The criteria for our turbo setup is intricate and comprehensive. We want a fast-spooling and quick responsive setup to ensure excellent corner exit speeds and controllable throttle input. We want the capability to produce substantial peak power and put down extremely quick lap times for time attack competition. We want reliability, which means no cracking manifolds, boost leaks, loose bolts or turbocharger failures. This is imperative to ensure the best possible results, but more importantly, to keep things safe; a cracked manifold could potentially result in a burned oil line and a severe fire. Not to mention less time spent wrenching means more time on track, and perhaps the most important part of all, more fun.
We clearly want our cake and to be able to eat it, too. Combining excellent response with high power output and reliability is no easy feat, but we're up to the task, and here's how it's going to work.
At the heart of our system is a newly developed Full-Race twin-scroll manifold. As with all Full-Race manifolds, this one is built in the USA from robotically TIG-welded stainless steel and backed with a lifetime warranty. The manifolds are built strong enough to support the turbocharger assembly without additional bracing, which greatly simplifies installation. The updated manifold design locates the turbo just ahead of the engine, allowing for better heat management, easier service and the ability to fit a larger, divided type turbocharger. The use of twin-scroll technology (divided housing) results in the pairing of cylinders 1 and 4 to feed one turbocharger scroll and cylinders 2 and 3 to feed the other.
By pairing the cylinders in this fashion, Full-Race ensures the engine's cylinders are scavenged as efficiently as possible, while minimizing flow reversion. This results in the most efficient use of the exhaust gas energy to drive the turbine wheel, providing quick spool and excellent response. ARP's high-grade manifold studs ensure the Full-Race manifold remains firmly attached to the cylinder head where it belongs.
Managing boost on a twin-scroll system requires one wastegate for each scroll. Considering the sustained high exhaust gas temperatures that the turbo setup will generate, we opted for a pair of TiAL's MV-S 2.0 wastegates designed for water cooling. TiAL has truly led the way regarding wastegate development and innovation, and the new 38mm MV-S gates are no exception. Included with the MV-S gates are the necessary fittings for the boost and water connections, as well as VBands for the inlet and outlet. Unlike many of the inferior knock-off gates that are prone to failure, TiAL's products are all made in the USA from premium materials. While the gates are designed to work with or without the water cooling, it's well worthwhile to carry out the extra plumbing necessary for road race, time attack or track-day applications. The MV-S's also feature a compact design, keeping weight down and maximizing fitment options. Finally, Full-Race manifolds are designed for and tested with TiAL gates, which makes installation a breeze and ensures optimum performance.
Maintaining consistently low intake air temperatures is always a challenge with turbocharged applications. Following some investigation and research, our initial idea to use water/methanol injection as our sole form of intercooling; we found that method to be inadequate. We looked at air to water systems, as well; the added weight and complexity, however, didn't justify the short-lived subambient charge temperatures. Consequently, we've finalized our design based on a 6x6.25x20-inch Bell intercooler core, coupled with AEM's water/meth injection (which we will get into more in a future story). We designed and fabricated a custom lower IC/rad support to carry the large intercooler core with the radiator stacked on top. Both the rad and IC exit ducts will be channeled through the hood, offering increased front downforce when compared to the more common V-Mount setups currently seen.
Traditional silicone couplers and clamps work well until they blow off under high boost. This doesn't meet our reliability requirements, so we found a coupler that does. Vibrant's new VanJen clamp is an elegant and lightweight solution that won't separate under even the most severe conditions, yet can be removed quickly when service/access is required. The clamp is constructed from aerospace-grade aluminum and comes ready to weld to Vibrant's lightweight aluminum intercooler piping. The VanJen offers angular and axial motion to ensure engine movement and thermal expansion don't result in excessive loading of any components. We've fitted the 2.5-inch VanJens to the intercooler inlet/outlet, as well as a 3-inch VanJen to the Gord Bush Performance bored-out OEM throttle body.
Last but not least, our turbocharger is truly a quantum leap forward in turbocharger technology. The BorgWarner EFR series (Engineered For Racing) is so new it hasn't arrived just yet (the turbo in the photos is merely for test fitting), but here are a few things to look forward to. The Gamma Ti turbine wheel (a titanium-aluminide alloy) is half the weight of a comparable Inconel turbine wheel, offering substantial improvements in response and allowing the use of a larger turbocharger than previously thought possible.
The turbine housing itself is formed from investment cast stainless steel, which has allowed for reduced wall thickness and lighter overall weight, while offering excellent reliability and a smoother flow surface. The dual row ceramic ball bearing centersection reduces drag, helping to offer the fast spool we are looking for and features a new dual seal to keep the oil where it belongs. There are also options for dual internal wastegates, and the blow-off valves are built into the compressor housing and come complete with boost control solenoid. EFR turbos are an impressive step forward in turbocharger technology, and we can't wait to get ours.
Once it arrives, we can finish up the charge piping and any final fabrication before we strip the chassis for sandblasting and powder paint. With the turbo components we're using, quick response with high power output and reliable performance will finally be together at last. It'll be possible to have our tasty turbo cake and eat it, too.
Complete Turbocharger Kits & Custom Manifolds
Wastegates & Turbocharger Components
Gord Bush Performance
Machine Work & Engine Assembly
Automotive Fabrication Components
Custom & Direct Fit Air/Air & Air/Water Intercoolers