This engineering study evaluates the projected performance of Dave Cooper's Jensen-Cooper on the historic 2.56-mile Riverside International Raceway Short Course using known historical benchmarks and a detailed analysis of drivetrain, tire, braking, aerodynamic, and induction system variables.
| Vehicle | Lap Time |
|---|---|
| 1972 Ferrari 365 GTB/4 Daytona Competizione | 1:35.20 |
| 1973 Huffaker SCCA Jensen-Healey | 1:36.40 |
| Stock Ferrari Daytona | 1:43.40 |
| Stock Jensen-Healey | 2:00.9 |
The objective is to determine how the unrestricted systems architecture of the custom Jensen-Cooper addresses the limitations inherent in the historic Huffaker competition car and how those improvements influence lap time performance on Riverside's Short Course.
Initial predictive modeling indicated that the primary performance divergence would occur at terminal velocity along Riverside's long back straight.
When top speed is effectively capped by track layout rather than power output, the critical metric becomes rate of acceleration rather than terminal velocity. The taller 24.86-inch rear tire and close-ratio Getrag gearbox maintain engine operation deeper within the torque band while minimizing rpm drop between shifts. The result is improved longitudinal acceleration throughout the lap.
Would the wider rear tire package dramatically increase cornering grip through raw contact-patch area alone?
Performance gains originate primarily from footprint geometry rather than simple section width. The 225-section rear tire creates a longer longitudinal contact patch, improving braking and traction under acceleration. Up front, the shorter sidewall of the 205/50R15 package provides crisp turn-in response through Riverside's technical sections.
Unlike a peaky vintage race engine, the Jensen-Cooper delivers consistent torque across a broad operating range. The Gripper LSD mechanically redirects power away from slipping inside wheels and converts available torque into forward acceleration with minimal energy loss.
The Huffaker race car remained restricted by SCCA D-Production requirements using a Zenith-Stromberg CD175 intake system. The Jensen-Cooper utilizes individual-runner Jenvey electronic fuel injection.
This represents one of the largest performance separations between the two cars. The Jenvey system eliminates fuel slosh, throttle lag, and intake restrictions, providing immediate throttle response and maximizing volumetric efficiency throughout the operating range.
Riverside rewards deep braking. The modern four-piston braking package provides superior thermal management and repeatable stopping performance, enabling later braking zones while maintaining stability through the retained rear drums.
Measured drag coefficient: Cd 0.38
Matching the approximate aerodynamic efficiency of the Huffaker race car means the Jensen-Cooper's horsepower advantage is not consumed by increased drag. Additional power is translated directly into acceleration rather than atmospheric resistance.
Corner Entry
BCC 4-Piston Calipers + Drilled/Slotted Rotors → Maximum thermal dissipation → Deeper braking capability
205/50R15 Bridgestone RE-71RS Front Tires → Crisp turn-in response
Apex Transition
Jenvey Individual-Runner EFI → Instant throttle response → No fuel slosh
180 lb-ft Torque Plateau → Predictable power delivery
Getrag 235/5 Dogleg 5-Speed → Reduced rpm drop
Gripper Multi-Plate LSD → Transfers torque to loaded wheel
225/50R16 Bridgestone RE-71RS Rear Tires → Extended longitudinal contact patch
Aerodynamic Efficiency Profile (Cd 0.38) → Race-car-level drag efficiency
Corner Exit Acceleration
Maximum traction efficiency driving acceleration toward the 135 mph braking threshold.
Using the proven 1:36.40 Huffaker Jensen-Healey lap as a benchmark, the Jensen-Cooper's additional horsepower, broad torque plateau, electronic fuel injection, close-ratio gearing, limited-slip differential, modern tire package, and improved braking system collectively create a substantial performance advantage.
Engineering analysis indicates that these integrated improvements reduce lap time by approximately four seconds compared to the historic Huffaker car.
| Vehicle | Lap Time |
|---|---|
| 1972 Ferrari Daytona Competizione | 1:35.20 |
| 1973 Huffaker Jensen-Healey | 1:36.40 |
| Jensen-Cooper (Projected) | 1:32.40 |
A secondary engineering analysis examined the effect of mechanically shaving Bridgestone RE-71RS tires to competition tread depths of approximately 3/32 to 4/32 inch.
The reduced tread depth effectively moves the tire closer to a racing slick behavior profile. The resulting gains in stability, heat management, and response are projected to reduce Riverside lap times by approximately 0.50 to 0.80 seconds.
| Configuration | Projected Lap Time |
|---|---|
| Full-Tread Bridgestone RE-71RS | 1:32.40 |
| Shaved RE-71RS (3/32–4/32) | 1:31.70 |