917 engine animation
 

Thought this was pretty cool to stare at for a while, especially at full screen... if it's a repost, sorry.

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pretty cool

very nice!

Awesome video, but what supports that big gear?

Also, what did they call the shaft drive that turned the distributor etc.?

That's a keeper!

That's cool!

i think the cams need to be checked, the timing looks to be off about 5 degrees.

pretty cool. that would make a great screen saver. anyone know how to do that? i would never touch my computer.

The shaft which drove the distributors and flat fan was known as the 'skew shaft' i believe. As for the support of the large intermediate gears which drove the camshaft, assume it was a similar bearing set-up as the intermediate shaft in the 911 engine. If more knowledgeable minds care to chip in, would be great.

The cool thing about this CAD animation, is that the guy that did it states he used simple pix from books, some photos and a couple of diagrams, similar to the guy that built the minature working Ferrari 512. I am always amazed at this integration of technical and artistic expertise.

the big gear you see is the intermediate cam drive gear - both upper (intake) and lower (exhaust) cams are driven off that gear.

what's not so obvious in the video is that power is taken from the crankshaft at the middle - not the end. Like the 911, the 917 (type 912) engine has an intermediate shaft, however the 917's intermediate shaft takes power from the crankshaft from a bevel gear in the center, and then turns the flywheel at the back of the case.

really neat, thanks for posting.

Sorry for the mundane questions but...

It's clear the large gear is driven by a gear on the crank. What is not clear to me is where the shaft would run that supports that large gear. It looks like it would interfere with the piston rods.

Nice !
Juicersr > it is a 312PB, i met him, i have pics of the (amazing) model :)
He met the guys who built the car in italy too ...

The shaft supporting that gear does not run the full length of the engine. it's on a "tower" that goes between the case and the rocker boxes, between the two center cylinders. I'll see if I can find a pic for you. there's also some great pictures in "Excellence was expected" volume 2 that clarify things.

http://ic2.pbase.com/u15/917carl/upl...ggeardrive.JPG

Here we go. See that gray "dot" of sealant? Thats the end of the stub shaft supporting that big gear, which turns the two cam drive pinons.

http://ic2.pbase.com/u15/917carl/upl...78.MVC020S.JPG

Pretty neat, huh ?

Here is the 4.5 liter 917 crank with drop shaft. The gear on the left end of the drop shaft runs the oil pump. The splines on the right are for the flywheel.

http://forums.pelicanparts.com/uploa...1260571087.jpg

The lower shaft is titanium and I believe that the crank was forged in 2 pieces and electron beam welded together with the gear in the center.

Those parts used to be worth their weight in gold. I'd have to check if that is still true at $1200/oz.

That is so awesome!

Does anyone here know how cam timing was set? Also, were solid tappets vs rocker arms used?

I saw some pictures in a thread earlier... Looks like they used tappets.

correct...the model is of 312 pb.

Ferrari Pete is correct, there were no rocker arms per se, instead, tappets that bear directly on the cams. The twin cam engines in the 962 and 959 have a similar valve gear arrangement.

awesome, my fav porsche motor