Forget meth, blow, angel dust and smack, speed is the drug of choice for true connoisseurs. The only problem is, very few cars come from the factory with the sort of raw acceleration and "push you in the seat" power that you demand. Enter the aftermarket forced induction kit. Turbocharging and supercharging have existed for years, and ever since wheels have turned in anger, engines have been boosted.
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 Your three usual suspects...  Your three usual suspects (L to R): The centrifugal Vortech s/c, the Roots-type Stillen s/c, and the turbocharger. |
 Red: Vortech SC 336HP/295TQ...  Red: Vortech SC 336HP/295TQ
Green: Stillen Stage 2 SC 313HP/285TQ
Blue: Greddy Turbo 347HP/322TQ
Grey: 2003 Nissan 350Z232HP/223TQ
NOTE. Graphs are from different dynos and are for rough approximation only. |
One of the easiest and most cost effective ways to see horsepower gains of more than 30 percent on a stock engine, forced induction remains one of the most sought after upgrades on the market today. Intakes and cat-back exhaust systems are great ways to lay the foundation for big power, but they won't be able to do it alone. The majority of import engines are finely tuned from the factory, and only minimal gains will be found with bolt-ons. Plus, if you're looking to build a naturally aspirated monster, expensive individual throttle bodies and mucho aggressive camshafts will affect driveability so much, you'll wish you went with forced induction in the first place.
In fact, some of the most popular platforms of today were made that way because of the power potential that forced induction can offer. Just take a look at the Subaru WRX, Mitsubishi Lancer Evolution, Mazda RX-7 and the Nissan 240SX/SR20DET swap-these things can make power easy. If and when you do decide to get pressurized, you'll soon discover that there are more turbo and supercharger kit offerings than there are fingers to count with. The key is to figure out what you want from your car ahead of time and plan accordingly. Let 2NR be your guide.
The Basics
The first thing you'll need to know is that a supercharger and a turbocharger are pretty much the same thing. Both are essentially air pumps, cramming more air into the intake than an engine can suck in on its own. Boost, which is normally measured in pounds per square inch (psi) or bar (1 bar = 14.7psi), is the amount of air pressure that an engine will see over a naturally aspirated setup. The difference between the two chargers lies in the fact that turbochargers make boost through the spinning of a turbine wheel that is pushed by exhaust gases, while supercharger compressors are driven by a belt connected to the various pulleys on an engine's face. Because they are driven by different methods, turbos and superchargers make boost and power in different ways, giving potential buyers a different driving experience.
Although the basic principles can be applied to any platform, in this article we'll be using the Nissan 350Z as our example and will focus on the three main types of aftermarket forced induction kits, the centrifugal supercharger, the turbocharger, and the positive displacement/Roots supercharger.