Diamond Shaped Pistons - Team Camaro Tech
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post #1 of 9 (permalink) Old Jul 3rd, 01, 08:10 PM Thread Starter
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Ok I dont think it exists, but why dont car companies or engine manufactureers try designing engines with different shapes for pistons and cylinders, like squares and stuff. Especially like on high revving engines where cubic inches arent important? I think they should design something, who knows manybe even valves, and they might find better compression or fuel economy. I know its an expensive idea but thinking long term it might do some good. Maybe the government should stop funding aids research and focus more on octogon pistons hhe. Ok any replies would be cool
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post #2 of 9 (permalink) Old Jul 3rd, 01, 08:51 PM
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Take a 3" square (which would be hard to make rings for) and compare the area of the top of that piston to a 3" circular piston...

simple geometry. I think the greeks had this one wired.

next someone will want a square crank...?!

I am NOT downing you at all Sik68, it is creative minds like yours that have gotten technology where it is..you are a visionary

remember, people said the Spruce Goose was impossible???
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post #3 of 9 (permalink) Old Jul 3rd, 01, 08:51 PM
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How would you hone a square cylinder bore, or get a coencetric seat on a triangle valve? How do you think a square rod journal would work? (Ok, that may be a bit much )
Actually, honda used to have a few hand built oval cylinder 1000cc twins with 8 valves per cylinder that they used as an engineering experiment...it was determined that the machine work was simply much too expensive to ever see production, besides being very complicated to get a good hone job on the oval cylinder.

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post #4 of 9 (permalink) Old Jul 4th, 01, 12:13 AM
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Yup, honda used those oval cylinders on race bikes with some surprising results. As for the square/cubical piston, I know it displaces more area (like a square pizza giving you more toppings), but I imagine the corners would be prone to cocking in the bores thus allowing for accelerated wear in the corners of the cube. For this, a round piston is desired. Diamond shaped pistons would be fruitless (diamons as in the gem cut), as they would effectively make for a lesser compression ratio -> the top would be similar to a flat top piston, only with material removed from around the edges therefore removing material which would normally compress the gasses.

I think the idea behind the oval piston was to simulate "twinned pistons", where the oval effectively makes up for 2 pistons running side-by-side without a cylinder wall between them. It did work, and worked well, and for all I know Honda still has plans for this design.

[This message has been edited by BreathWeapon (edited 07-04-2001).]
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post #5 of 9 (permalink) Old Jul 4th, 01, 12:49 AM
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for the same reason they use arches and round/oval cylinders for bridges and all.... a round cylinder is as strong as it gets. try standing on a soda can, then a milk carton....and you'll see what i mean.ie: i once seen a waterbed store showing a bed set up on styrafoam cups to show weight distribution.

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post #6 of 9 (permalink) Old Jul 4th, 01, 03:51 AM Thread Starter
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Interesting everybdy, thanks for the feedback
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post #7 of 9 (permalink) Old Jul 4th, 01, 07:21 AM
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I imagine another possibility for bad things happening with a squared edge piston is hot spots. With sharp edges, heat would distribute in different ways causing possible pre-ignition I would think.
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post #8 of 9 (permalink) Old Jul 4th, 01, 09:36 AM
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Stop funding Aids Research ? Is that a Joke ?
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post #9 of 9 (permalink) Old Jul 5th, 01, 01:40 PM
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Those Honda engines werent 1000cc, it started out as the NR500 of 1981,for racing, then were built in limited numbers for the street, called the RC30.It was a 750cc oval piston engine, revved to 18000, yes 18000 rpm. the NR 500 was not a racing winner,often called the "never ready"500.Honda is still developing oval piston tech,and may soon be seen in the soon to turn four stroke Gran-Prix series. P.S. The NR500 had 2 connecting rods per cyl, and when the press was shown parts after the program was ended, they gave them a rod marked #5, to see if they could figure it out.Kevin Cameron of Cycle World mag and road race top tech figured it out for the rest of us.
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