Lingenfelter Chevrolet Corvette ZR-1
From the July 1991 Issue of Car and Driver
“I know it’s hard to believe, but some guys who bought ZR-1s, the first thing they tell me, you know, is they’re disappointed. They don’t care about top speed. They say to me, ‘Man, out there at stoplights, I expected this thing was just going to lift its front wheels when I goosed it. But it doesn’t.’”
Blasphemy? Maligning the manliness of a Corvette ZR-1 is like accusing Norm Schwarzkopf of wearing pantyhose. Unpatriotic. Except that, in this case, the blasphemer—John Lingenfelter, raised in East Freedom, Pennsylvania—has made a handsome living tinkering with Corvettes for almost 23 years. With eleven assorted NHRA class championships in his hip pocket, Lingenfelter is the quintessential all-American hot-rodder. A hot-rodder with a degree in mechanical engineering from Penn State.
“My goal,” says Lingenfelter, “was to increase the ZR-1′s output by about 100 horsepower. With no new pieces of hardware. With tailpipe emissions that equaled or were better than stock.”
Get a grip, John, we said.
Which deterred this 45-year-old, silver-haired racer not one whit. He is Kenny Rogers on a caffeine jag. During a daylong interview, Lingenfelter deposits himself in a seat exactly once, and then only because he cannot eat his chicken sandwich standing up. Like a pre-schooler, he is in perpetual motion.
“That’s an old twin-turbo salt-flats motor over there, and here’s a 557-cubic-inch 950-horsepower marine motor for a 41-foot Apache, and you know this dyno measures up to 1450 horsepower but it’s not too accurate with anything below 300, and that’s my own invention, a tuned-port box; God, with that thing on a 383 [cubic-inch small-block], it just kicks ass. Where are the keys to that white 383? Oh, here. You gotta drive this.”
Then he disappears.
Taking notes is nearly impossible. Photographer Dick Kelley says, “Okay, John, just 60 seconds to get the right lens, then I’ll take your portrait.”
“Great,” says Lingenfelter, “time enough for a phone call.”
Then he disappears.
Lingenfelter Racing, on the outskirts of Decatur, Indiana, is housed in an unprepossessing industrial building that might be mistaken for a large laundry were it not for the wail of the dyno and a row of Corvettes parked in the back lot. Inside are 26 employees, all nearly as frantic as Lingenfelter.
C/D readers may recall a Lingenfelter Corvette we tested in December 1989. With a 383-cubic-inch (6.3-liter) small-block mated to an automatic transmission, that car painted black stripes to 60 mph in 4.3 seconds, then tore through the quarter-mile in 12.8 seconds at 109 mph. Which is quicker than a ZR-1 from a car that is nearly $20,000 less expensive. Smog-legal. And it hasn’t broken yet.
Not long thereafter, we began hearing from John again. “Of course, I admire the ZR-1,” he said. “Thirty-two valves, four cams, 5.7 liters—it’s great—but the people who buy these cars always want more power.”
“Call us,” we said, “if you decide to do something about it.” Because Lingenfelter’s whole life is more or less a series of low elapsed times, it wasn’t long before he called. We met him next to the Decatur K mart four hours later.
“Initially,” says Lingenfelter, “I was just messing around, you know, having a look.” His idea of messing around involved a $130,000 investment: two ZR-1s purchased for practice. So that he knows what he is working with—some ZR-1s run a lot stronger than others—John’s first move is to yank the LT5 engine and measure it on the dyno. Then he lovingly dismantles the thing and sets to work on the heads. He installs titanium retainers to reduce valvetrain weight, recuts the valve-seat angles, then painstakingly blends the ports and polishes the runners until the inner walls shine like Santa Fe silver. Finally, he degrees all four camshafts.
What comes next, in Lingenfelter’s words, is “to unrestrict” the exhaust. “I tried everything,” he says. “Duals, two into one, one into two, cut pipes, splicing them, welding them. Usually what happened is I’d get a big power gain—as much as 30 horsepower—but the car would make too much noise or sound blatty.”
What eventually satisfied Lingenfelter was a stock exhaust with “heavily radiused connectors.” That is, he eliminates the crimped and welded passages at the entrances to the collectors, to the catalytic converters, and to the mufflers. When the throttle is wide open, the exhaust’s timpani tones are now not much more raucous than stock. But when it is just idling, the Lingenfelter ZR-1 barks and snaps, belting out a basso-profundo 63 dBA, versus the stock ZR-1′s demure 57 dBA.
Our test car is fitted with the quietest, most restrictive exhausts that Lingenfelter offers. “The next step up, admittedly more noise, gains a tenth of a second and 2 mph in the quarter-mile,” he says. “I let each customer decide how loud his car should be.”
On the Decatur dynamometer, the modified engine is only 20 horsepower shy of Lingenfelter’s goal: it produces 455 horsepower at 7000 rpm and 395 pound-feet of torque at 5250 rpm (versus the stock ZR-1′s 375 hp at 5800 rpm and 370 pound-feet of torque at 4800 rpm). Every Lingenfelter engine is run-in on the dyno. If it is not within five horsepower of what has been promised to the customer, John disassembles it to find out why.
