>>"I don`t now what BVR will be for stelth fighters, as useing them would give them away"<<

Careful.

1.  The F-22 radar is very frequency agile, has very high bandwidth, has very very narrow beams with almost no side lobes, and uses very unusual waveforms.  It is a very low probability of intercept (LPI) design.  So the F-22 can actively transmit without "giving itself away".  The B-2 stealth bomber also uses very low LPI radars and comm gear.

2.  The F-18E is just now getting a similar radar, and the F-16E us supposed to get one too.  The F-18E has a couple of advantages relative to the F-16E on this score.  First off, in it's redesign from the C/D to the E/F, the F-18 nose and surrounding structure was specifically optimized for the new radar.  The F-18E/F also has much more powerful electric generators to power this new high power radar.  And during the redesign, the F-18E/F got a lot of stealth treatment in the forward aspect.  The F-16E with it's conformal tanks and avionics pods has INcreased rather than decreased it's forward aspect radar cross section (RCS).  In a BVR engagement, having an active elecronically scanned array (AESA) radar is a BIG advantage.  Having reduced forward aspect RCS is also a big advantage.  Having both is even a bigger advantage.

3.  Even if two aircraft have identical old style radars, but one aircraft is stealthy and the other is not, the stealthy aircraft has a HUGE advantage.  He can not only detect his opponent first, but can track and launch on his opponent way before his opponent can.