In the 1968 Indy 500 the lone STP-Paxton Turbocar raced in 1967 was replaced by three Lotus Type 56 Turbocars, all sponsored by STP Oil treatment and all three owned by Andy Granatelli. In the order finished, Joe Leonard was #60, Art Pollard was #20 and Graham Hill was #70.
Joe Leonard #60 started on the pole position but ended up 12th. He completed only 191 laps, out with a fuel shaft failure. He led 51 laps and earned $37,403. The car owner was an Andy Granatelli. The chassis was a Lotus and the engine was a Pratt & Whitney turbine, a slightly different variant than the Pratt & Whitney turbine used in 1967.
Art Pollard #20 started 11th and ended up 13th. He completed only 188 laps, out with a fuel shaft failure. He didn’t lead any laps and earned $12,833. The car owner was Andy Granatelli. The chassis was a Lotus and the engine was a Pratt & Whitney turbine, a slightly different variant than the Pratt & Whitney turbine used in 1967.
Graham Hill #70 started 2nd and ended up 19th. He completed only 110 laps, out with a crash. He didn’t lead any laps and earned $13,693. The car owner was Andy Granatelli. The chassis was a Lotus and the engine was a Pratt & Whitney turbine, a slightly different variant than the Pratt & Whitney turbine used in 1967. Racing-Reference.info
Mike Spence and #30 tragedy earlier in May: Following Jim Clark’s death in early 1968, Colin Chapman invited Spence back to Lotus as part of their Indianapolis 500 race team. Spence was due to race the revolutionary Lotus 56 gas turbine car. During practice at the Indianapolis Motor Speedway on Tuesday, 7 May, Spence, driving the #60 Lotus 56 turbocar (later qualified and driven by Joe Leonard), ran a lap of 169.555 mph – fastest of the month so far. Later in the afternoon, Spence was asked by Chapman to take out turbocar #30 for a test run after driver Greg Weld had difficulty getting the car up to speed. Spence quickly got the car to a lap of 163 mph, but on his second lap he misjudged his entry to turn one and collided heavily with the concrete wall. The right-front wheel of the Lotus swiveled backwards into the cockpit and struck Spence on the helmet. Mike Spence died in the hospital later that evening at 9:45pm from massive head injuries. His fastest lap speed set earlier that day would remain unsurpassed for the next five practice days. Wikipedia Link
Engines for both the 1967 STP-Paxton Turbocar and the 1968 Lotus 56 Turbocar: Variant of the Pratt & Whitney Canada PT6.
The ST6B-62 was a 550 bhp (410 kW) version of the PT6 developed for use in the STP-Paxton Turbocar, raced in the 1967 Indianapolis 500.
The STN 6/76 was a 500 bhp (370 kW) version of the PT6 developed for use in the Lotus 56, raced in the 1968 Indianapolis 500 and later in Formula One races, in 1971.
That puts both of them in the horsepower category of the PT6A-21 550 shp engine with applications to the Beechcraft King Air C90A/B/SE, Beechcraft Bonanza (turbine conversion), and Evektor EV-55 Outback. Wikipedia Link
The Lotus 56 used a modified version of the ST6 gas turbine used on the STP-Paxton Turbocar (“Silent Sam”) that almost won in 1967. The ST6 was based on a small aircraft engine that would become one of the most popular turboprop aircraft engines in history. But the car itself was an entirely new and more advanced design which introduced a distinctive aerodynamic wedge-shaped body rather than a cigar-shape, in the year of the introduction of front and rear wings to F1. USAC, the governing body of the Indy 500, had implemented new rules aimed at handicapping turbine powered racing cars by drastically reducing the air intake size. The Lotus 56 made up for reduced power with a sophisticated suspension design, retaining the 4 wheel drive concept of the Silent Sam, but with lighter weight, and advanced aerodynamics.
Lotus had suffered the death of driver Jim Clark in a Formula 2 race in Germany. Mike Spence was killed at Indianapolis while testing one of four 56s built. The remaining three cars with Graham Hill, Joe Leonard, and Art Pollard were entered for the race, with Leonard claiming pole position. Unlike the year before, when the STP-Paxton Turbocar easily outperformed the other cars in the race, in the race the turbine cars were relatively evenly matched with the other top contenders, much of which must be attributed to aerodynamics and chassis design and not to the turbine engine. Hill’s car crashed, Pollard’s car broke down, while Leonard was leading with just a handful of laps to go when the a fuel pump shaft failed. Shortly thereafter, the USAC imposed additional restrictions on turbine cars that essentially removed them from competition. For the second year in a row STP turbine cars had brought innovation to the Indy 500 and had failed to win while leading within a few laps of the end of the race. USAC subsequently banned turbine cars and four-wheel drive completely, but it was unusual enough that Mattel produced a model of the “Lotus Turbine” as one of the popular mass-produced die cast Hot Wheels cars.
In 1971 the Lotus 56 was raced in Formula 1 on occasion by Team Lotus but the large fuel tanks required to allow it to run an entire race without refuelling left it overweight and uncompetitive.
The Lotus 56, while never winning a race, demonstrated the importance of aerodynamics in racing cars, along with Jim Hall’s Chaparrals, and effectively set the mould for open-wheeled racing cars for the next ten years. Chapman’s Lotus 72 employed the same wedge nose shape and went on to win three world championships in Formula 1. Wikipedia Link
May 30, 1968 – The Indianapolis 500. After being unable to get the Thermo-King Special into the 500, Art was given a chance in the wedge shaped 4WD STP Lotus Type 56 Turbine #20 (shown above) after assigned driver Jackie Stewart stepped down with a fractured wrist he suffered in a formula 2 practice crash in Spain. Art was offered a $50,000.00 signing bonus from Andy Granatelli and Andy bought out Art’s contract with Gerhardt.
Art teamed up with 1966 Indy 500 winner Graham Hill #70, and motorcycle ace and 1968 Indy pole sitter Joe Leonard in the STP Turbines. Art Pollard set fast practice time of the day on May 20th with a speed of 168.099 mph. Hill crashed after 110 laps. Art Pollard’s fuel shaft broke 3 laps prior to Joe Leonard’s fuel shaft failure. Art placed 13th again, behind Leonard after starting 11th.
Again, Art missed Championship points by one position. Art was awarded $12,833.00. As usual, Bobby Unser won this race also. A side note to this is that Gary Bettenhausen took over the Thermo-King #11. Gary qualified the car 22nd and finished 24th after hitting debris due to Al Unser’s crash. Formula One driver Mike Spence was killed earlier in the month when a wheel folded up on impact with the wall and hit him in the helmet. Spence was driving an identical STP Lotus Turbine.
1. 1968 Indy 500, The Classics
2. 1968 STP Lotus 56 Turbine Indy 500 Car