Camaro and Firebird: What You Need to Know About Superchargers and Turbochargers
Like most performance enthusiasts, everyone is looking for more. Sometimes a small amount will do you. Add a bolt on here, take a bolt off there. If you want to add some serious grunt to your F-Body, a power adder is a definite way to go. Whether a roots, twin-screw, centrifugal, or turbo, boost can provide what you're looking for.
This article applies to the Camaro Z28/SS (1998-2002) and Formula/Trans Am (1998-2002).
There are several different types of forced induction. The major players in the boost wars break down into four different types: roots supercharger, twin-screw supercharger, centrifugal supercharger, and turbocharger. Each has its benefits and drawbacks. Each has its gotchas. As with any project, you have to figure out what your power goals are and how to accomplish them. You need to figure out how to go about making that power. One thing can be said for sure, it isn't exactly cheap to install any one of these power adders on your car, so it only makes sense to do your homework first. This will help you make the most of your hard earned money in the process. This article will give a brief description of each of these different devices. These will be general, as a more complete article would be contained in books, not in the thousand words or so revealed here.
Turbocharger Component Breakdown
Turbine
The turbine is the hot or exhaust side of the turbocharging system. Hot and expanding exhaust gases are funnelled out through the turbine. The housing is usually made out of cast iron, which can handle the heat and load due to it usually supporting the weight of the turbocharger as it is attached to the exhaust manifolds. The turbine is connected through the central shaft to the compressor wheel, which is on the cool side of the turbocharger. Depending on the type of turbocharger, these parts can spin up to 250,000 rpm.
Figure 1. Turbine and housing. This is the hot or exhaust side of the turbocharger.
Compressor
The compressor, as previously stated, is connected via the main shaft to the turbine. The compressor is built a lot like the turbine in shape and function, but instead of being acted upon by exhaust gasses, it acts upon the air as it forces it into the intake system. The compressor housing can be made out of many different materials, but in many cases is made out of cast aluminum. It is made this way because the cool side isn't affected as much by heat.
Figure 2. Compressor and housing. This is the cool or intake side of the turbocharger.
Center Housing and Hub Rotating Assembly
The center housing contains the main shaft and bearings. This is the connection which allows the turbocharger to perform the work. On most turbochargers, the center section will be cooled and lubricated by an oil flow, so pressurized oil has to be plumbed from the engine and back to the oil sump to support it. Some center sections can also have coolant ran to them, which serves to better cool the turbo and bearings for longer service life.
Figure 3. Center housing and hub rotating assembly. This contains the main shaft and bearings.
Roots Supercharger
Roots blowers were designed in 1860 by Philander and Francis Marion Roots. The basic design is an air mover and does not compress the air inside the unit like a turbocharger. The main principle is it moves more air than an engine can normally take in, so creates pressure after the air has entered the engine. The graphic below (Figure 4) shows the basic movement of the rotors in operation. Air (or air/fuel mixture, depending on the application) is moved around the outside by the case, not between the two rotors. In the illustration, the air is moving from left to right through the blower.
Figure 4. Roots rotors. Roots blowers are a positive displacement lobe pump.
Twin-Screw Axial Compressor Supercharger
The twin-screw axial compressor is a supercharger that compresses the air as it travels along the rotors of the device. This is accomplished by the exhaust side (where the air goes into the engine) being smaller than the intake side of the compressor. You'll notice the rotors are completely different between the two, with the male side (left) having three lobes and the female (right) having five. Different manufacturers will have different setups depending on their engineering demands.
Figure 5. Twin-screw axial compressor. Each rotor is radially symmetrical, but laterally asymmetric.
Centrifugal Supercharger
A centrifugal supercharger is sort of a mixture between a regular supercharger and a turbocharger. The compressor is much like what you'd find on a turbocharger, yet it's driven via a pulley and belt off of a crankshaft pulley. While heat occurs during compression of the air, there's no heat transference like you'd see with a turbocharger. There's no frictional heat caused from rotor interference like you'd see with roots style superchargers. Due to this, the air intake charge can be much denser than what you'd see in either case.
Figure 6. Procharger centrifugal supercharger. Uses a compressor like a turbocharger, but is driven off the crankshaft instead of exhaust gasses.
