Gary Hillen reveals the secrets to running 9s in his bolt-on C6 Z06
By Scott Parker
Photography by Michael Galimi
It seems there are a lot of records posted on the internet, many of which can even be a bit absurd. But fastest bolt-on C6 Z06 seems to have some merit, especially when the e.t. dips below 10-seconds. Sure the Z came with the mighty 427 cubic-inch LS7 with its Titanium valves and connecting rods that screams to 7000rpm, but one would think harnessing such ample torque through the independent rear suspension might be a real chore. Particularly when it must be done with a manual trans. There in lie the art and finesse of piloting Gary Hillen’s 2008 Z into the record books.
Gary hails from New Jersey, the land of fast Corvettes and many record setters. Among them is Rob Zona, who has graced the pages of GMHTP before and was influential in helping Gary refine his setup and get the Z down the old 1320 in a scant 9.97-seconds at over 138.8mph. Rewinding a second, Gary had previously owned a 2004 C5 Z06 and managed to whittle its time down to a 10.89 at 125mph using only bolt-ons. When he purchased the C6 Z in February 2009, it was already running nearly as fast bone stock with a set of Hoosier 275/40/17 drag radials (10.91 at 127). Next the bolt-ons were carefully selected to get the most out of the stock engine. American Racing 1 7/8-inch headers with a 3-inch X-pipe, Halltech Super Bee cold air intake, a ported stock throttle body and custom tuning by Troy Nikola would help free up significant power. However, in 2011 Gary also added a FAST LSXR intake manifold and swapped the cold air for Halltech’s new MF103 (with additional tuning by Matt Hauffe at Tune Time). These changes were influential in going from 10.19 at 134 to the eventual 9-second run.
Believe it or not, Gary credits the drivetrain setup as being the most important to his achievement. An RPS BC2 clutch, he says, provides the perfect combination of slip upon release and tightness up top to launch the car while taking advantage of the LS7’s top end power. The BC2 is a twin carbon disc design with a carbon floater as well as a “Strapless” billet aluminum pressure plate and cover that weighs in at only 25-pounds. At the other end of the torque tube is an RPM Stage 3 differential with a custom spool (based of the ZR1 center section), 300M shafts, and 4.10 gears. But surprisingly he uses a stock shifter and stock C5 axles to enact the drivetrain. “I use the C5 axles as a fuse rather than have something much more expensive break.” This strategy comes at a price, as he certainly goes through them on occasion. But it is hard to argue that it doesn’t work.
The chassis setup is surprisingly simple. The front sway bar is removed, yet every other suspension component remains as it came from the factory aside from the rear shocks. Adjustable coilovers have replaced the stock shocks for better control with various tires, however, the car had already managed a 1.36 sixty-foot with stock suspension. Speaking of tires, Gary has tried several sets, but what works best is a set of M&H 26x12-inch bias-ply slicks. The soft sidewall allows him to be extremely consistent, clicking of 1.3 short times at will. Though on the street, Mickey Thompson ET Streets are the rubber of choice. And yes this car sees plenty of street time. Often driving to the office and then to the track some 100-plus miles. The stock axle-back makes street driving very enjoyable with only solid motor and tranny mounts taking away from its street manners.
Believe or not there are few changes from the street to the track setup. Gary was tight-lipped on his fuel of choice, but he says almost all of the factory equipment stays put on track days. Though occasionally he does remove the factory heated seats for an Arizen racing seat. Tire pressure is reduced to 12.5-15psi depending on track conditions. With warm fluids and coolant temperature at 170, Gary typically does a short (3-7 second) burnout, and bumps in shallow. His launch RPM will vary from 4600-5800, which is done by feel (a two-step is only used during class racing). The clutch is slipped in a fairly slow and controlled manner, and not dumped. Gary says this is key to keeping the drivetrain from grenading, as he has on several occasions. Shifts are made at 6900rpm with a slight lift (not powershifted), and he goes through the traps at 7300 in Fourth gear.
Simple methodical testing with attention to detail– this is something that he picked up from Rob Zona, which has helped him achieve these impressive times. Of course many others are also to thank for Gary’s success, too many to list here. Perhaps it is best to give a quick nod to his New Jersey crew, all of the great companies that helped along the way, and of course the General for creating such an exquisite beast for hot rodders like us to push to its limits and beyond. The pursuit and championing of such endeavors is what makes life worth living.
CAR: 2008 Corvette Z06
OWNER: Gary L. Hillen
BLOCK: LS7, 427cid
COMPRESSION RATIO: 11:1
HEADS: Stock LS7, 2.20 intake, 1.60 exhaust valves
CAM: Stock hydraulic roller, 210/230-duration, .594/.590-inch lift, 116LSA
ROCKER ARMS: Stock, 1.8 ratio
PISTONS: Stock, hypereutectic
CRANKSHAFT: Stock, forged
RODS: Stock, Titanium
THROTTLE BODY: Ported stock 90mm
FUEL INJECTORS: Stock 42 lb/hr
FUEL PUMP: Stock
IGNITION: Stock coil-near-plug
ENGINE MANAGEMENT: Stock ECM, tuned by Troy Nikola
EXHAUST SYSTEM: American Racing 1 7/8-inch long-tube headers, of-road X-pipe, stock axle-back
CLUTCH: RPS BC2
FRONT SUSPENSION: Stock control arms, shocks, springs, removed sway bar
REAR SUSPENSION: QA1 coilovers, stock control arms, sway bar
REAR END: RPM Stage 3, 4.10 gears, C5 axles, spool
BRAKES: Stock C5 front/rear
WHEELS: Bogart D10 17x4.5 front, 16x12 rear
FRONT TIRES: M&H 26x4.5
REAR TIRES: M&H drag slicks 26x12
BEST 60-FT.: 1.35