Building a custom turbo kit for your car is the ultimate way to gain horsepower. There are numerous full aftermarket kits available for many makes and models, but piecing together your own turbo kit lets you custom choose each piece, and also can save you money. If you take the time to search around for used parts, you can have all the horsepower gains of a full aftermarket turbo kit for half the price.
Find a turbocharger to use with your custom kit. This should be the first part you buy, as the characteristics of your turbocharger will affect supporting modifications needed. There are dozens of options for new turbochargers made by various aftermarket manufacturers. However, a cheaper alternative is to locate a used turbo. Turbochargers from production turbo cars such as the Mitsubishi Eclipse and Nissan Z cars are often sold in car enthusiast classifieds, and are much cheaper than purchasing a new unit.
Purchase a wastegate for your turbo, if needed. Most turbos are made with internal wastegates. However, these are sometimes removed in preference of an external wastegate. Ensure your turbocharger still has a working internal wastegate, or purchase an external wastegate from an aftermarket manufacturer.
Decide what sort of intercooler system to use. An intercooler is an air-to-air radiator that cools the charged air from the turbo before it enters the engine. Various front-mount units are available from aftermarket manufacturers. These can be found in kits with vehicle-specific piping, as well as without piping. Purchasing an intercooler unit by itself and having the piping custom fabricated by a performance shop can be much cheaper than buying a full kit. A blow-off valve is also needed. This is a mechanism that attaches to the upper intercooler piping and releases excess charged air when the throttle is lifted. Some intercooler piping kits come with a blow-off valve. Alternatively, many aftermarket manufacturers offer universal blow-off valve units.
Gather supporting modifications for your turbo kit. The cheapest intake solution is an aftermarket air filter attached directly to the turbocharger's inlet. Oil and coolant lines are needed to keep the turbocharger cool and lubricated. These can be custom fitted from various universal tubing sold by most auto parts and hardware stores.
Find an exhaust manifold to bolt your turbocharger to your engine. Various aftermarket manufacturers make custom manifolds for specific makes and models. A cheaper alternative is to have your stock unit modified by a custom exhaust shop to accept the turbocharger you choose.
Finish your custom turbo kit's hardware with a custom downpipe. This is the piece of the exhaust that attaches the manifold to the rest of the exhaust system. Various universal units are offered by aftermarket manufacturers. Alternatively, a custom downpipe can be fabricated by an exhaust shop and fitted to your vehicle.
Tune your new custom turbo kit with some type of engine management software. For many makes and models, ECU reflashes, or performance chips, are offered by aftermarket tuners. These revise your vehicle's tuning maps to ones customised for a turbocharger. A more expensive option is to purchase a fully-tunable ECU and have it tuned professionally by a performance shop. This method often yields greater horsepower and reliability than a less-extensive performance reflash.
When buying used parts for your custom turbo kit, ensure that all parts are in good condition and working order to avoid reliability issues.