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2.7 cam reprofile...choices
I want to reprofile my CIS 2.7 cams. I realize I have to be careful about the valves, and can go with at least an SC grind. Can I use a 964 regrind, or is that too much? And realizing that this is subjective...what do I gain in hp using the SC grind vs a potential 964 grind. I do not want to "relieve" my pistons and create valve pockets.
Thanks Speedo |
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06-26-2008, 05:56 PM
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Join Date: Jul 2001
Location: Portland Oregon
Posts: 7,007
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You can use the SC profile without any problems and that one does offer some flexibilty for variations in valve timing.
964 cams will also work but you need to be more fastidious about splitting the overlap and that cam does make the engine "peakier" (less low-end torque).
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Steve Weiner Rennsport Systems Portland Oregon (503) 244-0990 porsche@rennsportsystems.com www.rennsportsystems.com |
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06-26-2008, 09:41 PM
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3 restos WIP = psycho
Join Date: Feb 2005
Location: North of Exit 17
Posts: 7,665
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What about the Super-C2 or Sport-964? Did John think they'd not clear? You know you want to rev this car instead of having it be some lumbering torque monster with no top end...
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- 1965 911 - 1969 911S - 1980 911SC Targa - 1979 930 |
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06-27-2008, 04:03 PM
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I talked with a few local folks yesterday...
...when I dropped my engine pieces and parts off to get cleaned and checked, and ordered my hardware and gasket set prior to the rebuild. The reality is that a few have heard of the SC to 964 upgrade, but not used it. Staying with the CIS piston, nobody has messed with a different profile. I got a lot of argument against notching the piston for the valve suggesting that this could both weaken the piston and/or create "hot spots" and cause detonation. I am going to go ahead and send the cams off to DR and then discuss a reasonable compromise with John.
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06-28-2008, 04:37 AM
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1974 Porsche 911 2.7
