SOLD 06/23

1975 Porsche
911 RSR IROC Tribute

Freshly rebuilt engine and transmission. Regular CSRG, HMSA competitor. Safe, satisfying, and reliable. Beautiful presentation with "IROC" style graphics.

  • VIN9115200545
  • Exterior ColorBlue
  • Interior ColorBlack
  • Mileage87009 Miles (TMU)
  • Engine3.0L flat 6-cylinder
  • Engine no.*6403192*
  • Transmission5-speed manual
  • StatusSold
  • StockFJ2751


1975 Porsche RSR Tribute
Chassis No. 9115200545
Engine No. 6403192

General History

Few cars can rival the original Porsche Carrera RSR. Porsche Rennsport factory cars are considered among the most desirable of the 911 series race cars and rightly so. Their track record, history, and unquestionable performance make the RSR not only something special, but also of extraordinary contemporary value amongst collectors and enthusiasts. In recent years, RSRs have been restored and extensively rebuilt after years of demanding track use. And while just 39 factory-assembled examples were built in 1974, a few dedicated vintage racing enthusiasts have attempted to build vintage racing examples. As one might expect, tribute outcomes vary depending on financial limitations, hardware choices, and professional expertise. In the case of this example, the build quality, careful choices of both components and fabrication team, precision sorting, testing, and recent restoration have all contributed to making this RSR Tribute an exceptional depiction of these ground-breaking performance cars.

History of This RSR Tribute

This RSR Tribute began as a complete, street driven 1975 Porsche. With a keen interest in racing, the owner. Mike Lyle engaged veteran race car builder Don Cox to build the first iteration of this Porsche. Cox, a Penske Racing Team engineer with extensive Porsche experience, built the car to racing specifications. One of many Spec 911 builds and SCCA/NASA cars built by Cox, the car began racing with Lyle at the wheel in 1995. After numerous racing events in the midwest, efforts in 2017 and 2018 continued, refining the RSR Tribute. in 2019 Lyle brought the car to the west coast. After a bump in 2019, Lyle engaged experts at Flying Lizard to professionally repair the car. The current owner purchased this RSR Tribute in 2020. After the 2020 racing season, the current owner commissioned a substantial cost-no-object build to exceptional mechanical levels engaging some of the top names in vintage racing.

Entrusted to specialists including Huffaker Engineering, Wayland Motorsports, and RetroSport, to name just a few, this Porsche was fully disassembled for extensive rebuild and restoration in preparation for future racing duty. With all major components removed, the entire car was evaluated for improvements, new structural features, and rebuilt or new components as needed. Photos documenting this work include modifications to the front storage compartment, which was completely stripped, front fenders removed, and a new tubular steel cage fabricated and installed for added strut tower and forward structural reinforcement. New strut tower metal structure was fabricated and welded with new front fender inner seams, and new air inlet ducts. Brake ducts were also fabricated along with a new front air exchanger box. The front floor was cut to allow a safety FuelSafe fuel cell to fit into a custom steel frame. Specialized front suspension components were fitted to the chassis, new CV inner joints, CV boot kits, new trans cooler, and a Weldon 9200A differential pump. A new oil cooler was also installed along with rebuilt front struts and new spherical balls on top of the strut assembly. The center section of the car was also pared down to the essential steel structure and fortified with perimeter side impact tubular steel framework integrated into the roll cage which also supports front cross bar protection and perimeter roll cage tubing for the front and rear of the passenger compartment. While the drivetrain was removed for rebuild, all systems were evaluated and fully addressed including the addition of a new Sparco Evo racing seat, Sparco seat bracket set, and harness. Final paint was applied throughout the interior and exterior along with graphics replicating the original 1974 Bobby Unser livery.

With the new engine and gearbox installed in the car, the owner participated in further vintage events before returning to the shop for another level of development, raising the bar to the high standard presented today. After a December 2020 nut and bolt takedown, full brake inspection and further refinement, Huffaker and the owner made the decision to remove the engine and transmission for further development. With the engine and gearbox removed, the suspension, steering, and other systems were reevaluated at Wayland Motorsports. The front and rear suspension was removed and rebuilt with an RSR rear coil over setup, Racing 934 rear shocks, RAR adjustable bump-steer kit, replacement camber plate welding (plasma torched box plates), and other noted details as itemized in the records accompanying this car. The engine was broken down and fully inspected for crankcase wear. Machining for the spacers, valves, exhaust porting, rocker touch up, and a new GTR3 main bearing set were prepared as well as further machining and measuring to confirm specs during engine reassembly (total invoice $26,700). The transmission was rebuilt by RetroSport including a complete 915 main shaft set, new gear sets (specs on file), shifting and guide sleeves, synchros, and a short shift kit (Factory option M241), invoice total $7,600.00. The transmission was completed and shipped to Huffaker for final assembly.

