• Sep 9th 2008 at 1:59PM
  • 36

Mazda has announced a clever new start-stop system that promises fuel economy gains of 10% or more without the need for an electric motor. The Smart Idle Stop System (SISS) uses only direct injection and combustion to restart your vehicle, while most start-stop systems use an electric motor and traditional engine start-up process. SISS stops the pistons in the optimal position for an engine restart, and then injects fuel into the cylinders before the engine begins to rotate and lets the power of combustion turn the engine over to start. This enables an SISS-equipped Mazda petrol engine to restart in 0.35 seconds, or half the time of start-stop systems using an electric motor. The catch: SISS only works with automatic transmissions.

Mazda's SISS system will be available in 2009, but the Japanese automaker hasn't yet announced which models will receive the fuel-saving technology, nor has it disclosed whether SISS will be available in the States at launch. With Americans becoming increasingly sensitive to fuel economy and petrol prices, we hope we're not left out in the cold. Hit the jump to review Mazda's press release.

[Source: Mazda]


Mazda Motor Corporation has independently developed an idling stop system, called the Smart Idle Stop System (SISS), which improves fuel economy by about ten percent (in Japan's 10-15 mode tests*1) in urban areas where vehicles frequently stop at traffic lights or in heavy traffic during operation. The SISS uses direct injection technology to achieve an excellent engine restart, ensuring drivers do not experience any discomfort with the new system. Mazda plans to introduce this core environmental technology to the marketplace in 2009.

Idling stop systems save fuel by shutting down the engine automatically when the car is stationary, and restarts it when the driver resumes driving.

Conventional idling stop systems restart a vehicle's engine with an electric motor using exactly the same process as when the engine is started normally. Mazda's SISS, on the other hand, restarts the engine through combustion. Mazda's system initiates engine restart by injecting fuel directly into the cylinder while the engine is stopped, and igniting it to generate downward piston force.

In order to restart the engine by combustion, the pistons must be stopped at exactly the correct position to create the right balance of air volume in each cylinder. The Smart Idle Stop System provides precise control over the piston positions during engine shutdown to accomplish this. The SISS indexes each cylinder and initiates fuel injection before the engine begins to rotate. This enables the engine to be restarted in just 0.35 seconds*2, roughly half the time of a conventional electric motor idling stop system.

In addition to saving fuel, Mazda's Smart Idle Stop System ensures that the engine will restart quickly and with exactly the same timing every time. Drivers will feel no delay when resuming their drive, which means they can enjoy a comfortable and stress-free ride.

*1 The 10-15 mode test is the Japanese standard for emission certification and fuel economy for light duty vehicles. It consists of two separate drive cycles. The 10-mode drive cycle is a low speed drive cycle test, while the 15-mode is a higher speed assessment.
*2 For vehicles with automatic transmissions. Restart times measured by Mazda.

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    • 1 Second Ago
      • 7 Years Ago
      I think they've only tested it in automatic cars. I don't think it's only for automatic cars. It's possible that they didn't want to reveal the start-up times for manual trannies because it takes a second to put the car in gear, while the slushbox does it more quickly.
      • 7 Years Ago
      It's gas powered with an electric start Jerk Nuts now go fix my computer its breaking down right now
      • 7 Years Ago
      My only problem with this is AutoBlog filing it under “Green” (see top of article). This is just technology advancement – Mazda R&D getting results. 10 years from now when start/stop tech is commonplace if we look back at the ‘Green’ tag, we’d laugh at the absurdity. Minor improvements to (fossil) fuel economy and calling it Green is Greenwashing.
        • 7 Years Ago
        i completly agree, news that is just car news is tagged as green and i never see it.
      • 7 Years Ago
      Mazda should focus on building nothing but Miller-cycle engines equipped with this new start-stop technology for all their piston engines. The brand will then be identified with this niche of highly efficient but powerful engines, as it is with the rotary engine. It'll tie in perfectly with their zoom-zoom monicker.
      • 7 Years Ago
      Wouldn't this technology make it possible to eliminate the starter all together?
        • 7 Years Ago
        But how is that really any different than starting your car on a cold day? If you leave your car parked outside in 0 degree weather, as long as the engine turns over and produces fuel, air and a spark, it will still produces reliable power even with a cold block. At normal temperatures, it doesn't take very long for an engine to warm up.
      • 7 Years Ago
      That's why he's a 'mechanic' and not a 'technician'.
      • 7 Years Ago
      I'm a mechanic and I can not understand how this little feat can save 10% on gas. Plus, I think this is very risky for the engine. If it shoots gas at the wrong piston location, it could destroy the engine. I don't think this will catch on.
        • 7 Years Ago
        Huh? Today's engines already know the position of the cylinder and when not to "shoot" gas into the wrong piston.

