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  1. #1

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    Why SC clutch on 4-tec?

    When you lift off throttle, vacum occurs in plenum.... and this vacum opens the BOV, and release the overboost.
    The way i see it theres no need for any clutch??
    I Really wants to understand this.
    How do they do on cars?

    //Magnus


  2. #2
    formerly Gold06RXP Turbo Nick's Avatar
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    Well there is no blowoff on the 4-tec from the factory. Also when you come unhooked and the engine revs up quickly and then you land back in the water dropping the RPMs rapidly back down the clutch lessens the strain on the SC shaft. Without the clutch if you came unhooked the SC shaft would twist in half from being accelerated and decelerated so quickly

  3. #3

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    If you go unhooked the trottle are open..... and theres no boost going in to the wall?
    If ive got a waste gate opening at 16lbs then when it hooked? (BOV and waste gate sounds like the same thing here, am i right?).

    If i have a belt driven lysholm kompressor in a car, and suddenly lift of or change gear..... isnt the 4-tec SC shaft more secure than a belt??

  4. #4
    I stole my dads ski RXT_IAN's Avatar
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    The problem is that the rpm of the engine can change so much so quickly the momentum of the sc compressor wheel on the end of the shaft is enough to break the shaft, people have welded the clutch and found out the hard way i believe...

  5. #5
    Kiwi spanner handler
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    Hitting the rev limiter due to cavitation,unhooking or damaged prop putz alot of stress on the shaft/clutch which the blow off valve cant help

  6. #6
    Banned User
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    On vehicles, the slip occurs on the belt...

  7. #7
    speedskixp's Avatar
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    Quote Originally Posted by mageri View Post
    When you lift off throttle, vacum occurs in plenum.... and this vacum opens the BOV, and release the overboost.
    The way i see it theres no need for any clutch??
    I Really wants to understand this.
    How do they do on cars?

    //Magnus
    The sc spins 5.2 times faster than the engine rpm ao if your turning 8000 rpms the sc is turning 41600 rpms. When your engine drops from 8000 to 6000 for example the sc goes from 41600 rpms to 31200 rpms in an instant. Due to the momentum the sc wheel has spinning that speed at cant slow down that fast and if there were no clutches it would snap the sgaft instead of slipping.

  8. #8

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    I understand what you all guys saying.

    Ok, we pretend the engine produce the same power even
    if i remove the pipe between charger and inlet, and let the charger run in the free air..... would the shaft break then?

    So you guys mean it can not handle its own rotating mass?

    A turbo runs up to 120000rpm with suddenly drop in rpm....

    How often do the "welded shaft people" break their shafts?
    And how often do the "clutchpeople" have a damaged engine caused by clutch washers in their oilpumps?

    All of you are maybe right, but im not convinced.....yet

  9. #9
    Hydrotoys's Avatar
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    all of the welded shaft break somewhere. Either the shaft, or sheared gears, or SC.

    No one is here to convince you. The data speaks for itself.

    Try it if you must...

  10. #10
    speedskixp's Avatar
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    The difference between the turbo an sc is that the turbo is not shaft driven and can free spin. The sc is connected via shaft and when the engine drops rpms it does too, instantly.

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