
OBD II (On-Board Diagnostics Generation 2)
Your Mustang's engine is controlled by a computer, OBD II is an engine diagnostic system in the computer that monitors your smog equipment. It is a new specification that went into full effect in 1996. The most noticeable changes pertaining to new Mustangs is the inclusion of 2 additional oxygen sensors AFTER the catalytic converters located on the h-pipe.
Rack & Pinion (Steering, Steering Rack)
"Rack & Pinion" is a term used to describe generic steering mechanisms in newer cars. Your Mustang has an all incased "steering rack" that is hydraulic powered. It is located just at the bottom of your engine at the front of your stang. The steering rack is held in place with two bolts and 2 thick rubber bushings.
SN95 or SN95 Mustang platform
This is the code number assigned to the Mustang which came to be in 1994. It replaced the FOX4 Mustang platform. It is referred to as the "SN95" platform. Because of this, current '94 to '98 model stangs are sometimes referred to as "SN95" Mustangs. Some elements of the older FOX platform still remain in the SN95 models.
SUBFRAME CONNECTORS & G-LOAD BRACE
Subframe connectors are steel bars that re-enforce the Mustang's chassis. Your Mustang chassis "flexes" under load, quite a bit actually, subframe connectors greatly reduce the amount of chassis flex and allows the suspension to work better. These subframes are welded onto the bottom of your Mustang under each door (approx.), on the bottom of your Mustang's chassis along the driver and passenger sides. It is recommended that subframes (and roll cages) be welded in and not bolted in, drilling holes in the chassis only weakens the chassis. You don't want bolts popping loose in a bad accident. A g-load brace re-enforces the chassis just below the rear of the engine. It gives you greater steering response by reducing tower flex. '96-'97 Mustang GT's (and Cobras) come with g-load braces and upper strut tower braces, standard.
Notice the diagram above. Each accessory on your engine has a "pulley" on it. The pulley is the wheel that is mounted on each accessory. Your engine has several accessories. Alternator, water pump (pulley with fan attached on 5.0 stangs), power steering pump, air conditioning compressor, and a possible air pump (5.0), or supercharger. There are also several idler wheels that are in place to put tension on the belt so it won't slip. There is a spring inside the belt tensioner that holds these idler wheels tight against your engines accessory belt (often referred to as the "fan belt" in the past). The crank pulley is driven by the crank shaft inside your engine. It is the pulley that "drives" or turns all the other accessory pulleys in your engine.
As you can see, the stock crank pulley (above) is rather large. By using a SMALLER pulley for the crank, we can reduce the amount of horsepower used to turn the other engine accessories. A smaller crank pulley has more leverage to turn the other accessory pulleys. We can also further reduce the amount of horsepower used to turn accessories by INCREASING the size of some other accessory pulleys in our engine. The most common accessories chosen for these larger pulleys are the Alternator and Water pump. These larger pulleys are referred to as "underdrive" pulleys, because of their larger size, they will rotate less frequently, hence the name "underdrive" pulleys. If we only had a smaller crank pulley in place, we would need to get a new belt, the stock belt would be too long, by using larger pulleys on the alternator and water pump WITH this new smaller crank pulley, we can retain the stock belt.
After looking at all this you may ask " hey, does it take that much power to turn the alternator and other accessories ? ". Yes, it does, if you ever tried turning a stock alternator under load, you almost can't with your bare hands. As much as 10-20HP is used up by accessories, but there are some accessories that we can't do without, like: alternator, power steering and water pump. If you are willing to do without power steering and air conditioning you can gain even more power. With everything in place, you can expect a 5 HP gain on a stock Mustang by using underdrive pulleys.
Keep in mind, because you are now "underdriving" your alternator, you will need to make sure you rev your engine above a certain RPM (depending on the alternator underdrive pulley) to like 750 or 900 RPM before your battery starts to receive a full charge. This means that at idle on a stock Mustang, your battery may not be receiving a full charge from your "underdriven" alternator. The cheap fix for this is to adjust your idle to 750, 900 or whatever until you get a full charge. The dealer or performance shop must adjust your idle, unless you have an ECC programmer (software and cable). There are companies that sell underdrive pulleys that DO give you a full charge when you are at idle on a stock Mustang (at the expense of a little more HP lost to drive the alternator). Inquire to the dealer that you are buying the pulleys from "At what RPM does the alternator pulley give my battery a full charge?" They will tell you. Underdriving the water pump does not cause problems.
Ok, so you think this is something you bolt to the front of your stang to scoop air up into your engine? No, actually a windage tray bolts to the bottom of your engine block between your crank and your oil pan. When you drive your stang, g-forces splash oil up onto the crank and prevent it from turning as free as it could be. A windage tray keeps oil down in the pan and prevents oil from clinging to your crankshaft. Don't worry, the crank gets plenty of lubrication during engine operation. Using a windage tray gives you more HP, like 5 or more depending on your mods.