The weird and wonderful cars of the ‘500,’ part 2

Published On April 5, 2016 » 7382 Views» By Marshall Pruett » Blogs, IMS, IMS History, Indy 500

We’re chronicling 100 days of Indy 500 history on #SpeedRead leading up to the historic 100th Running. With 54 days to go, racing journalist Marshall Pruett continues his look back at milestone cars and technology.

More Pruett: The mighty “Offy” | Penske’s ’94 dominator | The “Fantastic” Turbine | Murphy’s Miller straight-8 | Yunick’s winged Watson More 100 days

We have fallen in love with the Indianapolis 500’s most accomplished designs since the Marmon Wasp won the first race in 1911. Since then, countless favorites have graced Victory Circle—Millers, Kurtis Krafts, Eagles, Penskes—and dozens of other race-winning cars or inspiring machines have enriched the great race.

And then, as history has recorded, we have the cars that reached too far or, in some cases, not far enough in pursuit of glory at the Indy 500. They stand as the weird and the wonderful, and some represent interesting footnotes—or origins—in chassis and engine design.

A week ago we featured Part 1 in our look back at a handful of cars that aren’t household names, yet have become beloved entries in Indy’s technological march to May’s 100th 500. Here’s part 2 for your reading pleasure — expect Part 3 next week and very possibly a Part 4. There’s no shortage of material from the race’s illustrious history.

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1. 1980 SKIRTS ALLOWED

It was a brief moment in Indy 500 history when the use of Formula 1-inspired sidepod sliding skirts were permitted, yet with their use, the Speedway’s flirtation with ground effects saw speeds shoot sky high.

Continuing the ground-breaking aerodynamics found that carried Mario Andretti to his 1978 F1 world championship in the Lotus 79, most Indy 500 constructors followed suit by using giant underwing profiles to produce huge amounts of downforce. Just as F1 constructors learned, by sealing the outer edges of the sidepods to the ground while their cars were at speed, downforce figures spiked to unsurpassed numbers.

Spring-loaded skirts were fitted inside the sidepods, and the skirts were usually cut from a durable plastic that would wear and be replaced after each session, if necessary. With the springs pushing the skirts down onto the track, bumps and curbs would push upward on the skirts, lightly compress the springs, and the skirts would then return to their normal position to continue sealing the underwing. The spring-loaded systems allowed F1 cars to demolish lap records as Grand Prix cars entered their first true era of advanced aerodynamics.

The Indy 500 was a hotbed of aerodynamic development from the first race in 1911, but with the little black skirts affixed to his Chaparral 2K, and some held from the concept pioneered by Lotus, Johnny Rutherford earned the first Speedway win for a ground effects car in 1980.

Citing concerns over safety (the skirt systems in F1 were often problematic as one side would lock in its upward position and bleed most of the downforce from the bottom of the car), sidepod skirts were banned for 1981.

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2. 1931 CUMMINS DIESEL

The flying rectangle. Most Indy 500 fans know the story of the 1952 Cummins Diesel, which became the first turbocharged car (turbodiesel, to be more accurate) to win pole position, but it wasn’t the first diesel to race at The Brickyard. The company entered the first diesel-powered car back in 1931 with Dutiful Dave Evans behind the wheel. The mountainous 361-cubic-inch (5.9 liter) four-cylinder engine helped Evans to qualify 17th and, thanks to its massive advantage with fuel economy, allowed Evans to finish 13th on the Cummins Diesel’s debut after becoming the first driver to go non-stop for 500 miles at Indy.

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3. 1978 EAGLE-AMC

We know Chevrolet continues to represent the USA at the Indy 500, just as Louis Chevrolet did in the great race’s formative stages. We know Ford has a rich history at the Speedway with everything from engines to cars it had commissioned. How about the niche American Motors Corporation, better known as AMC, that built a small and dedicated group of followers from 1954-88?

In a reminder of how a small, determined company can use the Indy 500 as a marketing machine, AMC took on the established engine suppliers with a turbocharged V8 engine featuring aluminum heads and an aluminum block. In the hands of privateers for the 1976 and 1977 Indy 500s, the stock-block AMC turbo V8 showed potential, but its production-based steel construction was a weighty liability. With AMC interested for the 1978 race, the factory produced lightweight aluminum engine components which carved approximated 250 pounds from the V8’s street version.

