You can't get SP8 because it does not exist yet. Build from the SP branch or upgrade to 4.6.1.GA.
Thanks for your reply, can you please help me in building sp from branch.
please suggest necessary steps how to build the system to get sp8.
This link may be helpful
mostly focused on building XTS w/ TS 4.6.1 and AS 5.1, but it includes very specific build steps. Just substitute your desired versions in the SVN urls and you should be able to build everything.