Individual throttle bodies for the air-cooled Porsche 911.
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Rennen ITB replaces the butterfly valve with an elliptical roller barrel. The bore tapers continuously from air horn to cylinder head - at full throttle, nothing obstructs the airflow. Bespoke systems for 2.7 to 4.0 litre engines, 2-stud and 3-stud heads.
Representative system visualisation, not measured data. JSR’s flow data indicates approximately 20% less airflow restriction at full throttle than a conventional butterfly ITB of comparable size.
A throttle body designed around the airflow, not around a plate.
No butterfly in the airstream
A conventional ITB leaves its shaft and plate in the bore at every throttle opening. The Rennen elliptical roller barrel rotates completely out of the airflow at full throttle.
Continuously tapered bore
Each throttle body tapers from the air horn down to the cylinder head, keeping air velocity high and the flow path clean along its entire length.
Atomisation by design
At part throttle, the airflow is directed over the injector, improving fuel atomisation where road cars spend most of their time - not just at wide-open throttle.
Three systems · One platform
From Carrera 3.2 restomods to 4.0-litre race builds.
Small bore · 2-stud
Small Bore ITB System
For 2.7–3.0 litre engines with 2-stud heads. Intake bore options: 39 mm or 41 mm.
Six elliptical roller-barrel throttle bodies, CNC-machined from EN-AW 6082-T6 aluminium with a hard-anodised finish.
Complete throttle linkage
Full linkage including rod ends - ready to fit, no modifications needed.
Fuel rails
Fuel rails with bracket for short or long injectors. Made for the EV6 injector type; other types made to order.
Options to suit your build
Stacks/trumpets and plenum flanges in various sizes, custom bore sizes, and an A/C-compatible flat right-hand-side throttle body.
Engineered & made in Denmark
Machined by CNC. Built by hand.
Every Rennen ITB system is CNC-machined from billet EN-AW 6082-T6 and built up by hand at JSR Engineering in Denmark - barrels fitted to their sealed bearings, linkages assembled and set, and every system inspected before it ships.
On the machine · in-process inspection, Denmark
Behind the scenes · JSR workshop, DenmarkHand assembly · linkage set-up and inspection
Sound & motion
Six throttles. One voice.
Video - 964 3.6 on Rennen ITB · coming soon
Sound - throttle response at idle and load · coming soon
UK & Europe
Distributed exclusively by Design 911
Rennen ITB systems are distributed exclusively in the UK and Europe by Design 911, the Porsche parts specialist.
Rest of world
Global distribution by Rennen Plus
Rennen Plus is the global distributor for Rennen ITB and your first stop for quotes, orders and product enquiries. Dealer and distributor enquiries are welcome from other regions.
Small bore · 2-stud
Medium bore · 2 or 3-stud
Large bore · 3-stud
