The Hellion system includes...
The Hellion system includes the engine oiling system hoses. Pressurized oil from the engine is fed into the bearing and then returned to the engine sump, similar to the method used by centrifugal supercharger systems for years.
Wastegastes And Bypass Valves
As you can probably imagine, since boost pressure is created by exhaust pressure and a spinning compressor wheel, it is possible to feed the engine more boost than the fuel's octane rating or even the engine itself can handle. This condition is called overboost, and it can be controlled by a valve called a wastegate that bypasses exhaust gases around the turbo and into the exhaust flow. Wastegates are boost-referenced to regulate the maximum amount of energy delivered to the turbine and therefore the amount of boost created by the compressor. The type, location, and size of the wastegate are the keys to an effective system.
Most factory turbos have an integral wastegate where the mechanism is built into the turbo housing and actuated by an arm that connects the compressor to the turbine. Although it is compact and functional for a low-boost single- or twin-turbo setup, it cannot be clocked for installation and puts the gate in the least desirable part of the system. External wastegates are sized according to the amount of power you wish to make and should be located where it can collect all of the exhaust pulses, such as the end of the header collector or manifold. Gases should be prevented from turning back on themselves or turning sharply to exit the turbine. Since the gas will take the path of least resistance, it is possible that at high rpm the turbine will continue to increase speed if the path to the exhaust is restricted or the wastegate is too small.
There is a debate about the...
There is a debate about the use of split-exhaust housings being more efficient than a single housing. On a four- or six-cylinder engine, grouping the exhaust pulse may create a more efficient system, but from what we've heard, the V-8 will not see the difference. Save your cash.
The bypass valve is plumbed into the cold side of the system and is designed to prevent surge and compressor damage. In a high-rpm/high-boost situation, if you quickly lift off the throttle, there is no way for the pressure to get into the intake manifold. Because the turbine and compressor are still spinning, pressure stacks up against the throttle blades. This pressure can stall the compressor wheel or cause a surge as it reverses direction, creating a low-pressure area and raising and lowering the compressor's speed. The bypass valve simply vents the pressure to the atmosphere when the throttle is closed. It is also the source of the chirping noise you sometimes hear when turbo cars lift to shift gears.
Heat, Detonation, And Intercooling
Early factory turbo cars had no intercooler and therefore no protection from the additional heat built by the turbo's ability to rapidly compress and heat the incoming air. This, combined with pump gasoline, introduced detonation, which is still the number one way to destroy your engine. The solution ranged from terrible static compression ratios as low as 6.0:1 to the turbo Corvairs' Turbo Rocket Fluid that was really just a jug of water/methanol that was introduced to the intake air stream to cool the charge. It worked great until you forgot to fill it. Low-compression engines with large turbos made for sluggish, low-rpm street cars that would suddenly wake up for some snap oversteer and wild, smoky fishtails. Just ask anyone who owned an early '70s Porsche 930.
The idea of an efficient engine with a reasonable compression ratio that has good low-speed response and uses enough boost to create real power is possible with an intercooler. The intercooler is simply a heat exchanger that sits between the compressor and the intake to reduce the heat that was added in the process of compressing the air. On the surface, intercooling the air charge allows you to run more boost or run a smaller turbo on an oil-cooled engine. What it is really doing is stabilizing the intake air charge to prevent detonation and expanding the entire compressor map, which allows you to make more power with a smaller engine and less violence. We also recommend an MSD with an adjustable timing curve or a boost references timing control system to avoid rattling the engine.
 To prevent exhaust leaks,...  To prevent exhaust leaks, the kit comes with ball-flange-type connectors everywhere. You can buy these separately from Hellion if you want to upgrade your current exhaust. |  The cold side of the turbo...  The cold side of the turbo system from the compressor to the intake manifold uses T-bolt clamps instead of the worm-drive stuff. |  The hot side of the turbo...  The hot side of the turbo system from the exducer housing to the exhaust system uses V-band clamps. They give you the freedom to position the turbine exactly where you want it and eliminate bolted and welded flanges. |