Is it possible to create a new 8gig partition as installer in lion
You can do a clean reinstall from the recovery partition without needing any external media:


Hold command-R on startup
Erase the Macintosh HD volume from Disk Utility
Choose Reinstall OS X


If you don't erase the OS X volume first, Reinstall OS X does an upgrade install.

See OS X Lion: Erase and reinstall Mac OS X.

"Startup disk" probably means the main OS X volume (like Macintosh HD) here:


  Select your startup disk from the list on the left, and then click the Erase tab.


If you erase the whole drive, it also erases the recovery partition and EFI partition, and your Mac will try to start up in internet recovery mode when it is restarted.