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oval pistons !!
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oldtimer
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PostPosted: Sun Nov 27, 2011 3:16 pm    Post subject: oval pistons !! Reply with quote

Irealise I must be pretty gullible falling for this sort of thing but it is a challenge for my present therapist (Peter Scott) or any other kind soul prepared to minister to one of the Slightly Bewildered.
It has been put to me that such an engine was produced by a major player,namely Honda,whom I would have considered above such frivolous enterprises.Are any of the usual long suffering members aware of such a thing and,if so, the purpose?
My thanks in anticipation
oldtimer
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Jim.Walker



Joined: 27 Dec 2008
Posts: 1229
Location: Chesterfield

PostPosted: Sun Nov 27, 2011 4:31 pm    Post subject: Reply with quote

As far as I am aware ALL engines have oval pistons!
The cross section of a piston cannot be of equal mass or symmetry because of the gudgeon pin bosses etc.
Accordingly a piston made circular would become oval as it heated to running temperature. To combat this and make the piston circular when at running temperature they are machined oval on the opposite axis in the first place. It is not by much, but it is measurable.
As for Honda, they may have built an engine with visibly oval pistons. There are plenty of patented designs, most of which got no further, with strange (or even without) pistons. The * and jet engines obviously have no pistons. Renault also patented one in the late 1950s, but I do not know whether it was ever built.
Jim.

This Forum keeps deleting a name spelt W-A-N-K-E-L where the asterisk is!
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47Jag



Joined: 26 Jun 2008
Posts: 1480
Location: Bothwell, Scotland

PostPosted: Sun Nov 27, 2011 4:50 pm    Post subject: Reply with quote

Oldtimer

In the quest for more torque Honda did make a oval/elitical piston bike racing engine but it wasn't a great success due to ring failures. It had two con-rods. VW also made a 2.3L diesel engine with oval bores again in the search for more torque and to get more displacement for a given block length.

Art
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47Jag



Joined: 26 Jun 2008
Posts: 1480
Location: Bothwell, Scotland

PostPosted: Sun Nov 27, 2011 5:01 pm    Post subject: Reply with quote

I found this on tinternet. Skip to 2:25 where it actually shows the engine.

http://www.youtube.com/watch?v=na9JaiZFjb8

Art
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Penman



Joined: 23 Nov 2007
Posts: 4759
Location: Swindon, Wilts.

PostPosted: Sun Nov 27, 2011 5:10 pm    Post subject: Reply with quote

Hi
That's strange.
A 4 pot engine with 8 rods, 2 per piston, and 8 valves per pot.

Can't call the pots, cylinders though.


Here's a picture of the VW engine.

http://forums.tdiclub.com/showthread.php?p=1261823
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oldtimer
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PostPosted: Sun Nov 27, 2011 5:25 pm    Post subject: oval pistons Reply with quote

My thanks to all my usual heroes,Jim,Penman,Art for helping me with their usual equanimity although I note the absence of my "shrink"".Perhaps the burden is getting to be a bit much and I can fully understand!
oldtimer
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peter scott



Joined: 18 Dec 2007
Posts: 7119
Location: Edinburgh

PostPosted: Wed Nov 30, 2011 5:34 pm    Post subject: Reply with quote

Just there too late, but I didn't know the answer anyway.

Peter Sad
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oldtimer
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PostPosted: Wed Nov 30, 2011 7:04 pm    Post subject: oval pistons Reply with quote

Hello Peter,
Good to know you are around and I reckon that this oval piston business seems to have been more in the realms of the Hairy Biker brigade and,therefore,not the sort of thing that well brought up gentlemen like yourself care to know about.
My thanks to the chaps who were ready and able to shine some light on what I, initially,believed to be nothing more than a test of my gullibility.
John
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