Corvette Z06 Performance Packages - Inside The HPE Toybox

With 505 hp and 470 lb-ft of torque in stock form, the hand-built, all-aluminum LS7 engine is the ultimate factory-issue Gen IV powerplant and thanks to its forged-steel crankshaft, titanium connecting rods, and 6-bolt main caps, this 7.0-liter small-block can support even greater levels of axle-mangling output.

To meet the growing demand for such tweaks, tuners such as Houston's Horsepower Engineering (HPE) are working overtime to develop packages capable of extracting every last iota of power from the mill. HPE was founded in 2003 by owner Chuck Anders, and the 13,000-square-foot facility has been pumping out some of the industry's wildest GM-powered hot rods ever since. In fact, the shop currently lays claim to the fastest LT1 F-body and fastest stock-block LS1 in the country.

According to Anders, "The LS7 is a fantastic engine with excellent street manners, but substantial power gains can be made by optimizing the tuning, camshaft, and exhaust system. Our Stinger package offerings for the Z06 Corvette can add from 30 to well over 200 rear-wheel horsepower to a car and are designed to bring out the true personality of the LS7.

"Our Stinger Tuning package optimizes the stock camshaft and exhaust, while the Stage II and III Stinger Packages use custom cams and system-matched performance parts to significantly increase engine power. Although the Z06 features tubular exhaust manifolds and a 3-inch exhaust system, the LS7 heads are quite restrictive on the exhaust side. Anything you can do to increase the flow of the exhaust helps power. By utilizing a set of American Racing 1 7/8-inch headers and a 3-inch mid-pipe with high-flow cats, [we can] increase exhaust duration. Throw in a ported HPE throttle body and a Callaway Honker air intake, and the engine wakes up very nicely."

Follow along as we detail three of HPE's Z06-upgrade kits: the Tuner package, the Stinger Stage II, and the Stinger Stage III with nitrous. Next, we'll strap these beastly Vettes to HPE's Dynojet 248 chassis dyno, followed by a quarter-mile test session at Lonestar Motorsports Park, in Sealy, Texas.

How much horsepower can these Zs channel to the rear wheels, and is there any hope for the stock Goodyear F1 SuperCar EMT tires? Let's find out.

Stinger Tuning Package
The Stinger Tuning package retails for $733 and consists of the following:

* Custom dyno tuning
* Motorad 160-degree thermostat
* Custom throttle-body-porting service
* Labor, thermostat replacement

Finally, HPE custom ports the factory 90mm throttle body to remove its machined-in leading edge. According to Anders, throttle-body porting alone can uncork 7-10 rear-wheel hp on most LS-series engines.

At the heart of the package is a custom dyno tune created on LS7 Edit. (HPE utilizes both a Dynojet Model 248 and a Mustang MD-1750 dynamometer for tuning purposes.) The factory LS7 ECU is set to run at a rather rich 11.7:1 air/fuel ratio at wide-open throttle. By adjusting the timing and power-enrichment (PE) tables, along with a host of other variables, HPE retunes the WOT air/fuel ratio to between 12.5:1 and 13:1.

Cooling is also important. HPE installs a 160-degree Motorad thermostat and ramps up the pulse-width-modulated fans to 100 percent capacity at a lower coolant temperature (188.6 degrees F). The resulting reduction in engine temps allows an increase in ignition timing (27-30 degrees versus the factory-specified 23-26), while also reducing detonation.

Owner: Dale Vickers
Car: '07 Z06
Color: Machine Silver Metallic
Current Mileage: 3,100
Modifications: HPE Tuner Package, HRE 543-R wheels (18x9.5 front, 19x12 rear)