Roller Barrel ITB Upgrade Kit. Porsche 964 3.8ltr / 4.0ltr  ❭  ITB38403BOLT

Rennen ITBs for Air-Cooled Porsche 964 - Advanced Roller Barrel Individual Throttle Bodies 

The Rennen ITBs by JSR represent the next generation of individual throttle body technology for air-cooled Porsche 964 engines. Designed and engineered specifically to extract optimal performance from classic Porsche flat-six engines, these innovative roller barrel throttle bodies deliver exceptional airflow, sharper throttle response, and improved engine efficiency compared to conventional butterfly valve throttle body systems.

Fits:

• Porsche 964 (911) C2 1989-93
• Porsche 964 (911) C4 1989-93
• Porsche 964 (911) RS 3.6L 1991-93
• Porsche 964 (911) RS 3.8L 1991-93

Developed through extensive research, flow simulation analysis and real-world testing, the Rennen ITB system provides a premium induction solution for performance-focused Porsche enthusiasts, restorers, track-day drivers and motorsport applications.

Whether you are building a high-performance Porsche 911 engine or converting a classic air-cooled Porsche to modern EFI, Rennen ITBs by JSR offer a significant advancement in intake technology.

Why Choose Rennen Roller Barrel ITBs?

Unlike traditional individual throttle bodies that utilise a butterfly valve positioned directly in the airflow path, the Rennen ITB system features a precision-engineered tapered roller barrel design.

This innovative approach provides several key advantages:

Unrestricted Airflow

The roller barrel design eliminates the butterfly valve obstruction found in conventional throttle bodies. With no throttle plate disrupting airflow, air moves more efficiently into the engine, improving volumetric efficiency and overall performance.

Increased Air Velocity

Because there is no butterfly valve occupying space within the throttle bore, the throttle body diameter can be optimised to maintain higher air velocity. Higher intake air speed promotes superior cylinder filling and enhanced engine response throughout the rev range.

Superior Fuel Atomisation

At partial throttle openings, airflow passes directly over the fuel injector. This promotes exceptional atomisation of the air-fuel mixture, improving combustion efficiency, drivability and throttle progression.

Instant Throttle Response

The short distance between the roller barrel and the inlet valve creates a highly responsive induction system, delivering immediate engine response and a direct connection between driver input and engine output.

The ITB kit comes with the ITBs mounted on intake manifolds and with fuel rails made for the EV6 injector type. 

Advanced Flow Simulation & Development

Extensive computational fluid dynamics (CFD) analysis and development testing have been carried out to optimise every aspect of the Rennen ITB design.

Flow simulation data demonstrates:

• Direct airflow over the fuel injector during part-throttle operation.
• Significantly reduced turbulence around the injector area compared to traditional butterfly throttle bodies.
• Up to 20% less airflow restriction at full throttle when compared with conventional ITB systems.
• Improved airflow consistency across all cylinders for enhanced engine balance and performance.

The result is a highly efficient induction system capable of supporting both fast road and high-performance motorsport applications.

Premium Motorsport-Grade Construction

Every Rennen ITB by JSR system is manufactured to the highest standards using precision CNC machining and premium materials.

Precision CNC Machined

All components are machined from high-grade 6082-T6 aluminium to ensure exceptional dimensional accuracy and durability.

Perfect Airflow Distribution

Tight manufacturing tolerances ensure evenly distributed airflow across all throttle bodies, promoting balanced cylinder performance and simplified engine tuning.

Easy Synchronisation

The robust design incorporates minimal joints and connections, allowing straightforward throttle synchronisation and reducing the need for ongoing adjustment.

Long-Term Reliability

Throttle barrels are mounted within sealed ball bearings for smooth operation, durability and long service life under demanding conditions.

Premium Sealing Technology

All sealing surfaces utilise Viton O-rings to prevent false air entry and maintain optimal engine performance.

Quality Components Throughout

Only premium bearings, rod ends and stainless-steel fasteners are used throughout the assembly, ensuring reliability and durability in both road and track environments.

Hard Anodised Finish - Available in Gun Metal or Black Finish

All aluminium components receive a hard anodised gunmetal grey finish, providing corrosion resistance and an attractive motorsport inspired appearance.

Specification
Fuel Rails machined for EV6 injector type
3 bolt inlet manifold to cylinder head mounting
50mm velocity stack ID
120mm velocity stack length

The Ultimate Porsche Individual Throttle Body Upgrade

For enthusiasts seeking the ultimate air-cooled Porsche induction system, Rennen ITBs by JSR combine cutting-edge engineering, advanced airflow technology and premium construction quality. The innovative roller barrel design delivers exceptional throttle response, improved airflow efficiency, enhanced fuel atomisation and proven performance gains.