Bolt-on upgrades boost C7 Z06’s performance and handling

Words and Photos: Carl Zander

Corvette’s Z06 has signified top of the food chain performance ever since it debuted in 1963 as a member of the C2 Generation of Corvettes. The full-race option designed by Corvette originator Zora Arkus Duntov, it cast the die for the high performance street editions that were to follow — the C5, C6, and now, C7 Corvettes.

The product development team at Estero Bay Chevrolet, a southwest Florida dealership specializing in Corvettes, wanted to investigate the possibility of being able to recommend to its C7 customers a group of bolt-on upgrade products that would enhance the performance and handling of these already potent Corvettes. These product upgrades had to be effective, offer significant improvements, not involve engine internals or software, and be able to be installed by the customer with little outside assistance…unless requested by the customer.

To begin the project, Pat Denson, managing partner of Estero Bay, contacted Man Machine Interface, Inc. (MMI) to determine their interest level in a project involving identifying, acquiring, and installing a group of bolt-on performance and handling upgrades that fit the above parameters.

Increasing air flow in

The stock air induction system for the Z06 consists of a trapezoidal-type filter and a plastic-based induction tube that leads to the throttle body.

The filter material is paper, which is pleated and has 166 square inches of filter area. The induction tube has a semi-smooth interior and multiple vertical and horizontal bends that require the incoming air to travel through a 180-degree path from the filter to the throttle body.

The tube is joined to the filter housing by a ribbed bellows-type rubber coupling. These features slow and disrupt the air flow into the throttle body. The stock system is rated at 242cfm.

To improve the Z06’s air induction system, Advanced Flow Engineering’s (AFE) Momentum high flow air intake system was selected for use. The AFE Momentum system consists of a high flow conical filter and a roto-molded, cross-linked polyethylene induction tube. The filter element is five layers of oiled, fine mesh cotton gauze formed in a pleated pattern and held together by a rigid, fine screen, steel frame. The filter area is 197 square inches.

The induction tube is a one-piece, semi-venturi shaped, straight horizontal tube with a mirror-like polished interior and a wide single 90-degree bend at the throttle body.

The AFE system has a flow rate of 303 cfm, 25 percent greater than the stock system, and provides high velocity, undisturbed air flow to the throttle body, which produces a significant increase in both horsepower and torque. An additional benefit of the AFE system is that its straight horizontal induction tube frees up space behind the radiator, which improves engine cooling. The AFE system installs without any cutting or drilling and requires no special tools.

Air-fuel combustion

The stock Z06 7mm diameter spark plug wires were swapped out for Magnecor’s KV85 competition, 8.5mm diameter spark plug wires (part number 85311).

The stock wires have a carbon-impregnated, fiberglass strand core conductor and a relatively thin insulating outer jacket. Mag-necor wires are constructed of a high-capacity metallic inductance EMI-suppressed conductor made up of stainless steel wire wound over a ferromagnetic core.

The outer jacket is high-strength, aerospace-grade silicone rubber that resists 600-degree heat on a consistent basis. The Mag-necor wires assure the most intense, high-voltage ignition spark current to the spark plugs throughout the entire engine rpm range and under high heat conditions, thus improving air-fuel mixture combustion.

Increasing exhaust gas flow out

While many Corvette enthusiasts would contend the stock Z06 performance exhaust system is perfect right from the factory, a detailed analysis reveals the weak link in the system is the “X” pipe. The stock “X” pipe has a single “X” joint and is constructed of multiple 2.75-inch diameter components, all welded together.

The component pipes and junction pieces are not mandrel bent and are not of a full uniform diameter throughout. The exhaust gases are partially disrupted and restricted as they pass through the stock “X” pipe, creating backpressure.

To resolve this problem, the stock “X” pipe was replaced with a Corsa Performance “X” pipe (part number 14761). The Corsa “X” pipe is a double “X” joint pipe constructed of 3-inch diameter T-304 stainless steel. Two fully mandrel bent pipes are welded together in two locations, forming a double “X” connection. The two component pipes are of uniform diameter throughout.

The result is much less disruption and restriction of exhaust gases as they pass through the pipe, thus improving the elimination of exhaust gases, reducing back pressure, and increasing horsepower and torque. While the installation of the Corsa “X” pipe can be accomplished using jack stands, the use of a lift is highly recommended. No drilling or cutting is necessary, and no special tools are required.

Cooling it down

Z06s, especially those with the 8-speed automatic transmission, run on the hot side in city driving, when outside temperatures are high, and also when running at the track. As mentioned in the preceding, the AFE air induction system with its straight induction tube helps increase cooling.

