Bosch Water Injection Claims 13% FE Boost

Discussion in 'General' started by Jay, Sep 2, 2016.

  1. Jay

    Jay Well-Known Member

    The Bosch WaterBoost water injection system claims "up to" 5% increase in engine performance, a 4% decrease in CO2 emissions and a 13% increase in fuel economy. I would put these claims in the same category as magic fuel or oil additives that you see in sketchy Popular Mechanics ads except for the name "Bosch" which lends credibility.

    IEEE Spectrum story here:
    Last edited: Sep 2, 2016
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  2. brick

    brick Answers to "that guy."

    Good find. 10 years ago when naturally aspirated port fuel injected gasoline engines were overwhelming norm I would have been skeptical, too. Things are different today. One of the biggest problems with small turbocharged direct-injection engines is detonation from high boost pressure and high compression ratios. Transmission programming to climb to the highest, most efficient gear as soon as possible exacerbates the problem. The OEMs play some great tricks with injection timing, spray pattern, combustion chamber design, and even inlet geometry to prevent knock but these engines really are running on the ragged edge of stability to meet torque goals. Running rich to cool the intake charge at high load is the only thing left, and that's happening any time you get into the throttle on one of these engines. The FE benefits can completely evaporate. It doesn't help PM emissions, either.

    If we could cool the intake charge without throwing away extra fuel it would be a big deal. Evaporating water or a seasonally necessary water/ethanol mix instead of gasoline should do the trick, as it's been done before in high-performance turbocharged applications. The principles are sound, and with today's very power-dense turbo-DI engines the benefits might finally be worth the minor hassle of an extra tank to fill.
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  3. Jay

    Jay Well-Known Member

    Water injection systems go way back to WWII aircraft engines, I think. Why have they not caught on before now? Well, I say that as if they have now "caught on" which is premature. I even installed a crude water injection system on my carbureted Ducati motorcycle in the 70s when I was young and stupid. I remember that the water lines installed in the intake lines and my bike sucked water like crazy at idle and not at all when the throttles were open. I got scammed.

    My car gets it's best gas mileage in hot, dry weather and it's poorest gas mileage in wet, humid weather.

    Presumably this Bosch system would not work in freezing temps if it requires pure demineralized water only.
    Last edited: Sep 2, 2016
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  4. brick

    brick Answers to "that guy."

    They do, and that application had the same goal as this Bosch system: to stabilize combustion in very high-output turbocharged engines. There simply hasn't been a need for water injection in the mainstream auto industry until now. Some engines exceed 150hp/l and generate huge amounts of torque at engine speeds barely above idle. That involves cramming a lot of air and fuel into the cylinder at higher temperatures than less power- and torque-dense engines, making them more prone to knock. Keep in mind we're not talking about any kind of water-for-fuel snake oil nonsense in this context. We're talking about controlling cylinder temperatures by evaporating small amounts of water inside the combustion chamber instead of doing the exact same thing with extra fuel. In cold weather applications water is typically mixed with a little alcohol to prevent freezing.
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  5. Worked awesome in my turbo diesel!
    I think I put about 300,000 miles on the truck running the water methanol injection.

    Just mix in methanol in the winter to keep it from freezing
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  6. Rex B

    Rex B Member

    Back in the late 1970s when octane dropped, Holley came out with a $50 water injection kick to run muscle cars on low-octane. We sold them by the hundreds. I still have one somewhere

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