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Under the skin: Why the Lotus Emira's four is more exciting than its V6

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The Lotus Emira’s M139 engine is hand-built by Mercedes-AMG on a ‘one man, one engine’ basis
The familiar supercharged 3.5-litre Toyota V6 engine might be the obvious choice for many buyers of the new Lotus Emira, but the smart money could well be on the alternative: the turbocharged 2.0-litre Mercedes-AMG unit.

The M139 is the latest four-cylinder engine from Affalterbach, and it is claimed to be the most powerful turbocharged four-cylinder production engine in the world.

In AMG applications, there are two versions, one producing 382bhp and 204lb ft and the other delivering 415bhp and 369lb ft. Lotus quotes the power output of the Emira “across the range” as being between 355bhp and 395bhp, encompassing both V6 and four-cylinder engines. At those relatively conservative levels, the door is left wide open for Lotus to further tap into the AMG engine’s huge potential in the future.

Sheer performance aside, an engine’s attributes have a major influence on how thrilling a car is to drive, or not. The M139 is free-revving at the top end, thanks to a torque curve that extends maximum torque up to 5000rpm in both AMG versions of the engine. It is high-revving, too, with the redline at 7200rpm, and its maker claims its power delivery is similar to that of a naturally aspirated engine.

The design of the induction and exhaust system has a lot to do with that. The turbocharger is twin-scroll, which means it is fed from the exhaust manifold through separate passages, with two cylinders feeding each scroll.

The advantage is fast response at low engine speeds combined with enough capacity to produce high power at the top end. 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 roller bearings that reduce friction and improve response as they whizz up to a maximum of 169,000rpm.

Elsewhere, the piezo direct fuel injectors and spark plugs have been repositioned, making room to significantly increase the size of the exhaust valves (compared with those in the previous M133 engine), allowing freer passage of the exhaust from the combustion chambers.

The engine also has two-stage injection, with a second set of solenoid port injectors firing additional fuel into the inlet manifold at high power output. There have been some changes made in order to install the engine into the Emira. Although still mounted transversely, it sits amidships and drives the rear wheels.

In AMG cars, it has been rotated through 180deg (compared with the old M133) to improve packaging. This puts the exhaust and turbo at the back, against the firewall, with the induction system at the front in the front-wheel-drive AMG cars, but the engine has been adapted to fit the Emira with a new air intake system and a new exhaust system.

It sounds like a compelling package: this new hand-built engine could potentially be the best-ever four-pot fitted to a Lotus.

Source
 
Good article!

I wonder what engine will be more tuner friendly? I'm also waiting for the side by side sound comparison video.lol
 
View attachment 144

The Lotus Emira’s M139 engine is hand-built by Mercedes-AMG on a ‘one man, one engine’ basis
The familiar supercharged 3.5-litre Toyota V6 engine might be the obvious choice for many buyers of the new Lotus Emira, but the smart money could well be on the alternative: the turbocharged 2.0-litre Mercedes-AMG unit.

The M139 is the latest four-cylinder engine from Affalterbach, and it is claimed to be the most powerful turbocharged four-cylinder production engine in the world.

In AMG applications, there are two versions, one producing 382bhp and 204lb ft and the other delivering 415bhp and 369lb ft. Lotus quotes the power output of the Emira “across the range” as being between 355bhp and 395bhp, encompassing both V6 and four-cylinder engines. At those relatively conservative levels, the door is left wide open for Lotus to further tap into the AMG engine’s huge potential in the future.

Sheer performance aside, an engine’s attributes have a major influence on how thrilling a car is to drive, or not. The M139 is free-revving at the top end, thanks to a torque curve that extends maximum torque up to 5000rpm in both AMG versions of the engine. It is high-revving, too, with the redline at 7200rpm, and its maker claims its power delivery is similar to that of a naturally aspirated engine.

