917 180 degree V 12

[steamer]

My last calculation young man is you're 5 hours ahead of me....it's past your bed time!!!

Dave

[Vixen]

Yes, it's past bed time but this stuff is so interesting. And less of the 'young man'  please.     

Looking again at the hellafunctional website. The big wheel looks to have something like 56 teeth, Porsche would have used a module gear form rather than DP. However 32DP would work just as well, especially if you already have the cutters available.

Till tomorrow

Mike

[steamer]

Yes, it's past bed time but this stuff is so interesting. And less of the 'young man'  please.     

Looking again at the hellafunctional website. The big wheel looks to have something like 56 teeth, Porsche would have used a module gear form rather than DP. However 32DP would work just as well, especially if you already have the cutters available.

Till tomorrow

Mike

Sir!  Yes Sir!


Yes   I think I have some 32 DP cutters...so it's promising.....the biggest thing I think we accomplished today is ....it's not that unreasonable!....dare I say   maybe even doable!!!!


Tomorrow IS another day!     Have a good night my friend!   

Dave

[steamer]

PS   Thank you for a fun and very informative and constructive conversation!   I enjoyed it no end!...

Dave

[steamer]

The next thing to have me noodling is the cam timing...is it intended to be brought into proper time by shifting the cam drive gears on the cam shaft with a bunch of index holes on the cam and the second gear on the cam drive?

Dave

[Vixen]

Well, if you have a full size 917 and intent on extracting every last ounce of torque and fraction of a horsepower, then vernier adjustment of the camshaft timing would be important.
For a model demonstration runner I would have thought the main requirement would be for ease of starting and reliable operation. This could be achieved by the use of conservative valve timing without much overlap, reduced valve lift, perhaps smaller diameter valves and a lower CR. The smaller valves would also allow the use of a screw in cage rather than a valve seat insert.
Ease of manufacture and ease of operation being the main requirement. The conservative valve timing events would be well within 'normal' machining limits for a fixed cam/gear. I would also think about reducing the CR  as appropriate for the type of fuel to be used.

Just my initial thoughts.

Mike

PS.     Hamilton on pole for the British GP tomorrow.

[steamer]

Agreed on all points....CR of about 6.5/1 or so?    Makes ignition requirements a bit easier too I would think

I ask as I wanted to understand how the real one did it.    To your point though, getting rid of that joint would be a good thing and gets rid of a potential problem

1/2" and 3/8 intake and exhaust perhaps....too soon to tell.... it would need to be laid out for sure.

I guess you answered the question though...with reduced "aggressiveness" of engine timing, timing the cams shouldn't be a problem...within a gear tooth anyway.

Dave

[steamer]

PS.     Hamilton on pole for the British GP tomorrow.

Was there any doubt?   8-)

[Vixen]

The 917 engine is just a Beetle engine on steroids. You can get a good look at the external oil pipe plumbing in your latest photo.

With 120cc or so to play with, you could use 'farm engine' valve timing to make an easy handling engine. It will still sound impressive enough.
CR 6.5:1 on gasoline, CR 8.5:1 on alcohol not sure about propane or even how you could use it.

Mike

Unfortunately Mercedes seem bent on having a German World Champion in a German car. They could still nobble Hamilton with technical problems or poor race tactics yet again.

[steamer]

I'd think ANY 12 will sound awesome!     

Yes the political drama of F1 is amazing...Some of the "out of bounds" rules they've come up with seem draconian .....

Let em Race!

Dave

[Jo]

PS.     Hamilton on pole for the British GP tomorrow.

  I have qualifying recorded for after dinner    

Jo

[Vixen]

Jo,      Just sit back and enjoy the third qualifying session with a glass in your hand. Sorry if I let the cat out of the bag for you

Mike

[Jasonb]

Ah Jo, a true fan would have watched it live

Mike good bit of downhill this afternoon, did not expect that Though that crouched down on the top tube position looks painful

[Vixen]

Yes, an incredible down hill finish for today's stage of the Tour De France. Froome caught the whole field napping. He developed that painful 'over the handlebars crouch' in the wind-tunnel. It puts more weight over the front wheels so he can get round the down hill hairpin bends faster.

Mike

[Jo]

Ah Jo, a true fan would have watched it live

A true fan would be at Silverstone this weekend   

Those of us who can't can make the most of the weekend in the garden/workshop and watch it at our leisure 

Jo