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Turbochargers & Superchargers: Theory and Application



  • benztunerbenztuner Posts: 76
    Has anyone actually driven a car or installed a turbo system that isnt placed in the engine compartment. I have heard of some turbo kits that are for newer cars, such as the C6 Corvette, that are not installed in the engine compartment due to the lack of available space. Instead the turbos are placed at the tail lights and the tubes bringing the exhaust to the turbos are ran from the engine along the rocker into the rear of the car and so on. There is a slight loss of boost but the air temp drops about 100 degrees F and in turn gives an extra 10 HP. I have not seen any of these kits done or driven any of the cars, so I was just wondering if anyone has seen them or driven a car with them? I am interested to see how well they work.
  • paisanpaisan Posts: 21,181
    Heard about one for the GTO as well.

  • qbrozenqbrozen Posts: 22,085
    sounds like a lot of money and effort for 10 hp.

    '17 F150 Crew 2.7; '67 Coronet R/T; '14 Town&Country Limited; '09 LR2 HSE. 44-car history and counting!

  • paisanpaisan Posts: 21,181
    I think he meant 10hp more than a turbo in the engine bay.

  • qbrozenqbrozen Posts: 22,085
    you may be correct.

    '17 F150 Crew 2.7; '67 Coronet R/T; '14 Town&Country Limited; '09 LR2 HSE. 44-car history and counting!

  • maudit87maudit87 Posts: 20
    link title

    That might help. They also have sections explaining Turbos and Supers in detail.

    Looks like a Turbo also increase gas mileage in cars that arn't floored all the time. :D

    Sorry if that was already posted but I wasn't getting a clear cut answer, and that did the trick.
  • 944s944s Posts: 42
    yeah, ive seen that same setup on a C6 vette and i think it was a Twin turbo setup, the turbos were located before the mufflers, with a front mount intercooler. havent driven it, but that s**t looks and sounds dope son!
  • A bit late to this thread, but a good read so far, and to my surprise, a couple of supercharged Riviera owners posting here! For the Riviera nuts out there, check

    I'm a fan of both turbo and blown applications, but feel that each has their place. For all-out racing, it's turbo hands-down. The most efficient power adder for getting huge output. It's raw, nasty, peaky horsepower for going fast, period.

    But then you have daily driven cars with turbos attempting to use lighter turbines, dual turbines, sequential turbines, tuning, etc. to make a "street-friendly" torque curve... basically to do what a blower does naturally. I can understand it, but I don't completely agree with it. If you want throttle response (low-end torque), get a large displacement N/A or add a blower. It's that simple.

    I own a 1998 Buick Riviera with the 240 hp supercharged 3.8L V6. It's my daily driver, bought 4 years ago with 24.5k miles. It used to go 0-60 mph in 8.5 secs, and run the quarter in 15.5. To the earlier posters claiming this engine is boring and can't be compared to Japanese turbo motors, you'd be surprised at what happens when you spend a few dollars to mod the 3.8L supercharged V6. You'd be astounded at what can happen with a bit more $.

    Soon I began modding the car, adding the following bolt ons: cold air intake, SC overdrive pulley, high-lift rocker arms/valve springs, exhaust headers, custom tuned PCM, and not much else. The car now does 0-60 mph in 5.7 secs, and ran a 13.9 in the 1/4 mile. This is a 4000+lb FWD Buick on street tires. I have amps and a sub box in back, even kept the jack and spare tire in!

    On the dyno, over 300 crank hp and 370 lb-ft. Still have stock exhaust system and original transmission. The best part is, the car just turned 146k miles and I still drive (abuse) it 60 miles to work each day. I have no back up vehicle, this is it! You want fuel economy? I averaged 31.5 mpg on my last 600 mile trek through the mountains.

    But my car is slow compared to the top FWD 3.8L V6s running 8 and 9 secs in the 1/4. Interested in learning more? Check these links:
  • paisanpaisan Posts: 21,181
    They each have their place. SC is good for low end and provides power across the entire RPM range, however, the newer turbos provide peak torque which is where the smaller displacement motors need the help. The advantage of the turbos is that since they don't kick in until higher RPMs, when you are out of the turbo, you gain milage.

    I like both and both can be used for different purposes, tuning on either one can be tricky and expensive.

  • I was thinking on doing the turbocharged /supercharged Buick 3.8 does anyone know of people doing this other than VW?
  • waterdrwaterdr 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 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 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 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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