Williams will not be getting an early taste of its 2012 power plant.
The British team, currently Cosworth powered, will reunite the famous title-winning Williams-Renault alliance next year.
But Renault Sport F1 chief Jean-Francois Caubet played down speculation the new combination will get a head-start on the test track.
"Our philosophy is staying the same," he is quoted by France's autohebdo.fr. "We will probably not test before the end of the year, but early next year instead."
Caubet also revealed that the Williams deal has been on the cards for some time.
"We were in discussion since last season but it was impossible to complete the agreement until now. We were about to sign before the arrival of the V6 (regulations), which delayed us a bit more," he added.