What's the point of making a next gen modern fighter jet if you are using older generation components.
4th Gen Engine is not a good option for a 5th Gen platform. RD-93 is a enormous heat source. PAF won't be looking west for engine. They will get their engine from China.
Please, just get over this.
Who said that jet engines whether 1st to whatever gen are not enormous heat source. Modern engines have better exhaust nozzles to reduce IR signatures.
The UEC press release states, "
The RD-93MA engine has improved performance. In particular, increased thermodynamic parameters, an improved design of the fan and the hot part, an upgraded automatic power-plant control system... An additional emergency engine start mode was provided... and the possibility of emergency fuel drain was realised. All this is due to the specifics associated with the possible use of the power-plant on a single-engine aircraft..."
Increased thermodynamic parameters means turbine inlet temperatures were increased, and to counter it turbine module and engine exhaust nozzle must have been redesigned to cater high temperature of engine exhaust gases.
Generally this is being done by increasing bypass air flow around turbine stages and exhaust nozzle, redesigning of turbine stators and blades, use of ceramic or similar material in and around turbine stages and engine exhaust nozzle. This in turn reduces the IR signature.
In addition to this, design of fuselage engine intake and rear fuselage which houses engine exhaust nozzle and tail pipe, matters most in reducing RCS as well IR signatures. If PAF is using YF-23 fuselage design fusion then no doubt they are seeking stealth characteristic for this plane.
Furthermore do not underestimate Russian technologies especially their engine technologies, they were competing US till 1990s. Now they are making their own fifth and sixth gen aircraft (unarmed wing man).
Somewhere in this thread, I quoted one of PAF senior officer's remarks regarding durability and reliability of the RD-93 engine. He affirmed that the engine flew 7000 hours which means the metallurgy used in engine critical parts has improved (a lot) since its first production in early 1980s.
Here I must admit that Chinese jet engine infra structure is improving but still not at par with Russian technologies. They need at least 5 to 10 years (at the current speed of improvement) to be at par with Russians and Western technologies in jet engine designing and manufacturing. Who knows, they become the leaders in the jet engine tech after 10 years.