Engine shutdown.

Discussion in 'PSI Superchargers Tech Questions' started by So Long Racing, Dec 5, 2016.

  1. So Long Racing

    So Long Racing New Member

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    What's the best way to shut down your engine? We've just been cutting the fuel off to kill the engine but I think I read on here that some use their ignition. Wouldn't using the ignition put the engine in danger of hydro locking?
     
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    So Long Racing, Dec 5, 2016
  2. Joad Donnelly

    Joad Donnelly Member

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    I've always been a fan of shutting the fuel off first and then killing the ignition when it starts revving up. I've killed it with the ignition though in some hung throttle situations with no ill effects that we saw but that was back in the roots days & I've never had to do it with a screw but I would expect the same results. I've seen some outlaw cars with no fuel shut-off valve (to save weight I'm guessing) and these were on quick cars so I doubt there has been many problems with doing the ignition kill only shut-off method.
     
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    Joad Donnelly, Dec 6, 2016
  3. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    Killing an engine with fuel shutoff is still pretty common with a roots because the drag of the blower and to some degree the fuel system design - the motor dies pretty quick. With a screw, the lower drag of the blower and fuel system design, they tend to run a little longer after you pull the fuel shutoff. Now if you drive it off the track and let the engine return to idle, this may not be that hard on a screw, but if you are killing the engine while you are slowing down, this can cause a lot of heat in the blower. With many of today's blowers being very tight clearances and coatings, it is recommended to only use the ignition kill. I have never seen anyone hydro lock an engine from this.

    On a side note, with the vast majority of cars running some sort of ignition retard box, a stand alone mag kill switch is not only redundant but a potential problem (if the switch goes bad). Killing power to the retard box (grid, command module, six shooter, 8973) will instantly kill the ignition because the mag will lose signal input.
     
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    Will Hanna, Dec 6, 2016
  4. So Long Racing

    So Long Racing New Member

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    Thanks for the reply. I was referring to shutting down from an idle. Haven't had the opportunity to lean on the car yet but the additional info was much appreciated for she will be drilling me with questions ( many of which I don't know the answers to) So I'm Loading up my brain with as much info it can hold so I can keep her in the know. She's done putting around wants to stretch her new combo's legs.
     
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    So Long Racing, Dec 7, 2016

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