C6 Corvette Twin Turbo System - The Perfect Pair

APS And DTE Team Up To Create The Ultimate C6 Twin-Turbo System

Chris Endres Jan 12, 2007 0 Comment(s)
Vemp_0703_01_z C6_corvette_twin_turbo Convertible_front_view 1/27

Think of the great pairings in history: Chips and salsa. Pizza and beer. Corvettes and tire smoke. Jenna Jameson. Air Power Systems and DynoTech Engineering.

Air Power Systems and DynoTech Engineering? Absolutely! And when you see their kick-ass twin-turbo setup for the C6, you'll understand why.

While it may not yet be a household name stateside, Air Power Systems (APS) is an Australian firm with over twenty years of experience in designing and manufacturing turbocharger and intercooler systems. APS also has an extensive background in EFI engine-management systems for select performance vehicles. APS officials tell us the company's signature lies in the quality and durability of its components, the attention to detail put into every system, and unswerving dedication to the notion that performance must always be reliably achieved.

DynoTech Engineering (DTE) is perhaps best known in the Corvette world for its innovative drivetrain fortifications. You've no doubt seen DTE's bright-red differential struts on the most serious Corvettes around. Located in Fort Wayne, Indiana, DTE also offers a broad array of powerful forced-induction performance packages for GM vehicles.

With the introduction of the APS twin-turbo system for the C6, a new performance era is upon us. Follow along as DTE guides us through the finer points of the install. As you'll soon see, the APS system is not only brutally powerful but also an aesthetically pleasing performance package.

Vemp_0703_02_z C6_corvette_twin_turbo Garrett_turbocharger 5/27

Twin-turbo systems are nothing new to Corvettes, but the APS system bears the distinction of being the first one available for the C6. The turbos are obviously the star of the show, and the APS units come loaded for bear. The system's foundation is a pair of twin-ball-bearing, water-cooled Garrett turbochargers. Traditional turbochargers employ a bearing supported by a film of oil that forms a cushioning layer between it and the turbocharger shaft. The shaft relies on a constant supply of fresh, clean oil over a very wide contact area in order to maintain sufficient clearance from the bearing itself. A similar approach is used to isolate the main shaft from thrust loads. Though this design is simple and fairly reliable, high friction results in sluggish turbocharger response, or lag. Unlike standard turbos, ball bearings are utilized on both sides of the APS turbo's main shaft, doing away with the typical floating bearings. The design is robust and compact in size. The opposed, angular, contact-bearing cartridge eliminates the need for a thrust bearing, which is commonly a weak link in standard turbos.

Vemp_0703_04_z C6_corvette_twin_turbo Turbocharger 6/27

Water-cooled center sections are not a new innovation, but they are gaining popularity due to their reliability. With traditional turbos, engine oil provides both lubrication and cooling. This is an effective compromise between cost and performance, but in high-performance applications, durability can suffer. By enclosing the turbo's bearings in water passages, engine coolant is used to reduce turbocharger-bearing temperatures. This practically eliminates oil coking and lacquering, which can foul the bearings in standard turbochargers. The water-cooled bearings of the APS turbos remain cooler than the oil's coking-threshold temperature at all times, virtually eliminating the problem.

Vemp_0703_03_z C6_corvette_twin_turbo Oil_flow_control_module 7/27

Another advantage of the dual-ball-bearing design is that it requires less engine oil to provide proper lubrication for the turbo. This reduces the load on the engine's oil pump, allowing more oil volume to vital engine components for improved engine durability. The oil flow through the turbocharger is controlled by an oil-flow control module (shown) that also serves as a debris separator to keep foreign particles from entering the bearing assembly. Frictional losses with ball-bearing turbochargers are reduced by 40-50 percent as compared with a conventional turbo. The improvement in turbocharger response, particularly in the low- and mid-turbocharger-speed range, is quite evident from the driver's seat.

Vemp_0703_05_z C6_corvette_twin_turbo Turbocharger 8/27

The additional plumbing associated with turbochargers has always contributed to elevated engine-bay temperatures. APS solved this problem by positioning the turbos up under the chassis, away from the engine compartment.

Vemp_0703_06_z C6_corvette_twin_turbo APS_blow_off_valve 9/27

Each turbo is equipped with its own blow-off valve (BOV). The BOV is designed to release boost pressure from the turbocharger when the throttle is quickly closed. It prevents the formation of a pressure-shock load on the turbocharger compressor and allows the turbo to continue spinning freely during gear changes. This ensures that as the next gear is grabbed and the throttle mashed, the turbos spool quickly and provide near instantaneous boost. APS has designed a lot of performance headroom with these turbos. So much, in fact, that they can support (with a built engine) approximately 1,000 hp at just 15 psi of boost.

