How to Twin Turbo Your Car

by Alexander Eliot
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A turbocharger pressurizes the air intake system of an engine, drastically increasing the airflow into the cylinders. This drastically increases horsepower potential beyond what is achievable with a naturally aspirated engine. Twin-turbo systems are more efficient turbocharger setups for engines with two cylinder banks, such as V6 or V8 engines. As each bank of a V-configured engine has its own cylinder head, a twin-turbo system can be used to bolt a turbocharger to each of the engine's exhaust outlets. This allows for the use of smaller turbochargers and shorter piping, thus reducing turbo lag while improving overall turbocharger efficiency.

Step 1

Replace your engine's stock exhaust headers with turbo-specific exhaust manifolds. This will allow installation of the twin turbos to your engine. Purchase two turbochargers, as a single turbo is mounted on each exhaust manifold.

Step 2

Purchase aftermarket, turbo-specific intakes to install on the turbocharger inlets. If your vehicle's airflow sensor is mounted into the intercooler (Step 3), a universal cone-shaped air filter can be connected directly to the turbocharger inlets instead of using full intake pipes.

Step 3

Purchase an intercooler and piping kit. Intercoolers route the charged air from the turbochargers through a radiator system, substantially cooling intake temperatures. On many twin-turbo setups, the intercooler is also where the turbos' down-pipes flow together, before the pressurized air enters the engine through a single intercooler up-pipe and throttle body. Note that installation of an intercooler and piping will require cutting modification to the front bumper and/or other vehicle components.

Step 4

Purchase a blowoff valve to install onto the intercooler up-pipe. Blowoff valves open when the engine throttle is lifted, releasing excess charged air from the intake system. Most intercooler flanges are universal, accepting blowoff valves from any manufacturer.

Step 5

Purchase various rubber and/or steel braided lining for your twin-turbo system's vacuum system and oil/coolant lines. These will take the place of stock lines, and are mounted to various connections on the turbocharger and intercooler system. Refer to turbocharger vacuum and fluid diagrams if you're unsure of the lines needed.

Step 6

Install an ECU tuner on your twin-turbocharged engine. As the turbos vastly increase the airflow into the engine, stock ECU fuel maps cannot be used with the turbo setup. There are various piggyback systems which plug into the stock ECU. These allow you to edit the stock fuel curves, so that more fuel can be added in compensation for the charged air of the turbo system. Alternatively, various standalone ECU systems are available which make all engine parameters fully tunable. For best performance results, purchase one of these standalone systems, and have your engine tuned by a professional using a dyno system.

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