Since the late 1990's, many diesel cars have been fitted with a Variable Geometry Turbo (VGT) or Variable Vane Turbo (VVT). These turbochargers are very effective in minimizing the effects of turbo lag, resulting in a more responsive throttle especially at low engine speed/RPM. These systems work by changing the speed and direction of the exhaust gases onto the turbine wheel. The most common of these systems is Garrett's VVT turbo, which incorporates a ring of small movable vanes around the turbine wheel. At slow engine speeds, the vanes are in the closed position, narrowing the gap between them which effectively accelerates the exhaust gas onto the turbine wheel. At high engine speed, the vanes open up slowing the exhaust gases, which stops the turbo from creating excessive boost.
While this type of turbo is astounding in itself, there are flaws. The biggest flaw, is that with any moving part in an exhaust system of a diesel, it can get clogged with soot, especially on higher hosepower applications. When the vanes do get clogged and are unable to clear themselves out, it requires disassembly of the turbo, and a thorough cleaning.
With the release of the 2004.5 LLY 6.6L Duramax, came GM's first Variable Turbo technology, produced by Garrett. We offer direct replacement turbos from Fleece Performance, Industrial Injection, and BD Power. For those looking for a more simplistic operating turbo for higher horsepower applications, we recommend either the BD Super Max turbo, or Industrial Injection Silver Bullet turbo, which both do away with the Variable Geometry. However, for those that want the advantages of a Variable Geometry Turbo, we highly recommend the Fleece Performance Cheetah turbo, specifically designed for quick response on trucks with heavier fueling. And for those wanting to do something even more extreme, we offer Industrial Injection's TWIN TURBO kit which reuses the factory VGT turbo, creating uncompromised power!
With the addition of any performance turbo, we highly recommend a BD Full Bore exhaust manifold to ensure equal exhaust flow through both manifolds.