The work on project Rallye Golf VRT is reaching a fevered pitch. The big-ticket items are in place, and the incidentals are following suit nicely. At this point in the project we are ready to let loose the details that will set this car apart from your average boy racer. Let’s talk turbo…
Our partner in turbo construction for this project was Innovative Turbo in California. Their experience and expertise in custom turbo applications for Audi and VW engines is well documented. They have supported racing and development for the two brands for a number of years. Knowing the requirements and goals for the Rallye Golf VRT project, a turbo was selected to fully encompass the true meaning of the word “overkill”. The turbo is known internally as the GT72. It’s built on a full T4, undivided Tang-style frame.
The turbine housing is a .81AR Q trim, with the center section being water jacketed and full ball-bearing equipped. The Ball-bearing option is a must in this application, as we intend to try to alleviate extreme turbo lag when the car is driven on the street. Designing piping to feed and exit air from this beast is a bit of a challenge. Ron Weaver, head fabricator on this project, has done a remarkable job feeding the 3.5” downpipe and exhaust through the small area available. The compressor outlet for the charge pipe is 2.5” and maintains this diameter to the custom built Forge Motorsport intercooler. The outlet from the intercooler is 3” all the way to the ported throttle body that is mounted to the Euro 2.9 intake manifold.
Stand-alone engine management is an obvious necessity with such large amounts of positive airflow. In choosing a management system, we wanted to use a very complete, proven system that would be capable, as well as reliable. The system of choice for our project is the Autronic SMC with the CDI ignition. Aussie Imports is the official distributor of the Australian-based engine management package, and is completely familiar with the VW turbo scene. (Note: Last year’s winner of the european car 1.8T challenge, also a Rallye Golf, was equipped with Autronic engine management).
Anchoring the motor at the front is a custom-built 2” chromoly subframe. This is also a superior mounting point for the oil cooler, radiator, and intercooler. As an added bonus, the small diameter subframe provides a large opening for the intercooler. The current intercooler is actually a smaller version of the permanent unit – we weren’t positive we could fit the full size unit until we had everything assembled. This will do nicely for our break-in period, as the boost levels will not surpass 15psi.
The Rallye is almost ready for the street at this point, and the finished parts have received paint and powdercoat. The pictures in this segment reflect the parts as they were fitted during fabrication, so you’ll all have to wait till next time to see the finished package!
We will have quite a few more installments covering performance, equipment testing and events that the Rallye will be attending. We’re having a lot of fun with this build up, and we will follow it through to absolute completion right here on VWvortex. Stay tuned!
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