Mazda RENESIS: Rotary Engine 16X

It’s been 40 years since Mazda introduced the first rotary engine in the Mazda Cosmo Sport in 1967. This year, Mazda puts another marker on the history of the Mazda rotary engine with the RENESIS 16X, the successor to the 13B-MSP in the Mazda RX8.

The new 16X rotary engine uses new trochoid-shaped chambers aimed at improving thermal efficiency and increasing torque across all engine speeds. Mazda has been continuously researching the best shape for the trochoid chambers ever since the first 10A rotary in 1967, followed by the 13A, 12A and now the 13B.

The new trochoid chamber has had its rotor housing width and thickness reduced while the trochoid outline has been increased, resulting in a displacement increase to 800cc per rotor – this means a 1.6 litre displacement as the engine’s 16X name indicates. This is despite exterior dimensions of the engine being about the same as the current 13B.

The trochoid shape has had its radius and eccentricity increased. Stroke has also been increased, this means better torque. Due to the change in shape, not only is an increase in displacement achieved but the surface area-to-volume ratio of the combustion chamber is reduced, enabling a reduction in cooling losses. Flame growth is also promoted. The engine uses side housings made of aluminium, and this together with other weight reduction methods make the new 16X lighter than the 13B.

The 16X rotary engine is also the first gasoline rotary engine to use direct injection. This was developed from the hyrogen injection system used in the hydrogen rotary engine. Gasoline is injected via a high pressure spray during the intake cycle. This spray also tends to reduce fuel adhesion to the chamber wall, promoting a more homogenous air-fuel mixture. This results in better torque and thermal efficiency. Power and fuel economy is expected to be 20% better than the technologies in the 13B can achieve.

A concept version of this engine is installed in the Mazda Taiki Concept, and in that car it drives the rear wheels through a 7-speed dry twin clutch gearbox.

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Paul Tan

After dabbling for years in the IT industry, Paul Tan initially began this site as a general blog covering various topics of personal interest. With an increasing number of readers paying rapt attention to the motoring stories, one thing led to another and the rest, as they say, is history.

 

Comments

  • nanashisan (Member) on Nov 05, 2007 at 3:35 pm

    im looking forward for 16x engine. reliabilty also increase with reduction of cooling losses. since it saves fuel better than previous one, i wonder it will consumes like 1.6l or 1.8l piston engine. i heard 13B drinks fuel like 2.0l turbocharged engine.

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  • 4G63T DSM (Member) on Nov 05, 2007 at 5:20 pm

    nanashisan said,
    November 5, 2007 @ 3:35 pm

    i heard 13B drinks fuel like 2.0l turbocharged engine.

    ——

    It makes close to the power of a 2.0L turbo engine, so whats the issue of it using just as much fuel?

    Nice to have the 16x. The rotary is a marvel on compactness and simplicity. They should have put a rotary in the Miata.

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  • ksec (Member) on Nov 05, 2007 at 5:35 pm

    I heard the RX8 has 28 – 30 MPG. Where in reality it is around 19 – 20.
    20 % of that is still only 24. Which is still in the low end.

    I hope we also get the 7-speed dry twin clutch gearbox as well. I will be happy if the new Mazda achieve around 30MPG.

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  • proton.GL.. (Member) on Nov 06, 2007 at 2:44 am

    although renesis is direct injection , its not as good 4 sroke as direct injection where combustion sparks A/F in the most concentrated cavity on the piston head took place,

    and renesis also allow it burn its engine oil to preserve its seal from wearing out fast and unevenly, (makan minyak itam sikit), so regular topping up engine oil needed,

    feels like 2T moto oil add, on yesteryear yamaha cup,

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  • aesthari (Member) on Nov 06, 2007 at 10:32 am

    Any rotary news is exciting news nowadays, I’m looking forward to see the rumored 4th gen RX-7 too!

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  • hameed koyakuti (Member) on Nov 06, 2007 at 11:54 am

    Summary of Tokyo motorshow is that most manufacturer is turning to better environmental friendly car, that includes hybrid, electric, biodiesel etc. Despite all that, it is still much concentration on internal combustion engine which stills burns something / fossil fuel / petro based.

    With the fossil based petro fuel, personally, i think the energy giants should concentrate on agricultural / waste fuel, solar cell, and hydro electric energy. The fossil fuel is depleting so fast, not to mentioned the escalating world petrol price.

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  • szw (Member) on Nov 06, 2007 at 12:22 pm

    new engine , new gearbox

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  • jamsbong (Member) on Nov 06, 2007 at 6:40 pm

    sounds good to know that the new rotary can be 20% more fuel efficient. The current renesis engine consumes more fuel than a 3.5V6!

    The main contribution comes from the new direct injection system. Direct injection is much better at giving torque at low-end of the power curve.

    Can’t wait to see the next 9000RPM engine that is perfectly smooth at all speed.

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  • proton.GL.. (Member) on Nov 06, 2007 at 7:14 pm

    x16 direct injection occure during INTAKE stroke,

    while 4 stroke manage to inject fuel at COMPRESSION stroke, at the most intense homoginous right at the spark plug at the piston cavity, giving the best explosive power,

    well mazda still continue its rotary, as it an icon of mazda rx car, anyway it improves a bit, but still id prefer piston engine for its superiority, if rotary is good enough they might been used widely, worlwide for its simplicity of design,

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  • Freelance Designer on Jun 01, 2011 at 11:08 am

    Don’t let Mazda fool you! They did not come up with this engine design on their own. It is my design along with the Sky related products and the Furai. They have not paid me for my work, so I will be writing A book to tell my story.

    I just finished some designs for A hybrid system, that will dominate all hybrid technology you can buy today. It should be about 20% more efficient than the best hybrid system out there.

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