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Question for you number guys out there.
I am starting to build my back up race motor (2.5L long stroke this time). Since I am using a 2.4-2.7 crank and making up some new custom pistons this time, I have a question. The original 911 ST motors had 86.7mm pistons. VARA allows us to go 60 over.
My question is, how big of a piston can I run over the stock 86.7mm to take advantage of the 60 over rule? Keeping it legal 
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Chad Plavan 911ST Race Car/2.5L SS Race Motor #02 1972 911T- Numbers matching- Restoring to stock 2011 Porsche Spyder Wht/Blk/Carbon Fiber Buckets/6-Speed (Sold) 2016 Elan NP01 Prototype racecar- Chassis #20, #02 |
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12-29-2005, 07:05 AM
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I would rather be driving
Join Date: Apr 2000
Location: Austin, TX
Posts: 9,108
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I assume 60 over is in thousandths. So 0.060" = 1.524mm. 86.7mm + 1.524 = 88.224mm. This bore gives 2.58L displacement with a 70.4mm crank.
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Jamie - I can explain it to you. But I can not understand it for you. 71 911T SWT - Sun and Fun Mobile 72 911T project car. "Minne" - A tangy version of tangerine #projectminne classicautowerks.com - EFI conversion parts and suspension setups. IG Classicautowerks |
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12-29-2005, 08:53 AM
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Thanks!
LOL. Simple enough. I thought it was more involved than that.
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Chad Plavan 911ST Race Car/2.5L SS Race Motor #02 1972 911T- Numbers matching- Restoring to stock 2011 Porsche Spyder Wht/Blk/Carbon Fiber Buckets/6-Speed (Sold) 2016 Elan NP01 Prototype racecar- Chassis #20, #02 |
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12-29-2005, 09:07 AM
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