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razorscooter posted:
I dunno, crankshaft lash on a powerful V16 seems like it'd be pretty ludicrous. OFFICER 13 INCH posted:I take it you love the inline 8 all wheel drive ford Tempo then what
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Oct 11, 2014 01:40
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atomicthumbs posted:I dunno, crankshaft lash on a powerful V16 seems like it'd be pretty ludicrous. Cadillac said with the 1000hp v16 in the cadillac sixteen concept, they had to adjust the timing on the last few cylinders because of the amount the crank flexed under load. This engine might not have the same issue because the load is on the center, rather than the end.  apparently the block weight 175lbs, only 68 more than an LS6 block Powershift fucked around with this message at 01:58 on Oct 11, 2014 |
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Oct 11, 2014 01:51
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Powershift posted:Cadillac said with the 1000hp v16 in the cadillac sixteen concept, they had to adjust the timing on the last few cylinders because of the amount the crank flexed under load.
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Oct 11, 2014 02:05
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Rev. Dr. Moses P. Lester posted:That sounds quite disturbing from an engineering perspective. Yeah, that was GM's slogan at the time.
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Oct 11, 2014 02:08
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Powershift posted:This engine might not have the same issue because the load is on the center, rather than the end. Fun fact; the Porsche 917's flat-12 (actually, 180-degree V12) takes power off the centre of the engine via a gear-driven jackshaft...I imagine the experimental 16-cylinder 917 engine did the same. Also of note is that Porsche attempted to do the same thing with a naturally-aspirated, V12 successor to their TAG-badged F1 engine, but that engine, the Porsche 3512, turned out to be an unmitigated failure on account of its size and weight. On the other hand, the failure of the 3512 forced Porsche to design a V10 successor, which was ultimately developed into the engine found in the Carrera GT, so it wasn't all bad in the end.
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Oct 11, 2014 02:16
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Don't a few longer engines run the timing chain/gear/whatever in the middle for the same reason? Seems like it would have solved the Cadillac engine's problems, anyway.
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Oct 11, 2014 02:19
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Im pretty sure the central takeoff in the 917 was purely to drive the fan though under the assumption if the engine wasnt turning anymorw you didnt really need the fan any more. E: i should find the pictures I posted a few years ago of the last 917 built using a dragons horde of NOS parts including the last unused NOS 917 frame 
INCHI DICKARI fucked around with this message at 02:31 on Oct 11, 2014 |
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Oct 11, 2014 02:22
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OFFICER 13 INCH posted:Im pretty sure the central takeoff in the 917 was purely to drive the fan though under the assumption if the engine wasnt turning anymorw you didnt really need the fan any more. Not quite; there are two shafts driven off the central gear. The upper one drives the fan and distributors, the lower one is actually where the drive comes off the engine.  And yes, post those pictures!
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Oct 11, 2014 02:38
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Rev. Dr. Moses P. Lester posted:That sounds quite disturbing from an engineering perspective. Yet also gives me a very weird boner.
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Oct 11, 2014 02:39
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OFFICER 13 INCH posted:Im pretty sure the central takeoff in the 917 was purely to drive the fan though under the assumption if the engine wasnt turning anymorw you didnt really need the fan any more. gently caress, that thread was amazing
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Oct 11, 2014 03:29
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MrChips posted:Not quite; there are two shafts driven off the central gear. The upper one drives the fan and distributors, the lower one is actually where the drive comes off the engine.  No wonder trying to put a porsche designed flat 12 in a 1948 car bankrupted cisitalia.
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Oct 11, 2014 04:17
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Fucknag posted:Don't a few longer engines run the timing chain/gear/whatever in the middle for the same reason? Seems like it would have solved the Cadillac engine's problems, anyway. No, it wouldn't have. The timing chain is only responsible for the cams, which would flex a lot less than the crank; the crank will flex the most wildly at the point furthest from the transmission. They would essentially have had really unusually ground cams where the lobes for the last few cylinders would have been in the 'wrong' place compared to the others from a purely theoretical standpoint, unless timing just refers to ignition timing. In that case, the last few cylinders would've been making less power than the frontmost because they would have slightly retarded cam timing under full load. The cizeta would not have had any of these issues because it had the transmission load in the center and had two crankshafts anyway AFAIK.
