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Supercharger query

Discussion in 'Tuning' started by robthehungrymonkey, May 4, 2005.

  1. robthehungrymonkey
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    robthehungrymonkey Member

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    Can someone with substantially more knowledge than me explain the finer points of supercharging?

    More specifically, in a few things i've been reading recently they've mentioned the supercharger taking away "about 20bhp", this confused me, as I thought it was supposed to add power!

    Just interested really.

    ROb.
    #1
  2. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    [ QUOTE ]
    Can someone with substantially more knowledge than me explain the finer points of supercharging?

    More specifically, in a few things i've been reading recently they've mentioned the supercharger taking away "about 20bhp", this confused me, as I thought it was supposed to add power!

    Just interested really.

    ROb.

    [/ QUOTE ]

    From the belt, it may loose some power as it adds more load on the engine...but the charper itself compensates for this in the air it blows into the engine.

    Do you know how a supercharger works? dont want to insult your knowledge!
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  3. robthehungrymonkey
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    robthehungrymonkey Member

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    THanks RIch, I know how it works (me thinks), but as you said, the power generated far outweighs the power need to spin the belt. But why would they mention it in that way? I will try and re-read it, and see if I can make any sense of it. Was just bugging me!
    #3
  4. imported_VaulterTim
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    imported_VaulterTim Guest

    I think Supercharged cars generally have more low-down torque than Turbocharged cars because they are belt-driven and hence produce boost all the time (well more of the available time anyway, i.e. a greater percentage of the rev-range) as opposed to having to wait for a turbo to spin up to produce boost.

    I think that can sometimes offset the so-called 'loss of power'.

    To give it a more appropriate term, I would describe a Supercharger as preventing the engine achieving the power it possibly COULD achieve if it didn't need to drive the 'charger simply due to losses in the drive-train from engine to 'charger via the belt etc.

    That's my twist on things anyway! /ubbthreads/images/graemlins/grin.gif

    Cheers

    T
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  5. dummi
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    dummi smoking a6

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    you could optimise it with pulleys though,

    thirsty like aircon drains power.
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  6. gc48067
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    gc48067 Member

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    What we are talking about here is efficiency - if a Supercharger "takes" 80bhp to drive but supplies 180bhp there is obviously a net gain in power. If another supercharger produces 180 but only requires 20BHP to drive it is more efficient than the first.

    Don't forget that pretty much every component in the engine requires some power to drive it - eg hand cranking the pistons around with the head off still requires some effort.

    For the avoidance of doubt a supercharger is directly run off the engine (gearing or pulleys) so spins at a speed relative to the engine speed - eg if geared at twice engine speed would be doing 6000RPM when the engine is doing 3000RPM and 12000RPM when the engine was doing 6000RPM (in reality they spin MUCH faster). A simple upgrade to pulley based Supercharge installs is to swap the pulleys which increases the gearing (and therefore boost).

    A turbo is driven off the exhaust gasses with no physical connection to the engine. The turbo takes time to spin up when boost is required and there is no direct link between turbo speed and engine speed - the speed of the turbo is regulated by allowing exhaust gasses to bypass the turbines.

    Hope this helps.


    Greg
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  7. dummi
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    dummi smoking a6

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    turbos too use engine power, cause back pressure, restriction to the engine ability to chuck out burnt fuel, which ever you use as Greg says is a net gain
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  8. nervus
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    nervus Active Member

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    I agree that brakes and suspension would make a huge difference to the S3.

    I have held off re-mapping untill i get some decent brakes. The standard ones are poor (even at standard bhp).

    I honestly think i could be push my S3 faster/harder/with more confidence with uprated brakes and suspension than i could with any re-map or power upgrade. The car is fast enough for its chassis as it is.

    Im uprating my brakes to a Brembo Gt kit, replacing the dampers and anti-roll bars before the Jabba re-map. If the Gmbh springs are still good, ill retain those as the the ride hight looks just right.
    #8
  9. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    [ QUOTE ]
    I agree that brakes and suspension would make a huge difference to the S3.

    I have held off re-mapping untill i get some decent brakes. The standard ones are poor (even at standard bhp).

    I honestly think i could be push my S3 faster/harder/with more confidence with uprated brakes and suspension than i could with any re-map or power upgrade. The car is fast enough for its chassis as it is.

    Im uprating my brakes to a Brembo Gt kit, replacing the dampers and anti-roll bars before the Jabba re-map. If the Gmbh springs are still good, ill retain those as the the ride hight looks just right.

    [/ QUOTE ]

    Wrong forum? You going crazy? /ubbthreads/images/graemlins/laugh_roll.gif
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  10. nervus
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    nervus Active Member

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    Oh yeah /ubbthreads/images/graemlins/laugh_roll.gif /ubbthreads/images/graemlins/laugh_roll.gif /ubbthreads/images/graemlins/laugh_roll.gif
    #10
  11. IanL-S3
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    IanL-S3 Member

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    so can you supercharge and turbo charge a everyday road car without the engine going pop?

    And has anyone done it to an Audi or S3 in particular?
    #11
  12. gc48067
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    gc48067 Member

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    Compression ratio is the main issue - it needs to be low for a turbo car, most non-turbo cars have higher compression which leads to problems.

    Things like ecu etc can also cause problems but hey guess that is where the fun starts.


    Greg
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  13. Soupie69uk
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    Soupie69uk Owner

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    I remember seeing a video of an old XR2 that was turboed and supercharged and a few other mods sounded superb!!!!!
    #13
  14. HTC
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    HTC Active Member

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    The MK2 golf that was at GTI international with "tramp" written on the back is turboed and supercharged.
    #14
  15. nervus
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    nervus Active Member

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    The group B Lancia Delta S4's were also supercharged and turbocharged - awesome
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  16. dummi
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    dummi smoking a6

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    in theory you could have as many turbos linked together feeding each other, awesome
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  17. Khufu
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    Khufu Active Member

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    There was a supercharger kit on ebay the other day, it was reserved at £1100 - was a bit tempted for my NA 1.8 A3 /ubbthreads/images/graemlins/smile.gif
    #17
  18. IanL-S3
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    IanL-S3 Member

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    [ QUOTE ]
    There was a supercharger kit on ebay the other day, it was reserved at £1100 - was a bit tempted for my NA 1.8 A3 /ubbthreads/images/graemlins/smile.gif

    [/ QUOTE ]

    you cant do that!! you'd no longer be the 3rd slowest! /ubbthreads/images/graemlins/smile.gif
    #18

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