Project Hyper Miler Jetta MKIV TDI Part 4, Upgrading the Turbo with Garrett

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After speaking to the VW diesel experts at KermaTDI, we learned that they don’t recommend the EGR Delete kits because they frequently see reduced MPG and a little bit of HP loss. Call it an $80 experiment that proved they were right. We think that deleting the EGR can reduce some of the volume of flow across the motor which can add to pumping losses.

Here you can see the engine with the EGR delete installed. It’s that black pipe between the intake and the rubber hose in the upper left of the picture.

The first real upgrade came from our partners at Garrett. Their GT1749V turbo is a real gem, bolting to our ALH with only the smallest of mods.

The GT1749V comes equipped with a smart actuator, an industry exclusive, and a position sensor, which enables the turbocharger to communicate automatically with the Engine Control Unit (ECU). The kit is easy to install and suitable as a performance upgrade or replacement turbocharger.

The Garrett VW TDI Kit also promotes a longer turbo and engine life span and increased reliability by lowering exhaust gas temperatures. It features Garrett® patented Variable Nozzle Turbine (VNTTM) design, GT wheel aerodynamics and significantly increased compressor flow over stock. It can support up to estimated 175hp. The turbine, compressor and oil connections fit with no modifications beyond an adaptor from our partners at KERMATDI. Includes smart actuator with a position sensor (not used on our ALH) and the highest performance, durability and reliability in the industry.

Here is the turbo coming out of the box, talk about secure packaging!

Perhaps the coolest thing about the turbo is the Variable nozzle turbo.  This feature helps promote fast spooling like an exhaust housing with a small A/R but also have good flow like a larger A/R housing for better power.  The exhaust housing A/R is a reasonable 0.65.  However since diesel engines have lower exhaust energy than a gasoline engine, this can still have lag, especially when considering a diesels low redline.

Enter the variable nozzle. At low RPM a part of the exhaust housing called the tongue moves inward when pushed by the smart actuator to pinch off the exhaust flow much like you putting your thumb on the end of your garden hose so you can squirt the water farther. This increases the velocity of the exhaust gas hitting the turbine causing it to spool faster.

Imagine the water from a hose pouring on a pinwheel.  Now imagine putting your thumb on the end of the hose and squirting the water at the pinwheel, the pinwheel will spin up much faster.  This is exactly how the variable nozzle works on the GT1749V to speed spool and boost response while having decent top end power.

Here you can see the old, 288,000 mile turbo next to the shiny new one from Garrett.

The install was very straight forward, pretty much remove and replace. After draining all the fluids for the engine, we removed the water and oil lines from the turbo. One of the oil lines was a bit of a PITA due to its location under the exhaust manifol, but with a little patience it’s doable even while on your back in your own garage. Once you get past that hurdle you can proceed with the process of removing the turbo/manifold combo from the top side of the engine. You will notice however, that the outlet on the turbo is in a different place on the new turbo, and that the lower mount is 90deg off.

Luckily, KERMATDI has a direct-fit solution for this, in the form of a inlet hose adapter.

They also make this retrofit kit that has a bracket that allows the new turbo to bolt to the engine block.

Unfortunately, in my zeal to get it all back together, I neglected to take more pictures of the parts before bolting them to the car and test driving.