Variable Geometry Turbocharger Facts


MarineDiesel’s VGT Series of engines was named as such for a very good reason: We use Variable Geometry Turbochargers (V.G.T.) in their design.

What is a VGT?

A VGT is a type of turbocharger that has internal vanes that open and close, changing the amount of air and exhaust that enter the engine. Thus, the geometry of the turbocharger changes, based on RPM.

Old, non-turbocharged diesel engines that are naturally aspirated were inefficient. Adding a turbocharger increased the amount of power and torque produced by the engine. By changing the geometry of the turbocharger, the compression ratio can be changed, thus making the engine more efficient, and substantially increasing the amount of power and torque produced, particularly at the low RPM range. Additionally, standard turbochargers tend to produce a lag at low RPM. The VGT solves this problem by further compressing the air into the engine.

The use of the VGT produces higher, sustainable torque across the engine speed range. In part, this is why our VGT Series of engines has a much higher level of overall torque, rather than the spikes, peaks, and valleys common in the toque curves of engines made by our competitors.

Since the power of the engine is increased by the VGT, it means that we produce, at only 515 kilos, the lightest, most powerful, 500 hp marine engine on the market.

Honeywell (the manufacturer of the Garrett VGT we use), has an interesting video that has an explanatory animation. We hope you find it interesting.