The acquainted supercharged 3.5-litre Toyota V6 engine is likely to be the plain selection for a lot of patrons of the brand new Lotus Emira, however the sensible cash may effectively be on the choice: the turbocharged 2.0-litre Mercedes-AMG unit.
The M139 is the newest four-cylinder engine from Affalterbach, and it’s claimed to be essentially the most highly effective turbocharged four-cylinder manufacturing engine on the earth.
In AMG purposes, there are two variations, one producing 382bhp and 204lb ft and the opposite delivering 415bhp and 369lb ft. Lotus quotes the facility output of the Emira “throughout the vary” as being between 355bhp and 395bhp, encompassing each V6 and four-cylinder engines. At these comparatively conservative ranges, the door is left huge open for Lotus to additional faucet into the AMG engine’s enormous potential sooner or later.
Sheer efficiency apart, an engine’s attributes have a significant affect on how thrilling a automotive is to drive, or not. The M139 is free-revving on the prime finish, because of a torque curve that extends most torque as much as 5000rpm in each AMG variations of the engine. It’s high-revving, too, with the redline at 7200rpm, and its maker claims its energy supply is just like that of a naturally aspirated engine.
The design of the induction and exhaust system has loads to do with that. The turbocharger is twin-scroll, which suggests it’s fed from the exhaust manifold by separate passages, with two cylinders feeding every scroll.
The benefit is quick response at low engine speeds mixed with sufficient capability to provide excessive energy on the prime finish. Pairing the exhaust ports avoids exhaust back-pressure created by the presence of the turbo hampering the scavenging of exhaust from the engine. The compressor and turbine of the charger spin in curler bearings that cut back friction and enhance response as they whizz as much as a most of 169,000rpm.
Elsewhere, the piezo direct gas injectors and spark plugs have been repositioned, making room to considerably improve the scale of the exhaust valves (in contrast with these within the earlier M133 engine), permitting freer passage of the exhaust from the combustion chambers.
The engine additionally has two-stage injection, with a second set of solenoid port injectors firing further gas into the inlet manifold at excessive energy output. There have been some adjustments made in an effort to set up the engine into the Emira. Though nonetheless mounted transversely, it sits amidships and drives the rear wheels.
In AMG vehicles, it has been rotated by 180deg (in contrast with the previous M133) to enhance packaging. This places the exhaust and turbo on the again, towards the firewall, with the induction system on the entrance within the front-wheel-drive AMG vehicles, however the engine has been tailored to suit the Emira with a brand new air consumption system and a brand new exhaust system.
It seems like a compelling bundle: this new hand-built engine may doubtlessly be the all-time four-pot fitted to a Lotus.
Excessive energy density