By October 2021, the completed engine and transmission was installed and prepared by Huffaker for the next events. While the engine was being built, Huffaker continued work including scaling the car, alignment, new exhaust construction, and racing prep for the remaining season. In 2022 the car was prepped for Laguna, followed by post Laguna prep including upgraded steering u-joints, front end alignment, and valve adjustment. Further racing in 2023 was followed by track support, a fresh battery, nut and bolt (April 2023), helicoil for transmission bolt, head re-torque, as well as brakes and fluids.

Having previously been dyno tested by Huffaker and returning significant performance results, this time the fresh engine delivered an impressive 348hp at 7,200 rpm with 258 lb. ft. torque. This Porsche has since continued to offer exceptional results befitting the RSR heritage evoked in this build. As part of ongoing sorting, a three-page driving assessment was performed by SRS racing in January 2020. This driving report and detailed restoration/build documentation are offered with the car along with dyno test results, charts, and notation for review. Since the most recent rebuilds, this car has been raced only once, logging approximately 90 minutes of track time.

Condition Overview

Today this Porsche RSR Tribute presents with excellent visual and mechanical features throughout. Beautifully finished in correct Bobby Unser 1974 IROC livery reflecting the original car he’d driven to third place at Daytona in a grid consisting of some of the best drivers competing that season. The vivid blue color presents beautifully over the 911 profile accented by molded front and rear bumper caps, wide rear fenders, integrated front air dam, vented whale tail, covered headlights, and large diameter dual exhausts. The accurately depicted Unser livery and period correct sponsorship markings are correct and properly scaled to the car. A set of lightened rear and side plastic windows finishes the lightened exterior. The paint is excellent overall, proudly combining 911 racing features with modern vintage racing updates for track use. Having been more recently restored, the paint finish is of high quality with evidence of track use on the forward-facing rear fender flares, typical of race car use.

The factory-lightened interior is functionally elegant, delivering a purposeful feel with a focus on sparse features also updated for modern racing safety and vintage racing use. A factory dashboard and Porsche instrumentation are cleanly displayed and properly finished, though lightened for track use. The perimeter roll cage displays three event stickers from recent races. The roll cage features double tube protection and rear bar support mounts for the driver’s Sabelt 6-point racing harness mated to a recently fitted Sparco seat. The roll bar contains event stickers depicting 2021 and 2022 CSRG 18th and 19th Annual Charity Challenge at Sonoma Raceway as well as a 2023 CSRG vintage racing event. Other racing events for 2022 and 2023 are noted in the logbooks accompanying this car. Further updated safety provisions include a quick release steering wheel, a FireSense fire bottle with May 2018 manufacturing date, contoured passenger racing seat with Schroth Racing 6-point harness (also attached to the rear portion of the roll bar), and a lightweight fabric door pull.

The engine compartment continues the themes of exceptional preparation. The PMO carburetors, Electromotive ignition, carbon fiber engine shroud, and matching blue finish on the engine make for a striking engine compartment. Paint quality in the engine compartment is beautifully presented, backed by excellent finishes to all components and internal structure. The front storage compartment is also finished with the same level of refinement and quality as the rest of the car. An Optima battery is installed along with the FuelSafe fuel cell, recently ducted air hoses, new fuel lines and fuel pump. This car is accompanied by photos of the rebuild and restoration, dyno charts and test information, a 2020 driving report, service invoices and detailed descriptions of the components and features of the engine and gearbox rebuild, and four racing logbooks

This Porsche RSR Tribute represents a rare opportunity to race something as close to an actual Porsche Rennsport Carrera without the worry of risking an authentic artifact of Porsche history. This exceptional example is ready to be enjoyed by the next fortunate enthusiast. Though this car has been fully sorted and prepared by racing professionals to a very high standard, we recommend a racing shop review the car before use in a competitive vintage race or supervised demonstration event.

Select photography curtesy of Allen Rosenberg

The above vehicle information is complete and accurate to the best of our knowledge at the time it is posted to this website. Corrections or additional information is always appreciated. All advertised prices exclude government fees and taxes, any finance charges, any dealer document preparation charge, and any emission testing charge. Vehicles are subject to prior sale. All advertised to be true but not guaranteed. We assume no liability for errors or omissions.

Inquire About This Car

Fantasy Junction  •  510-653-7555  •  1145 Park Ave, Emeryville, CA 94608