Metallurgy tech question-GEBE

Discussion in 'Rack Mounted Engines' started by grinningremlin, Jul 16, 2013.

  1. grinningremlin

    grinningremlin Active Member

    I have two GEBE set-ups.One has the older solid aluminum clutch housing, and the other has the newer hi-temp vented plastic housing.The site says "the new housing is lighter, and vented, to help keep the engine and bell cooler".Now I'm sure it's lighter, but my question is, wouldn't a vented aluminum housing keep the engine cooler than a plastic one?Every heatsink I've ever seen was AL fins, seems it would draw heat away from the bulk of the engines metal.
    Instead of buying the plastic one I'm considering honeycombing the AL one, but wanted a few sounding boards opinions.

  2. grinningremlin

    grinningremlin Active Member

    I suppose I should state my question more clearly.Would a vented AL clutch-housing help the engine run cooler than a vented plastic housing? AL is a good heatsink, it pulls heat from the engine, if vented, dispersing heat over a wider area, effectively making a better cooler ( in my mind) than plastic.The plastic wouldn't heat up/reflect but there would be no more area of metal, so only the bell/clutch-shoes are cooler.
    Trying to get a cooler running engine without having to spend more $$.
  3. grinningremlin

    grinningremlin Active Member

    Here's pics of old-new.Letter "G" in the kit layout is the old (solid cast AL); the new plastic has vent slots.Though I believe you're correct about the noise dampening, my idea wasn't to add anything, it was to drill some vent holes in the AL housing.A vented AL housing/heatsink would seem to cool an engine more than plastic.

    kitwoutengine.gif newclutch.jpg
  4. HeadSmess

    HeadSmess Well-Known Member

    the vented clutch works vaguely like a centrifugal blower...air comes in through backing plate, through clutch bell and is flung out via clutch housing vents.

    really important on where vents actually are. and is the clutch bell slotted to allow airflow? even seen fins on the bell to increase the pumping effect...

    small intakes, large outlets, hot air expands! those plastic slots look pointless...

    id use the ally myself. at least it wont ever get hot enough to melt or let the bearings wriggle! slots? personal taste :)

    if one where to be mad enough to attach heatsinks. flat matched surfaces, silicon or silver thermal transfer pate, and mount the things with proper screws! jb weld/epoxy has terrible thermal conductivity...
    grinningremlin likes this.
  5. grinningremlin

    grinningremlin Active Member

    Thanks HeadSmess!That's what I was looking for, a little science.Your comment had proved itself before I asked the question, the used plastic one was "wobbly" within the housing when I got it.You answered my question, and saved me a bit of $$.Thanks again, GG.
  6. HeadSmess

    HeadSmess Well-Known Member

    if i had one of these kits and had that ali housing id make it look like honeycomb :) mill out most of the sides and leave just the four corner "pillars". the snazzy "cnc" look :) lightweight and ventilated. and you get to watch the clutch bell spin... if that appeals in any way...? :jester:
  7. grinningremlin

    grinningremlin Active Member

    Sorry Sub, but you're the one spreading false advise, here are some researched facts:
    "J.B. Weld has a thermal conductivity of .00590 vs Silver which has a thermal conducivity of 4.3, or copper at 4.0, or even Nickel at .91. Basically J.B. Weld is 728x LESS thermally conductive than Silver. Arctic Silver Adhesive has about 60-65% silver content."
    Look at the body of HeadSmess's posts, then look at yours.Even if I couldn't do my own online research, I think I'd take his shot in the dark over yours.
    Maybe some people use it for that, but with a little research, they'd think again.
    HeadSmess likes this.
  8. HeadSmess

    HeadSmess Well-Known Member

    aw, thanks GG!

    i knew it was bad but 728 times? wow.

    in subs defence he also said "rivet". ill accept rivets as suitable. they hold planes together!

    makes you wonder what the T.C. is for just a straight alloy/alloy join... pretty good if the surfaces have good contact ;) is all the transfer paste does. fills in the gaps with highly conductive goop instead of an adhesive with worse T.C. than air... aluminium is for heatsinks simply cus its got good T.C. combined with lightweight and cheap cheap. unlike copper and silver...

    and you cant get more thermal conduction than the heat source will allow! so a nickel heatsource will only ever have a T.C. of 0.91 or worse, no matter whats applied to its surface. to me, that says for every watt per cm2 i apply, it can only lose 0.91 watts. overall temperature rises. the same surface area of silver would take more than 4.3 watts per cm2 to heat up

    (thats just my take on it and is probably wrong but shall do for now as a visualisation, mostly to do with the fact of...what does the figure 4.3 or 0.91 actually relate to? whats the standard used? anyways...)

    side note. apparently gold , being the best thermal conductor combined with its density, makes for the best cookware. holds heat and transmits it very evenly. as tested by some scientist that got a special permit because , for some bizarre reason, its forbidden to have gold in any form other than bullion, natural nugget or jewellery in the states...(verification please? im lazy) therefore, a 24carat 5kg frypan is considered a no-no :jester:

    so a gold heatsink would be ideal... oh, to live on the counterweight continent!

    i personally hate gold. platinum baby :)
    Last edited: Jul 23, 2013