Scheduled Maintenance
Maintenance schedules are dependent upon the what the manufacturer states. For must turbochargers, you need to ensure your engine oil is changed on time, due to it being run through your turbo bearings. Synthetic oil is highly recommended due to its ability to withstand heat related issues, which can occur with dino oil (sludge buildup; caramelizing). You should also regularly check the end play of the main shaft. It should remain fixed. When the end play becomes noticeable, a rebuild may be in order. Roots and twin-screw superchargers are fairly self sufficient. They will usually continue running until they aren't. Most do not require maintenance. Centrifugal superchargers most often have their own oil supply (do not rely on engine oil to lubricate). They still require an oil change periodically, but require it much less frequent than does engine oil, which would be supplied to a turbocharger.
Common Questions
What is an intercooler?
An intercooler is a device which is used to cool the compressed air before it enters the engine. This allows for a denser air charge, allowing the engine to produce more power with less of a chance of pre-ignition. An intercooler is usually either an air-to-air interface or air-to-water. Air-to-air intercoolers are much more common due to the simplicity of the design. Air-to-air intercoolers look much like a coolant radiator, but has air flowing through it versus some type of liquid. As the air enters the intercooler, it is heated due to being compressed. It travels through tubes that have fins attached to them. These fins transfer the heat from the charged air to the outside air. The size of the intercooler is based on the horsepower and boost levels. The larger the boost, the larger the intercooler.
Figure 7. Air-to-air intercooler.
Air-to-water (or air-to-fluid) intercoolers are utilized much like air-to-air intercoolers, but have some type of fluid to transfer heat away from the air charge. The coolant works much like a cooling system in a vehicle, with a separate coolant reservoir, pump to move the fluid around, radiator for air to cool the fluid, and piping for the coolant to make its travels. Air-to-water intercoolers are commonly used where space is a premium between the forced induction device and where the air enters the engine. Newer superchargers such as what is used on the ZL1 Camaro and ZR1 Corvette use this style of intercooler, but can be found in other applications as well.
Figure 8. Air-to-water intercooler.
What is a blow off valve?
A blow off valve (BOV) is a device which is a pressure relief valve to prevent over pressure inside the intake tract. It is placed between the compressor and the intake manifold on engine. It releases excess boost as well as prevents compressor surge. A BOV can be used in turbocharging or centrifugal supercharging situations.
Figure 9. Blow off valve (red object).
What is a wastegate?
A wastegate bleeds off exhaust gasses before they reach the inlet of the turbine housing. This helps control boost and overall engine power. It acts as a controlled bypass for a percentage of exhaust gas to escape and not be used to build more boost. A wastegate can be internal to the turbo or external in the exhaust tract.
Figure 10. External wastgate.
Can I put forced induction on my stock LS1?
The simple answer is yes. While a stock engine can handle boost, it can only handle certain amounts. Generally speaking, the LS is a stout motor, but any engine is susceptible to permanent damage when pushed way beyond the factory intentions. Typically, for a stock LS1 engine, you don't want to exceed more than 6-8psi of boost, depending on the turbocharger. This is due to the higher static compression ratio of the engine. This is also due to the stock components that make up the rotating assembly of the engine. If you are wanting to make serious power with forced induction, your only real choice is a complete rebuild with optimal components, such as forged crank, connecting rods, and pistons. The stock LS1 is a strong engine and can produce a lot of power with forced induction, but as the boost levels and horsepower rises, its longevity decreases.
Common Issues
Turbocharger Oil Starvation
One of the typical problems with a turbocharger is oil starvation in the central housing and hub rotating assembly. If enough oil is not transferred through to lubricate as it's supposed to, bearing failure can occur. This can also happen if the return is not of sufficient size to return the oil fast enough to the sump. While this isn't technically oil starvation, the same end results occur due to lack of sufficient oil flow. To combat this, you need to size your main oil supply/return lines correctly as well as ensure a proper supply of oil (oil level in sump is where it should be). Keep your oil clean and changed on time so as to combat sludge buildup that might prevent good oil flow to the turbo.
Turbocharger Lag
Turbo lag is inherent in any turbo system, but is easily reduced by the proper sizing of the turbocharger for the needs of the engine. Depending on your power goals and where your engine will see most of its time, will entail what kind of turbo sizing it will require. Getting the correct back pressure to boost ratio is imperative.
Camaro and Firebird Engine Modifications
Engine Modifications
Yes! You can go even faster.
This article applies to the Camaro and Firebird (1990-2015).
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