Turbochargers & Superchargers: Theory and Application



  • waterdrwaterdr Member Posts: 307
    The debate between turbos and SC will probably last longer then any of us, mostly because technology changes which gives improvement.

    Generally speaking, the problems with turbos is lag, while an SC gives you boost right away and is completely linear.

    However, much of the lag has been reduced from newer turbos.

    Either way, I think turbos are generally superior in design to SC's. This is because a SC is driven off of a drive belt which requires power. This means that if you have a turbo and a SC on the same type of car and each make the same RWHP, it will take more engine hp for the car with the SC. Thusly, you can make more power with a turbo before creating problems for the motor then with a SC.

    Also, turbos can be easily adjusted. This allows for multiple tuning configurations w/o having to swap a pulley.

    With all that said, I have an after-market SC on my car because the turbos are a lot more expensive.
  • nitrousxlnitrousxl Member Posts: 12
    Excuse my ignorance, but what exactly is the problem with using a supercharger for low RPM's and letting a turbo take over at high RPM's? Seems like a good way to add power without much weight. Also it seems that TC's improve the gas mileage when the car isn't being floored all the time, what about SC's?
  • paisanpaisan Member Posts: 21,181
    SCs can't be turned off at higher RPMs, they are directly proportional to the engine RPMs. I think there have been some cars with SCs and TCs on the same car but can't recall which if any.

  • waterdrwaterdr Member Posts: 307
    Anything is possible on paper....sure, this could be done, and there might even be a car or two out there with such a setup, though, not likely off the showroom floor. The biggest challenge would be cost and complexity of tune.

    A solid option, however, is adding a waste gate to a super charger. Waste gates are generally used on turbos, but there are a few after-market applications where tuners have employed a waste gate on an SC. This gives you the benefit of being able to nearly turn the SC "on" or "off" by allow air to by-pass the intake during certain load conditions. A waste gate will give a SC a non-linear response if you want too.

    BUT, the greatest benefit to having a wastegate is that you can over-size the SC so more boost is added in the lower RPM ranges, then as RPM's increase and you hit a designed boost level, the waste gate can open proportionally to maintain a flat boost level throughout the rest of the rpm range. Make sense?

    I also think there are some SC applications that use a clutch to engage and disengage the blower pulley...similar to an AC system. This creates challenges for the tune, however.
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