While basic in concept, there is still a lot to know about Forced Induction (FI). While I can't take anything away from a strong normally aspirated motor, there is nothing like Forced Induction. The world's most powerful motors almost all use some form of FI. Since it's introduction back in the 1800's, FI has primarily been used only in race cars, working vehicles (such as 18 wheelers and busses), and airplanes. To start things off, there are three kinds of FI: Superchargers, Turbochargers, and Nitrous Oxide. The main goal of each of these types of FI is to add additional oxygen into your motor. It is with this additional oxygen that additional fuel may be added, which allows for a substantial increase in horsepower as well as an increase in engine efficiency.

Superchargers, also called Blowers, are essentially Air Pumps turned by a belt driven off of the engine's crank. They come in two main types: External Compression and Internal Compression. I realize that sounds like an overly simplified classification, but it really is that simple. External Compression Superchargers, also known as Positive Displacement Blowers, such as Roots Style, move a certain amount of Air with each revolution. They are classified as "external" compression superchargers as all of the "boost" is made in the manifold and not in the blower itself. This style of blower raises your effective compression all the time, or at least it tries to. This is why they are mainly used only on Race cars and Show cars, not on your typical daily driver. Most street driven cars with these blowers run low boost and low motor compression, such as with most OEM applications. In these cases the blower is more for looks than performance, or is an attempt to make a low performance motor into a higher performance motor. For this reason I don't recommend this style of Supercharger, and wont go into it any further in this article.

Most modern Superchargers are centrifugal style. These are classified as "internal" compression as they produce their "boost" in the blower before sending it on to the manifold. This design was heavily used way back in World War II in military planes. It was used to overcome the thin air at the high altitudes where the planes were forced to fly. It wasn't until recently that this design really took off for use in cars. While Paxton has been making this style blower since day one, it took a competition with Vortech to really bring the blower to popularity. Paxton superchargers have actually been used on some special edition cars that companies like Ford used to turn out in the sixties, but today things are a little different. The original design used by Paxton, which had a signifigant design problem eventually lead Vortech to do a slight change that made a huge difference in both performance and reliability.

Paxton has always used huge ball bearings as a form of planetary gear to step up the speed of the impeller. The impeller is what spins to create the boost. The problem with this design is that the bearing must fit very tightly so as not to slip. This means it takes lots of force to turn the blower and the tightly packed bearings are going to get very hot. As a test, I used a torque wrench to measure how much force it takes to turn a Paxton - 42 ft lbs. That means your motor has to really work to get its extra power. If it takes 60 horsepower to get 120, is it really worth it. The problem with all the heat is that the ball bearings begin to slip and you loose boost. This usually happens when you reach normal operating temperature. Paxton has tried to fix this with special fluid coolers and bearing retainers, but this is a patch at best. To create a new Super Blower, the Novi 2000, Paxton used a gear drive like the one Vortech has used since it's day one. The problem with the Novi 2000 is its cost. While I will admit it is a really great blower, it's just not cost efficient.

If it sounds like I am a little biased towards Vortech, your right! I started with a Vortech A-Trim back in 1992, before eventually upgrading to an S-Trim, and that same unit has worked flawlessly for over 68,000 miles. I have used a pulley configuration that Vortech does not recommend, to gain boost levels they claim are not possible, and it just keeps working perfectly. For these reasons I would find it tough to recommend any other blower more than Vortech.

Turbochargers are essentially a supercharger that is turned by your exhaust instead of your motor's crank. It is made up, primarily, of four parts: the turbine section, the impeller, the compressor, and the bearing housing (center section). The turbine section is where the exhaust passes through the turbo in order to spin the impeller. The impeller is, essentially, two fan blades connected together by a shaft. As the exhaust turns the impeller in the turbine section the other end is spinning in the compressor housing which is where air is pushed into the intake of the motor. The center section of the turbo holds everything together and is where the bearing that the impeller rides on are contained. While this is a very basic idea of what makes up the turbo itself, the complete turbo system has a few more parts to it.

The main advantages of a turbo is it's efficiency and it's adjustability. It's efficiency comes from the fact that your motor doesn't have to work so hard to make it's boost. This is very good for the crank and bearings, as a Supercharger's belt is always trying to pull upward on the crank - which is not good. The adjustability of the turbo comes from the wastegate, which is used to control how much of your exhaust will be used to spin the Turbo. This is used to regulate the amount of boost that is made by the turbocharger. Essentially, the more exhaust that enters the turbo, the faster it will spin, and the greater the amount of air it will move - creating higher levels of boost.

The down sides of a Turbo system is the complexity of the exhaust system and the slight amount of additional heat, both under the hood and in the oil. Obviously the additional heat under the hood is due to all the extra exhaust components that go along with a turbo kit. The additional heat in the oil is because engine oil is used to lubricate and cool the turbo's bearings. Turbo's also require a little bit of care and feeding. With a Turbo car, you really should let the engine idle for a short time after driving while the Turbo spins down and heat is pulled out of the bearings. While these are technically downsides, modern turbo systems have most of these factors worked out to where they are almost a non-issue. All in all turbochargers, especially factory equipped units, are a very good way to go.

The most important thing about setting up a FI system is proper Air to Fuel Ratio. This holds true for all motors, but is very critical for FI. This is because of the extremely high effective compression. I will use my motor as an example of this. It displaces 302 cubic inches and has a motor compression of about 9.5:1. Nothing radical so far. A Vortech Supercharger then adds about 14 lbs of boost, or almost doubles atmospheric pressure. This means that at peak boost, my motor effectively has about 18.5:1 compression. A compression that high would never be possible for a naturally asperated daily driver. [The formula for this is: ((boost/14.7)+1) x motor compression = effective compression] This shows the main advantage of FI. Under day-to-day driving the car behaves like any other mild compression motor. Then when you start to hammer on it, it becomes a high power, high compression motor, offering the best of both worlds.

Nitrous Oxide is a liquid containing two parts nitrogen and one part oxygen. By volume, that makes it about 33% oxygen. It is the extra oxygen in Nitrous that we are after as it has about 50% more oxygen by volume than the air around you. The oxygen is released from the nitrogen when it is heated, and turns from a liquid to a gas. In a Nitrous system, additional fuel is added to make use of all the additional oxygen. This is where the additional power comes from. This is also where the additional risk comes from. If the correct amount of additional fuel is not added, the motor will lean out and start to melt parts. In the early days of Nitrous this was a major concern, but we have thankfully grown past this for the most part. Nitrous kits are offered for almost every application, and are very safe and reliable when used according to the supplied instructions. It is primarily those who try strange jet combinations, or have inadequate fuel systems that have problems.

If you have ever considered using Nitrous because of its power per dollar, you are on the right track. While Nitrous does offer the most bang for the buck in the short term, it can add up over time. It's important to keep in mind that it will cost you about $30 to $50 each time you get the bottle filled, which when used a lot can add up rather quickly. Also, in order to get the most out of a Nitrous kit you will need a few extras - such as a timing retard, a bottle warmer, a purge kit, and ideally a progressive controller. Going this route things can quickly go from around five hundred dollars to well over two thousand dollars, or more - not including installation! While I'm not trying to talk anyone out of going with Nitrous, I do think it's important to understand that over a years worth of racing a good Nitrous kit can cost as much as a supercharger kit. While they will both work just fine, the supercharger will be easier to control, it doesn't have to be refilled, and is always ready. Just something to think about...