# MultiAir

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Automobile variable valve timing technology

Fiat 875 cc two cylinder TwinAir engine featuring Multiair technology

**MultiAir** or **Multiair** is a hydraulically actuated [variable valve timing](/source/Variable_valve_timing) (VVT) and [variable valve lift](/source/Variable_valve_lift) (VVL) engine technology enabling "cylinder by cylinder, stroke by stroke"[1] control of intake air directly via a gasoline engine's inlet valves. Developed by [Fiat Powertrain Technologies](/source/Fiat_Powertrain_Technologies), the technology addresses a primary engine inefficiency: pumping losses caused by restricting intake passage by the throttle plate that regulates air feeding the cylinders.[2]

[Fiat S.p.A.](/source/Fiat_S.p.A.), now known as [Stellantis](/source/Stellantis), launched MultiAir in 2009, employing a proprietary electro-hydraulic system to precisely control air intake without a [throttle valve](/source/Throttle_body)[3] to increase engine power and torque, reduce fuel consumption, reduce emissions, and improve engine operation, offering "a more controllable flow of air during the combustion cycle in comparison with mechanical VVT systems."[4] The technology allows engines to be lighter and smaller while reducing pump losses. It can be adapted to existing engines by replacing the camshaft with the MultiAir system, thus requiring a new head only.

MultiAir was licensed to the [Schaeffler Group](/source/Schaeffler_Group) in 2011, which also markets the system as **Uniair**.[5] Schaeffler began supplying Uniair systems in 2017 to [Jaguar Land Rover](/source/Jaguar_Land_Rover), branded as [Ingenium](/source/Ingenium_engine_family) technology.[6]

Compatible with both naturally aspirated and forced-induction engines, MultiAir technology was patented by [Fiat](/source/Fiat_Automobiles) in 2002 and was launched at the 2009 Geneva Motor Show in the [Alfa Romeo MiTo](/source/Alfa_Romeo_MiTo).[7] 1.4 L MultiAir engines for global markets are manufactured in [Termoli](/source/Termoli), [Italy](/source/Italy) at the [Fiat Powertrain Technologies](/source/Fiat_Powertrain_Technologies) factory and the FCA's [Dundee Engine Plant](/source/Dundee_Engine_Plant) (formerly of [Global Engine Alliance](/source/Global_Engine_Alliance)'s GEMA manufacturing branch), with critical systems manufactured and assembled by [Schaeffler Group](/source/Schaeffler_Group).[5]

In 2010, the 1.4 L MultiAir engine won the *[International Engine of the Year](/source/International_Engine_of_the_Year)*[8] as well as [Popular Science](/source/Popular_Science)'s *Best of What's New.*[1] In the same year, the Fiat [SGE](/source/Fiat_TwinAir_engine) engine (0.9 L turbocharged and 1.0 L naturally aspirated TwinAir units), also using MultiAir technology, was launched in the Fiat 500. It is produced in [Bielsko-Biała](/source/Bielsko-Bia%C5%82a), [Poland](/source/Poland). It was named [Best New Engine](/source/International_Engine_of_the_Year) in 2011.[9]

Both FIRE and SGE units are equipped with MultiAir and use indirect fuel injection.

The [GME](/source/FCA_Global_Medium_Engine) (Hurricane) and [GSE](/source/Fiat_Global_Small_Engine) (FireFly) MultiAir II engines, which use direct fuel injection, were first made available in 2016.

## Technology

***How it works*** "The MultiAir system is elegantly simple. An electrohydraulic actuator, a high-response, electronically activated solenoid—controls the pressure applied to hydraulic fluid (engine oil drawn from the sump) that fills a thin passageway that connects the intake valves and the camshaft. The solenoid valve regulates the amount of oil pumped by the cam action to either the valve or a bypass reservoir.

When pressurized, the hydraulic line behaves like a solid body and transmits the lift schedule imparted by the intake cam directly to the intake valve. When the solenoid is disengaged, a spring takes over valve actuation duties.

