1986 Chevy Corvette C4 - Yellow Beats All

A Nearly Unbeatable C4 Auto Crosser

Richard F. Newton Apr 1, 2002 0 Comment(s)
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This is the Corvette that Dave Hill and his Corvette engineering staff don't want to know about. The C4s, built from early 1983 (as an '84 model) 'til mid-1996, were former chief engineer Dave McLellan's creation, while Hill gets credit for the '97 and newer C5s. Some folks inside at GM have told us that McLellan deserves more credit for the C5 than he's been given, but that's another story entirely.

The point here is that, except for the Z06, the C5 is not a very good autocross car. Autocross, or Solo 2 in SCCA, is a unique form of competition. You have to drive around on an artificial course that's usually set up in a giant parking lot, you're racing against the clock, not directly against other cars, and a lap lasts less than a minute. If you think of an autocross as a qualifying lap in racing, you're pretty close. There's no chance to relax and very little opportunity to think about what you're doing. Driver ability and a good handling car are the important things for winning in autocross. It also helps for your engine to have a lot of low-end torque and to be hooked to a solid-shifting automatic transmission. When you're driving through cones on narrow courses, wide cars and long wheelbases are hindrances to getting the best time. Think about this-early ('84-90) C4s are 176.5 inches long and 71 inches wide on a 96.2-inch wheelbase, while C5s are 179.6 inches long and 73.6 inches wide with a 104.5-inch wheelbase. The same width and long wheelbase that make a C5 roomy inside and exceedingly stable at high speed make it awkward and unwieldy on a tight and twisty autocross course.

The old '85 to '87 Corvettes seem to rule the autocross courses around the United States. These old C4s flat beat everything that's come out of Chevrolet since the mid-'80s. When you look at the SCCA National Championships, you'll always find some of these old torque monsters in the standings.

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Roger Johnson's yellow '86 is one of the best of these unbeatable autocross Corvettes. It's so competitive that a couple years ago some members of the Corvette engineering team invited Roger and his '86 to the Milford (Michigan) Proving Grounds so their boss could see a real, winning autocross Corvette. Some of the team thought it might be useful if they could get a handle on why this old C4 was able to blow away the brand-new C5s. Of course, it blew away the new Corvettes, right on Chevrolet's home turf.

This yellow '86 is a legend amongst the autocross fraternity. While no one is sure if it's the driver or the car that is great, Johnson's driving ability is something that every Corvette owner who's ever run an autocross aspires to. On the other hand, most autocrossers would like to have his car.

There are several reasons that the '85-87 C4s make wonderful autocross cars. The old L98 just can't be matched for bottom-end torque-it'll damn near pull stumps out of the ground. The LT1s, LT4, LT5s, LS1s, and LS6s are all great horsepower engines, but each and every one of them lacks the raw low-end grunt of the old Tune-Port Injection 350. Fifteen years of technology has produced some great engines, but none of 'em can match the low rpm power of a well-tuned L98.

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Roger's car, which he bought brand new, only has about 5,000 miles showing on the odometer. The first thousand or so was on the street. The rest is a lot of Solo 2 runs, a whole lot if you consider that the average run is usually well under one mile, and lots of times closer to a half-mile.

In late 1987 the folks at Chevrolet convinced Roger that the new '88 Corvette with its re-designed, zero-scrub-radius front suspension would be the way to go. He even put the yellow beast up for sale while he prepped a new '88 version. Roger was serious about the '88's prep, with the car sent to C4 performance guru Kim Baker for special attention, while John Lingenfelter was making sure that all was perfect within the engine.




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