Getting started on a 917K

I just visited Fran at RCR, and put a deposit down on a 917K. The factory is a lot of fun and it is really impressive to see all the cars, chassis, body parts, etc. The day I was there a GT40 was being shipped out.

I'll be posting a lot on the progress, and building a website like I did for my Ultima.

Main question at this point is - is this the most active forum on the 917? Its rarer than many of the other marquees, but it would be good for me to find the best way to connect with other builders.

Craig, I think you are blazing a path that many will be interested in here. Many vintage GT car builds are enjoyed from Lolas to one-off modern era cars. They all raced together and definitly live here on the GT40s Forum.

Is it a aluminum mono chassis version (like the other RCR cars) or a space frame car like the original? Please join us here with your build. I know many of us are very interested in the 917 series of cars.

Mark, thanks for your reply - sounds like there are some 917 fans on this forum!

Howard, in response to your post - yes, this is an aluminium tub, but only from the firewall forward. The rear of the car is still a tubular space frame, approximately fitting the original 917 chassis, but designed to exactly match the original car's dimensions.

Any other 917 builders out there?

Finally! I love the 917.

I am going to like this thread. Lots of pics PLEASE!

Welcome Craig!

''All Hail Craig'' for being the first to step off the porch and put his money where his mouth is regarding the 917. Oh, those cars are soooo sweet, I too looked hard at the 917 but knew that I'd just hack the poor thing up and put a Big Block Chevy in it with Kinsler fuel injection jutting up over the roof! ...or something equally as obnoxious. You guys would have HATED me. So here I sit waiting for the delivery of the first super liteweight coupe from Fran. We all will be looking forward to your build.

Rob

Pardon a minor correction, but *I* am the first to step off this particular porch. I've had a deposit in on a 917 mono from Fran for a few weeks now. I have a local guy building an engine from a 993 for it (found and bought a donor longblock already) and already have a 930 gearbox sourced as well. Should put near 350HP to the wheels with TWM throttle bodies, Motec, and a fairly mild build. Plan for it to not only be streetable, but hoping to title it as a kit car in NC. Not that I'll drive it much on the street, but I'd like to be able to.

Welcome to a very small club, Craig.


--Donnie

Its a small club now...but not for long judging by the response I have been getting for the mono versioned car....

Awesome Donnie. I know a lot of guys that are busy with GT40 builds (and a lot of the rest of us) have been waiting to watch a RCR917 build so please keep the camera ready and post away.

Oh, I fully expect it to be a small club for a VERY short period. Especially once my car is done. I have every intention of getting it DONE first, too. Of course, that means *I* am not doing very much of it. I do hope to go get some pics of me "wrenching" on the motor and then once it is done I will probably deliver it myself to Fran and get some more pics of me helping "install" it. That'll help with the kit car status. But it'll mostly be professionally built, so I won't really be able to take many pics of it. We'll all have to bug FRAN to do most of that. Fran, I have no problem with daily pics of my car being built. *cough*

FWIW, Porsche Parade is not far from me in 2008 and I *really* want it done so I can take it out there and at least show it off. Fran's last target estimates put it well in time, but I'm gonna stay on him to keep it that way. I don't expect that will be too bad, though...my motor/tranny guys may be a different story, however.

I can't wait for this thing on a lot of fronts...it'll be my first "big power" air cooled car (I have an '87 911 that's mostly stock) and it'll be my first Motec car. It'll also be so damned cool looking I won't be able to stand it. Plus it should perform pretty dang well on the track, which is what this is really all about...


--Donnie

I think this, or the RCR forum would be just fine for posting your build progress. I don't think i have seen any other 'kit car' related forums that are run as good as this one. Dont worry, this forum will become a very popular after you start posting.

I'm really excited and am anticipating your progress with this. I'm hoping, down the road i can get one of these cars.
I already have questions for you; Where are you from? I hope you are local!
What are you planning for an engine?
If I remember correctly, I think Fran said something about the suspension for his 917 being a direct copy of the originals, geometry and everything. Do you know if thats true with the mono car? Probably a question better directed toward Fran?

I would also like to see the link for your build of the Ultima.

The suspension is a copy of the original. The rear section of the car isn't an exact copy, but is close enough that if you only remove the rear bodywork (front doesn't come off easily anyway) then the untrained eye won't really know it from the original. Well, you will, because none of the mono cloners are likely to stuff an original 12 cylinder in there, though Fran says you certainly could. Anyway, the rear suspension does have the same geometry, it's just the rest of the rear that's only "close" to original. The body is cloned off an original, just like Fran's GT40.


