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2024 Race calendar

1st April (Easter Monday) - Donington GP - 1 x 40min pitstop race
4th May - Thruxton - 1 x 40min pitstop race 
29th June - Brands Hatch GP - 2 x 25min races
3rd & 4th August - Snetterton 300 - 2 x 15min sprint races plus 1 x 40min pitstop race
21st/22nd September - Croft -  2 x 15min sprint races plus 1x40min pitstop race
26th October - Silverstone GP - Birkett Six-Hour Relay Race - End of season team event

Our series is open to ALL Porsches of any age or persuasion.




Race Format


A mixture of sprint, 15 & 40 minute races, plus qualifying, with a mandatory pit stop.


Great value racing – with the ethos of safe and gentlemanly driving standards.


Entries may be by single drivers or two drivers sharing the same car.


The CALM All Porsche Trophy Series offers competitors a great deal of freedom in tuning your Porsche whilst at the same time providing a framework that keeps cars competitive and cost effective.


The class structure will be organised on a maximum bhp (at the wheels – NOT the flywheel)  per tonne, including the driver, as follows:




  • SP1 181 - 230 bhp/tonne - Blue sticker 

  • SP2  161 - 180 bhp/tonne - Red sticker 

  • SP3 131 - 160 bhp/tonne - Yellow sticker 

  • SP4  Up to 130 bhp/tonne - Orange sticker



Invitation class

Any car not meeting any of the above but deemed a positive entry by the organisers, including fully electric driven cars, meeting the current MSA regulations


A coloured sticker, as described above,  will be provided to identify each class.  The stickers must be applied to the front and rear of the car.


Proof of power and weight must be lodged with the organisers before an entry can be accepted. All power to weight figures must be self declared and will be monitored and checked through the season.


The organisers reserve the right to adjust a competitor's class should lap times in qualifying dictate. 




All CALM races are run to the regulations published by Motorsport UK (MSUK) and it is the responsibility of all CALM drivers and entrants to make themselves familiar with the relevant rules and regulations published by MSUK.


All cars must always carry at least one forward-facing, fully functioning in-cockpit camera when on a live circuit. These must be switched on at all times during free practice sessions, qualifying and the race. The recording (media) must be surrendered upon demand to the Clerk of the Course and the meeting officials as evidence of any incident. Cameras should be mounted so as to capture an image that provides a ‘driver’s eye’ view that should include, where possible, the steering wheel, dashboard, and the view of the circuit ahead with a field of vision of approximately 100 degrees; where the centre of that field of view is pointing directly ahead in the direction of travel of the vehicle.


Driving Standards


All CALM races are strictly non-contact. Any contact incident during the course of an official practice, qualifying or race session will be reviewed and acted upon by the race officials in line with published MSUK rules.

The CALM organisers will also review any contact incidents and may also impose further penalties beyond any imposed by the race officials for persistent offenders and incidents that they deem to be particularly serious. In the most extreme cases, this could include suspension from the series and/or refusal of entries for future CALM events.




Limited production splitters, wings and other aero devices may be allowed provided they are approved by the organisers. The devices must, above all , be securely fitted to the car with robust fittings and must not exceed the roofline or width of the car. Any competitor wishing to fit such devices must obtain permission from the organisers before they use them on track.


The after market GT3 type fibreglass bumpers are allowed on all Boxsters.


Engine and Transmission


Original engine and gearbox type to be retained, internals are free, but no sequential gearboxes, unless supplied in original road car. 'Original engine and gearbox type' means the same engine (block and head) and gearbox as was available from the factory in period.


If fuel-injected, throttle bodies are allowed, fuel-injected cars may run carburettors but not vice-versa. Fuel injection and carburettor type are free. 


Suspension & Tyres


Cars may run on any treaded tyres in Motorsport UK list 1A/1B/1C. No slick or rain tyres allowed except for the Birkett 6 hour race.


Suspension, shock absorbers,springs arms, links, wishbones are free.


Pit Stops


A mandatory pit stop is required for all cars during our 40 minute races. This will allow a driver change in two driver teams, solo drivers can remain in their cars. The engine can be kept running during all pitstops. During the stop, each car must be stationary for 60 seconds, each team will be responsible for the timing of their stop. The organisers will use the official timing provided on the day to police the duration of each stop.




Awards are given at each round: Class winners, 2nd, 3rd  of each SP class will receive trophies.


All cars must display the correct sponsor's and other stickers as supplied by the club upon registration otherwise they may not be eligible for awards.


Technical rights of the CALM All Porsche Trophy organisers


The organisers have the right to overrule any of the above rules, including moving a car between classes and/or treat any applicant individually as seen fit to help promote and to enhance the series, and to protect and respect the position of all existing competitors.


The organisers welcome all new enquiries but advise all interested parties to contact us before building or purchasing a car so we can help ensure the car is suitable for the series. The organisers also reserve the right to re-classify any car from a meeting that does not comply with the series technical regulations or is not prepared to an acceptable standard. The organisers reserve the right to amend these regulations at any time in the year.


Interact with the CALM All Porsche Trophy Series on FacebookX (formally Twitter)Instagram, and YouTube

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