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identifying 2.2 911S crankshaft
My 71 911T allegedly contains a 911S crank in its 2.2L engine. I am preparing to disassemble the engine, as the car sat for many years in storage. A few questions:
How can I identify the crank as an S item on inspection? Is the benefit of using the S crank simply an increase in compression (changing the stroke range, as the displacement is ostensibly the same)? If it is present, should I expect to find other S items (rods, etc) or is it typically used with the standard T internals in such an application? Thanks |
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Home of the Whopper
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S crank is counterweighted, a T is not.
No increase in compression, that was done by the piston dome. You never know what else you may find. If the rods are nitrated they well be blackish in color, much darker than non-nitrated rods.
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1968 912 coupe 1971 911E Targa rustbucket 1972 914 1.7 1987 924S |
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A related question, then: is the S crank heavier overall (due to the counterweights)? This wouldn't make sense to me, as I think of S cars as being more free-revving, capable of higher rpms, etc. Or perhaps the counterweights allow smoother operation and thus higher revs despite an overall weight increase...
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3 restos WIP = psycho
Join Date: Feb 2005
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S crank is heavier, but SMOOTHER, due to conterweighting, giving the impression of possibly being revvier. It will spin higher than a non counterweighted crank since destructive torque rocking is much lower on the C/W crank. T cranks have been used in race applications to speed up revving, but you can achieve the same effect with a lightened flywheel while still maintaining the high RPM chraracteristics of the S crank.
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- 1965 911 - 1969 911S - 1980 911SC Targa - 1979 930 |
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Try not, Do or Do not
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27 lb 6 oz NCW vs 30 lb 12 oz. CW
It is relatively simple to lighten a counter weighted crank. The best way to achieve stable high RPM characteristics is to lighten both the flywheel and the counter weighted crank. Changing the fan ratio and running a small fan (226 mm) will do almost as mush. Lightened 67 mm crank (959 / 961) ![]()
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Henry Schmidt SUPERTEC PERFORMANCE Ph: 760-728-3062 Email: supertec1@earthlink.net Last edited by Henry Schmidt; 07-20-2006 at 03:00 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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You had to show more unobtainium parts for us to drool over, didn't you?
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- 1965 911 - 1969 911S - 1980 911SC Targa - 1979 930 |
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Try not, Do or Do not
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This one is available on the Pelican 911 parts for sale board.
Only $3,500.00 That's less than a weekend in Vegas. Hotel $325/night Buffet $4.50 x 5 1 comp at the "Nuddle Bar" Trixxie $450/hr One "all in" with suited connectors. $$$$$$$$$$
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Henry Schmidt SUPERTEC PERFORMANCE Ph: 760-728-3062 Email: supertec1@earthlink.net Last edited by Henry Schmidt; 07-20-2006 at 06:03 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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I take it back - obtainium at a price!
__________________
- 1965 911 - 1969 911S - 1980 911SC Targa - 1979 930 |
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