Honda NR500/NR750 engine....Oval pistons...

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KevJTD
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Honda NR500/NR750 engine....Oval pistons...

Post by KevJTD »

For a few years I've heard of this engine that had oval pistons and wondered about it, but never had a look at what it was.
This morning I've remembered to have a look!
Now, I assumed that it would be as a normal circular piston but in and oval shape, but for what purpose.
The reality is far more odd!

https://global.honda/heritage/episodes/ ... ngine.html

A V4 500cc engine initially, later to a 750, revving well into the teens. But each piston looked like an oval racing track with straight sides rather than a pure oval, the manufacturing must have been incredibly difficult, how do you make a piston ring for instance? How do you bore the cylinders?
Each combustion chamber had 8 valves, 8! Madness.
Giulietta JTD 170
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KevJTD
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Re: Honda NR500/NR750 engine....Oval pistons...

Post by KevJTD »

Some of the strangest ideas I've read about...
Attachments
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honda-nr750-01.jpg
NR750 1.jpg
Giulietta JTD 170
Lancia Delta integrale
Lancia Flavia coupe 1.8 1963
Lancia Dedra turbo
Renault Clio 197 RS

I'm bad with people things
But I should have tried more

junior
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Joined: Fri Dec 19, 2014 7:43 pm

Re: Honda NR500/NR750 engine....Oval pistons...

Post by junior »

They must have balanced and measured every part so very, very carefully to get those pistons to work at such high rpm.

Quite a success just to get it to run. Would also have been interesting to run a single cylinder one as a proper motorbike. :D

justsuds
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Re: Honda NR500/NR750 engine....Oval pistons...

Post by justsuds »

What Honda wanted to do was build a V8, but race regulations wouldn't allow it, hence the oval pistons. I wonder how much Honda spent on this project ?
John.

alfadave
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Re: Honda NR500/NR750 engine....Oval pistons...

Post by alfadave »

Nothing new here.

Our clapped out old Austin A35 had oval pistons!

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