Lola T616: the Mazda-engined Group C2 prototype

The Lola T616 was a sports prototype built to the Group C2 and IMSA GTP regulations and intended for the IMSA GT Championship and the World Sportscar Championship. With Mazda’s 13B rotary engine it became the second Mazda-powered prototype to win its class at Le Mans, following the 717C in 1983.

Lola T616 at a glance

based on one source (English Wikipedia). No free photographs of the T616 were found, so the page keeps the old picture of the record.

History of the Lola T616

The T616 was a derivative of the Lola T600, the first sports prototype to use ground effect, a feature the new car kept. The T600 had won IMSA titles in 1981 and 1982, but its competitiveness faded and the arrival of Group C2 rules led Lola to develop the T610 and T616 for smaller engines. The T616 kept the T600’s carbon-fibre reinforced aluminium honeycomb monocoque, with the engine acting as a semi-stressed member together with two tubular frames across the cockpit.

Jim Busby replaced the T600’s 6.0-litre Chevrolet V8 with Mazda’s twin-rotor 13B, a 1,308 cc unit with a twin-spark ignition system from Mitsubishi and Bosch mechanical fuel injection, giving 300 hp and 182 lb ft at 8,500 rpm. Lubrication came from a dry sump. The car carried two different fuel tanks: 120 litres for IMSA and 55 litres for the World Sportscar Championship. At the front the ride height was controlled by outboard A-arms and at the rear by outboard control arms, with the springs and Bilstein gas dampers mounted on top of the crossbeam so that the airflow through the underbody Venturi tunnels was largely undisturbed. Pete Halsmer described the car as a handful to drive, with poor handling and weight distribution that left something to be desired.

Four T616 chassis were built. Three used the Mazda 13B; the fourth carried Matty Holtzberg’s Polimotor, a plastic engine based on Ford’s LL23 inline-four, with much of the timing structure and the connecting rods injection moulded from Torlon, a thermoplastic made by Amoco, the car’s title sponsor. The Polimotor weighed 76.2 kg, 28.6 kg less than the Mazda rotary, and by 1982 with twin overhead camshafts it produced 300 hp at 69 kg. Holtzberg raced it in the 1984 and 1985 IMSA seasons with only one engine-related retirement, a metal connecting rod failure, before a lack of funding ended the programme.

Busby chose not to run a full 1984 IMSA season, picking only the big races. The T616 debuted at Daytona under the BFGoodrich banner: the No. 68 car of Halsmer, Quester, Grable and Knoop finished 11th in GTP, while the No. 67 stopped on lap 391 with a blown engine. At Miami the team took sixth and fifth, and at the 1000 km of Monza the cars finished first and fifth in C2, their best result of the season. At Le Mans the two T616s met Mazdaspeed’s factory 727Cs, which were almost ten seconds a lap quicker in practice but lost time with gearbox trouble; the No. 68 of Morton, O’Steen and Katayama won the C2 class, with Busby third in class, and all four cars finished. At the end of 1984 Lola withdrew factory support from the T600 family, and Holtzberg moved to the new GTP Lights class for 1985.

Design and features

• Rotary power: Mazda’s 13B twin-rotor engine of 300 hp in place of a big American V8.
• Ground effect kept: the T600’s underbody tunnels, with suspension mounted clear of the airflow.
• Two fuel tanks: different capacities for IMSA and World Sportscar Championship races.
• Le Mans class win: first and third in C2 in 1984, ahead of the faster factory Mazdas.
• The plastic engine: one chassis ran Matty Holtzberg’s Torlon-based Polimotor.

Lola T616 versions

• T616 Mazda (three chassis): the standard car with the 13B rotary.
• T616 Polimotor (one chassis): Holtzberg’s car with the plastic engine.

The T616 was derived from the T600 and was the last of that family before Lola turned to the Chevrolet Corvette GTP. More in the Lola collection.

Sources

• Lola T616, English Wikipedia: design, engine, chassis, racing history