The Integrated Exhaust Manifold (IEM) production-ready technology can significantly reduce manufacturing costs, emissions and weight on most gasoline-engined passenger vehicles.

Our cylinder head for a small 3-cylinder engine, is the latest of a number of IEM designs developed by Lotus Engineering. For a typical DOHC 16-valve 1.6 cylinder gasoline engine, an IEM has potential to:

• cut up to 5% of the total build cost save 20% of the mass of separate cylinder head and exhaust manifold
• improve engine durability

Two key drivers for OEMs are cost-down and the reduction of CO2 emissions. Our IEM technology brings to a practical reality an established principle that has been very challenging to implement in production. Over a series of design projects, we have developed a proven expertise in the application of IEM designs, and we can now deliver the significant benefits of this technology to our clients

By integrating the manifold tracts into the cylinder head the parts count is reduced significantly, saving costs throughout the development cycle and supply chain, from inventory and assembly to aftermarket supply.

Emissions reduction is achieved by locating the catalyst very close to the cylinder head which reduces exhaust gas heat loss upstream thereby cutting the catalyst light-off time. The reduction in overall engine heat loss is achieved through minimising the surface area of the manifold by keeping the exhaust tracts within the head. Through intelligent cooling jacket design, heat is retained in the engine rather than lost to the engine bay, accelerating engine warm-up so it more quickly reaches optimal efficiency. This also benefits the HVAC performance, reducing windscreen demist and passenger cabin warm-up periods. Engine durability is improved as a result of the reduction of thermal stresses in the engine. With the exhaust manifold integrated into the cylinder head, the stresses usually associated at the interface of different materials, for example where the cast iron exhaust and the aluminium cylinder head meet in a conventional design, are eliminated.

Also, due to the design of the cooling jacket and coolant routing, the coolant heats up far quicker, resulting in a more uniform heating of the entire engine, again contributing to reduced stresses in the engine. Integrating the exhaust manifold reduces the mass of the engine, further increasing overall vehicle efficiency. It also results in a more compact overall engine and reduced packaging demands for the engine under the hood, delivering a range of subsequent benefits for vehicle packaging. Lotus Engineering has already proved the concept to production readiness in several demonstrator programmes with a variety of cylinder head configurations.