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[SA] double valve springs vs single.

Discussion in 'General' started by Toyyyga, Apr 21, 2014.

  1. Toyyyga

    Toyyyga New Member

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    I've been told by a reputable tuner that in my ls3 with a mild cam I would definately lose a little power after installing double valve springs. That you will always make more power with a single until you go bigger cam bigger lift. Opinions please?
     
    Last edited: Apr 21, 2014
  2. gossie

    gossie Well-Known Member

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    If it aint broke, don't fix it, as they say in the classics. I can't believe it would be valve bouncing on the singles. Is it?
    Double valve springs will use more energy and with more pressure on the valve train will wear parts out faster.
     
  3. ari666

    ari666 250,000 hits

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  4. 07GTS

    07GTS Well-Known Member

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    ls3 has single spring, u won't loose power but like said u will have more pressure on all associated components, unless u have valve bounce or put a bigger cam in there would be no reason to change them, if u have mild cam then u should change to better springs, some like duels because if one brakes then the other spring stops it from falling in the cylinder...
     
  5. lowandslow

    lowandslow Well-Known Member

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    A friend of mine broke an inner spring when he was on his way back from Tasmania in his Blown 6lt VE. Lucky he had fitted duals when he done the cam swap otherwise it could have gotten messy. Pretty sure he limped it from near the Victoria border all the way to Wollongong near Sydney.
     
  6. 'ssv'

    'ssv' Member

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    Single springs wear out fairly quickly, I belive they are ment to be replaced every 20,000.
     
  7. Ian Johnston

    Ian Johnston Active Member

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    Where did you hear that crap from???
     
  8. somefool

    somefool Member

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    There is no way in hell that valve springs would have to be replaced as often as a service item. They dont 'wear', they just weaken/lose their tension over time. Over a long time. Unless they are poor quality items, obviously. Replace them when you do a rebuild/ or a cam upgrade (in which case they would become unsuitable for purpose anyway)
     
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    'ssv' Member

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    Wear out = loose tention.
    ive seen it happen, a collet/keeper snap and drop the valve.
     
  10. PIR4TE

    PIR4TE Banned

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    Go the singles, especially with your lighter intake valves and 'mild' cam. Of course it depends on whatever 'mild' actually means technically, I'm assuming mild increase in duration else what's the point?

    I use PAC 1500 series plus lightweight, thin moly rods. Swapping these alone retaining the stock cam will let you rev past 6400 with total control (no bounce), no undue stress / noise plus give excellent economy.

    Consider PAC1511 drop in beehive LS spring, the best drop beehive spring available.
    Features:
    • 130lbs @ 1.800”
    • 384lbs @ 1.140”
    • Spring rate 385lbs per inch
    • Coil bind 1.080”
    • Max valve lift .660”
    • Frequency 32952
    • Nitride surface heat treat
    • Polished
    • Nano peen
    • Extreme high levels of fatigue life
     
  11. greenacc

    greenacc Searching for the billion

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    Power loss would be due to the extra friction and load the double springs create. It would only be a small loss though.
     
  12. PIR4TE

    PIR4TE Banned

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    Power loss due to friction as a percentage of peak power is negligible and there are good arguments for wearing both a belt and braces outlined in this recent article in GMHTP. However for a daily driven high performance setup it is important to consider that valvetrain friction losses are dominated by losses at the cam face and lifter rollers particularly at low engine speed. I see people often stressing out the valvetrain with heavy dual and triple springs on <0.600 lift and blame GM for crappy lifters.
    Camshaft friction torque is highest at around 1500rpm, meaning your mild cam will likely spend most of its time cruising / driving at 1200-1800 rpm where increased frictional pressure of dual springs will promote wear. ie peak hp loss is not an effective measure of wear, longevity/reliability nor economy when driving typically.
    Your mechanic is correct, not strictly in terms of peak power loss but efficiency and longevity.
     

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