Hennessey Venom GT 0-300km World Record Run – TUNED

WekFest Long Beach 2012

This Year at WekFest Long Beach was a great turn out. Tons of the best cars you’ve ever seen. Check out more pictures on our Car Show Page on Clutchrides.com!




Turbocharged Vs. Supercharged

It’s one of the most common questions I am asked “What is better a supercharger or a turbo?” According to the Webster’s dictionary, a supercharger is defined as: “a device (as a blower or compressor) for pressurizing the cabin of an airplane or for increasing the volume air charge of an internal combustion engine over that which would normally be drawn in through the pumping action of the pistons”. A turbocharger is defined as: “a centrifugal blower driven by exhaust gas turbines and used to supercharge an engine”.
Both superchargers and turbochargers are forced induction systems and thus have the same objective – to compress air and force more air molecules into the engine’s combustion chambers than would normally be allowed at atmospheric pressure here on Earth (14.7 psi at sea level). The benefit of forcing more air molecules into the combustion chambers is that it allows your engine to burn more fuel per power stroke. With an internal combustion engine, burning more fuel means that you convert more fuel into energy and power. For this reason, supercharged and turbocharged engines normally produce 40% to 100%+ more power (depending on the amount of boost)

A supercharger is mounted to the engine and is driven by a pulley that is inline with the crank (or accessory) belt. Air is drawn into the supercharger and compressed by either an impeller (centrifugal-style supercharger), twin rotating screws (screw-type supercharger), or counter-rotating rotors (roots-type supercharger). The air is then discharged into the engine’s intake. Faster crank speed (more engine rpm) spins the supercharger faster and allows the supercharger to produce more boost. Typical peak operating speeds for a supercharger are around 15,000 rpm (screw-type and roots style superchargers) and 40,000 rpm (centrifugal-style superchargers).
A turbocharger operates in much the same way as a centrifugal (internal impeller) supercharger, except it is not driven by pulleys and belts attached to the engine’s crank. A turbo is instead driven by exhaust gasses that have been expelled by the engine and are traveling through the exhaust manifold. The exhaust gas flows through one half of the turbocharger’s turbine, which drives the impeller that compresses the air. Typical operating speeds of a turbocharger are between 75,000 and 150,000 rpm.

Now its time to compare Turbocharger to Supercharger. The cost of supercharger and a turbocharger systems for the same engine are slightly different, cost is generally cheaper for superchargers then turbo kits because turbo kits require more fine tuning and much more upgraded engine components then superchargers. Now lets talk about Lag. This is perhaps the biggest advantage that the supercharger enjoys over the turbo. Because a turbocharger is driven by exhaust gasses, the turbocharger’s turbine must first spool up before it even begins to turn the compressor’s impeller. A Supercharger, on the other hand, is connected directly to the crank, so there is no “lag”. Superchargers are able to produce boost at a very low rpm, especially screw-type and roots type blowers.
Efficiency is the turbo’s biggest advantage. The turbocharger is generally more economical to operate as it as it is driven primarily by potential energy in the exhaust gasses that would otherwise be lost out the exhaust, whereas a supercharger draws power from the crank, which can be used to turn the wheels.
Because the turbocharger is mounted to the exhaust manifold (which is very hot), turbocharger boost is subject to additional heating via the turbo’s hot casing. Because hot air expands (the opposite goal of a turbo or supercharger), an inter-cooler becomes necessary on almost all turbocharged applications to cool the air charge before it is released into the engine. This increases the complexity of the installation. A centrifugal supercharger on the other hand creates a cooler air discharge, so an inter-cooler is often not necessary at boost levels below 10psi. That said, some superchargers (especially roots-type superchargers) create hotter discharge temperatures, which also make an inter-cooler necessary even on fairly low-boost applications.
Because a turbocharger first spools up before the boost is delivered to the engine, there is a surge of power that is delivered immediately when the waste-gate opens (around 3000 rpm). This surge can be damaging to the engine and drive-train, and can make the vehicle difficult to drive or lose traction.
The turbocharger is generally more quite than the supercharger. Because the turbo’s turbine is in the exhaust, the turbo can substantially reduce exhaust noise, making the engine run quieter. Some superchargers are known to be noisy and whistle which, annoys some drivers I how ever love it!!
In general, superchargers enjoy a substantial reliability advantage over the turbocharger. When a turbo is shut off (i.e. when the engine is turned off), residual oil inside the turbo’s bearings can be baked by stored engine heat. This, combined with the turbo’s extremely high rpms can cause problems with the turbo’s internal bearings and can shorten the life of the turbocharger. In addition, many turbos require aftermarket exhaust manifolds, which are often far less reliable than stock manifolds.
Superchargers are substantially easier to install than turbos because they have far fewer components and simpler devices. Turbo’s are complex and require manifold and exhaust modifications, inter-coolers, extra oil lines, etc. – most of which is not needed with most superchargers. When it comes to power a turbo kit will produce more of higher power peak the super chargers. Turbochargers, because they are so complex and rely on exhaust pressure, are notoriously difficult to tune. Superchargers, on the other hand, require few fuel and ignition upgrades and normally require little or no engine tuning.
While the supercharger is generally considered to be a better method of forced induction for most street and race vehicles, the turbo will always have its place in a more specialized market. I hope this has helped you with making your decision on which kit works for you.