How Turbos Have Changed

OUT WITH THE OLD TURBO, IN WITH THE NEW TURBO

How Turbos Have Changed

In this week’s waffle I’m talking about the actuator used on the turbocharger on DAF mx-11 and mx-13 since euro 6

Variable Turbo Geometry plays an important part in efficiency and this was one of the big factors for replacement of the old internal waste gate turbocharger.

NO SMOKE WITHOUT POKE

We have a few components fitted to the turbocharger to enable correct operation as without a waste gate it can literally produce boost till it fails from oil starvation due to shaft speed or in bits from compressor surge, but in this week’s waffle we will focus on the actuator.

One of the major components of the turbo is the VTG actuator.

This component controls the direction of air via a nozzle ring at the turbine wheel

How this operates is to increase the turbo rpm lower down in the rev range or slow it down higher in the rpm range, such as to control exhaust back pressure during exhaust BRAKE application .

But having mechanical moving parts in the turbo isn’t without its problems.

This is why the VTG actuator is such an important component. Not only does it communicate with the engine can (E-can) it relays sensory information such as:

1.) turbo temperature

2.) VTG ECU temperature.

3.) Turbo output shaft position.

4.) Effort required to move the nozzle in the turbo.

When the ignition switch is turned on, quite a few components carry out checks and one of them is the VTG actuator.

Not only tests the range of motion in the turbo, but the effort required to do so.

This is where we get our diagnostic data from. With the VTG actuator doing what is called a learning sweep (along with the EGR and BPV) it can tell if the turbo is stuck or blocked.

The actuator can move the nozzle to a fail-safe position of 80%. By doing this sweep motion every key on, it prevents soot build up in the mechanism and the correct functionality of the turbo.

BUT HOW DOES IT WORK

To increase turbo speed, you need fast air flow and in order to do that, the VTG actuator limits the opening, supplying air to the compressor wheel.

This therefore results in faster spool up and increase boost. As the engine rpm increases due to the exhaust gas production, the actuator can compensate for it and increase the opening of the nozzle ring, slowing the turbo rpm down.

It’s literally like having a small turbo and a big turbo on one engine, just like compound turbo changing, no lag, just boost!

I hope you have found this article informative on how this sort of works and if you want to see the calibration and replacent of the VTG actuator the video can be found here