Adding a supercharger

Before we begin I should warn you that this is going to be much more expensive than upgrading an already supercharged car. You'll have to have a new computer system to handle the boost input, timing, fuel curves, etc. You'll also have to buy a kit, or every part of the system that you want, including the exhaust system. You may also have to build an engine to handle it.

Ideally you'll find a kit for your particular car. Turbo kits start at around $3,500 and go up depending on the make of car. Superchargers like the Vortec, ProCharger, and Paxton systems, generally start a bit lower. Don't overlook factory systems for parts either. Some manufacturers are using Eaton superchargers in newer cars, and most companies have turbocharged cars at one time or another.

Salvage yards can be a great source for parts, but you have to find cars as they come in. You almost have to camp at the salvage to get parts because they are sold so quickly. Some salvage yards will allow you to place an advance order and call you as soon as a car comes in.

You should go read the Engine Modification section before you go much further. The key to supercharging a normal car is keeping everything in balance. That means build the car as a complete package and not just an engine.

Ask Questions

Probably the most important thing that I can stress is not to be afraid to ask questions. Find someone that has done a conversion, or talk to the tech support people that make the kit you want to use. If you can afford it, have the kit installed buy a shop that has done the conversion before, or at least has a lot of experience with turbo/super charged applications. Find where people cruise in your area and find a similar car and talk to the owner. You can find sources by word of mouth that are much more dependable than adds in a magazine.

There is no such thing as a stupid question, only stupid answers. If you are doing the work yourself, and run into something you don't understand, ask someone. It's much cheaper to ask questions than it is to replace parts, or an entire engine.

Turbocharging or supercharging, which is best?

First, there is no such thing as a "best" solution. There is only what is best for you, your car, or your wallet. It depends on the goals that you have for the performance of your car, and how driveable the car will be when finished. Whether you are talking about turbos, roots type blowers, or vane blowers, they are all superchargers. The biggest visual difference is how they are driven. There is not enough room here to go into all of the internal differences and theory behind each.

Belt driven superchargers

Referred to as blowers sometimes. These use a belt system to drive the compressor from the crankshaft of the engine. They use sized pulleys and idler pulleys to control boost and belt tension. By changing pulley sizes, you can gain or loose maximum boost pressure.

Pros

No lag, virtually instant throttle response.

Makes power at all RPM levels.

Easier add on installation.

Greatly increased low end torque.

Cons

Power hungry. Robs engine HP throughout operating range.

Power requirement increases as RPM increases.

Power output limited to case size and RPM range.

Belt and pulley maintenance can be expensive.

May have to do without some mounted items (air conditioning, etc).

Exhaust turbochargers

These are driven from the exhaust heat/pressure of the engine. They use a wastegate system to control boost pressures. The wastegate bleeds exhaust gasses from the turbine side of the turbo to control the speed at which the compressor side spins.

Pros

No HP drain to produce boost.

Fully adjustable boost output.

Limitless boost potential by matching turbine and compressor sizes.

Cons

Stock power and torque levels at low engine speed.

Can produce a bog or "lag" at low speed.

Produces more under hood heat.

Expensive to modify turbo unit.

In short, both systems offer huge increases in HP, they just do it in different ways and at different places on the RPM band. Turbos can theoretically produce unlimited amounts of horsepower. The major limitation is the housing and blade sizes, blade pitch, number of turbos, etc. to get the power you want.

So why don't top fuel dragsters run turbos you might ask? I honestly don't have a clue. I would assume it is a matter of small case sizes, and the weight they would need to add to get the power they currently run.

As you might have guessed, I am a fan of turbos. That's not to say I don't like belt driven superchargers, I simply prefer the flexibility of turbo systems for street driveable applications.

Kits

Kits are a wonderful thing, but I have yet to see a kit that has all of the parts that you'll need. There is always something that needs to be made or replaced at the same time. Read the manufacturers recommendations carefully and follow them. Get the entire package installed and working before you start making changes or upgrades to other areas. Do one thing at a time, and finish each step before moving on to something else.

Basic engine

As stated above, be sure to follow the recommendations that came with your kit. There are generally many differences between factory turbo cars and non turbos. Compression ratios are generally lower, rods may be different (stronger), harder bearings, different head, etc. Find out these differences if the car manufacturer makes a turbo car.

Whether turbo or supercharging, it is important to remember that the more boost you run, the more torture you will be putting your engine through. If you are building a V8 with a Vortec supercharger, it is easier to have a goal for high 12 second passes without major engine work than it is for a 4 or 6 cylinder. Remember that all turbo or supercharging is designed to make an engine act larger than it is. Starting with a larger V8 gives you an advantage over smaller 4 and 6 cylinder engines.

Power to weight

The best formula for getting quick times at the track is to keep the car as light as possible with the most power possible. As I said before, you must build a car as a package, and you can't sacrifice safety for performance. If you have a killer power to weight ratio (say 10 lbs per HP) but you can't get the car stopped at the end of a run, you are driving a coffin.

The power to weight ratio of your car will naturally change as you add horsepower. You have to be able to plant that power to the street or track surface though. Making 500+ HP isn't worth spit if you go up in smoke and get beat by a stock VW.

Upgrading brakes, tires, springs and shocks, struts, and adding strut braces will all help to complete your package. Again, ask someone that has already done the conversion. Find out what other changes you'll need to do to get the performance you want. Try to get that information before you start the conversion, it can help you decide if you have the right car to begin with.

Modifications

Once your conversion is finished, the other pages on this site can be applied to your car as well. Pay particular attention to the cooling and ignition sections. They can both save you expensive repairs in the future.