912S supercharger

Category: General Tech Discussion 11 months ago
I'm interested in opinions of the Flygas supercharger offering. If anyone has any type of 912 supercharger installation or opinion about aftermarket supercharger vs. aftermarket turbocharger I am very interested to hear about it. I operate a Just Aircraft Highlander in Colorado with 912 ULS. My home field elevation is 8,800Ft and surrounded by 11,000Ft passes. I see several advantages of supercharger over turbocharger; runs cooler, no electronics, more HP (140HP), less weight, weight location (aft of engine), axis of air pump rotation (catastrophic pump failure sends parts away from firewall). Also interested in recommended engine monitoring (MAP, airbox pressure, etc.) and any flight ops best practices.
  • Re: 912S supercharger

    by » 11 months ago

    Hi Stephen,
    I do not know anything about this specific product, however i have turbo and supercharged a number of engines.

    "turbo" (actually turbosupercharging) an engine uses wasted energy from the exhaust to increase the inlet pressure. Supercharging uses crankshaft horsepower to run the supercharger and boost inlet pressure.

    In general terms supercharging is technically simpler but is harder on the engine particularly the crankshaft.

    Turbo-supercharging is a little more complicated but is more efficient and less hard on the engine.

    Unless you have a deep knowledge of engines any modification to a Rotax, or any engine that boosts power significantly (+20% and above) above normal and definitely anything that has a 45% increase in power will significantly decrease reliability.

    Due to your comments I believe what you are really interested in is "turbo normalising" that is boosting inlet pressure back to STP (standard temp and pressures) to regain that lost by altitude. Therefor the Boost is only back to 100 hp. This can be done with minimal decrease in reliability if done well.

    One of the things about our little aircraft is that we can have fun and try things like this...so do feel free to go ahead, just always have an eye on a good paddock as you fly.

  • Re: 912S supercharger

    by » 11 months ago

    Thanks GlennM -

    I took the Rotax Light Maintenance class last year and am convinced of the value of a Rotax expert to perform all non-standard service. I am working with my local Rotax representative but they have limited knowledge of aftermarket superchargers.

    Your reliability assessment makes sense, I'll ask the Flygas folks for data supporting engine life-cycle reliability. The Flygas supercharger can be tuned for desired HP, 140HP is the maximum offered for the 912 ULS. Possibly, if I dial my aspirations back to 100-120HP I can offset the reliability concerns.

    I've seen the 914 Turbo installation in similar A/C. The total weight, weight forward, heat management and complexity are a concern. Not to mention the number of service advisories on the 914. I'm in no rush and will keep looking for a reasonable approach to improved high altitude engine performance.

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