For 3.6–4.0 litre air-cooled engines with 3-stud heads - 993 3.8 conversions and big-displacement builds where intake restriction matters most. Intake bore: 45 mm.
Throttle barrels in sealed ball bearings; quality bearings and rod ends with stainless fasteners; all sealing by Viton O-rings to prevent false air
Included
Complete throttle linkage incl. rod ends, and fuel rails with bracket for short or long injectors - ready to fit, no modifications needed
Injectors
Made for the EV6 injector type; other injector types can be made to order
Air conditioning
A/C compressor option available with flat right-hand-side throttle body
Custom bores
Custom bore sizes available on request
Engine management
Standalone ECU calibration required. We recommend MoTeC and can provide a MoTeC base map.
Optional add-ons
Stacks - 50 mm bore, 120 mm length - $800
Plenum flanges - 50 mm bore, 57 mm OD - $200
Add-on pricing shown in AUD via Rennen Plus; regional pricing confirmed at quotation.
Recommended supporting components
Configure the complete package
Each Rennen ITB system can be configured with injector, MoTeC ECU and ITG filtration options according to engine size, camshaft, use case and installation requirements.
Fuel
Injector package
Specified to your engine and ECU - size, spray pattern and fuel pressure matched to displacement, cams and intended use.
Engine management
MoTeC ECU integration
Recommended for high-control builds. MoTeC base map available as a calibrated starting point; other standalone ECUs supported.
Filtration
ITG filter package
Road, tarmac or gravel specification - protection for the induction system without compromising the ITB airflow character.
Calibration is part of the system.
An ITB conversion only performs as well as its mapping. Plan for professional installation and dyno calibration - see Installation & Tuning.
For coil-on-plug ignition, note that crank trigger wheels are engine-specific - the 964 uses its own, and pulley diameters vary by model, so we machine a wheel to your diameter and TIG-weld it to the pulley. On the 964 the cam sensor lives in the distributor, so a new cam sensor must be installed for coil-on-plug.
Mechanism
Actuation, linkage & trigger hardware
Every Rennen ITB system is supplied complete with its actuation and throttle linkage - machined from billet, running on quality bearings and rod ends for precise, repeatable throttle response across all six bodies - plus the vacuum log, tube set and a crank trigger wheel machined to suit your engine for standalone engine management.
Throttle actuator · billet bracket & rod-endThrottle linkage · return spring & rod-endsCrank trigger wheel · TIG-welded to pulleyVacuum log, tube set & fittings
Specify your system
Tell us about your engine. We’ll quote the right system.
Every quotation is matched to your displacement, cylinder heads and engine management. Custom bore sizes are available on request.
