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Less brakes, more gas!
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Rods and Weights
Car: '82 ROW SC
I have a set of group 9 rods running on average 708g. I am thinking on trying to find a set of group 1 rods. Even if I were at the top of group 1 I would be saving ~60-65 g per rod... Not sure its is worth it, but seemed like a good idea when I was reading the spec book in the mens library the other day  Though, it seems they are not marked and must be weighed to determine weight group... best regards, Michael
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 Michael '82 Euro SC 'Track Rat' 22/29 Hollows, 22/22 Tarrets, Full ERPB F/R, Rennline Tri Brace, Glass bumpers, Pro 2000's, 5 pts, blah blah blah '13 Cayenne GTS |
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04-12-2007, 07:48 AM
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Moderator
Join Date: Dec 2001
Posts: 9,569
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Ahh, the revelations that come from reading the little white book in the smallest room in one's house! What a way to pass the time.
Yes, the factory used "selective assembly" to divide the production into various weight groups, to save the trouble of having to match every rod to the same weight. New rods won't work, because all new ones are from the heaviest weight group. The factory must have held out the heaviest group for the replacement parts. So you would need to call the various dismantlers and see if anyone has a set. Which seems a great deal of trouble for a savings of 9%. The engineering minded here can compute the exact reduction in rotating inertia from taking 390g off the crank at an average distance of 35.2mm from the center . . Now, on the other hand, were you to invest in some lightweight Ti rods. . . Pauter claims a weight of 390g per rod for the 2,2, suppose the 3,0 rod is about the same (aren't they a little shorter?) or a 45% reduction. . .
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'66 911 #304065 Irischgruen ‘96 993 Carrera 2 Polarsilber '81 R65 Ex-'71 911 PCA C-Stock Club Racer #806 (Sold 5/15/13) Ex-'88 Carrera (Sold 3/29/02) Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04) Ex-'89 944 Turbo S (Sold 8/21/20) |
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04-12-2007, 11:00 AM
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Less brakes, more gas!
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I figured you would appreciate this question, John
 Calling around is no biggie since its them that will be doing the digging and weighing... Henry probably has a set all ready to go having seen a pic of piles of rods in his shop. ~390g sounds like a lot when its running 6500 rpms. Would be hard to do inertia calcs w/o the rod cross sections, but we could guess Should also have the same effects as lightening the flywheel, just not as much. Also, seems like one of the few LEGAL changes you can make to the engine internals for a stock racer that might have some worth. I dunno... *shrug* Seems cheap though as I might be able to trade my current good set + a tiny bit of $$ and the engine is already apart. I would not recommend it if one would have to rip the engine down for no good reason... I think I'll look into it and see if I can find a set easily... Best regards, Michael
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Michael '82 Euro SC 'Track Rat' 22/29 Hollows, 22/22 Tarrets, Full ERPB F/R, Rennline Tri Brace, Glass bumpers, Pro 2000's, 5 pts, blah blah blah '13 Cayenne GTS |
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04-12-2007, 07:23 PM
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Ugly Betty