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Oct 11, 2014 04:44
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Photodump of the 917 engine build  Titanium crankshaft        Porsche crankshaft part number, call up the dealer$$$hip for a price quote  Manufacturers mark  Titanium rods  Titanium driveshaft  Oil pump assembly      I really hope this old guy's name is Hans or something          Piston and Cylinder  Low compression    Cam carriers     Valve lapping  Cylinder head             
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Oct 11, 2014 05:05
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Pictures of receiving the last NOS frame and assembling a rolling chassis    The chassis weighs 109 lbs. Back in the day they even had bungs on them because the frames were pressurized, so the technicians could check to see if they were cracked anywhere by the fact of whether or not they held pressure.   Porsche was known for their welding skills    Making shocks   Pressing bearings  Titanium hardware    Original 917 Balsa wood shift knob for weight savings       Axles      
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Oct 11, 2014 05:52
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I think I need a few minutes alone after seeing that. 
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Oct 11, 2014 06:20
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There's a lot more, unfortunately the pictures of hand laying the fiberglass in the body molds are so tiny as to be nearly illegible but the final assembly probably has 200 or 300 pictures alone to a full running chassis. I'm working on it, to say the least. It's worth the repost.
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Oct 11, 2014 06:24
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Why bother with drive shafts with cardan joints if there's a rag joint in there too 
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Oct 11, 2014 07:35
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Imgur is being cranky about finishing up the batches but for teaser for tomorrow for those of you who havent seen these already: 
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Oct 11, 2014 07:46
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EightBit posted:Why bother with drive shafts with cardan joints if there's a rag joint in there too Different functions. Cardan joints allow for angle changes, rag joints primarily absorb torsional vibrations. It's basically a CV axle with a damper stuck in the middle. Those engines have basically no flywheel, and with all the titanium you can imagine how light the rotating assembly is. That means the entire drivetrain accelerates a lot with each cylinder firing and decelerates a lot on each compression stroke; even with the close angle spacing of a 12-cylinder engine, that's a whole lot of oscillation above and below the average drivetrain speed. It puts a lot of strain on lovely 70s tires; the rag joint helps dissipate that and give the car smooth power delivery while still having an engine that revs to the moon at the touch of a feather (which you wouldn't get by slapping a big heavy flywheel on there, which is the solution on street cars). E: Also meant to mention, they probably use double cardans over typical ball-in-groove CV joints because the latter couldn't handle the 600 or so horsepower with late 60s metallurgy. Fender Anarchist fucked around with this message at 07:50 on Oct 11, 2014 |
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Oct 11, 2014 07:48
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13 INCH, we salute you
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Oct 11, 2014 10:12
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Holy poo poo, this is amazing. I haven't seen these before. Judging by the cars in some of the photos, looks like this took place some time in the mid-90's? What's the back story here? Looking forward to the rest of the pictures.
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Oct 11, 2014 19:42
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OFFICER 13 INCH posted:Porsche was known for their welding skills
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Oct 11, 2014 19:55
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Fucknag posted:Different functions. Cardan joints allow for angle changes, rag joints primarily absorb torsional vibrations. I'd say they're probably a lot lighter too.
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Oct 11, 2014 19:58
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GentlemanofLeisure posted:Holy poo poo, this is amazing. I haven't seen these before. Judging by the cars in some of the photos, looks like this took place some time in the mid-90's? What's the back story here? Looking forward to the rest of the pictures. I'm not sure I'll see what I can dig up tonight after work but in the unboxing picture with the Z3 isnt that an early to mid 00s Honda Odyssey behind it?