--Donnie

I'm a Porsche addict, and 917 is one I want to own one day....
(after 962, which I'm going to start soon)

For me 917 must have a flat 12 !!!
I know the real engine is very expensive and very difficult to find.
Do you ever think about put two 3.2L (or two 3.6) to get a flat 12 with a look close to the real one....(and the sound of course !!!!)

would it be possible to do that or it's too difficult ???

To my knowledge KraftwerkZ did couple two 911-engines to a 12-cylinder for one of their
cars. They even had a pic of that engine on their website.

But I think that´s not such a good idea. The 917 engine (internal code "912" to intentionally stir some confusion) was a 180 degree V-12 with two pins sharing one conrod which made for a rather compact engine. Your standard 911-engine is a flat 6 meaning each conrod sitting on its own crankpin. So by coupling two of these engines, tempting as it may be, you not only get a rather heavy engine but also one which is considerably longer than the original engine. This makes for a nice shift of the CoG towards the rear necessitating another suspension set-up. As another result you inevitably end up with a higher number of crankshaft bearings which increase the engine´s internal friction. Also, the resulting very long crankshaft would cause some quite severe longitudinal vibrations. On the other hand, if someone finds a doable way of tackling all these problems it would make for a more than appropriate engine for Fran´s 917.

Best,

Marcus

Marcus,
180° V12?--- You mean Flat 12 dont you? Joining two 911's back to back is doable, just depends how concerned you are about the harmonic situation and how you go about taking the drive out of the crank(s). If you envisage lots of street driving etc then its probably not a wise choice, but if you intend only club events/track days etc of limited duration then it would be a relatively inexpensive solution to the powerplant problem. There is more than one way of doing this -some relatively simple- depending on how much you need to have an original appearance.

Jac Mac

Jac Mac,

yes, I mean a flat twelve.
Just wanted to avoid any confusion since in German technical terms there is a distinction between a "flat" engine with the rods on separate pins and an engine with two rods sharing a pin. The former we call a "boxer"-engine (911, Beetle)the latter we call a 180° V12 (917).
I see it the same way you do, for track use the engine would be fine (and impressive, at that). I´d even put up with the non-original appearance, it still looking far more original than a simple 911 engine.

Cheers,

Marcus

Two 911 engines joined together will be too long...by sharing a crank pin the original 912 engine(its original designation) can be shorter(also less torsionals in the crank) the trans shaft and also the fan motor are driven from a bevel gear at the center of the length of the crankshaft..again to reduce "wind up" of the crank.. ..the 917 does have a large tail section but eventually you run out of space.....

Dont loose sight of the fact we are paying homage and building replicas.....even spending 350-400k for an original engine wont help as you need the bespoke transaxle also....

I did actually look into the original 180 degree V12 engine. I found some drawings on-line and in some of the books on the original car. The engine is impressive, and would be an absolute treat to have. I did quickly look into the engines fashioned from multiple blocks - and trust me their are some weird ones out there. The twin flat-6 is long, and I have to believe that its not very reliable. Some enterprising souls had built some V-12's from twin 6 inlines, so I'm sure that a flat-12 could also be built, but I'm not aware of any air-cooled inline 6's. Again, it probably only just works.

But I need something reliable and not insanely expensive, so I will be basing my drivetrain on a twin-turbo 993 engine (just the 6 cylinders). My plan is to try to layout the components like Mark Donohue's 917/30, and unlike the first year of the turbo 917, I will be using blow-off valves I find it amazing that they raced some races with turbos and no blow-off valves - the drivers reported having to take their foot off the gas a full two seconds before they wanted to slow down. Those guys had balls of steel (or in Porsche's case, it's probably cross-drilled titanium with a ceramic coating passing oil through them to save on the weight of hoses).

The one change I will make to the 993 is to have a horizontally mounted cooling fan like the original 912 engine. I'd appreciate any thoughts on how to do this. I have seen some photos of more contemporary flat-6 Porsche racing motors with a horizontal fan - anyone know how this is driven, and what shrouds might be available?

Maybe some sort of aircraft engine could be adapted?
Jabiru 5100 Engine

only makes 180hp... at 3000rpm!

WOW!!!

$20,900.00

That's a lotta scratch for that aircraft engine! Of course you may spend that much on a Porsche Twin Turbo 3.6L 6-cyl anyways building it up to monstrous proportions. But that's a ton of money for 180HP.