When you drive a stock ZR-1 and Lingenfelter’s ZR-1 back to back, as we did, what you notice first is not the horsepower difference—especially around town, where the engine rarely spins near its newfound power and torque peaks—but a difference in throttle response. Lingenfelter’s engine responds cobra-like to small movements of the throttle, revving as if its flywheel had been lifted from a McLaren-Honda. The word that comes to mind is “crisp.”
What’s more, none of the engine’s drivability is lost. Friendly? This is the Dalai Lama of small-block Chevs. It lights instantly, hangs for a few seconds at 1500 rpm, then settles into an easy lope at 700 rpm. If you forget to downshift as you turn the corner into the office parking lot, well, never mind. This 455-hp engine is perfectly content to rumble around town at 15 mph in third gear at 1000 rpm.
It isn’t until you nail the throttle and hold it wide open long enough to trigger the secondary intake runners that the gorilla begins to stir. Just before the secondaries open, you feel a tiny flat spot—something you don’t feel in the stock ZR-1. But once the tach gets north of five grand, the engine feels like it won’t stop pulling until a week from Wednesday. Lingenfelter recommends—holy smokes—a 7500-rpm redline.
Kick out the jams and you can spin the rear tires as if you’re in the bleach box at Pomona Dragway. Hang on and they’ll continue spinning until you’re well north of this country’s highest posted speed limit. This will cause your neighbors to search for their children. This will get you tossed out of your neighborhood. When Lingenfelter’s Corvette flattens its ears, the speedometer’s digits don’t just flash rapidly; they leap in clumps of 3 or 4 mph.
How fast is that? The Lingenfelter ZR-1 hits 60 mph in 4.1 seconds. That is 0.5-0.8 faster than the various stock ZR-is we’ve measured. It is 0.1 faster than a Ferrari F40. Once the Lingenfelter begins stretching its legs in post-5000-rpm territory, you get an even clearer sense of what 455 horsepower really means. One hundred mph hits you in the face in 8.9 seconds (1.72.3 seconds sooner than stock), which requires about the same distance available on the average entrance ramp to the Interstate. The quarter-mile evaporates in 12.3 seconds at 118 mph (versus 12.913.2 seconds at 108-111 mph). And the digits announcing 150 mph appear after you have held your right foot to the floor for only 24.7 seconds—almost an eleven-second improvement over stock! Top speed—ah, your honor, my client pleads temporary insanity—increases from 176 mph to 191 mph, and that was achieved on a day with a highly unfavorable, stiff quartering wind. To find a track where we could explore such velocities without fretting over pre-arraignment proceedings, we had to travel all the way to Firestone’s high-speed oval in Fort Stockton, Texas.
All of this is EPA-approved. There are no engine parts whose lifespan should be noticeably curtailed. Because of the reduced back pressure and reduced pumping losses, the Lingenfelter ZR-1 still averages 14 mpg. And nowhere—not even atop the gleaming all-alloy engine—is there a jot or tittle revealing that this is anything other than a stock ZR-1. No signs, plastic ‘plaques, or limited-edition signatures on the dash. “Guys who buy these cars,” says Lingenfelter, “would rather demonstrate speed than advertise it.”
Of course, Lingenfelter’s “demonstrations” are far from free. For the privilege of driving this go-to-jail Corvette, you must leave your ZR-1 in Decatur for a minimum of two weeks, after which you will be presented with an invoice for $13,500. Hide the razor blades. But that amount includes whatever exhaust note you choose (from dead-stock quiet to Top Fuel maniacal) and a 3.73 final-drive ratio in place of the standard car’s 3.45. As an option, you can stipulate a set of Bridgestone RE7 Is, whose sticktion elevates the car’s skidpad performance to 0.91 g—up from the conventionally shod ZR-1′s 0.87 g. Moreover, the Bridgestones are commendably predictable at the limit, encouraging a steady-state tail-out attitude that we find, ah, amusing. From a sheer drag-racing standpoint, however, the Goodyear Eagle ZR4Os are hard to beat.
John Lingenfelter is something of a contradiction. A conscientious engineer with the boulevard sensibilities of Jon Bon Jovi. A man who builds responsible engines with feloniously irresponsible outputs. A drag racer whose personal cars are a Chevy pickup and a Ferrari 308.
“Wait, before you go, try this,” he says, again in hyperactive triple-caffeine mode as he hands us another set of Corvette keys. This one is a development car. “Five hundred forty cubic inches,” Lingenfelter explains. “Six hundred fifty horsepower, 700 pound-feet. Top speed is 215, 217 mph. Quarter-mile at 132 mph in the low elevens. The guy can drive it to work, no problem. Decent mileage, too.” We take it for a whirl. It smokes its rear tires as we shift into third. At 79 mph.
Upon our return, we are giggling like seventh-graders in Mrs. Randolph’s sex-education class. Photographer Kelley has completely forgotten where he left his cameras. Lingenfelter greets us: “What I’d like,” he says, “is to do a limited edition of that car. Maybe fifty or so. But only 500 cubic inches. Full cats. Fully certified. And, you know, I’d tone it down. Something reasonable.”
“What is reasonable, John?” we ask. “Well, you know, only 550 horsepower.”