Retrofitting the Dual Exhausts system typically reduces the back pressure of the engine exhaust by 30% to 50%, which may require a synchronous increase in the Fuel Pump flow to match the intake efficiency. For example, after the Chevrolet Camaro SS was equipped with dual exhaust pipes (pipe diameter 76 mm×2), the exhaust flow rate increased from 180 CFM to 250 CFM, causing the ECU to adjust the air-fuel ratio from 14.7:1 to 13.2:1, and the fuel demand increased by 18%. If the original Fuel Pump (flow rate 260 L/h, pressure 58 psi) is used, the fuel supply shortage rate under high-speed working conditions (above 6000 rpm) reaches 12%, and the power loss is approximately 15%. According to the SEMA 2023 report, upgrading to the Walbro 340 L/h high-flow Fuel Pump can shorten the fuel injection pulse width from 10 ms to 7 ms, compress the fuel injection error rate from ±6% to ±2%, and increase the horsepower recovery efficiency by 22%.
The high-pressure direct injection engine is more sensitive to the performance of the Fuel Pump. Take the Ford Mustang GT 5.0L V8 as an example. When equipped with the dual exhaust and intake packages, the direct injection pressure in the cylinder needs to be increased from 150 bar to 200 bar. The impeller speed (3000 rpm) and plunger diameter (9 mm) of the original Fuel Pump cannot meet the requirements, resulting in an 8% decrease in low-speed torque. The adoption of Bosch HDP5 series Fuel Pump (flow rate 400 L/h, pressure 65 psi) can increase the stability of fuel supply by 35%, while reducing the peak fuel temperature from 75°C to 62°C and the cavitation probability from 5% to 1%. The test data of MotoIQ shows that after the dual-exhaust modification of Subaru WRX STI, the turbocharging value increased from 1.2 bar to 1.5 bar, and the Fuel Pump flow rate needed to increase from 300 L/h to 380 L/h (+26.7%). Otherwise, the fluctuation range of fuel pressure expands to ±4 psi (the safety threshold is ±1.5 psi).
The cost-benefit analysis shows the necessity of upgrading. Take the Dodge Challenger R/T as an example. If the Fuel Pump is not upgraded simultaneously (the original factory cost is about 180 US dollars), the probability of detonation caused by insufficient fuel supply increases by 25%, and the maintenance cost may exceed 1,200 US dollars. The installation of the AEM 320 L/h electronic Fuel Pump (priced at $280- $350) can reduce the system load current from 10A to 7A, increase the motor efficiency by 18%, and extend the service life to 100,000 kilometers. Industry statistics show that among dual-exhaust modified vehicles, 31% of engine failures result from insufficient performance of the Fuel Pump. After the upgrade, the failure rate drops by 48%, and the payback period of investment is approximately 1.3 years. Furthermore, the Denso 280 L/h Fuel Pump reduces the idle flow rate from 40 L/h to 25 L/h by optimizing the impeller lead Angle (increasing from 30° to 45°), improving fuel economy by 4%-6%.
Technological innovation drives the evolution of adaptation standards. The BMW M4 GTS adopts a combination of dual exhaust and dual-stage Fuel Pump in the track package. The low-pressure pump (flow rate 150 L/h) is responsible for the daily operation, and the high-pressure pump (flow rate 250 L/h, pressure 75 psi) is activated in the boost mode, increasing the peak power by 11% and controlling the fuel pressure fluctuation within ±0.8%. Delphi’s simulation experiments show that when the dual exhaust system is combined with the direct injection engine in the cylinder, the response speed of the Fuel Pump needs to be less than 50 ms (the average of the original factory is 80 ms), otherwise the deviation rate of the air-fuel ratio may exceed ±5%. Frost & Sullivan predicts that by 2026, the market size of high-flow Fuel pumps will reach 2.4 billion US dollars, among which 40% of the demand comes from the exhaust system modification market. The main driving factors include a 15% annual increase in the popularity rate of dual exhaust systems and the requirements of emission regulations for fuel pressure accuracy (with the error limit tightened from ±3% to ±1.5%).