The design of the induction and exhaust system has a lot to do with that. The turbocharger is twin-scroll, which means it is fed from the exhaust manifold through separate passages, with two cylinders feeding each scroll.

The advantage is fast response at low engine speeds combined with enough capacity to produce high power at the top end. 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 roller bearings that reduce friction and improve response as they whizz up to a maximum of 169,000rpm.

Elsewhere, the piezo direct fuel injectors and spark plugs have been repositioned, making room to significantly increase the size of the exhaust valves (compared with those in the previous M133 engine), allowing freer passage of the exhaust from the combustion chambers.

The engine also has two-stage injection, with a second set of solenoid port injectors firing additional fuel into the inlet manifold at high power output. There have been some changes made in order to install the engine into the Emira. Although still mounted transversely, it sits amidships and drives the rear wheels.

In AMG cars, it has been rotated through 180deg (compared with the old M133) to improve packaging. This puts the exhaust and turbo at the back, against the firewall, with the induction system at the front in the front-wheel-drive AMG cars, but the engine has been adapted to fit the Emira with a new air intake system and a new exhaust system.

It sounds like a compelling package: this new hand-built engine could potentially be the best-ever four-pot fitted to a Lotus.

Source
The A35 AMG is a little over 300bhp. It’s likely to be that engine with a different map/manifold etc. Surely?
 
No manual, no care. Doesn’t matter how fast or how much cheaper it is, my performance vehicles need a manual.
This exactly. Manuals will soon be extinct. There is no substitute for the fun of driving a manual transmission. Sure the AMG engine is nice new technology, but that does not overcome the driving experience of a clutch/shifter.
 
This exactly. Manuals will soon be extinct. There is no substitute for the fun of driving a manual transmission. Sure the AMG engine is nice new technology, but that does not overcome the driving experience of a clutch/shifter.
You driven a fairly recent single seater? Paddle shifts all day long.

I'll keep my manual Evora, and enjoy a manual, but I reckon I'll still love the Emira drive either way. I use my Evora in central London, so quite looking forward to relaxing my left leg!

Anyway, track day in less than 2 weeks. I'll get my fun.
 
You driven a fairly recent single seater? Paddle shifts all day long.

I'll keep my manual Evora, and enjoy a manual, but I reckon I'll still love the Emira drive either way. I use my Evora in central London, so quite looking forward to relaxing my left leg!

Anyway, track day in less than 2 weeks. I'll get my fun.
That is what I am saying. Manuals are going away which is why I am getting a manual. I get paddle shifting if you live in central london, but I don't. There is no substitute for 3 pedals in terms of driving experience and control. I am not worried about track times, I am focused on daily driving fun. So the engine might be more exciting, but the driving won't IMO.
 
My main concern is engine sound… i have a feeling the turbo 4 will sound very muted in comparison to the awesome v6. I’m not fussed about transmission so much. Both manual and dct have their pros a cons. I can’t help feeling that going for the AMG engine will feel hollow if I ever hear an emira v6 drive by… trouble is I’ve been told by lotus dealer that v6 will be $30k more than amg version!!
 
The A35 AMG is a little over 300bhp. It’s likely to be that engine with a different map/manifold etc. Surely?
The M139 engine is from the A45 and CLA45, not the A35. In the base state of tune it makes 382hp.


It's also used in the S variants of those cars, in a state of tune that produces 416hp.
 
As an owner of a GT410 Sport, and new to Lotus (I moved from a TVR Tuscan) the engine and its sound was a major piece of the jigsaw for my final decision, I think if the only engine option was 4 cylinders I’m not sure I would have been an owner.
But unfortunately many car brands are going towards smaller cc 4 cylinder configuration ie the BMW M140 has now lost its beautiful 3ltr straight six engine and has been heavily criticised for it in the motoring press. With Lotus also only be offering it in a non manual form I’m afraid it would not be for me, (Merc engine not the car)
 
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I’ve been trying to find some info on what the difference is between the normal m139 and the s-model (382 vs 416hp) but literally cannot find anything on the internet. It makes me think maybe it’s just a difference in the ECU rather than a bigger turbo.

