Supercharger Oil Cooling System
The report provides a comprehensive overview of the design, implementation, and testing of a supercharger oil cooling system tailored for Paxton SN60 and VS57 superchargers. These superchargers rely on a planetary ball drive mechanism, which is highly effective but prone to significant heat generation. Overheating risks are particularly acute during high-performance scenarios, such as sustained operation with boost levels exceeding 6 psi. This project was initiated to address these challenges, protect the hardware, and extend its service life by maintaining optimal oil temperatures.
Background and Motivation
Paxton SN60 and VS57 superchargers are valued for their performance but require careful thermal management to ensure longevity. Excessive heat, primarily from the ball drive and impeller, can degrade lubricating fluid, reduce efficiency, and cause mechanical wear. Existing aftermarket cooling solutions provided incomplete and inconsistent data on performance, often failing to address critical aspects such as fluid temperature targets or cooling system effectiveness. This project aimed to develop a reliable, self-contained oil cooling system that would ensure consistent performance and durability under demanding conditions.
Design Objectives
The cooling system was developed to meet five key performance criteria:
- Temperature Regulation: Maintain oil temperatures within a range of 150°F to 175°F.
- Flow Rate Control: Enable flow rates adjustable between 0.1 and 1.0 GPM to optimize cooling under varying loads.
- Filtration: Include a 5-micron filtration system to maintain oil quality and prevent system contamination.
- Measurement and Feedback: Integrate sensors to monitor temperature and flow rate, providing real-time data for control and diagnostics.
- Seamless Integration: Ensure the system’s aesthetic and functional compatibility with the existing vehicle setup.
Commercially available cooling kits, such as those from Paradise Wheels, were evaluated but deemed insufficient due to their lack of temperature monitoring, flow control, and unattractive design. These limitations prompted the development of a custom system.
System Components and Design
The custom cooling system consisted of several key components, each carefully engineered and integrated:
- Fluid Pickup Tubes: Custom-designed pickup tubes replaced the factory dipstick tubes, extracting oil from the supercharger reservoirs. These assemblies included internal O-ring seals for secure installation and integrated temperature sensors for real-time monitoring.
- Circulating Pumps: Two RB Racing 12VDC gear pumps (Model 03-140), rated at 1.0 GPM, were used. Each pump serviced an individual supercharger, providing independent operation and flow control. The pumps were mounted on vibration-isolated brackets to minimize noise and wear.
- Heat Exchangers: Two Moroso heavy-duty heat exchangers were mounted under the vehicle to maximize cooling efficiency. These exchangers were selected for their durability and ability to withstand road debris impacts. Their placement under the vehicle maintained a clean aesthetic and freed up space near the radiator.
- Flow Meters: Gems Sensors turbine flow meters (Model 173931-C) were installed to measure oil flow rates. Straight pipe sections upstream and downstream reduced turbulence, ensuring accurate readings. Flow meter data was transmitted to the ECU for monitoring.
Plumbing and Hoses: The system used -4 AN stainless-steel tubing for hard lines, complemented by braided stainless steel hoses for flexible connections. These materials ensured durability and resistance to heat and vibration. Double clamps secured lines to the vehicle’s frame and crossmembers, maintaining clear routing and separation from other systems.- Sensors and Wiring: Sensors monitored oil temperature and flow, feeding data into the ECU for system control. Solid-state relays regulated pump operation in standby mode, while mechanical relays activated full-capacity operation when oil temperatures rose above 175°F. A pulse-width modulated (PWM) signal enabled precise pump control.
Performance Analysis and Optimization
Detailed calculations and simulations guided the design process:
- Flow Dynamics: The Reynolds number was calculated for various components to ensure laminar flow through the pickup tubes, minimizing aeration and turbulence. Flow rates were optimized to achieve a balance between cooling efficiency and system reliability.
- Heat Transfer: Turbulent flow through the heat exchangers was determined to maximize heat rejection. However, achieving turbulent flow required higher velocities, which could induce turbulence elsewhere in the system. The final design prioritized laminar flow in critical areas and relied on larger heat exchanger surfaces to compensate.
The system also accounted for real-world variability, such as differences in line lengths and pressure drops between the two superchargers. Balancing valves were installed to equalize flow and maintain consistent performance.
Installation and Fabrication
The system’s installation required precision fabrication and integration:
- Pickup Tubes: Custom machined from aluminum, the redesigned pickup tubes provided secure seals and incorporated threaded ports for temperature sensors and fluid connections.
- Pump Mounts: Pumps were mounted to the vehicle’s frame rails using shock-absorbing brackets. Foundations were machined from 6061-T6 aluminum for strength and durability.
- Heat Exchanger Foundations: Steel plates secured the heat exchangers to the vehicle’s underside, ensuring protection from road debris while maintaining efficient airflow.
- Plumbing: Hard lines and hoses were routed along the frame rails and crossmembers, avoiding interference with other vehicle systems. Careful alignment and clamping ensured a clean and functional installation.
Testing and Validation
The system underwent extensive testing to validate its performance:
- The supercharger oil reservoirs were filled with ATF Type F fluid, and baseline flow rates were established using the turbine flow meters. Testing confirmed that the system maintained fluid temperatures within the target range of 150°F to 175°F.
- Flow meters provided accurate data, verified using a USB oscilloscope and interpolation calculations. At the design flow rate of 0.5 GPM, the flow meter signal frequency matched predicted values, confirming system calibration.
- Real-time monitoring via the ECU allowed for precise control of pump operation. Sensors detected temperature fluctuations and adjusted pump speeds accordingly, ensuring efficient cooling without unnecessary power consumption.
Conclusion
This project successfully achieved its goal of creating a robust and reliable oil cooling system for Paxton SN60 superchargers. The custom design addressed critical shortcomings in existing solutions, providing precise temperature control, enhanced durability, and seamless integration with the vehicle. By combining advanced engineering techniques with practical considerations, the system delivers optimal performance under demanding conditions, safeguarding the superchargers from overheating and extending their service life.
Future work will focus on refining system settings based on operational data and incorporating additional features, such as alarm systems for temperature or flow anomalies. This project exemplifies the importance of tailored engineering solutions in overcoming the challenges of high-performance automotive systems.
Click here to read the detailed project report.