Author Topic: 917 180 degree V 12  (Read 84955 times)

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Re: 917 180 degree V 12
« Reply #135 on: July 21, 2016, 04:46:18 AM »
roughed out a crank.....

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Re: 917 180 degree V 12
« Reply #136 on: July 21, 2016, 08:53:08 AM »
That looks to be a mighty robust crankshaft. Some of the photos seem to show the shape of the counterweight are different depending on their position, But I now see you are looking at that already.
Are you still thinking about making the crank in two halves, joined in the centre under the gearwheel?
If you decide to use a Hirth coupling, a common method is to pull the two halves together with a central 'bolt'. The 'bolt' usually has a left and right hand thread and is normally tightened by a spline or hex in the centre of the hollow 'bolt'

Mike
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Re: 917 180 degree V 12
« Reply #137 on: July 21, 2016, 12:11:10 PM »
Just drawing up what I see.   Probably split it in the center with a hirth.
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Re: 917 180 degree V 12
« Reply #138 on: July 21, 2016, 01:21:40 PM »
On the other hand.......it IS a beefy crank!!!....

It scales at .500" mains with .4375 throws with a 0.8125 stroke

Dave
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Re: 917 180 degree V 12
« Reply #139 on: July 21, 2016, 03:22:46 PM »
Here we have the classic problem of obtaining information from the internet for an engine that has seen many years of development changes. Compare the last photo you posted with the crankshaft in this photo



The shape of the counterweights of the inside webs are quite different. Both are correct, but clearly from different times in the engine's development history. Unless you have access to an individual engine, an exact replica may not be possible.
With the information resources available to us and the need to make the engine do-able in the home shop, the best we can hope for is a near scale model.
That said, a near scale model of the Porsche 917 engine is going to be something mighty special, an incredible challenge both to design and to make. But what an engine it would be when you get there.
Stick with it Dave.

Mike
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Re: 917 180 degree V 12
« Reply #140 on: July 21, 2016, 03:30:14 PM »





Here we have the classic problem of obtaining information from the internet for an engine that has seen many years of development changes. Compare the last photo you posted with the crankshaft in this photo



The shape of the counterweights of the inside webs are quite different. Both are correct, but clearly from different times in the engine's development history. Unless you have access to an individual engine, an exact replica may not be possible.
With the information resources available to us and the need to make the engine do-able in the home shop, the best we can hope for is a near scale model.
That said, a near scale model of the Porsche 917 engine is going to be something mighty special, an incredible challenge both to design and to make. But what an engine it would be when you get there.
Stick with it Dave.

Mike
Ya damn Skippy I will!
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Re: 917 180 degree V 12
« Reply #141 on: July 21, 2016, 04:21:06 PM »
And oh by the way......Mike, What has made this so enjoyable thusfar has been our wonderful discussions!   Please!   Keep dropping by!    I enjoy your input! :praise2: :praise2:



Dave
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Offline Jo

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Re: 917 180 degree V 12
« Reply #142 on: July 21, 2016, 04:34:05 PM »
Talking cranks I found a picture of an embryo crank just now:



I was wondering what it looks like today :noidea:

Jo
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Re: 917 180 degree V 12
« Reply #143 on: July 21, 2016, 04:42:57 PM »
About the same.   Got some time coming in august jo
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Re: 917 180 degree V 12
« Reply #144 on: July 21, 2016, 04:44:09 PM »
Jo
That's how most of my engines parts start out, as a block of material.
Sometimes the block is bigger, sometimes it's smaller, sometimes there is just a lump of misshapen scrap inside, but the reward comes when you find a perfect engine part hidden inside.
By the way, castings are rarely harmed in my workshop.

Just teasing

Mike
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Re: 917 180 degree V 12
« Reply #145 on: July 21, 2016, 05:08:30 PM »
Dave,
Kundensport are a specialist vehicle restoration/ race car preparation outfit. Do you think the crankshaft photo you posted earlier may be a modern 'special' ? The dark colouring of the crank webs suggests nitriding, I do not think that was standard Porsche practice back in the late sixties/ early seventies. I could be wrong yet again.

Mike
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Offline Jo

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Re: 917 180 degree V 12
« Reply #146 on: July 21, 2016, 05:50:19 PM »
By the way, castings are rarely harmed in my workshop.

Castings are not harmed in my workshop :hellno:

Post the very important fondling stage they venture out into the workshop to be transformed. I used to find, before I realised the importance of casting fondling, that sometimes I would get different features than shown on the drawing  ::).

Jo
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Re: 917 180 degree V 12
« Reply #147 on: July 21, 2016, 05:51:17 PM »
Been thinking about that Mike.  Is bet the photo I posted was to a turbo 917.     It would make perfect sense.
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Re: 917 180 degree V 12
« Reply #148 on: July 21, 2016, 06:13:20 PM »


 I used to find, before I realised the importance of casting fondling, that sometimes I would get different features than shown on the drawing  ::).

Jo

Ha ha, Perhaps I have been missing out on that obviously important stage of casting fondling. Somehow it does not feel right to do it with a solid billet of steel. May give it a try when nobody is looking.

Mike
« Last Edit: July 21, 2016, 06:22:41 PM by Vixen »
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Re: 917 180 degree V 12
« Reply #149 on: July 21, 2016, 06:21:28 PM »
Been thinking about that Mike.  Is bet the photo I posted was to a turbo 917.     It would make perfect sense.

Dave, you could be right about it being from a 1,500 HP Turbo 917. That crankshaft could well be an aftermarket product used to rebuild an original engine to make it more bomb proof.

Who you going to trust?

Mike

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