Vemp_0703_07_z C6_corvette_twin_turbo APS_intercooler 10/27

When air is compressed-in this case by the turbocharger-it is also heated. An intercooler's function is to lower the charge-air temperature as close as possible to ambient. This enhances power production because cool air contains more oxygen, which means more fuel can be added. And you know what that means: more power and more sh*t-eatin' grins for the driver. Accordingly, APS provides a pair of vertical-flow, high-efficiency intercoolers utilizing lightweight, cast-aluminum end tanks. Intercooler performance is measured by the amount of heat the unit can remove from the inlet-charge air as well as the pressure drop across the entire system. Each APS core measures 10x11x4 inches, and the claimed pressure drop is less than 1.0 psi. As for efficiency, the intercooler-outlet temperature is less than 15 degrees higher than ambient at any vehicle speed over 50 mph.

Vemp_0703_08_z C6_corvette_twin_turbo APS_intercooler_core 11/27

The APS intercoolers use bar-and-plate core construction for the highest flow and greatest efficiency possible. This type of construction results in an inherently strong intercooler core of high thermal inertia, which means they have massive reserves of cooling capacity. This is important in situations where ambient airflow over the core is low, such as the time between the burnout and launch at the dragstrip.

Vemp_0703_09_z C6_corvette_twin_turbo APS_intercoolers_installed 12/27

The intercoolers' design allows retention of the stock air-conditioning system with no degradation of performance. The use of two separate intercoolers allows a generous air gap to channel ambient airflow into and through the air-conditioning and engine-cooling radiators.

Vemp_0703_10_z C6_corvette_twin_turbo APS_turbocharger_exhaust 13/27

Exhaust gases that feed each turbocharger must arrive at the turbine with the maximum amount of gas energy possible. This ensures crisp turbocharger response and high horsepower.

Vemp_0703_11_z C6_corvette_twin_turbo Exhaust_manifolds 14/27

APS designed its High Energy Turbo exhaust manifolds to achieve the ultimate in terms of gas/energy transfer and outright performance. Cast in high-temperature ductile iron, the APS exhaust manifolds are built to withstand extreme horsepower levels. They have been designed to maximize flow and close-couple the turbine housings to the exhaust ports, making for the most efficient transfer of exhaust-gas energy possible. Cast manifolds perform this function much better than any fabricated solution. This is particularly important under spirited driving conditions that require frequent periods of on/off throttle, such as on a road course or during an autocross event. Notice the threaded bosses for heatshield attachment.

Vemp_0703_12_z C6_corvette_twin_turbo Dyno_test 15/27

APS provides engine-management program data on CD for download into the stock computer. The APS data is designed for 93-octane fuel in an otherwise-stock, LS2-engined C6 Corvette. The stock ECU is reflashed using the popular HP Tuner. The reflash can also be performed by the tuner of your choice with HP Tuner's software. In the case of our yellow convertible, DTE proprietor Phil Rickard performed a full-blown custom tune on the car on his shop's in-house dynamometer. Rickard has extensive experience with forced-induction Corvette applications (he cut his teeth working on Lingenfelter's twin-turbo program in the late '90s) and was able to pull considerably more power out of the car than would have been available with the "generic" APS programming. Given the extensive-and expensive-nature of the APS turbo upgrade, we'd consider a custom tune such as this mandatory for maximum power and reliability.

Vemp_0703_12_z C6_corvette_twin_turbo Dyno_test 16/27

APS provides engine-management program data on CD for download into the stock computer. The APS data is designed for 93-octane fuel in an otherwise-stock, LS2-engined C6 Corvette. The stock ECU is reflashed using the popular HP Tuner. The reflash can also be performed by the tuner of your choice with HP Tuner's software. In the case of our yellow convertible, DTE proprietor Phil Rickard performed a full-blown custom tune on the car on his shop's in-house dynamometer. Rickard has extensive experience with forced-induction Corvette applications (he cut his teeth working on Lingenfelter's twin-turbo program in the late '90s) and was able to pull considerably more power out of the car than would have been available with the "generic" APS programming. Given the extensive-and expensive-nature of the APS turbo upgrade, we'd consider a custom tune such as this mandatory for maximum power and reliability.

Vemp_0703_13_z C6_corvette_twin_turbo APS_fuel_system 17/27

The bolt-on precision fuel system comprises a range of components designed to support huge horsepower while retaining excellent fuel atomization, economy, and driveability in day-to-day driving conditions.

Vemp_0703_14_z C6_corvette_twin_turbo Fuel_pump_voltage_booster 18/27

APS supplies a set of drop-in quad-orifice fuel injectors that flow over 800 cc of fuel per minute. In addition, MSD's Fuel Pump Voltage Booster is utilized to deliver optimum fuel pressure to the injectors regardless of engine load or boost pressure. Installation is straightforward, maintenance is very simple, and long-term durability should prove exceptional.