Thanks to USAC rules that allowed stock-block engines to run at a larger displacement (209 cubic inch/3.4 liters) and higher boost (39.2 psi), the AMC turbo V8 pushed out almost 900 horsepower, and in the hands of Indy 500 veteran Roger McCluskey, the No. 11 Eagle-AMC qualified 11th, displacing a significant number of Cosworth DFX V8 turbos and the few holdouts running four-cylinder Offy turbos.

Knowing the advantage held by the Cosworth-powered teams, the little AMC effort was truly impressive. From its wonky hand-fabricated plenum chamber atop the engine to the bowling ball-size turbo and wastegate hanging off the back of the motor, the AMC V8 had bad intentions written all over it.

The AMC’s staggering power proved to be more than the gearbox could handle, and with its clutch thoroughly fried, McCluskey’s day ended after 82 laps in 25th place.

To think—16 years later, citing the impressive performances he’d seen with stock-block Indy 500 engines and their extra boost, Roger Penske and Ilmor Engineering took a page from AMC and exploited USAC’s rules to build the “Beast”

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4. 1967 SMOKEY YUNICK EAGLE-FORD

Motor racing’s brilliant mind was not going to let the rule makers at Indianapolis derail his aerodynamic explorations. Smokey Yunick’s surprisingly conventional 1967 Indy 500 entry was downright sane compared to most of the mad-cap cars he hauled to the Speedway. But the subversive Florida-based car builder couldn’t help himself when it came to the City of Daytona Beach Special, and while it doesn’t have a giant wing mounted over Denny Hulme’s head like his 1962 entry, it’s easy to appreciate Smokey’s subtleties.

He wasn’t the first to use wheel covers, and but he was most likely the first to bridge the topside exhausts with a piece of metal to provide rudimentary downforce at the back of Hulme’s Eagle. Using holes clamps to hold the flat plate in place, Yunick found a workaround that complied with USAC’s ban on wings, yet gave the New Zealander a small amount of extra grip for his rear Goodyear tires.

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Compared to Bobby Unser’s 1967 Eagle-Ford, Smokey’s version of the same car looks truly advanced—a year or two ahead of its contemporaries—in a good way, for once. With Yunick taking an unfamiliar approach to the Indy 500 in 1967 by trying to beat his rivals at their own game instead of trying to win through unrestrained innovation, he achieved his best result at Hulme motored from 24th to fourth at the finish.

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5. 1965 MICKEY THOMPSON CHALLENGER WHEEL SPECIAL

This car—and the contraption beneath its front wheels—own a special place in my heart. Of the many weird concepts that managed to reach pit lane at Indy, 1965’s Mickey Thompson Challenger Wheel Special is in a category of its own.

Bearing in mind the 500’s rear-engine revolution began in 1961, the choice to show up in 1965 with a front-engine car involved a special kind of self-confidence. Jimmy Clark would blitz the field in his rear-engine Lotus 38 in 1965, sealing the fate of the front-engine Indy 500 car, but that didn’t seem to faze Thompson.

With most of the field—27 of the 33 starters—in rear-engine cars, Thompson did as expected by bucking popular trends with his front-engine, front-wheel-drive Indy car. Yes, a FWD car, a “puller,” attempted to make the show as recently as 1965. Blind-faith Bob Mathouser attempted to get the Chevy-powered mutt up to speed but ultimately failed to muster the pace needed to make the grid.

And what exactly was the platform beneath the Mickey Thompson Challenger Wheel Special? A miniature rolling dyno, perhaps? No, that’s Indy’s biggest starter, which used batteries and electric motors that turned metal barrels to spin the front wheels and fire the engine.

Coming next Tuesday—Part 3 of our Weird and Wonderful Indy 500 cars, where we’ve saved some of the craziest cars for last.

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About The Author

Marshall Pruett

Marshall Pruett transitioned from more than 20 years as an open-wheel and sports car mechanic, engineer and team manager into his current role as a writer and reporter in 2006. Follow him @MarshallPruett [https://twitter.com/marshallpruett]
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