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Oct 11, 2014 20:17
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OFFICER 13 INCH posted:I'm not sure I'll see what I can dig up tonight after work but in the unboxing picture with the Z3 isnt that an early to mid 00s Honda Odyssey behind it? 1999-2004 (the 2005 lost the roof rails) edit: 2003 http://www.gunnarracing.com/project/Carl917/Carl917-1111.htm nm fucked around with this message at 21:56 on Oct 11, 2014 |
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Oct 11, 2014 21:52
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That is an awesome ride, officer 13 inch!!!! Thanks for sharing it. Those mechanical guys look like they should be wearing 'Vote 4 Pedro' shirts  . Transmission seems unusually long, what is that a 7-speed in there??? Did a clutch myself, on a '92 Toyota Corollae: minor details A3th3r fucked around with this message at 01:10 on Oct 12, 2014 |
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Oct 12, 2014 00:34
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A3th3r posted:That is an awesome ride, officer 13 inch!!!! Thanks for sharing it. Those mechanical guys look like they should be wearing 'Vote 4 Pedro' shirts That's how long the average transmission is. Is your transmission that much shorter?   
Powershift fucked around with this message at 00:52 on Oct 12, 2014 |
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Oct 12, 2014 00:43
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Last local C&C of the year saw some interesting stuff:              
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Oct 12, 2014 00:59
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I love Countaches but I'd kill for a Diablo in that metallic pink purple some of them came in. First photodump of the final assembly of the 917 after the bodywork was molded.   Original Cibie headlights           Shifter with reverse lockout lever         Making a ballast resistor    Clutch balancing marks      Ballast resistors in place       starwarsimperialmarch.mp3      Fuel pumps I think  Fabricating fuel lines       Using the Porsche factory tool to make brake lines  A 917 brake flaring 
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Oct 12, 2014 04:03
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Photodump 2  NOS 917 rear window             917 Caliper bits    Different styles of 917 Caliper, early, Gulf converted Girling, Girling, and then later styles if I remember correctly                     Marking out the fuel tank for the fuel cell/etc     Nut coolers  Brake coolers     This man's hands have had better sex in one afternoon than you or I will ever have in our entire lives    
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Oct 12, 2014 04:31
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Final run:    Not pictured: throbbing erection the approximate length of Mulsanne        The first start      Fuel cell    Oil tank                        
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Oct 12, 2014 05:04
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drat that is a of a photo dump. Glad that it was so well documented.
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Oct 12, 2014 05:44
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needs more aero imo
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Oct 12, 2014 05:46
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Chinatown posted:needs more aero imo *cant hear you* *does 230mph in the rain at 2am in the dark* Wikipedia posted:There are at least eleven variants of the 917. The original version had a removable long tail/medium tail with active rear wing flaps, but had considerable handling problems at high speed because of significant rear lift. The handling problems were investigated at a joint test at the Österreichring by the factory engineers and their new race team partners John Wyer Engineering and after exhaustive experimentation by both groups, a shorter, more upswept tail was found to give the car more aerodynamic stability at speed. The changes were quickly adopted into a new version of the 917, called the Kurzheck, or short-tail, with the new version being called the 917K Or maybe the twin turbo curbstomp of a car the 917-30 is a little more your flavor   
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Oct 12, 2014 05:55
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And just in case anybody could keep up with *that* motherfucker... 
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Oct 12, 2014 06:13
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Porsche... and Audi?!?!?!?!
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Oct 12, 2014 06:20
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Fayez Butts posted:Porsche... and Audi?!?!?!?! Well, they're both basically Volkswagen, right?
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Oct 12, 2014 06:23
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What is a ballast resistor?
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Oct 12, 2014 06:34
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MetaJew posted:What is a ballast resistor? Lowers the coil voltage to around 9V (and surely limits the current too, but IDR what the actual values are) for less energy while running. Typically bypassed while starting. Modern coils don't need one, I don't think; anyway my MSD blaster coil doesn't use one whereas my stock one did. I want to say that it was for preservation of the coil windings so they wouldn't melt under sustained operation? Someone older than me who was actually around then could probably clarify.
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Oct 12, 2014 06:51
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Well, at least the fuel system is modern. Wonder what kind of lap times they did around Willow Springs. When I was doing the time attack thing our best time was a 1:23.1 in a subaru with treaded r-comps. A Porsche cup car will go 1:19 or so. jamal fucked around with this message at 07:25 on Oct 12, 2014 |
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