Haikou CN6 Dongfeng 3308-mm Wheelbase Sewage Treatment Vehicle: Government Procurement Case Study and Engine Configuration Analysis In Haikou—a tropical coastal city with frequent rainy seasons and year-round humidity exceeding 80%—municipal sanitation departments demand more than basic sewage suction and treatment capabilities from such vehicles; they prioritize corrosion resistance, durability under humid-heat conditions, and operational stability under high-load duty cycles. This article analyzes the vehicle selection rationale and real-world performance of the CN6 Dongfeng 3308-mm wheelbase sewage treatment vehicle, based on a recent procurement project completed by a district-level urban management bureau. Project Background: Operational Challenges in Humid-Heat Environments The urban management bureau of a district in Haikou is responsible for maintaining local sewage networks and responding to emergency incidents. During the rainy season (May–October), operational frequency doubles compared to the dry season. Conventional sewage treatment vehicles often exhibit chassis rusting, hydraulic seal degradation and leakage, and poor engine cooling efficiency after only 2–3 years of service. Consequently, this procurement prioritized evaluation criteria including anti-corrosion coating processes, seal material specifications (requiring certified resistance to humid-heat aging), and engine reliability under frequent start-stop cycles and high-load operating conditions. Following multiple rounds of tendering, the Dongfeng 3308-mm wheelbase chassis-based model offered by Chengli Special Purpose Vehicle Co., Ltd. (officially certified model CLW5070GSSD6 series sewage treatment vehicle) was selected as the winning bid, with three units delivered. Customer feedback stated: “Chengli manufactures locally in Suizhou; the chassis uses original Dongfeng components backed by Dongfeng’s nationwide warranty program. The superstructure underwent full-body electrophoretic anti-corrosion treatment, and fluororubber—selected for its superior weather resistance—was used for all sealing components, which is critically important in Hainan’s high-humidity environment.” Engine Comparison: Differentiated Selection Among 85 kW / 100 kW / 120 kW Options The Dongfeng 3308-mm wheelbase chassis supports three mainstream CN6 diesel engines: Yuchai YC4F85-T60 (85 kW), Yunnei Power D25TCIF1 (100 kW), and Yuchai YC4E120-60 (120 kW). These engines differ significantly in torque output, fuel consumption, and suitability for specific operating conditions—directly impacting procurement budgets and lifecycle operating costs. | Engine Model | Max. Power (kW) | Peak Torque (N·m) | Fuel Consumption (Full Load, L/100 km) | Max. Operating Altitude (m) | Recommended Application Scenario | |--------------------------|------------------|---------------------|-----------------------------------------|----------------------------|------------------------------------------------------------------------------------------------| | Yuchai YC4F85-T60 | 85 | 320 | ~14–16 L | ≤1500 | Urban roads, light-duty operations; suitable for street-level units with constrained budgets | | Yunnei Power D25TCIF1 | 100 | 380 | ~15–17 L | ≤2000 | Mixed urban/suburban road conditions; medium-frequency start-stop scenarios (e.g., rainwater pump stations) | | Yuchai YC4E120-60 | 120 | 450 | ~17–19 L | ≤2500 | High-altitude regions or continuous high-load operations (e.g., large-scale sewage treatment plant transfer) | Note: Fuel consumption figures are derived from official CLW5070GSSD6 certification parameters and real-world testing conducted in Haikou; actua