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1972 Chevrolet Chevelle - Street Sleeper

Homebuilt, Silent, and It’ll Surprise You

Ro McGonegal Nov 7, 2011
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It always warms the recesses of our little black hearts when we find a story like this. It’s a gut check. It’s a reality check. It’s what this hobby is really all about. Not a pile of parts, but a pile of people who make and massage them. It’s Dave Gehrke doing his damndest to keep it all honest and adhering to the basic tenants of the life: Do as much as you can with what you’ve got, and what you don’t, you noodle out, create, and put together (with maybe a pal or two) in the comfort of your environment.

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Dave bought this ’72 in 1987. It’s been defiled, mocked, and fortified with several big-blocks since. He even toyed with idea of slinging a Duramax between the rails. Then he went for an LS engine. The conversion was done long before there were any aftermarket assemblies to ease the process, so he called on his high school buddy Tom Izzo at Speed, in nearby Schaumburg, Illinois. The cherry was an iron-block 6.0L LQ4 that once plodded mundane in a van. He ran the car normally aspirated but planned to turbocharge it one day. In that configuration (325 hp and 370 lb-ft of torque), it tripped the beams in (yawn) 13.63 seconds.

Clearly, this performance caliber did not excite. At the time, Dave didn’t have any fabrication skills or the tools to perform them, but forged ahead full of Monster. “The following off-season, I bought a welder, a chop saw, and other tools and started the turbo install,” he says. “The original plan was to put a single turbo on, but I got a screaming deal on [Borg-Warner John Deere agricultural] turbos and could not pass them up. With 15 psi on the stock short-block, the car ran mid 10s the second season out. Since then, the short-block has been upgraded to max out the turbos … Each one is capable of 550 wheel horsepower, so I figure there is another 100 wheel horsepower to be had with some more boost and timing.”

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His best 60-foot time is an agonizing 1.82 seconds and the best quarter came up in 10.53 at 135 mph. The problem isn’t lack of bite but the rather slow spool-up time the turbos require with an A/R of 1.22. The A/R denotes the rated volumetric efficiency of the turbocharger’s two sections—compressor wheel (engine boost) versus the turbine wheel (that drives the compressor from the exhaust). A large numerical A/R takes more time to spool up than a smaller one. A relatively small engine displacement such as Dave’s 370 would accelerate quicker with an A/R anywhere from 0.48 to 0.63 and an rpm range of 3,000 to 8,000. “There’s also more power left in the tune-up with good gas and more boost,” he says. When he’s wrung all there is from the industrial snails, he plans to upgrade the hardware.

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What’s one of the things he likes the most about his combination? The flies it draws. “Every time I go to the track and make a pass there is always a crowd around it. It is so quiet with the cast-iron ‘mufflers’ [exhaust manifolds] on it that no one has a clue how fast the car really is.”

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Dave says that the build wouldn’t have been successful without the help and nourishment lent by his friend Jim Norman and the staunch support of his wife, Tracey. He had thought of selling the brown bag after his daughter was born, but his wife talked him out of it. Lovely woman, Tracey is. “Jim and I spent countless hours drinking Monster and Newcastle Brown while working on the car. The hobby wouldn’t be one without like-minded people, and in Dave’s realm that includes Larry Hamilton, Jim Moran, and Dan Marks—guys who Dave would call regularly for advice and wisecracks, and Chuck Johnson at Finish Line Transmissions in neighboring Wood Dale. Nice going, lads. Everybody else take notice.

In the misty future, Dave sees some big brakes, more suspension, and to be threading the autocross needle with his sleeper.


One of the beauties of the LS engine family is its six-bolt main bearing construction. Among other things, it allows the use of a stock nodular iron crankshaft in an otherwise heavily modified engine. Since boost was in the offing, Dave used Callies Comp Star rods and Wiseco forged pistons to complete the rotating assembly. His pals at Speed did the machine work and assembled the long-block for him. Cam timing is by a COMP roller that features 232 degrees duration, a 0.575-inch lift, and a 114-degree LSA. It’s connected to the crank with a double-roller timing chain. Rather than spring for another pair of cylinder heads, Dave played the stock 317s with some port work, larger valves (from an L76 6.0L), Patriot valvesprings, Harland Sharp trunion upgrade for the OE rocker arms, and COMP pushrods and hardware. The combustion chamber configuration and the Wiseco pistons yield a compression ratio of 10.0:1. ARP studs secure the heads and ARP bolts are used throughout. The induction system is composed of a swoopy Edelbrock Pro Flow XT manifold, 80-lb/hr injectors, cast-iron manifolds (truck on passenger side, Caddy LS CTS-V on the driver side), twin Borg-Warner S256 tractor turbos, an intercooler Dave got off eBay, and a dual-cone K&N filter. The oil pan is from an F-body and equipped with turbo oil drains. Now, stop smirking. At the crank, this convoluted conversion puts out 694 lb-ft at 5,500 rpm and 796 hp at 6,500 rpm on pump gas. Dave thought of nothing less than a Finish Line Transmissions Stage 4 Plus 4L80E to manage the grunt. The Precision Industries 10-inch torque converter was built with a 3,200-stall speed and the rage is transferred to a custom driveshaft built by Elgin Driveline. A worked ’70 Chevelle 12-bolt holds 3.42:1 gears and an upgraded factory Positraction.

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Considering the sleeper’s current mission, the chassis uses SPC adjustable upper control arms, the front bar from a WS6 Trans Am, and Monroe shock absorbers. Dave boxed the lower controls arms and secured them with poly bushings. Wheel movement is checked by ’96 Impala shock absorbers. Hotchkis 2-inch drop coil springs are pocketed front and rear. The steering gear is strictly stock.


Has it got a seat and a steering wheel? Alrighty then, we’re ready to roll. The column shifter and the stock dash don’t look menacing, but there’s a boost gauge, a shift light, and an ever-handy Scanmaster (hooked to the ALDL) that monitors engine parameters. Other salient features, Dave says, are the “junk eBay [audio] unit with an iPod jack custom duct tape holding the seat together!” We love this stuff.

Wheels & Brakes

No self-respecting sleeper would traipse the streets on pretty wheels. Those deep-set Wheel Vintiques hoops (15x8 and 15x10) and dog dish caps carry BFG 235/60 Radial T/A in front and M/T 275/60 ET Street Radials on the drive wheels. Brakes are no more than it really needs: F-body rotors on a B-body spindle conversion in front and those irrepressible factory drums out back.


As Dave imparts, “factory paint and 39 years of dings! The cowl hood was painted to ‘match’ as best as could be.” Clothes don’t necessarily make the car, either. CHP



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