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The "Bridgeport diet:"

Discussion in 'The Hokey Ass Message Board' started by c-10 simplex, Apr 8, 2013.

  1. c-10 simplex
    Joined: Aug 24, 2009
    Posts: 1,331

    c-10 simplex

    Please discuss, in great detail, the practice of removing metal from an engine block, specifically small block chevies, in order to remove weight. This is also, apparently, know as the "The Bridgeport Diet?"

    Pictures would be nice.
  2. rottenleonard
    Joined: Nov 7, 2008
    Posts: 1,971


    Interesting thought, Can you really lose enough weight to make it worthwhile without destroying the integrity of the block? how much weight are we talking?
  3. CutawayAl
    Joined: Aug 3, 2009
    Posts: 2,144

    from MI

    The most radically lightened blocks I have seen were done for sprint cars. Bosses, lumps, and anything else that can be sacriuficed are removed. Internal and external machining is done to thin things up anywhere it can safely be done. The entire casting inside and out is ground as though it was being prepared for plating or a smooth paint job. The grinding only removes a few pounds and is a lot of work, but it is a weight reduction that also eliminates imperfections that might grow into cracks. Some of the machining I have seen was done with a CNC mill. I suspect there are people doing that CNC machining are doing more than just their own engines.

    I did a Google search for "sprint car lightened block" and found assorted responses I didn't take time to read. There is probably something there you would find interesting.
  4. c-10 simplex
    Joined: Aug 24, 2009
    Posts: 1,331

    c-10 simplex

    i think Smokey Yunick was saying about 32lbs---181lbs. (stock block) down to about 148lbs. with no loss of strength. But i would have to double check on that. An alum sbc weighs about 90-100lbs.

    i just wanted to know if anyone has done it and if so how, specifically. Or if any shops can do it?
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  5. Checkerwagon
    Joined: Jul 30, 2007
    Posts: 449


    First off: Smokey is a remarkably gifted exception to every rule that we mortals must adhere to. I do not doubt that Smokey could take more weight off a small block than anyone else. I'm guessing that your common sense will guide you with your project.
    My philosophy has been to make "whatever" part as light as possible... until it breaks. Then build that "whatever" piece stronger.

    As stated above, grinding off bosses and flanges that are not required is the start. Blasting the thickness of the block will reduce even more weight. Yet, remember that a course surface will dissipate more readily.

    Weight saving is the essence of HP to Weight ratio. When I was racing my m/cycle, I reduced the bike's weight by 37lbs. There was nothing left to cut/drill/remove. So, I went on a diet and lost 27lbs. Yes, I went faster, but not by much, tenths of mph over a mile.

    Obviously, you are looking at every method to reduce weight. Keep that attitude and keep asking questions. Get a triple beam scale and measure everything. The devil is in the details.

    All the best,
    Cleveland OH
  6. coupemerc
    Joined: Jul 16, 2007
    Posts: 406


    Here are some picture of an iron SBC that I am building for a Jr Fuel car. JF requires cast iron by rule. It has about 30 lbs taken out of it by LSM. This is pretty standard stuff to build a small motored JF car. Structural integrity is maintained by using a cryogenic treated compacted graphite core before lightening.

    Attached Files:

  7. Very nice work coupemerc, and I can see doing it in a Jr. Fuel car where weight is everything and you're restricted to an iron block. I think most other apps would be better off with an aluminum block. I can't imagine that the alloy block cost would be much more than the machine shop bill on the iron block.
  8. Mnhotrodbuilder
    Joined: Jul 12, 2010
    Posts: 1,142

    from Afton, MN

    nmpontiac, I do agree that buying an aluminum block is easier unless someone is set on period parts or it may not be an option for their given application. I am watching this one close to find out if there is a way to shave fat off my desoto's. I would be very happy to lose 20lbs.

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