pulley insert to change diameter 1

[edearl]

I need to change a 6 in diameter pulley to an 8 inch diameter by inserting a ring apparatus consisting of two half-moon rings which when bolted together is balanced and strong enough to support the delivery of 10 hp thru the belt driven system. I would call it a pulley enarger insert. Are there any sources or experience known about doing in this manner?
The pulley on my Perkins marine diesel would be difficult to remove and replace expense wise- so I want to just enlarge my existing pulley.

 

[unclesyd]

Does the existing pulley have a reverse key?

 

[Tmoose]

split sprockets were/are popular on go-karts with chain drive.

http://www.gokartsupply.com/sprocket.htm

I thought timing belt drives were becoming popular, so I would not be surprised if the concept is well proven