Overview
The 903's second season in the CALM All Porsche Trophy was run in the Invitation Class, still on the Paxton supercharger and 306bhp. It brought an Invitation Class win on a wet Easter Monday at Donington Park, a best lap of 1min52.077secs at Brands Hatch that would stand as the car's record there for two years, and a season finale at Croft cut short by contact on the last lap of the first race.
Brands Hatch also delivered the lesson that shaped everything that followed. Racing in the June heat, excessive intake air temperatures were limiting what the Paxton-supercharged engine could deliver. With no intercooler possible on the Paxton, that observation set the direction for the Rotrex supercharger and intercooler programme over the following winter.
Round 1: Donington Park National Circuit, 1st April 2024
The season opened on Easter Monday at Donington Park with a single pit stop race for 32 cars. Qualifying ran in showers and the 903 lined up 24th with a 1min41.963secs. The race was run on a wet and slippery track, and the car worked its way up to finish 18th overall, setting a best lap of 1min35.526secs and winning the Invitation Class, the best result of the 903's UK racing to that point.
Round 2: Thruxton Circuit, 4th May 2024
The 903 did not take part.
Round 3: Brands Hatch Grand Prix Circuit, 29th June 2024
Round 3 was part of MSVR's Super Touring Power festival, with a shared grid of 46 cars, 23 of them Porsches, alongside Bernie's V8s and Historic Outlaws, and 22,000 spectators booked in. It was dry and warm throughout. The 903 qualified with a 1min56.415secs, improved to 1min55.370secs in the first race and then to 1min52.077secs in the second, where the series report had the 903 in a group of four cars "swapping places" for the whole race. It won the Invitation Class in both races. It was also here that the heat exposed the intake air temperature ceiling on the Paxton.
Round 4: Snetterton 300 Circuit, 3rd & 4th August 2024
The 903 did not take part.
Round 5: Croft Circuit, 21st & 22nd September 2024
The CALM All Porsche Trophy made its debut at Croft, a six-hour drive north, with qualifying, two 20-minute sprint races and a 40-minute pit stop race in changeable conditions. A slipping clutch in qualifying left the 903 last on the grid with a 1min53.179secs, but the problem was sorted in time for the first sprint race. There, with a best lap of 1min47.999secs, the car was well on its way to the Invitation Class win and a close race with Hugh Peart's 924, when a last-lap coming together with another car while being lapped ended it. The nearside rear wheel was damaged beyond repair and the steel rear swingarm badly bent, and the 903 could take no further part in the weekend. The winter repair replaced the swingarms with the later aluminium type with larger wheel bearings, together with later outboard wheel flanges and new spring plates.