Ruthless Pursuit of Power: The Mystique of the C6 Corvette LS7 Engine - Page 1 of 26
Ruthless Pursuit of Power: Lucky Seven Edition: The Mystique of the 7-Liter, 7000-RPM, LS7 - Page 1 of 26
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by Hib Halverson
© May 2013— Updated: November 2014
No use without permission, All Rights Reserved
For a long time, the only C6 Z06es I drove weren't mine. Great to be able to beat on, ah...test somebody else's expensive Vette and have fun doing it.
I first had C6Z seat time in the Fall of '06. In Detroit to research an article for the late-great, Corvette Quarterly magazine on the car's LS7 engine, I conned GM Communications out of a Z06 for four days. Between crappy weather and commuting to various interviews and photo venues, for three days all I did was cruise greater Detroit. That began my understanding of the LS7 mystique. In all that mundane driving, the engine was surprisingly docile, for such a big engine got great mileage and, other than "LS7" stamped on the beauty covers, it looks like any other Small-Block V8. But, don't let that stuff fool ya--the car is clearly bi-polar.
Image: Author
The OMG Effect
On the last day, I drove down to Lingenfelter's in Indiana to drop in on my pal, Graham Behan, who's Chief Engineer there. The run down to Decatur was a rainy, windy trip but the weather dried-up for the trip back and there wasn't traffic on US 24 North. Outside Ft. Wayne, as I cruised the speed limit watching ahead and behind, I wondered: what'll this sucker do? I back-shifted to fourth and floored it. The exhaust bypasses popped open and the LS7 took a deep breath. I watched the HUD count into triple digits and listened to the wind noise increase. I lifted and let the car coast down to something legal.
Hmmm...so that's what 470 pounds feet of torque feels like. Cruising along at 75 in sixth once again, I mused, now that was fun. But, I want to experience 7000 RPM. My Valentine 1 had been silent for miles. Checked the mirrors-- a few cars way behind--nothing in sight ahead, so this time, I pushed over into third and stomped on it. RPM on the HUD passed 6 going for 7. Got fourth and kept my foot on the floor. 160 on the HUD and about 7000. I lifted.
OMFG! Now THAT'S some motor!
Image: GM Communications
Image: Sandy Rubel
Five years went by before I got a second drive in a C6 Z. Summer of 2011. After a six-day route reconnaissance for the 2014 Corvette Caravan, my Wife, The Fairest Sandra the Red, and I were at the National Corvette Museum's Labor Day Celebration. At these events, Harlan Charles, Chevrolet's Corvette Product Manager, and Design Staff's, Kirk Bennion, host a seminar what's coming in the next model year. This always includes an outdoor briefing around new Vettes, in this case, a 2012 Grand Sport and a '12 Z06. The Z was a "captured test fleet" car assigned to Tom Hill, (now retired, but back then) the Engineering Manager at Bowling Green Assembly. Once the walk-around concluded and the crowd thinned, I caught-up to Hill.
"Hey Tom, uh...how 'bout a drive in your Z06?"
After Harlan assured Tom I was unlikely to stick his company car into a farmer's field out in the boonies, off he and I went in his full-boat, arrest-me-red, '12 Z06 in search of some back roads. While this car had all the whistles and bells (pointless options such as nav, fancy leather, heated seats), the important stuff was: carbon-fiber roof and aero kit, transaxle coolers, Magnaride shocks, J57 carbon-ceramic brakes, Michelin PS Cup tires--all part of RPO Z07 "Ultimate Performance Package"--and last, but certainly not least, the big, nasty, LS7 427...better living through displacement, titanium engine parts and CNC'ed heads.
A Z06 is bad fast. It outperforms a host of "exotic" or "super" cars costing several times its price. Can we quantify that? You betcha. Testing conducted by GM back in June of 2011 had a Z06 doing Nurburgring's famed "Nordschleife" in only three seconds more than a ZR1. The two cars had the same driver, GM's Jim Mero, along with the same aero kit, suspension, brakes and tires. On a time basis, that's less than a 1% deficit--in spite of the "big" Z's 26% more horsepower. Z06es are cool/calm/collected around town and, if you can resist driving it in a sporting manner, the seven-liter Small Block delivers surprisingly good mileage--so much so that Z06 and 427 Convertible owners never paid a gas guzzler surcharge. Cheap fun, amazing performance, good mileage--ah--the stuff of legends.
"Launch Control", also part of RPO Z07, offers a clear understanding of the 427's high fun factor. When enabled, this system leverages the car's electronic throttle control (ETC) to add a level of computer enhancement to the driver's control of throttle opening during standing starts and high RPM gearshifts.
Image: Author
Image: Author
Launch Control produces drag strip starts with amazing consistency. Come to a stop. Push the "Performance Traction Management" button on the console twice. Confirm "Perf Trac" appears on the IP. Straighten the front wheels, select first gear, push the clutch in, then floor the throttle--ETC will hold about 4000 RPM. Quickly release the clutch and keep the throttle wide open. As the LS7 goes by 6500 RPM, keep your foot on the floor, pump the clutch and grab second gear. During the power shift, ETC reduces throttle opening for a fraction of a second to prevent engine overrev and ease the load on the transmission and clutch. You can keep doing that for each gear or until, as Tom Hill suggested in an email after our drive, "...speed exceeds comfort".
During the standing start, the ECM controlling ETC, balances wheel spin and torque output, making you look like a drag racing pro every time. Using Launch Control is easy except that, at first, it may be hard to break the habit of lifting to limit wheel spin once you pop the clutch. I did that the first time and the car bogged because, as soon as you lift, Launch Control disables then traction control then intervenes to stop wheelspin. "Don't lift! Keep your foot on the floor," Tom Hill instructed as I lined-up for a second try on another straight stretch.
Wheels straight, first gear, floor it, ECM holds about 4000. I dumped the clutch. Steered a bit as the rear end drifted a tad right. As soon as the car hooked, the LS7 was WFO and RPMs were headed towards the 7100 RPM rev limiter. My foot flat on the floor, I stabbed the clutch and flicked the shifter to second. RPM was headed up, again. I stayed in it only to the top of second then, jumped on those big carbon brakes and came to a very quick stop.
I had try a third time. With the tires warm, the car left harder. Between 6500 and 7000, I power-shifted to second. As the LS7 pulled towards 7000, again, I banged third. I stayed in it for a second or so. Maybe a bit fast on a two-lane, back road. But, it wasn't my fault. Really--I couldn't help it. That freakin' engine is so awesome. The car gods made me do it. But, enough already! Let's get on to the techie stuff.
Image: David Kimble for GM Powertrain