Anglo American orders nine 100 kW Ballard fuel cell modules for mining truck demo project
2020 MINI Cooper SE EV comes to US with MSRP of $29,900

ECONAMIQ: Flexible over-expansion with cylinder deactivation can reduce ICE fuel consumption by up to 20%

Dutch start-up ECONAMIQ is developing a novel engine technology which saves up to 20% in fuel consumption. The “ECONAMIQ principle” uses flexible over-expansion in combination with cylinder deactivation technology to increase performance and efficiency without significantly changing the engine layout or architecture.

By over-expanding into adjacent de-activated cylinders, ECONAMIQ creates an additional power stroke within the existing engine architecture, with a significant thermal efficiency increase and cost savings as a result.


Top: P-V diagram schematic including the ECONAMIQ over-expansion method. The residual pressure of at the end of the power stroke is used in an extra low-pressure stroke of the non-burning cylinders. Bottom: Overview of the basic approach. Source: de Jong (2019), ECONAMIQ.

The new ECONAMIQ technology builds on existing concepts such as cylinder deactivation and variable valve timing with a unique patented combination of routing gasses for increased system efficiency.

The company presented its first results at the annual ASME ICEF (Internal Combustion Engine Fall) conference in Chicago. ECONAMIQ expects the technology to be implemented in several vehicles in the upcoming years.

An adaption of cylinder de-activation technique called ECONAMIQ over-expansion can be applied to engines to improve fuel efficiency. Using the pressure from the exhaust gas from the active cylinders, the ‘idle’ cylinders could be expanded to extract more work out of the engine during partial load operation. Using the virtual simulation environment GT-Power, this cycle is applied to a 4-cylinder SI engine.

This engine model is simulated for a part-load operation point and compared with a standard 4-cylinder engine model and 4-cylinder engine model equipped with cylinder deactivation. From these simulations various variables for engine operation (valve timing etc.) are optimized to further reduce fuel consumption of the engine. A final brake specific fuel consumption reduction of over 10% is achieved using the overexpansion cycle, while improving engine performance on two burning cylinders over 10% as well.

With this improvement it is shown that the over-expansion cycle has a significant benefit compared to a standard ICE and cylinder deactivation techniques. These simulations are being validated on an engine test dyno using a natural aspirated ICE.

—de Jong (2019)

By utilizing the proven architecture of existing combustion engines, our technology can be integrated in engines with 4 or 8 cylinders relatively easily, as well as (range extender) hybrid electric vehicles. We therefore offer an attractive and industry friendly solution to OEMs for them to comply with increasingly challenging emission regulations and standards.

—Arjen de Jong, PhD, Chief Technology Officer of ECONAMIQ.

Hybrid electric vehicles could especially benefit from this new technology, since the rapid engine warm up and high efficiency cycle that ECONAMIQ offers uses less fuel during power-assisted operation or battery charging.

ECONAMIQ provides greater savings potential than the popular downsizing of internal combustion engines, while the benefits of a larger displacement is preserved.

The internal exchange of flue gasses according to the ECONAMIQ principle ensures that the engine reaches operating temperature faster. In addition, engine vibrations are reduced during cylinder deactivation.

Figure 2

Visualization of the over-expansion modification.

The paper presented at ICEF 2019 reveals the outcome of a simulation and validation study confirming the viability of the technology using a unique modular test setup approach.


Indicated fuel consumption vs engine indicated power. Baseline engine in blue, CDA (cylinder deactivation) in orange, ECONAMIQ in green. de Jong (2019)

Next steps in the development include further optimization of the channel routing, shape and a dynamic test bench setup planned for 2020.

ECONAMIQ focuses on applying unconventional solutions on proven technologies. Its current focus is geared towards the vibrant and rapidly changing transportation sector with a strong focus on energy efficiency and cost reduction.

ECONAMIQ is headquartered in Utrecht, The Netherlands with subsidiaries in New York (NY) and San Jose (CA).


  • US20190153912A1: Combustion engine

  • Arjen de Jong (2019) “Novel Engine Cycle Enabling Partial Load Fuel Efficiency Beyond Full Load Conditions” ASME ICEF 2019 ICEF2019-7172



Over-expansion engines have been around for a long time, but this use of deactivated cylinders as secondary expanders looks like just the sort of clever twist that could bring it to market.

One other detail:  when operating in double-expansion mode, this engine is going to get a LOT quieter.  The change in engine note and volume when the mode changes may be disconcerting to some drivers.

Account Deleted

Looks like a variation on Gerhard Schmitz 5-stroke engine (it is referenced in the patent) and developed by Ilmor Engineering. It achieved fuel consumption of only 226 g/kWh (36% efficiency).

A Facebook User

Hi EP - elsewhere you commented that at 1 GJ/T, you can remediate atmospheric CO2. What method are you referring to?

What method are you referring to?
The one in that post.

Very clever. I wonder if the 5 (+1) cylinder version with it's cooler running cylinder can achieve much greater efficiency given it adds complexity and dimension / weight. Both would return more than adding extra conventional cylinder.
Wile the 5 cycle can/does use water injection on cycle 5 the same method may be applicable to this.
Old school water injection has seen some interest / application? in some current engine designs.


Well, I came into the discussion on this topic rather late. I reckon that there is a significant potential for hyperexpansion. Sure! However, most mechanisms proposed so far to utilize this potential tend to become very bulky and complicated. Here we see another such example. One should also note that there already is an engine that uses a high expansion ratio and high charge pressure. This is the diesel engine. As indicated, the maximum cylinder pressure for a diesel engine is rather high in comparison to an otto engine. Millerization, which is also an option to utilize hyperexpansion, could be used on a diesel engine (as well as on an otto engine), which reduces the max pressure and/or further improves efficiency. The authors promise a 20% reduction in fuel consumption. Well, this is also what a diesel engine can provide and they aim on a moving target. So, by the end of the day, it boils down to if they can make this engine less complex and cheaper to manufacture than a diesel engine.


They also need to keep the exhaust gas hot enough to keep the aftertreatment working.  Might be a bit of a conflict.

Rick Breunesse

Emission Control is always priority so cold starts can be done in 'normal' mode (all cylinders). Once light-off temps are reached the overexpansion mode can be enabled if engine load request is <50% (eg. cruising, low load). Just like how cylinder de-activation is used. It can be part of engine heating strategy too as the block can potentially heat up quicker in overexpansion mode.

Rick Breunesse

@peter-xx the 20% in the article is referring to spark ignited natural aspirated 4 or 8 cylinder engines (subject to this technology). In a sense this competes with downsizing and turbocharging of engines. This can be cost efficient as the turbo components and cooling for such can be removed. Required technology would be cylinder de-activation and a movable camshaft like Mercedes Camtronic.
When applying to charged engines a compressor would make more sense. Where turbo engines profit from higher load conditions this principle profits from low load conditions.

Josefina Madeira Neto

I use additives cylinders. I recently wrote a technology term paper on this topic. I made some logical conclusions. On the advocate side, I created a unique work about the capabilities of diesel engines. I described this in my blog. This work received good reviews from critics. Internal combustion engines must be doped


Very good Idea

DE 10 2013 006 703 B4

Take a look


The comments to this entry are closed.