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MCE-5 Development to Show Vehicle Equipped with Prototype Variable Compression Ratio Engine

1.5L VCRi engine with two-stage turbocharger. Click to enlarge.

At the upcoming 79th International Motor Show in Geneva, France-based MCE-5 Development will showcase its first vehicle application (a Peugeot 407) of a prototype 1.5-liter MCE-5 VCRi (variable compression ratio) gasoline engine. The four-cylinder 1.5L VCRi, equipped with a two-stage turbocharger, develops 220 hp (164 kW) of power (comparable to that of a 3.0L V6 engine), and 420 Nm (310 lb-ft) of torque at 1,500 rpm (comparable to a V8 gasoline engine).

Fuel consumption on the NEDC is 6.7 L/100 km (35 mpg US) with 158 g CO2/km. The technology can be applied to smaller displacements, MCE-5 notes.

The results highlighted in Geneva are on a development engine that is not equipped with GDI (gasoline direct injection) or optimized combustion chambers. A 2010 version of the MCE-5 VCRi engine will be equipped with GDI, optimized combustion chambers as well as the advanced management of engine temperature, of the cylinder head, pistons and exhaust manifold.

The power and torque on the 2010 version will respectively be ramped up to 270 hp (201 kW) and 460 Nm (339 lb-ft), while average consumption on the NEDC will drop below 6.0 L/100 km (39 mpg US), with less than 140 g of CO2/km. With this type of engine, reaching the target of 120 g of CO2/km seems realistic by 2012-2013 for high-performance vehicles, with a strong reduction in fuel consumption for the whole vehicle range, MCE-5 suggests.

The MCE-5 engine has been 12 years in development. Earlier this year, twelve companies including major European Tier 1 automotive industry suppliers, combined to propose to carmakers a program intended to develop and manufacture the MCE-5 VCRi engine in the coming 6 to 8 years.

Main components of the MCE-5 VCR engine block. Click to enlarge.

The VCRi engine principle. The MCE-5 engine provides continuous and reactive compression ratio control with a range between 7:1 and 20:1 to each cylinder of the engine. The MCE-5 engine block integrates power transmission and compression ratio control through a combination of a rod-crank mechanism, long-life gears and exclusive actuators.

A common cylinder head is used for both the combustion chambers and upper control jack chambers—one for each combustion cylinder. The jacks are placed on the cold side of the cylinder head and under the intake pipes.

MCE-5 Compression Ratio control system with common CR control shaft. Click to enlarge.

The compression ratio control mechanism is placed under the control jacks and is based on an eccentric shaft driven by an electric servomotor. A non-reversible wheel-worm ensures transmission between the servomotor and the eccentric shaft. The time to change from minimum to maximum compression ratios is less than 100 ms.

Rocker arms are driven by the eccentric shaft to maintain the control jack rods in the required vertical position.

MCE-5 moving parts. Click to enlarge.

The MCE-5 VCR engine block has no impact on other engine parts or vehicle components. Its connection to gearbox, pipes and peripherals requires no additional device, as well as its integration into vehicles, which remains conventional.

Other attributes of the MCE-5 approach include:

  • Piston kinematics remain exactly the same as that of a conventional engine with the same rod/crank ratio. This remains true whatever the compression ratio.

  • The crankshaft is particularly rigid (crank is reduced by half).

  • The crank-case rigidity is at least equivalent to that of conventional engines, providing a rigid and precise bearing line and an optimum geometrical environment for all moving parts.

  • The roller-guided piston is no longer subjected to rod thrust (no piston radial stress) or to piston slap. Forces that generate torque on crankshaft are entirely assumed by rollers: this arrangement reduces friction losses and widely extends the cylinder lifespan. This constitutes a strong response to the durability problem of highly downsized high-loaded engines.



"compression ratio control with a range between 7:1 and 20:1"
but can it take advantage of the high compression with regular gasoline?
this would be ideal to mate up with a separate ethanol reservoir. the ethanol ratio could be metered according to compression ratio.


