Performance parts are judged by use, not theory.
From Idea to Intake. The Engineering Story Behind JSR ITBs
The JSR ITB story began in 2019, when a group of Porsche enthusiasts set out to modernise their own 911 with EFI. Reviewing the available ITB systems, they found plenty of options but few that balanced airflow, drivability, and packaging. Traditional butterflies felt restrictive, while flat slides lacked progression.
Their answer was a new take on roller barrel throttles. By redesigning the throttle opening with an elliptical profile, JSR achieved the required airflow in a more compact and efficient package, reducing bulk without compromising performance.
Extensive CAD work, simulation, and real world testing led to a design that delivers a smooth, uninterrupted airflow path from the velocity stack to the intake valve. At part throttle, airflow passes cleanly by the injector for excellent atomisation and crisp response. At wide open throttle, the system offers a near straight intake path, maximising flow and power.
JSR Engineering was founded by Jannik and René, both with backgrounds in mechanical engineering and manufacturing. United by a deep passion for Porsche, they continue to develop and refine their systems using constantly evolving test cars.
In 2025, JSR ITBs found a natural home at Rennen Motorsport in Australia, where performance parts are proven through real road, track, and competition use. Tested across Rennen’s own air cooled Porsche builds, the system is now offered locally as Rennen ITBs by JSR. Not a catalogue product, but an engineering led solution focused on usable, repeatable Porsche performance.
Now available and seeking worldwide distributors who share the same passion for Porsche performance.
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Actions speak louder than words
Rennen Gravel Rally Porsche 911
Built In House. Built for Australian Gravel.
The Rennen Motorsport Gravel Rally 911 is a purpose built competition car, engineered and assembled in house specifically for the harsh realities of Australian rally conditions.
Australian gravel is fast, rough and unforgiving. Deep corrugations, square edge hits, embedded rock, bulldust and extreme heat place enormous stress on suspension, drivetrain and chassis integrity. This 911 is developed to withstand that punishment without compromising balance or control.
Engineered for Durability and Performance
- Rennen built 3.2 litre engine running 40mm Weber carburettors
- Speed Custom gearbox engineered for rally durability
- EXC TC gravel rally shocks tuned for sustained high energy impacts
- Fabspeed exhaust system delivering responsive and reliable power
- Perma Tune ignition system built to handle vibration and heat
- MoTeC electronics providing precise control and data capability
Rennen Tarmac Porsche 911
Engineered for Precision. Built to Attack.
The Rennen Motorsport Tarmac Rally 911 is a purpose built competition platform developed in house for high speed sealed surface performance. Tarmac rallying demands absolute precision under braking, stability at speed and immediate throttle response. There is no margin for softness or delay.
Our cars are calibrated for aggressive turn in, controlled weight transfer and consistent grip through long high load corners. Every system is engineered to deliver confidence at the limit.
Core Engineering
- TracTive Suspension tuned for high speed tarmac stability and adjustability
- Fabspeed exhaust system optimised for power delivery and response
- Rennen ITBs by JSR for sharp throttle input and improved airflow
- Rennen lightweight body panels for reduced mass and improved balance
- MoTeC M130 ECU and PDM30 power management system for full vehicle control
- PE Racing pedal box for precise brake bias and driver feel
