1. Complexity: Sleeve valve engines are more complex to design and manufacture than traditional poppet valve engines. This complexity results in higher production costs.
2. Maintenance: Sleeve valve engines require more maintenance than poppet valve engines. The sleeves have to be frequently lubricated and inspected for wear. They are also more difficult to replace when they fail.
3. Performance: Sleeve valve engines do not perform as well as poppet valve engines in certain areas. They tend to lack low-end torque and efficiency compared to poppet valve engines.
4. Cost: Due to higher production costs, sleeve valve engines have been more expensive than poppet valve engines.
Due to these disadvantages, the sleeve valve engine has faded away from the automotive industry and has been replaced by the more efficient and cost-effective poppet valve engine.
