Don't Delete Your Diesel VGT Turbo! Standard, Wastegated, And VGT Explained

Is your VGT giving you trouble again? We know it can be frustrating when you're looking at thousands of dollars of turbo damage yet again. And we know that it has lead many operators to pull the VGTs all together.

Before you do it though, it's important to be aware of the benefits a VGT can offer.

 

Often though VGT failure is a symptom of a bigger problem in your engine, not a fault of the turbo itself. In this post, we're taking you through VGT turbos and why keeping it on your engine might benefit you in the long run.

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The Differences Between Standard Turbos, Wastegated Turbos, and VGT Turbos

We hear a lot that operators want to install a fixed vane turbo on their engine to avoid VGT turbos, because they're not pleased with the performance. It breaks down on them, they're looking at expensive repairs, and replacement is something they think will just break down on them again.

It's true VGTs have had trouble in the past, when they first came out, they weren't reliable and we weren't comfortable selling them. We couldn't find a manufacturer we trusted to deliver a quality product. Recently, the technology has approved and we're able to source quality, reliable VGT turbo parts.

And more than that, we're seeing that often the turbo isn't the point of failure, it's a symptom of the engine it was running on.

Standard Turbos

2321811 CATERPILLAR C15 ACERT TURBOCHARGER NEWIn a standard turbo the exhaust gas travels through the turbine or exhaust side spinning the shaft and the compressor wheel. Air is also drawn in by the compressor wheel which is then compressed into high pressure, high temperature air. This will then be forced through the outlet to a cooler, and then into the engine.

The exhaust gas spins the compressor wheel and then supplies higher volumes of air into the engine. This increases output and boosts the horsepower of your engine.

Wastegated Turbos

TURBOCHARGER WITH WASTEGATE FOR NAVISTAR DT466 DT466E I530E

With a wastegated a turbo, there's going to be a pneumatic actuator attached to the exhaust housing and has a line that runs through the compressor housing the sensors boost pressure.

As the boost pressure rises the pressure increases in the sensing line as well. This then pushes against the spring and overcomes the spring pressure, the valve opens inside the exhaust housing letting some of the exhaust gas bypass the turbine wheel. Essentially the wastegate controls the speed of the turbo.

As engines have advanced, wastegated turbos have become less efficient. As emissions requirements have become stricter the wastegate isn't precise enough to handle the level of performance required on the diesel engine. That's why the VGT was built.

VGT Turbos

Diesel Engine VGT Turbocharger RedVGTs don't have a wastegate that regulates exhaust flow, a VGT more accurately controls the air fuel ratio, allowing for more horsepower.

The vanes inside the VGT are what allow you to maximize your boost at a much greater RPM range. This is because they're adjusting the vanes. At low RPMs the actuator tells the vanes to stay slightly folded, not letting as much air through. At higher RPMs the vanes start to open, which lets more air into the engine, keeping the air fuel ratio accurate.

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Why Is Your Air To Fuel Ratio Important?

If the air fuel ratio is incorrect your engine won't combust properly, which leads to the following problems:

  • harsh engine conditions

  • high exhaust temperatures

  • high cylinder pressures

  • high compressor outlet temperatures

This can lead to problems throughout your engine! VGTs still get a bad reputation despite so many improvements to the technology. Often this comes from operators with deleted their engines. They've taken off the EGR cooler but they've left the variable geometry on. It's a lingering piece of an emissionized engine.

In their mind, it's the turbocharger that's causing the problems rather than the fact that when the engine was built, the systems were optimized to work together. Without all the components the VGT isn't going to function as intended, and the engine conditions will begin to cause a failure.

 

Why You Shouldn't Delete VGT Components

We hear about head gasket failures, cylinder head cracks, and lack of valve lash because of the high temperatures and high pressures. To try and solve those problems, operators often want to put on a non-wastegated turbo or pinch off the wastegate. Going back to the components that have worked for them in the past.

But what it comes down to with a deleted engine is the calibrations are off. A variable geometry turbo can be a big turbo or small turbo, whatever kind of turbo the engine needs to run properly. But when some of the components have been deleted, the engine is no longer running under optimized conditions.

If the calibrations haven't been correctly changed, then you'll start seeing those catastrophic failures. Because it's against federal emissions regulations, HHP does not handle calibrations of deleted engines. When you delete the VGT you'll be losing out on some of its unique benefits.

What You Lose By Deleting Your VGT

The optimized VGT is going to be a far better turbo in most situations than your standards turbo. If the VGT is deleted, you'll lose some of the following:

  • Engine Breaking Force

  • Loss Of More Precise Airflow

  • Loss Of Boost At Low Engine RPMs

 

Why Buy From Highway and Heavy Parts?

Highway and Heavy Parts is committed to helping you diagnose your diesel engine problems. Our team of experts can assist you in pinpointing your issues and finding the right parts for your job.

We know you want quality, affordable parts that will last and you want them fast. That's why HHP only sources components from the highest quality manufacturers. You're getting the best possible diesel engine parts, oftentimes the exact parts you'll find the OEM dealer.

If you're having trouble with your VGT turbo, we have a huge inventory of parts and to get you back up and running. Most parts ship in two days or less. Don't sacrifice quality for the best price possible, we have it all right here. High-quality replacement parts backed by an industry leading warranty.

Our mission is to take the risk out of buying a diesel engine parts for our customers. So if you're looking for affordable OEM quality diesel engine parts with expert advice on the other end of the line, we're here to help. If you have any questions about variable geometry turbos you can call me our ASE Certified parts techs at 844-447-1453. Or you can chat with us online at highwayandheavyparts.com.

From diagnosis to delivery, we're Highway and Heavy Parts!

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VGT Turbocharger Resources

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