To further improve cooling, two 12-ounce bottles of Red Line Oil’s Water Wetter were added to the radiator. Based on the readout of the dash temperature gauge, this reduced the Z06’s normal operating temperature from approximately 210 to 195 degrees.

Handling and control

Increased performance is useless unless it can be effectively controlled. The next area of the project centered on improving the Z06’s handling and control. The stock brake rotors were removed and cryogenically treated. This process cycles the rotors from 70 to -315 degrees and then back to 70 degrees during a 24-hour period of time. The cryogenic treatment improves the metallurgical characteristics of the metal, which increases brake performance efficiency, durability, and strength; reduces warpage; and eliminates cracking at the machined slots of the rotor.

The rotors were also zinc dichromate plated to prevent rust, which negatively effects rotor cooling. To help improve handling, especially under track conditions, nitrogen was used, instead of compressed air, as the tire fill. Nitrogen is a dry gas with molecules larger than oxygen, so it helps prevent tire deterioration and is about three times less likely to escape from the tire. Nitrogen also maintains proper tire pressure because it does not expand like oxygen when tires get hot under track and drag racing conditions.

Preserving the investment

Since the Z06 will be driven to various shows and track events throughout the country, body protection in the way of a nose mask and a full-body cover were considered necessities. There was no doubt the Z06 would see stints above the century mark, so it was a requirement that the nose mask not only offer excellent protection, especially from road debris, but also be very secure and stable at high speeds.

Speed Lingerie’s mask is made of a heavy vinyl offering optimum debris protection, and is super secured using Quickly tracks and stainless steel snaps. The workmanship is outstanding, and the fit is perfect. Best of all, because of SpeedLingerie’s color matching — which includes racing stripes if the Z06 is so equipped — when the mask is installed, it is practically invisible.

For full-body protection overnight or for extended periods. Cover craft Industries’ Weather Shield HP custom-fit car cover was the obvious selection. The cover provides indoor and outdoor protection with exceptional water resistance.

Interior

Two high-use/high-wear areas of the Z06 interior, the seats and the driver’s and passenger’s floors, require heavy-duty protection. Seat Armour’s Corvette Seat Towels were used to protect the seats from abrasive wear, stains, spills, and perspiration — and keep the seats cool under high temperature conditions. These seat towels are particularly effective if the Z06 has a light color interior such as Kalahari, Gray, or Adrenaline Red, as in our project Z06. As any Corvette owner knows, it is a frustrating and constant battle to keep the driver and passenger floor areas clean and pristine. To resolve this problem, WeatherTech, the industry leader in floor liner design and manufacturing, was enlisted. WeatherTech’s Digitalfit floor liner set, in black, was installed. These floor liners are very strong and durable and are easily installed and removed for cleaning. The fit is outstanding. When installed, they blend in with the interior beautifully.

By the numbers: What’s it worth

The following is a breakdown of the retail cost of the bolt-on performance upgrades: AFE Momentum air induction system $627; Magnecor KV85 spark plug wires $157; and Corsa Performance double “X” pipe $599 — for a total of $1,383.

The results of the bolt-on performance upgrades were very impressive. Dyno testing the stock Z06 revealed a baseline maximum of 558 rwhp and a maximum of 584 lb-ft of torque. The AFE air induction system produced a maximum of 601 rwhp and a maximum of 604 lb-ft of torque, for a net increase of 43 rwhp and 20 lb-ft of torque. Placing the emphasis on horsepower, AFE’s 43 rwhp gain is approximately equivalent to 48 (43 plus 12 percent) rated horsepower at the crank.

Magnecor’s spark plug wires and Corsa’s double “X” pipe add approximately 4- and 10- rated horsepower respectively. That puts the total rated horsepower gain for the upgrades at 62 hp and the overall rated horsepower for the Z06’s LT4 engine at an awesome 712 hp. At the total retail cost of $1,383, that yields an incredible $22.30 per rated horsepower increase.

SPECIAL THANKS: Needless to say, the impressive results achieved with the project Z06 are amazing. The author would like to extend a special thank you to Paul Hardley of Advanced Flow Engineering and Brent Noward of Corsa Performance for their invaluable input to this article.

Sources: Advanced Flow Engineering, Inc., afepower.com; Corsa Performance, corsaperformance.com; Covercraft Industries, Inc., covercraft.com; Estero Bay Chevrolet, Inc., esterobaychevrolet.com; Magnecor, Inc., magnecor.com; Man Machine Interface, Inc., zrinetregistry.com; Red Line Synthetic Oil Corporation, redlineoil.com; Seat Armour, Insync Business Solutions, Inc., seatarmour.com; SpeedLingerie.Com, Inc., Speedlingerie.com; WeatherTech, Macneil Automotive Products Limited, weathertech.com