BOOST SELECTION
Darren’s biggest concern with the new build was to ensure that the engine made good power from around 3000rpm and right through to rev limit. With Rich ensuring that the head flowed a massive 270cfm, a new Garrett GTX3584RS turbo was tasked with making the boost. Tim from TTT Auto Engineering built a new six-into-one stainless manifold, using schedule 10, 304L stainless. The runners are a 40mm internal diameter and as close to equal as Tim could achieve in the space, which he told us is actually tighter than in the old R34 chassis: “The biggest thing I concentrated on was ensuring [that] the runners had good flow. Not tight-radius bends, just nice and flowing.” The water-cut flange was first port matched to the ported head, and then bolted to a large piece of alloy for welding. Doing this ensures the flange stays flat, as alloy is a great dissipater of heat. “After tacking each runner in place, I then purge welded, which ensures you get full penetration,” Tim said. ‘Purge welding’ is a technique where argon is flowed through the part to ensure you have shielding on both sides of the material being welded.
Both the Turbosmart Comp-Gate 40 wastegates will feed out of the block for the foreseeable future, and, although MotorSport New Zealand (MSNZ) does not allow this, the next two events Darren will contest, do. Fingers crossed that the new law is passed before the D1NZ season starts; if not, they will be plumbed back into the downpipe. If this happens, Tim will replace the new three-inch downpipe with a 3.5 inch.
“The biggest thing I concentrated on was ensuring [that] the runners had good flow”