Why Do I Want a VSR Balanced Turbo for My Diesel Engine? 


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It's probably safe to say that you want your turbocharger to be balanced. Otherwise, you run the risk of poor performance and failure. But did you know that not all balancing processes are equal?

VSR balancing, for example, helps to reduce the risk of failures. But how exactly does it work? Why might you want a VSR balanced turbo in your diesel engine? We've got the answers for you!

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About VSR Turbocharger Balancing

When a turbocharger is VSR balanced, the shaft and wheel inside the bearing housing, the rotating assembly, is put on a VSR balancing machine. It's then put through high-speed balancing. 

Basically, this means it gets spooled up to roughly 30,000 or 40,000 RPM. During this process, we look for harmonics in that shaft and wheel, which are then ground to be made level. It has to be balanced for the turbo to function properly. 

The smaller the turbo, the faster they spool. The larger turbos don't spin as fast, but an average turbo, say an ISX turbo is still going to spin at 70,000 to 80,000 RPM. So, the VSR balancing portion of this, most places aren't doing this. 

We have a turbocharger general guide, just for you!

Why VSR Balancing? 

Some places will have a standard balancer, which is okay, but it's not going to get all the harmonics out of that shaft and wheel. The obvious reason to balance a turbocharger is to keep it true, so that it's level, but you also want to eliminate issues caused as RPM builds. That's when you get those different harmonics happening. 

So, if they're not using a VSR balancing machine, different rebuilders will put a little notch in the compressor wheel. They'll notch the bolt, the nut that goes on it, and then they notch the shaft. On a low-speed balancing machine, you then have to take the assembly apart to get it back in the turbo. (Hence the notches). The rebuilder will then realign the notches as it's reassembled, but that creates a problem. Even though the notches are lined up, it's still out of balance. It'll just go out, inherently, even if you've torqued it. That just what happens with metal.

Ultimately, the VSR balance will eliminate that flaw caused by taking it apart. When the balance is measured the first time, the components are inspected to make sure they're okay. In some cases, the shaft might be out, for example. Balancing it as an assembly allows all the harmonics to be removed and the final assembly can be verified once it's put into the cartridge. Because of this, once it's put on the truck, failures occur less frequently. 

Need a VGT? We have variable geometry options available!

What is Aspect Ratio and How Does it Affect Turbo Performance? 


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How fast does your turbo spool? Something that can contribute to that determination is the Aspect Ratio of your turbocharger.

Aspect Ratio (AR) is commonly used to indicate a turbocharger housing size. The Aspect Ratio is the ratio of the area of the exhaust turbine inlet to the radius from the turbine impeller center. AR affects the spool up time of the turbo (Turbo Lag) and the maximum air flow. 

Larger numbers will increase the airflow, but will also increase the spool up time. Too large of an AR will result in sluggishness and take too long to spool up. 

Smaller numbers, on the other hand, will decrease the overall air flow, but increase the spool up time. Too small might spool up extremely quickly, but might not allow for enough air flow. This could cause high EGTs.

AR is calculated by taking the cross sectional area and diving the radius from the turbo center line to the center of the area. Example: The turbine housing has an area of 125.4 mmand a radius of 95 mm. 125.4/95=AR of 1.32

Your Aspect Ratio, then, can play a large role in the overall performance of your turbocharger.

If you're curious about how turbochargers work, check out our blog going through the finer details of turbocharger function.


Final Thoughts on VSR Balancing and Aspect Ratio

You want to have a turbo that functions at its best. Having a proper AR and a well-balanced turbocharger can help with this. We carry a wide selection of turbochargers that have been VSR balanced to bring you the best performing diesel engine components out there!

Do you want the best balanced turbocharger for your diesel engine? Talk to our ASE Certified Technicians about VSR balanced turbos, or any of your other diesel part needs! Call us at 844-304-7688, or request a quote online!

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