This electrohydraulic link allows independent operation of the two components, which enables near real-time control over the valve lift profiles, said Bernard. Whereas a closed solenoid normally transmits the pressure generated by the camshaft’s intake profile to the valve, an open solenoid breaks the hydraulic link between cam and valve, decoupling their operations."[10] ***Society of Automotive Engineering, 2010***

For variable valve lift, competing technologies (e.g., Honda's [VTEC](/source/VTEC) and BMW's [Valvetronic](/source/Valvetronic)) use electromechanical concepts, achieving valve lift variation via dedicated mechanisms; it can also be combined with [camshaft](/source/Camshaft) phasers to allow control of both valve lift and phase. In contrast, MultiAir uses managed hydraulic fluid to provide variable valve control.

Control of a MultiAir engine's intake valves works via a valve [tappet](/source/Tappet) (cam follower), moved by a mechanical intake cam, which is connected to the intake valve through a hydraulic chamber, controlled by a normally open on/off solenoid valve.[11] The system allows optimum timing of intake valve operation.

MultiAir technology can increase power (up to 10%) and torque (up to 15%), as well as reduce consumption levels (up to 10%) and emissions of [CO2](/source/Carbon_dioxide) (up to 10%), particulates (up to 40%) and [NOx](/source/NOx) (up to 60%)[3][7] when compared to a traditional petrol engine. The system also provides smoother cold weather operation, greater torque delivery, and no engine shake at shut-off.[12]

## Development

Research on critical related technologies started in the 1980s when engine electronic control reached market maturity. MultiAir was developed over ten years at Fiat's Centro Ricerche Fiat (CRF) in Orbassano outside Turin,[13] after a five-year delay during Fiat's 2000-2005 partnership with General Motors.[14] The vice president of Fiat Powertrain Research & Development, Rinaldo Rinolfi, led the team who developed the technology at a cost of over $100 million.[15]

## Other systems

More advanced, fully [camless](/source/Camless) valvetrain systems are under development but are not yet production-ready.[16] The [Valvetronic](/source/Valvetronic) system used by [BMW](/source/BMW) allows the valve timing and lift to be varied, but not the cam profile. The ability to vary the latter is characteristic of camless and the MultiAir systems.

## Applications

- [Fiat FIRE engine](/source/Fully_Integrated_Robotised_Engine)

- [Fiat SGE (TwinAir) engine](/source/Fiat_TwinAir_engine)

- [Fiat GSE (FireFly) engine](/source/Fiat_Global_Small_Engine)

- [Fiat GME (Hurricane) engine](/source/FCA_Global_Medium_Engine)

- [Chrysler Tigershark engine](/source/Tigershark_engine)

## See also

- [Camless](/source/Camless)

- [Variable valve timing](/source/Variable_valve_timing)

## References

1. ^ [***a***](#cite_ref-MA9_1-0) [***b***](#cite_ref-MA9_1-1) ["Fiat's Multiair engine wins Popular Science Award"](https://web.archive.org/web/20160303010027/http://www.allpar.com/news/2010/11/fiats-multiair-engine-wins-popular-science-award-6549). Popular Science via Allpar.com. November 17, 2010. Archived from [the original](http://www.allpar.com/news/2010/11/fiats-multiair-engine-wins-popular-science-award-6549) on March 3, 2016. Retrieved May 31, 2016.

1. **[^](#cite_ref-cardriver_2-0)** Mark Gillies (October 2009). ["Fiat's Multiair Valve-Lift System Explained"](http://www.caranddriver.com/features/fiats-multiair-valve-lift-system-explained). Car and Driver.

1. ^ [***a***](#cite_ref-BestNewEngine_3-0) [***b***](#cite_ref-BestNewEngine_3-1) ["Best new engine 2010"](http://www.ukipme.com/engineoftheyear/winners_10/bestnew.html). *"International Engine of the Year"*. Retrieved 2010-09-15.{{[cite web](https://en.wikipedia.org/wiki/Template:Cite_web)}}: CS1 maint: deprecated archival service ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_deprecated_archival_service))

1. **[^](#cite_ref-MA1_4-0)** Mike Hanlon (March 7, 2009). ["Fiat releases MultiAir engine technology – is this a fundamental internal combustion engine design breakthrough?"](http://www.gizmag.com/fiat-releases-multiair-engine-technology--is-this-a-fundamental-breakthrough-in-internal-combustion-engine-design/11184/). Gizmag.

