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Do Block Gaurds Cause Engine To Over Heat?

Discussion in 'Engine Building' started by lsvtec hatch93, May 27, 2003.

  1. lsvtec hatch93

    lsvtec hatch93 Senior Member

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    do blockgaurds make the motor over heat? and how are they installed?
     
  2. E_SolSi

    E_SolSi Member of the 20 nut club Moderator VIP

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    here ya go

    wow i had to look a whole one post below yours to find this .... damn i need a nap now
     
  3. pissedoffsol

    pissedoffsol RETIRED

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    from the title, i would never have thought to look in that post either.. give him a break.

    here's the real deal:

    98% of cracked sleeves start from the bottom or middle, where the rod/stroke ratio is the worst- not at the top. they eventually crack towards the top, but thats not where it starts. with a block guard, you are holding in heat, and not really preventing any cracks from happeneing.
    the best way to not crack a sleeve, is by tuning out ALL detonation.

    The "overheating" problem from blockguards has nothing to do with the size of the cooling passages... it deals with the fact that the hottest part- the part where combustion occurs is at the very top of the stroke, right where the block guard lies on the outside. water can't pyhsically touch the sleeve there, because the guard is in the way. thus it gets even hotter, and leads to more detonation, and see above what i said about detonation.
    Thats exactly the problem, it is going to keep a disproportionate amount of heat in the upper cylinder wall and base of the head around the cylinder. So if you're heating metal, its expanding right? And if you put different amounts of heat to a piece of metal, its going to have different coefficients of expansion right? Well, you're going to be putting more heat into a relatively small albeit important section of the cylinder wall as opposed to the rest of the wall which will be "cool" in comparison.

    more info: http://www.theoldone.com/archive/block-gua...odification.htm

    IMO, sleeved, or stock.
     
  4. lsvtec

    lsvtec GNU/Linux Evangelist

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    The rod/stroke ratio doesn't vary based on crank position, it is a constant for any given rod/crank combo. What you are talking about is the amount of sideloading or the horizontal component of the force being applied to the piston. And that component is largest when the angle formed at the wrist pin by the center line of the rod and an imaginary line connecting the center of the wrist pin to the center of the crank is at it's maximum value or in the middle of the stroke (because the horizontal component is given by the sine of the specified angle, it will increase as the sine increases).
     
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