23 replies to this topic

[Foamy]

Nice job by those guys to get it running.

 

[rav7kaa1]

That is nice to see a piece of history come back to life.

Thanks for sharing.

[Tex]

I want one!

[obnoxious001]

I guess that thing is due for a rebuild by the amount of smoke out the pipes, but still hurt to watch them spray ether in the thing to try and force it to run!  I think if the carbs were rebuilt with fresh fuel in them, it would have fired up nicely on gasoline, since he was pointing to two of the carbs that were apparently acting up on the one bank. 

[LindsayB]

I think they said that they had been working on it for a day prior. I kind of hope that anyone who gave them a Porsche 917 that had been sitting in a museum for 30 years, also asked to have some basics done before firing.
 
Oil and filters replace
water and fuel replaced
plugs swapped out
 
I also expect someone probably sprayed oil in the plug hole as a lubrication when the plugs were out.
 
I expect the issue in getting it to fire was valve sealing/compression as accumulated gunk had built on the seats.
 
Which after a minute or of running cleared itself. The smoke was probably the residual oil clearing itself out.
 
Seems to me like they did most of the right things.
 
Does anyone know if these were carbureted or injected - (they seemed intent on fuel pressure in pre start up).

[Cheater]

Injected, definitely.

[Cheater]

Want to see the restoration of this car? Hope you have a lot of spare time... LOL!

Porsche 917 restoration

The video Foamy posted is part 23...

Lindsay, take a look at Gunnar Racing's WEBSITE. It does seem these guys might know what they're doing with Porsches!

[TSR]

Bosch Kugelfisher indirect mechanical injection like all racing Porsches since the "906".

Generally two plugs per cylinder on the 1970 engines, a single one in 1969. There is a flat-12 engine in most of the 917s, plus a flat-16 in two prototypes that never raced. The flat-12 engines are little more than a 908 flat-8 with another 4 cylinders added and two crankshafts with a center junction.
 

[Cheater]

Boy, there is some interesting stuff on YouTube...

Porsche 917 engine animation



P, I think it is more accurate to say the 917 engine had a two-piece crankshaft with the power-take off in between them. And even then, I'm not 100% sure the crank was two separate pieces. Can't find my Paul Frere references...

[Cheater]

Well, Philippe, it sure looks like a one-piece shaft to me:



From Building 917 Engine at pbase.com.

[Dr. Gamma]

What a work of art!!! Would love to be able to tear down and rebuild one of these motors!!!

Just curious, on a few of the pictures it shows fourteen pistons with the crank sitting on the bench, not twelve pistons. Spares??

[Cheater]

Bob,

 

Good catch! I didn't see that myself.

 

I simply don't know. That pic was something I Googled up.

 

I would assume you are correct though...

 

I just got a kick out of potentially nailing PdL with what seems to be an erroneous comment. Sure as heck doesn't happen very often, as the guy is spot-on 99.9% of the time. LOL!

[Dr. Gamma]

Got to see the Can-Am Porsche 917s run back when they were normally aspirated all the way to the turbo Panzers that Penske ran in 1973!!!

Can't believe how big those motors were.

They looked as long as an aircraft motor!!

Only two valves per cylinder, too!!!

[TSR]

Well, Philippe, it sure looks like a one-piece shaft to me

 

Actually they are two pieces with what is called a Hirth coupling. However this particular crankshaft on the picture could be of later manufacture...

[Cheater]

P,

 

Yes, I am familiar with Hirth couplings, but I agree... this shaft doesn't seem to have that construction.

 

One of these days, I will locate my Frere Porsche 917 books and we'll have the full and accurate story...

[TSR]

A page in the book "The Porsche Book" by Jurgen Barth (preface by Paul Frere) explains how the two crankshaft halves, coupled with a Hirth design, were then electron welded. It provided a much straighter crankshaft than the one-piece design for whatever reasons.

I saw one of these engines apart at the Vasek Polak racing shop in Redondo Beach years ago, and there were 917 crankshaft halves on shelves, prior to welding. Not sure why Polak had them but it is known that he bought much of what was left of the 917 project and parts from Porsche after the cars were deemed no longer relevant to their needs.

 

I actually own two sets of NOS front wheels from a 917, that I got thought Vasek, they were supposed to end in coffee tables but I never got around it.

[Cheater]

We're spliiting hairs, or actually cranks, here. If a crankshaft electron-welded from two-piece into a single piece, with a power take-off gear straddling the weld. is is then a one-piece crank or a two-piece crank? LOL!

 

Can I have one of those 917 wheels? I could use a new coffee table...

[LindsayB]

Can I have one of those 917 wheels? I could use a new coffee table...

 

Is this some sort of wheeling and dealing?

[Cheater]

Simple begging is probably the more appropriate term, Lindsay... LOL!

[Phil Hackett]

Could this car have come from the Vasek Polak estate?

 

He used to have the 917s, amongst other racing Porsches, prominently displayed in the giant window in front of his dealership. You couldn't miss seeing them when driving down PCH (Phillippe. it was HERMOSA BEACH... Redondo Beach is a few blocks south of the showroom).

[TSR]

Yes, Hermosa Beach of course. They all sound the same to me!

Yes, he had some of the oddest 917s, with experimental bodies that never made it to the races... never even painted, just as tested in white fiberglass!

[Phil Hackett]

I don't think you'd forget whether you live where you do or Costa Mesa, right?

[TSR]

Getting old and senile, boss...

[Dan Ruddock]

This crank design was stronger because the twisting forces only had to go half way through the crank to the center drive gear which drove an output shaft to the flywheel. Most twelve-cylinder engines did not do this and suffered from cam and ignition timing inaccuracies from crank flex/twist.

The flywheel RPM was not the same as the crank RPM as the two gears did not have the same number of teeth for improved gear wear. In its day this engine this engine was state of the art for air-cooled.

Four-valves per cylinder was not an option when designed because that would take up too much of the room for cyl head cooling fins, one of the reasons air-cooled engines are dead (but I still love them for their simplicity).

Dan