Tony Thomas wrote:
Not sure why you say this Rob. A 21 double cupped will definetly help on
the hole shot but will overrev by about 250 rpms. The double cupping adds
bite and creates extra drag which reduces the rpms without adding pitch.

You almost answer your own question here...

It
will also slow the boat down considerable due to the fact that your now
turning a 21 instead of a 23. Expect about 5 mph drop in top end if you
keep the rpms at 4600 (don't overrev).

This should be somewhat offset by the switch to a precision SS prop from
a cast aluminum wheel - typically minimal loss of top end...

As for the Torque Shift prop - I don't care for the maintenance of the prop
springs and the cracked hubs and the stress on the lower unit. They do work
but are not worth the money and maintenance costs.


For a Mercruiser Alpha, you are correct, but a Volvo SX should be able
to handle it... esp. with the V-6.

Rob