Nerd-O-Scope: APR 2.5 TFSI Stage III GTX Turbocharger System

Nerd-O-Scope: APR 2.5 TFSI Stage III GTX Turbocharger System

by Khiem Dinh

Photos Courtesy of APR

Khiem Dinh is an engineer for Honeywell Turbo Technologies at the time of this writing.  All statements and opinions expressed by Khiem Dinh are solely those of Khiem Dinh and not reflective of Honeywell Turbo Technologies.

I’ve been messing around with turbos and turbo kits for more than a decade in enthusiast and professional capacities. When I saw this APR kit released for the Audi TT RS, I was extremely impressed. It is the best kit I’ve seen released for any car, bar none. Even better than the $100k kits used on some very exotic cars. What makes it the best? It’s all in the details as they say along with the engineering process used to design and develop the kit. Follow along as we examine how the kit was made and analyze why it’s so good.

You could say I’ve been around the block a few times when it comes to putting turbos on cars. It all started with my good ole Nissan SE-R. Then I helped a buddy turbo his Civic. Then I helped a buddy turbo his 240SX. Then I helped a buddy swap turbos on his Z32 300zx. And a FC RX-7. And a FD RX-7. And a Scion tC. And an Evo X. There are probably a few other cars I have forgotten. Along the way, I’ve learned lessons in how to make things reliable (I racked up 80k miles after installing the turbo on my SE-R which saw plenty of hard use and track time) by breaking things. Having had a hand in developing some kits, I’ve learned a few things in the design process too.

In the modern design world, everything is done on computers with 3D modelling. Why? It allows you to accurately design and test fit many design iterations of components in a virtual world before committing to real hard parts.


In order to create the virtual 3D environment, you need models of the components. If you’re a company (such as APR) designing stuff for someone else’s stuff (like Audi cars), you’ll probably have to create your own models. APR has a cool tool which is a hand held 3D scanner. The little circular black and white dots are placed on the object you want to scan to give the scanner very well defined reference points which improves the accuracy of the scan. Some very expensive scanners have a resolution down to microns creating very exact models.
The super high resolution 3D scanners can cost a gazillion dollars, but this Faro arm does not (still not cheap however). The Faro arm allows for very exact measurements which you want when taking measurements of the head. The more exact the measurements, the better you can design your own components (such as the exhaust manifold to bolt to this head). It is clear APR has invested heavily in the tools to do good engineering work. There is a lot of capital cost up front, but huge savings in time and reduced design iterations down the road.
Once you have your 3D model environment set up, all the parts can be designed and virtually test-fitted.

Once everyone is happy with the designs, parts need to be test-fitted. APR just happens to have their own stereolithography machine to generate rapid prototypes. Stereolithography uses a laser to solidify a liquid polymer and it builds parts a layer at time until the final 3D piece is created. Why do you need to test fit? Well, many things don’t become apparent until you actually try to put hard parts on the car. For example, a part may be designed to fit within a space, but after much @#$@ @#@$&!! Why won’t it &*#@ go in!%!, you realize the part you designed can’t actually get to its final resting space. Or, something is in the way of getting being able to put a wrench or socket on a bolt. Or when the engine moves, something will hit something else. These are just a few of the issues that become apparent once you start trying to install parts on the car.

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