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

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.

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...

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.

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)

http://forums.pelicanparts.com/uploa...1153434461.jpg

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