The key words here are "engine provides >continuous and reactive< compression ratio control"

The engine could likely run on any octane fuel you care to put in the tank and just let it mix in the tank. It could then adjust on the go by sensing for knock.

can it take advantage of the high compression with regular gasoline?
At low throttle settings (especially using the Atkinson cycle), I'm certain that it could.  The higher static CR combined with late intake-valve closure would keep a similar real CR while increasing the expansion ratio, potentially recovering more expansion energy.  The reduced piston side forces should also cut friction.
Sean Lee

This application can be used in HCCI engine. Good Ol' ICE forever!


No piston slap is the only improvement with this engine, the rest is a cludge.


This pure french genius

Mannstein you completely missed the point, yes not only this architecture avoid piston friction therefore allow hard downsizing without restriction but offers very high potential.

-Atkison mode since the reduced friction of the piston allows more expansion without loss of torque.
- High efficiency at any load due to varying compression Ratio allowing fully unthrotled operation at all speed.
- Possibility to work in very lean mode thanks to increase varying compression ratio
- Truly multifuel capabilities with max efficiency foor every fuel
- Possibility to work in HHCI thanks to continuous control of compression ratio
- increased efficiency at low load because of the possibility to work at high compression

This engine is a revolution , add a start and stop an regenerative alternator and you will hit 50MPG combined without hybrid


Likely to be french genius with french reliability (sorry Treehugger).
Many moving parts in very hot areas around cylinders.
Too complex: "... has been 12 years in development", and "... program intended to develop and manufacture the MCE-5 VCRi engine in the coming 6 to 8 years."
It tells alot about complexity.
Possibly will be very suitable for racing where engines are not supposed to last for years.


"This pure french genius"

The first to have an engine with VCR were Saab AFAIK (Saab Variable Compression), but it never made it into production. GM stopped the development when they took over.


Way too heavy, way too complex, way too expensive and too many parts to wear and get noisy.
Variable compression is not that valuable.
Eliminates piston slap?
Do they still use spash oiling instead of oil pumps in France?



if Variable compression was not valuable then Peugeot who is one of the best engine designer wouldn't have put money in it. Even Lotus and Mercedes and Honda have Variable compression prototypes. It is not because it is looked down by US compagnies that it is not valuable, I tend to think it is the opposite in fact.

You said complexity? this is way less complex than an hybrid and can get close in term of fuel efficiency


The Saab design was based on rotating block and couldn't adapt fast and didn't have these piston slap free design.

When you hard downsize piston slap is the limitation so eliminating piston slap allows to downsize without restriction then saving weight, friction and pumping losses.


12 years is what you need to developp a new engine, how many years GM and Honda and others have been working on direct injection enginses, much more thant that. MCE-5 is a small start up, there is nothing surprising here, at least they show results, not like Scuderi who keep blablating for years and show nothing

I really think that this concept is the most promising appraoch around for next generation gazoline engine.


Actually, if variable compression was valuable then it would be in production – not prototypes. It’s not a new idea; Check out the original Atkinson engine;
One of it’s advantages was over expansion without reducing compression ratio - but even this was easy by just moving the lower povot point.
“Peugeot one of the best engine designer” are you serious?
I think what Nicolas Sarkozy actually said was “Peugeot should be able to design one of the best engines”
Because you think it is looked down by US companies, is not a good reason to think it is valuable.
Every engine-break-thru scam artist says “can get close [to a hybrid] in term of fuel efficiency”. Corollas and TDIs already do, and they are way less complex than this thing.
When you hard downsize, piston skirt and con rod length are important but piston slap is not a limitation, even in highly supercharged engines like the (not Peugeot designed) Novi V-8 Indy Cars.
Not unike Scuderi, MCE-5 Development has only a prototype at the Geneva Motor Show in Geneva after 12 years.

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