1. ^ [***a***](#cite_ref-MA2_5-0) [***b***](#cite_ref-MA2_5-1) David Zoia (March 7, 2011). ["Schaeffler Expects Other Takers for MultiAir Technology"](https://web.archive.org/web/20160806050130/http://wardsauto.com/news-analysis/schaeffler-expects-other-takers-multiair-technology). Wards Automotive. Archived from [the original](http://wardsauto.com/news-analysis/schaeffler-expects-other-takers-multiair-technology) on August 6, 2016. Retrieved May 30, 2016.

1. **[^](#cite_ref-springerprofessional.de_6-0)** springerprofessional.de: [Drivetrain | UniAir Valve Control for Ingenium Petrol Engine | springerprofessional.de](https://www.springerprofessional.de/en/drivetrain/companies---institutions/uniair-valve-control-for-ingenium-petrol-engine/12263614), accessdate: 27. January 2018

1. ^ [***a***](#cite_ref-alfaromeopress_7-0) [***b***](#cite_ref-alfaromeopress_7-1) ["「MultiAir」 is launched on the Alfa Romeo MiTo"](http://www.alfaromeopress.com/index.php?method=news&action=zoom&id=4453&format=print). *alfaromeopress.com*. Retrieved 2009-06-18.

1. **[^](#cite_ref-green.autoblog.com_8-0)** ["Fiat's 1.4-liter turbocharged Multiair powerplant wins "Best New Engine of 2010" award"](http://green.autoblog.com/2010/06/30/fiats-1-4-liter-turbocharged-multiair-powerplant-wins-best-new/). *green.autoblog.com*. Retrieved 2011-01-22.

1. **[^](#cite_ref-ukipme.com_9-0)** ["Fiat 875cc TwinAir"](http://www.ukipme.com/engineoftheyear/winners_11/bestnew.html). *ukipme.com*. Retrieved 2012-01-03.{{[cite web](https://en.wikipedia.org/wiki/Template:Cite_web)}}: CS1 maint: deprecated archival service ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_deprecated_archival_service))

1. **[^](#cite_ref-MA5_10-0)** Steven Ashley (October 7, 2010). ["Inside Fiat's innovative MultiAir system"](http://articles.sae.org/8703/). Society of Automotive Engineers.

1. **[^](#cite_ref-fiatgroupautomobilespress.com_11-0)** ["The Fiat Multiair Technology: how it works"](http://www.fiatgroupautomobilespress.com/press/detail/10457). *fiatgroupautomobilespress.com*. Retrieved 2014-07-28.

1. **[^](#cite_ref-fiatgroup.com_12-0)** ["Multiair"](http://www.fiatgroup.com/en-us/innovation/crf_activities/prt/Pages/Multiair.aspx). *fiatgroup.com*. Retrieved 2009-06-29.

1. **[^](#cite_ref-webcitation.org_13-0)** WebCite query result: [WebCite query result](https://web.archive.org/web/20160710131103/http://www.examiner.com/article/fiat-s-engine-innovation), accessdate: 16. June 2016

1. **[^](#cite_ref-boston.com_14-0)** The Boston Globe: [Fiat hopes tech will make Chrysler deal work - The Boston Globe](https://archive.boston.com/business/articles/2009/06/25/fiat_hopes_tech_will_make_chrysler_deal_work/), accessdate: 16. June 2016

1. **[^](#cite_ref-pittsburghlive.com_15-0)** ["Fiat retrofits Chrysler engine, shelves dinosaurs to save gas"](http://www.pittsburghlive.com/x/pittsburghtrib/business/s_631378.html). *pittsburghlive.com*. Retrieved 2009-06-29.

1. **[^](#cite_ref-autobloggreen.com_16-0)** ["Valeo has customers for seamless engine with "smart valve actuation""](http://www.autobloggreen.com/2006/12/12/valeo-has-customers-for-camless-engine-with-smart-valve-actuati/). *autobloggreen.com*. Retrieved 2009-06-29.

## External links

- [Official Fiat Powertrain website](https://web.archive.org/web/20130821052537/http://www.fptpowertrain.com/)

- [How it works video in YouTube](https://www.youtube.com/watch?v=5IrPcmMHqHE)

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Adapted from the Wikipedia article [MultiAir](https://en.wikipedia.org/wiki/MultiAir) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/MultiAir?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.