Weird and wonderful Indy cars: The dynastic McLarens

Published On August 10, 2016 » 2819 Views» By Marshall Pruett » Blogs, IMS, Indy 500

Regular #SpeedRead readers will recall Marshall Pruett’s eight-part series on “Weird and Wonderful Cars of the ‘500’” that appeared in the weeks leading up to the 100th Running of the Indy 500 presented by PennGrade Motor Oil. Now, the feature continues with one car featured biweekly.

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The numbers associated with McLaren’s M16s are the only things that could be described as gaudy and impolite. The rest of the immaculate machines, in the original 1971 M16A form or the M16B/C/D/E evolutions that followed through 1976, earned three Indianapolis 500 wins and set a motor racing dynasty in motion at “The Greatest Spectacle in Racing.”

Powered by the volcanic Offenhauser four-cylinder turbo, those McLarens sent Roger Penske and Mark Donohue to Victory Lane for the first time in 1972, and under the Bruce McLaren Motor Racing banner, wins in 1974 and 1976 followed with Lone Star JR—Johnny Rutherford—behind the wheel.

Roger Penske's first "500" win came in 1972 in a McLaren driven by Mark Donohue.

Roger Penske’s first “500” win came in 1972 in a McLaren driven by Mark Donohue.

The tidy chassis designed by Gordon Coppuck, and its revision by the legendary John Barnard towards the end of its tenure, was a revelation. The wedge shape, clean airflow behind the front wings, compact sidepods, and gigantic rear wing presented its drivers with impeccable chassis balance.

Easily mistaken for a barn door, that never-ending rear wing wasn’t built simply to impress with its sheer size; it played a significant role in taming the 800-plus horsepower dispatched through the McLaren’s rear tires. And as that Offy was boosted harder and pushed farther to its limits, the red-hot four-banger crept north of the magical 1,000 horsepower mark and the M16s were duly developed to cope with the hell visited upon the Brickyard’s track surface.

Three Indy 500 wins across a six-year span was an impressive feat for the M16 series, and with a quick compare and contrast of its major figures to today’s Dallara DW12 chassis when it was originally delivered in 2012, the differences are readily apparent.

From a McLaren press kit circa 1974.

From a McLaren press kit circa 1974.

The first number of interest is the height of the McLaren. At just 32 inches tall, the M16 was noticeably shorter than the current-day DW12–with its overhead air intake and roll hoop structure–that reaches 44.4 inches. The widest point of the M16 was 63.5 inches; the DW12 takes that number up to 79.2. When it comes to length, the McLaren was an even 180 inches long while the Dallara comes in at 197.3. The Dallara’s wheelbase extended out to 121 inches in its earliest iteration; the McLaren was a modest 106 inches.

More than a foot lower, narrower, and shorter, the M16 was a compact beast.

The Dallara came with an approximate front/rear weight distribution ratio of 43/57, and that number has improved—moved forward a few points—after some modifications permitted by INDYCAR. The McLaren was measured at 30/70, yet its drivers rarely complained of innate understeer.

The M16, with large fuel bladders saddled to the sides of the cockpit, carried 40 gallons of fuel. DW12 drivers have less than half that amount—18.5 gallons—to deal with and it sits in a bladder between the cockpit and engine bay.

The McLaren, long before the advent of carbon-fiber tubs, bodywork, and brakes, tipped the scales at 1,500 pounds without fuel. The Dallara, with more systems, auxiliaries, and a massive amount of safety advancements from nose to tail, crossed the scales at something in the 1,565-pound region in its first season.

One was raw, the other is heavily refined, and together, the M16 and DW12 represent diametrically opposed methods of achieving the same means. Today’s drivers can lap Indianapolis without having to lift off the throttle, which speaks to all of the advancements in aerodynamics, tire technology, and suspension design.

The thought of turning a single lap at full throttle during the M16’s era was nothing but a dream, but that isn’t the measure of a car’s greatness. Imagine strapping into Donohue’s race winner, or Rutherford’s rocket, spooling up that giant Garrett turbo, and unleashing 1,000 hp in a straight line.

Then imagine mashing the throttle in the short chutes, and then trying to stay buried in the gas heading towards Turn 1 until your supply of bravery ran dry. And then picture picking up the throttle exiting Turn 1, lifting again before Turn 2, feeling that 1,000 hp come to life out of Turn 2 and into Turn 3 before lifting and going through the same process into and out of Turn 4.

Two hundred laps of trying to connect all four corners with insane power in a McLaren M16, all while fighting with 32 other drivers with similar cars and the same kind of power. Just imagine.

Johnny Rutherford's 1976 win marked the third "500" title in five years for McLaren.

Johnny Rutherford’s 1976 win marked the third “500” title in five years for McLaren.

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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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