Get a feel for all the components that go into a performance turbocharged car. You only want to get what you need. Included is a helpful roadmap you can use to figure out why we use the components we do!
Turbo
The Turbo pressurizes and delivers the air needed for combustion. The most important aspect of a turbo is the sizing, which in part determines flow rate. Measured in pounds per minute (lb/min) or kilograms per second (kg/s), the flow rate of a turbo is crucial to figure out the most amount of air that can be pushed out of it. The amount of air being delivered by the turbo has to be matched by fuel.
Intercooler
The Intercooler is responsible for cooling the compressed air from the turbo. Cooler air is denser, therefore more air exists per unit volume, resulting in more mass. The more air that exists, the more fuel that it can combust with, therefore creating more power.
Intake Manifold
The Intake Manifold delivers the cooler, denser air from the intercooler to the cylinder head, evenly distributing it among each cylinder. Upgrading the intake manifold can help to deliver air throughout all power ranges, especially higher end rmps where a stock intake manifold may limit the amount of power you can force out (stock redline is in the 6000s, so the manifold isn't made to see past that)
Fuel Pump
The Fuel Pump delivers fuel from the gas tank to the fuel pressure regulator. Fuel pumps are measured by their output of liters per hour (lph). The pressure output of fuel pumps vary, which is why Fuel Pressure Regulators are used.
AFPR
Adjustable Fuel Pressure Regulators are used to set a base fuel pressure for the engine, and self-regulate to increase fuel pressure under boost and decrease fuel pressure under vacuum. The base fuel pressure depends on the vehicle. For a second generation DSM, the base fuel pressure is 42.6 psi. Using the AFPR, this can be adjusted so that the correct base pressure can be achieved independent of the fuel pump used. The regulation comes in to play under boost. If the turbo was delivering 10 psi to the engine, the fuel pressure would rise to 52.6 psi from the base 42.6 psi. This maintains the 1:1 ratio of fuel to air for combustion. This is why having an AFPR is important!
Fuel Rail
The Fuel Rail delivers the regulated pressurized fuel from the AFPR to each individual injector for each cylinder. The fuel rail is usually upgraded if the stock fuel rail is a limiting factor of fuel flow due to being to small.
Fuel Injectors
Fuel Injectors are a very crucial part of the fuel system. Measured in cubic centimeters per minute (cc/min, ex. 1000cc) the fuel injectors deliver the right amount of fuel to each cylinder to match the amount of air delivered by the turbo. The bigger the turbo, the more airflow the turbo delivers to the engine, therefore the bigger injector needed to deliver more fuel. Because of this, it is important to have injectors that are matched to the turbo. You may hear people talking about "running out of injector". This happens when the turbo is still delivering more air to the engine but the fuel injectors are delivering at their highest capacity. When you add more air and not enough fuel, you run the risk of running lean, which can be catastrophic to the engine, especially at high speeds and power. The best way to combat this is to get injectors that flow MORE than the highest your turbo can flow. It is always better to run rich than lean.
Cylinder Head
The Cylinder Head consists of Camshafts, Valves, Springs, Retainers, Valve Guides, Lifters, and the Head itself. All of these compopents work together to deliver the right amount of air and fuel mixture at the right time, and expel exhaust gasses at the right time.
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Camshafts: With a high flowing turbo and bigger intake, camshafts help to increase power flow at higher rpms.
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Valves & Valve Guides: When using aftermarket camshafts, getting stronger valves can help handle the forces of higher rpms. Also, oversized valves can be installed to increase air flow even more if you are pressed for it at those higher rpms.
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Springs & Retainers: The high rpms put a higher force and vibration from the camshafts to the valves, and to keep them in place, aftermarket springs and retainers can help to open and close the valves at those higher speeds.
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Lifters: Lifters make sure that the camshafts maintain contact with the valves/rockers to open and close them. You may hear the term "lifter tick" and that happens when the lifters are worn out and the camshaft loses contact with the valves/rockers. Aftermarket lifters (known a lot as "no tick lifters") can be installed as a replacement, as most have been revised to perform better than what was originally in the car however many years ago it was made.
