Turbochargers are complicated and extremely precise pieces. They are used in diesel engines to get additional power, increased throttle response, and improve fuel economy. Variable geometry turbochargers or VGTs for short have additional vanes that move according to the specific demands of the engine at any given time.
Each VGT turbo manufacturer will have a specific vane design. Some will pivot, while others may slide to the designated position. When the VGT was introduced, the entire system was vacuum operated. But, like with anything, it eventually switched over to electronic control units due to their increased efficiency and reliability.
When the vanes are altered, the geometry of the turbo changes, hence the name. These small, yet critical changes will optimize the turbo’s performance for the needs of the engine. When the RPM is low, the space inside the turbo expands and decreases the overall speed of the airflow.
Keep in mind that a variable geometry turbo changes the speed of the turbine and not the specific amount of exhaust air going in.
Variable geometry turbos were engineered to work with modern emissions equipment such as DPF’s and EGR’s. As such, during the regen process, airspeed needs to be 100% controllable to get the high temperatures needed for burning off excess matter.
Advantages Of A Diesel Engine VGT’s
In terms of versatility, VGT turbos are much better than traditional, fixed-geometry turbos. They help increase torque thanks to their variable geometry. This means that your diesel engine gets top performance and efficiency, even at low RPMs. Additionally, turbo lag and flow is greatly reduced thanks to this equipment.
Technology is always advancing, and turbocharger manufacturers are always looking for an added edge. VGT’s have always been at the very top in terms of turbo tech. By optimizing the geometry, fuel consumption can be decreased and power is increased. It is a win, win situation!
Want to know how to keep the turbo on your diesel engine in top condition? Check out this article on Highway & Heavy Parts!
Disadvantages Of A Variable Geometry Turbo
In theory, a VGT is better from all points of view. But everything sounds good in principle. The truth is that some variable geometry turbochargers are known to run out of air on the top end. And like with any new machinery, there are going to be design flaws that will make themselves known over time.
Due to their complexity, VGT’s can cost considerably more to repair when they do fail. Although efficient, the cost of repair can quickly offset the savings they offer. More moving parts mean an increased chance of failure. Even though classic turbochargers of yesteryear were not as efficient, they were much more durable than the variable geometry turbos found on today’s modern diesel engines.
Not sure what is wrong with your turbocharger? Here is a failure diagnostics checklist that is sure to help shed some light on your turbo problems.
Buying A Variable Geometry Turbocharger
Ultimately, the decision to go with an engine equipped with a VGT will depend on whether or not your budget allows for it. DFI is here to provide you with an unbiased opinion. This way, one can accurately choose the engine and type of turbocharger that time comes.
Unfortunately, you cannot change to a variable geometry turbocharger from a classic system and vice versa. The way it came from the factory is what you are stuck with. While certain companies will offer conversion kits, converting to a VGT is not financially worth it. Plus it is illegal due to strict emissions regulations.
On top of that, authorized shops will not work on any engine that has been converted to a VGT. So, unless you got a vast knowledge about diesel engines and a full mechanic shop at your disposal, we do not recommend converting your classic turbocharger to a VGT.
Do you have more questions about turbocharger problems and failures? Have a look at this blog post about turbocharger problems!
Final Words
Call our ASE-certified techs at INSERT CORRECT PHONE NUMBER HERE or request a quote online today INSERT CORRECT PHONE NUMBER HERE for any additional questions about Variable Geometry Turbochargers, or any other general questions you may need clarifying.