        As far a saving gas, if the engine can be shut off while idling/coasting, it could add up to a decent amount of fuel savings.
      • 7 Years Ago
      In the picture right there it not only shows the starter motor starting the engine (arrows in the 3rd pic), but it also says "combustion + motor assist".

      So this uses an electric motor to start the car, every other start-stop system.
      • 7 Years Ago
      There is cost in accelerated starter and engine wear. According to the diagram, it appears the starter assists the engine during a restart after a stop. That leads to increased starter wear and tear. Also, a stopped motor means no oil is pumping. Oil starts to sink towards the oil pan (albeit slowly) when the engine is stopped. This leads to slightly greater wear on the engine during the restart. Although the wear may be minimal, it is definitely not trivial as this type of restart system could add thousands of additional restarts in the life of the car.
      • 7 Years Ago
      Stop-start applications have been available off and on for decades in Europe. I think the early VW Rabbits in the 80s had it.
      I can't figure out why it has never been available in the US.
      I understand that the early versions resulted in no driven accessories while stopped, which would suck to lose air conditioning when you're stuck in traffic (which is when stop-start would kick in the most), but now they can just use the same techniques as hybrids have to use.
      Another downside would be when the car gets old and has been somewhat neglected. It may not want to start in a third of a second when it's 10 or 15 years old.
      • 7 Years Ago
      10% How about that.

      I guess all those hacks who wanted CAFE to increase (for cleaner air, security, no wars) really were right, it's not all that difficult to make more efficient cars.

        • 7 Years Ago
        TJ i agree, Is that why GM and Ford are begging government for money? Government is buracracy.......
        • 7 Years Ago
        Before we pop the champagne corks, lets find out how much the system will add to the typical car, and what impact it has on EPA ratings.
        • 7 Years Ago
        this plus a dual clutch trans would be an unbeatable combo

        it would be extremely nice if they could find a way to get this on manual trans
        • 7 Years Ago
        No Welfare:

        If you had the opportunity to receive a multi-million dollar low interest rate government backed loan for research and development, you as a business would not take it?

        You would be in dereliction of your fiduciary responsibility to the stockholders NOT to take it.

        And how, might I ask, does increased bureaucracy and regulation correlate to a low interest loan? It doesn't, so your post is retarded anyways.
        • 7 Years Ago
        10% plus no need for a start motor. That's a nice improvement, too.
        As long as it works on DSG-style transmissions, this is good stuff and hopefully makes it to other brands.
        • 7 Years Ago
        I agree, it isn't that hard to think of ways to save gas. Think of all the tons of CO2 that will be saved each day in the LA rush hour commute when almost every car there shuts it engine off when not in use.

        However, this doesn't say how well A/C would work in those situations. It's just not convenient to not have the A/C running on hot, smoggy days while sitting in traffic. Maybe they can incorporate an electric motor just to run the compressor.
        • 7 Years Ago
        wow. These pro-CAFE people are going to need socialized medicine when they dislocate their shoulders patting themselves on the back so hard.

        Note: Increased government regulations are an impediment to private sector innovation, not an incentive.
      • 7 Years Ago
      It probably uses the automatic trasmission as the brake to stop the cylinders in exactly the right position. Loosing AC is not a trivial matter in 90 plus degree heat and loosing the heat isn't trivial on a 0 degree morning before the car has warmed up. This could be partally solved by disabling the stop system when conditions exceed some limits hot or cold. VW had a heat storage device a few years ago which could probably be used to some good effect. Who wouldn't want to save 10% at little or no cost?
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