Author Topic: 917 180 degree V 12  (Read 84978 times)

Offline Art K

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Re: Momentary lapses of reason......
« Reply #45 on: July 07, 2016, 12:40:16 AM »
That 917 engine would be quite the thing to scale, I think I'll stick with something a little more domestic. I am missing :'( the tour this year, we gave up cable. No sitting in front of the TV watching the French countryside go by for me this year. What race engine was it that got its start as a fire pump engine? It had to be light enough to be carried into place. I have the book at home and I'd look it up but I'm on vacation. Picked up a cool book at the NAMES show a few years ago.
Art
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Offline Roger B

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Re: Momentary lapses of reason......
« Reply #46 on: July 07, 2016, 07:23:03 AM »
I think that you mean the Coventry Climax  :headscratch:
Best regards

Roger

Offline steamer

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Re: Momentary lapses of reason......
« Reply #47 on: July 07, 2016, 05:21:11 PM »
I just noticed what appears to be scavenging oil pumps in the bottom cam shaft galleries.   This would make sense to me   Was wondering how they got the oil out of that part of the engine.

Dave
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Offline Vixen

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Re: Momentary lapses of reason......
« Reply #48 on: July 07, 2016, 07:05:20 PM »
Dave,
Well spotted. The two shorter pumps are the scavenge pumps, one drains the front of the dry sump and the other drains the rear. The longer pump is the pressure pump which supplies the lubes to the crankshaft bearings camshaft bearings etc. Note, that the combined length (volume) of the two scavenge pumps is always larger then the pressure pump, usually about 1.5 times larger. This is because the scavenge pumps pick up more air, froth and used oil than the volume of oil delivered by the pressure pump.

Mike
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Offline steamer

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Re: Momentary lapses of reason......
« Reply #49 on: July 07, 2016, 07:22:52 PM »
Yes Mike, those are quite clearly visible, and your explanation as to which ones do which is spot on!.    However, those aren't the ones of which I speak.

Warning!    largish picture file attached.

In the cut away on the front side and back side of the cam shaft boxes, at the bottom.   if you enlarge that picture you will see a pair of small gear pumps driven off the ends of the lower cam shaft.  My only explanation for these is they must be auxiliary scavenge pumps to move the oil from the bottom of the cam boxes back to the sump.

Is this the correct explanation?     is the question.

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline steamer

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Re: Momentary lapses of reason......
« Reply #50 on: July 07, 2016, 07:27:44 PM »
I did some research online today regarding this.  the illustration is correct, there is definitely something there, and it appears to be a oil pump.   and considering the fact that all the other pressure lines are internal to the engine, I am assuming it is a low pressure return line.

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Vixen

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Re: Momentary lapses of reason......
« Reply #51 on: July 07, 2016, 07:37:44 PM »
Dave,

Ah, those little pumps.
You are quite correct, there are four small scavenge pumps driven off the ends of the camshafts. As you surmise, their purpose is to drain the surplus oil from the ends of the cam boxes. Multiple scavenge pumps to drain specific points is not uncommon, The MB W165 has 7 scavenge pumps and three pressure pumps.

Mike
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline steamer

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Re: Momentary lapses of reason......
« Reply #52 on: July 07, 2016, 07:41:43 PM »
Thanks Mike!   I'm still trying to trace the pressure side of the engine...It would appear there is an oil "rail" machined into the case that runs front to back on the engine, and that there are cross drilled holes to the mains.    I haven't figured out the feed to the cam boxes yet though.  External pressure lines from the case?.

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Vixen

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Re: Momentary lapses of reason......
« Reply #53 on: July 07, 2016, 08:14:38 PM »
Dave,

The oil galleries are not too clear on the cross section drawing. However, you can see the cast in external oil galleries more clearly on the photos below. The main scavenge pumps, pressure pumps and pickup strainers are sandwiched between the two halves of the crankcase and connect to the external cast in oil galleries on either side of the crankcase. The galleries also connect to some sort of manifold box on the front of the engine. The oil return pipes from the cam box scavenge pumps are routed into this box. I am not sure exactly how the pressure oil reaches the cam boxes, probably by external pipes or perhaps through the central cam drive casing. The big bore pipes to and from the oil tank and cooler also connect to the manifold box on the front of the engine.

Hope this helps

Mike








It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline steamer

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Re: Momentary lapses of reason......
« Reply #54 on: July 07, 2016, 08:30:02 PM »
Hey Mike,

Found it...it's up through the cam gear case I think

http://hellafunctional.com/?p=386

5th photo down....you see the 4 studs that hold the gear case to the crank case, in the upper left position of that flange, you can see the oil hole leading to the oil gallery...

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Vixen

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Re: Momentary lapses of reason......
« Reply #55 on: July 07, 2016, 08:47:48 PM »
Dave,

I am sure you are correct about the oil port in the gear case. A ported oilway is a far better engineered solution than external pipes.
That hellafunctional website is one of the best to show the internal details of the engine. You can now sit there for hours searching out the details. Did you notice the serial number for the crankshaft? It starts 912..... so is the genuine article and not a repro.

Mike
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline Admiral_dk

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Re: Momentary lapses of reason......
« Reply #56 on: July 07, 2016, 09:33:43 PM »
I'm sorry to but in here, but I think that the hole you spotted just oils the gear train for the cams - not enough area to oil all camshaft bearings there. Look at the bigger holes from the gallery over each cylinder in the same picture - I suspect that they are the suppliers through external "hoses".

I will agree with Vixen that it would be better if they where "internal" - on most bikes I have worked on they are big holes around two (or more) studs in the cylinder block, holding the head - but perhaps Porche where worried about that would be heating the oil too much. I've only once worked on a VW Beetle engine in my teens and the details eludes me now  :old: - in case you wonder - all old Porche engines fit in the Beetle and vice versa (on the others gearbox), they are that similar.

Offline Art K

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Re: Momentary lapses of reason......
« Reply #57 on: July 08, 2016, 01:31:40 AM »
Roger,
Thanks, that's the ticket. Coventry Climax. I think that building one of those would be momentary lapse of reason enough for me, except it wouldn't really be a momentary thing at all.
Art
« Last Edit: July 08, 2016, 08:59:01 PM by Art K »
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline Vixen

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Re: Momentary lapses of reason......
« Reply #58 on: July 08, 2016, 10:14:33 AM »
Dave,
Other than the bore and stroke, do you have any other dimensions for the engine? How do you intend to scale the drawings?

Mike
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline steamer

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Re: Momentary lapses of reason......
« Reply #59 on: July 08, 2016, 07:10:28 PM »
Mike,

Blow up the section drawing twice model size to scale dimension for the start.   Working from the crank out, redraw to correct scale, and perform the required engineering to make the parts work.   That will drive the external dimensions and features, along with photo's ect.  Finishing with external geometry and features.   Enough to make it look right anyway.
 

Currently looking at 1" bore x .75 stroke with .562 crank pins and about 122cc   Bit of a beast, but it makes for part sizes that are easier to deal with.

Now if you happen to have a friend with a full set of working drawings of the original, well that might help.....and I'll make sure I play the lottery tonight too!.

What had me thinking this morning was to have the case and cam tray 3D printed in aluminum, with the hole features undersize, and then treating the parts as castings and finishing to size..... I have quite a bit of experience now in that arena...

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

 

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