Pressure Washer Pump 3600-4400 PSI Max 4.4 GPM, 1 inch Shaft Horizontal Tripl by | Jul 21, 2026The triplex plunger design makes the pump run more smoothly, powerful and durable. Max Water Flow 4.0 GPM 2.6 GPM 2.8 GPM 2.5 GPM 10.5 GPM 10.5 GPM. Horizontal Engine: The pump is installed horizontally onto the engine.