Vemp_0703_15_z C6_corvette_twin_turbo Turbocharger_air_duct 19/27

The method by which air is routed from the air cleaners to the turbochargers, on to the intercoolers, and finally to the engine has a huge impact on engine power and torque delivery. Twin air filters feed air to each turbocharger via durable hoses and precision-TIG-welded, stainless steel ducts (shown). Once the air is compressed by the turbochargers, the charge air is routed to each intercooler via reinforced high-temperature silicone hoses.

Vemp_0703_16_z C6_corvette_twin_turbo Air_intake 20/27

A truly "balanced" solution is implemented in the APS intercooled twin-turbo system. The total ducting-path length and effective bend radii of the left turbocharger are precisely matched to that of the right-side turbo. This ensures that both turbochargers operate in harmony throughout the entire engine-rpm range, regardless of throttle position and boost pressure. As our test drive showed, the result is perfect street manners in day-to-day driving conditions but with prodigious power on tap with just a press of the throttle.

Vemp_0703_17_z C6_corvette_twin_turbo APS_fuel_return_system 21/27

For ultra-high-horsepower applications, APS has developed the optional Extreme Performance Full Return fuel system. Designed to operate with high-power turbocharged/supercharged forced-induction systems, the heart of the system is the drop-in replacement surge-tank/fuel-pump assembly. This unit incorporates twin high-volume fuel pumps, a return circuit, and a provision for the stock fuel-sender assembly. The Extreme Performance setup is essentially two complete fuel systems, each with its own pump, rail, and pressure regulator. This system delivers a huge volume of fuel at a steady fuel pressure that is balanced and boost-referenced. Each of the individual systems is capable of supplying enough fuel to support 500 hp.

Vemp_0703_18_z C6_corvette_twin_turbo APS_exhaust_system 22/27

APS's high-output stainless steel exhaust is claimed to deliver tremendous exhaust-gas flow and low backpressure. Both are critical for delivering maximum horsepower, crisp throttle response, and great gas mileage. Premium 3-inch stainless steel tubing is precision-welded to perform at the most extreme power levels. The correct tube diameter, smooth-radius mandrel bends, and muffler design are all essential for high performance.

Vemp_0703_19_z C6_corvette_twin_turbo Catalytic_converters 23/27

Turbocharger-specific metal-matrix catalytic converters and a 4-bolt-flanged balance tube are included.

Vemp_0703_20_z C6_corvette_twin_turbo Mufflers 24/27

Careful attention has been paid to exhaust noise and quality without compromising performance. The APS system reputedly produces a strong exhaust note without creating drone at highway-cruising speeds. We were unable to verify this as our test C6 was equipped with a different exhaust setup.

Vemp_0703_21_z C6_corvette_twin_turbo Dyno_test 25/27

As installed on an otherwise-stock C6, the APS system delivered 552 rwhp and 513 rwtq on the DTE chassis dyno. This equates to around 690/641 at the crank-on an otherwise-stock LS2 engine! These numbers were achieved on 93-octane fuel, through high-flow catalytic converters, the stock H-pipe, and Magnaflow mufflers. Boost pressure was set at 9 psi, and the DTE turbo-specific torque converter was left unlocked. As of this writing, the car has made a best pass of 10.89 at 129 mph on Mickey Thompson E.T. Drag Radials.

Vemp_0703_25_z C6_corvette_twin_turbo LS2_engine 26/27

While there are a number of APS-authorized dealers in the U.S., DTE was among the first to install the package, and its techs already have a wealth of experience with the system. That experience has taught them a few things, and they have responded accordingly. DTE now adds the following exclusive components to every APS twin-turbo install it performs:

- Comp heavy-duty pushrods
- Comp heavy-duty valvesprings
- DTE-exclusive stainless steel hose clamps
- Random Tech high-capacity stainless steel catalytic converters with custom turbo-outlet mounting flanges for retained emissions compliance and OEM appearance
- Rear O2-sensor harness extensions
- Fully welded exhaust system for leak-free joints and OEM fit and appearance
- Low-temperature thermostat
- Mobil 1 synthetic engine oil
- ACDelco oil filter
- NGK V-groove spark plugs
- Custom billet-aluminum DTE fender badges and coil-cover decals
- DTE custom, dyno-based PCM calibration
- DTE written two-year/24,000-mile component and workmanship warranty
- Stage II '05 automatics also receive an upgraded torque converter and transmission.

Sources

DynoTech Engineering Inc.
Fort Wayne, IN 46804
APS Engineering Pty. Ltd.
South Croydon, VIC 3136
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