If the base Lotus is only supposed to be 360hp, I’m quite keen to find out how easy it will be to increase it to 416hp
 
My main concern is engine sound… i have a feeling the turbo 4 will sound very muted in comparison to the awesome v6. I’m not fussed about transmission so much. Both manual and dct have their pros a cons. I can’t help feeling that going for the AMG engine will feel hollow if I ever hear an emira v6 drive by… trouble is I’ve been told by lotus dealer that v6 will be $30k more than amg version!!
$30K more? Ouch. That doesn't seem possible. Especially when the V6 only has 2 more cylinders and comes from a common manufacturer. If that's the case I'll unfortunately have to get a refund on my Emira deposit and walk it over to Chevy. A much less expensive, 500hp, hardtop convertible is tough to beat.
 
$30K more? Ouch. That doesn't seem possible. Especially when the V6 only has 2 more cylinders and comes from a common manufacturer. If that's the case I'll unfortunately have to get a refund on my Emira deposit and walk it over to Chevy. A much less expensive, 500hp, hardtop convertible is tough to beat.
30k is a heck of a lot I agree, but that is most likely AUD and not USD….
Either way, it does seem really strange to charge such a premium for the v6, given that the i4 is going to be in the future performance version
 
$30K more? Ouch. That doesn't seem possible. Especially when the V6 only has 2 more cylinders and comes from a common manufacturer. If that's the case I'll unfortunately have to get a refund on my Emira deposit and walk it over to Chevy. A much less expensive, 500hp, hardtop convertible is tough to beat.
30k AUD - think of it as a likely 10-15k premium in USD.

The Chevy thing is complicated - the C8 is a wonderful car but the target market for them is mostly not interested in being associated with the elderly, cliqueish owner community that dominates the ownership experience of the older Corvettes. The "jean shorts and New Balance sneakers on a pudgy older conservative white guy" stereotype is unfortunately the dominant one around that brand. That's not an appealing set of cultural signals for the Millennial buyers they desperately want to attract. The Corvette marketing people really need to do something to break those stereotypes and show the brand as something more than that.

Lotus, despite being English, is mostly free from those negative cultural touchpoints, in the same way that Porsche is. They are aspirational brands for young highly educated professionals, in addition to the expected petrolheads who also love these brands.
 
30k AUD - think of it as a likely 10-15k premium in USD.

The Chevy thing is complicated - the C8 is a wonderful car but the target market for them is mostly not interested in being associated with the elderly, cliqueish owner community that dominates the ownership experience of the older Corvettes. The "jean shorts and New Balance sneakers on a pudgy older conservative white guy" stereotype is unfortunately the dominant one around that brand. That's not an appealing set of cultural signals for the Millennial buyers they desperately want to attract. The Corvette marketing people really need to do something to break those stereotypes and show the brand as something more than that.

Lotus, despite being English, is mostly free from those negative cultural touchpoints, in the same way that Porsche is. They are aspirational brands for young highly educated professionals, in addition to the expected petrolheads who also love these brands.
Hmm, 'despite being English'.
Sweeping generalisation?
 
Hmm, 'despite being English'.
Sweeping generalisation?
Don't read too much into that. I wasn't making a racial statement. What I mean is that the British car brand that has the most mind share in the general public (particularly in the US market) is Jaguar, and their owners are stereotypically similar in demographics to the Corvette crowd.

Lotus slots into a different category, both culturally and in their engineering and design ethic.
 
Don't read too much into that. I wasn't making a racial statement. What I mean is that the British car brand that has the most mind share in the general public (particularly in the US market) is Jaguar, and their owners are stereotypically similar in demographics to the Corvette crowd.

Lotus slots into a different category, both culturally and in their engineering and design ethic.
Xx ;)
 

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