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Porting: Porting of the head also helps at high flow rates and can give air a more streamlined path to travel based on the performance you are going for with your build. When you are pressed for that much more air flow, you porting can help you squeeze some more flow out of the cylinder head, but is most beneficial combined with the above modifications.
Engine Internals
Engine Internals are what go in the engine block. These internals are the Pistons, Rods, Crankshaft, and Bearings. It is not necessary to upgrade the internals of an engine, but when you are pushing the limits of the stock engine, then it is time to upgrade.
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Pistons & Rods: As you increase the air and fuel being forced into the combustion chamber, the internal forces seen in the pistons and rods are higher than they were made to handle. Forged pistons and rods have a stronger mechanical structure that can handle the higher power in the combustion chamber. The stronger rods can withstand the higher moment of force transfer to the crankshaft.
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Crankshaft: The crankshaft delivers the power from the pistons and rods to rotational power to the flywheel. For some purposes, the crankshaft can handle the higher amount of power that forged internals can deliver, but once you reach the limit of the crankshaft, you can go with a forged crankshaft along with the other internals.
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Bearings: The bearings are the main interface from piston to rod, rod to crankshaft, and crankshaft to block. As you undergo higher rpms, upgrading the bearings help keep the shafts rotating and lubricated to what is needed.
Turbo Manifold
As you know, the exhaust gasses from the combustion chamber are sent to the Exhaust Manifold, or a turbocharged car, the Turbo Manifold. The manifold routes these gasses to the turbochargers turbine, which uses the velocity of the exhaust gasses to spool the turbo. The manifold is important because the routing of it determines how well the gasses flow to the turbine. There are lots of calculations that are put into the science of these manifolds, and those that know what they're doing may have a higher prices manifold, but it is priced that way for a reason. If you want to take advantage of the best spool possible, a good flowing manifold matters.
Exhaust
The Downpipe and the Exhaust refers to everything coming off of the turbo. Unlike a NA engine, because of the backpressure between the cylinder head and turbine being used to spool, the exhaust can and should be as free flowing as possible. When you are pushing a lot of power, the exhaust just becomes a matter of where you want to dump your exhaust gasses, hood, bumper, or back are common.
Wideband O2
The Wideband O2 Sensor is used to monitor the Air Fuel Ratio (AFR). A narrowband sensor sees 0v or 1v, lean or rich. This is good to establish idle and being in a closed loop system (fuel input adjusts based on lean or rich), but when you are doing anything with your car other than stock, such as a bigger turbo and bigger injectors, it is important to make sure you are mixing the right amount of fuel to air.
Clutch & Flywheel
The Clutch transfers the power from the engine to the transmission via the clutch and flywheel. Upgrading your clutch is important as you make more power because the stock clutch is only good for a stock car. Research the best option clutch for your car.
Transmission
The Transmission takes the power from the engine and "transmits" it to the wheels. The stock transmission of any car has its limits, and you may be able to achieve your goal without building a transmission up. As you push more and more power out of the engine though, you can reinforce the internals of the transmission so you can transfer all of that power to the wheels without breaking any gears.
LSD
A Limited Slip Differential helps minimize the power distribution variability between all driven wheels of a car. This very helpful on a high horsepower AWD car, is more helpful on a RWD car, and most helpful on a FWD car.
Axles
High Horsepower Axles are really useful to help against sheering shafts at high torque, like at launch. Every stock item has it's limists, and when you start breaking axles, that's one way to know to step it up. Do your research to figure out to figure out the limits of your stock axles, and if your goals are past that, get stronger axles.
Tires
The Tires are one of the most crucial pieces. After you have gotten all that power from the turbo to the engine, through the clutch and transmission to the axles, the wheels deliver the power to the ground. It is important to maintain grip and that is why so many go with low treadwear tires made for track, or slicks that allow for the best traction.