Much doubt that would have ANY effect, esp. not in this design. Pls. also take note which other comtemporary stealth fighter designs use this (I could be wrong but I believe that none do). Besides, any J-85 derivative engine would be a turbojet, meaning all air taken in passes through the engine and combustion chamber (it is not a turbofan as used in Saab Viggen, let alone a high bypass turbofan as used in e.g. A-10).
See
https://aviation.stackexchange.com/questions/16876/how-do-stealth-aircraft-reduce-the-heat-signature and illustrated here
https://aviation.stackexchange.com/...lth-aircraft-designs-use-podded-engines/23960
for B2 design
Burying engines deep inside the fuselage minimizes the thermal visibility or infrared signature of the exhaust. At the engine intake, cold air from the boundary layer below the main inlet enters the fuselage (boundary layer suction, first tested on the Northrop X-21) and is mixed with hot exhaust air just before the nozzles (similar to the Ryan AQM-91 Firefly). According to the Stefan–Boltzmann law, this results in less energy (thermal radiation in the infrared spectrum) being released and thus a reduced heat signature. The resulting cooler air is conducted over a surface composed of heat resistant carbon-fiber-reinforced polymer and titanium alloy elements, which disperse the air laterally, in order to accelerate its cooling. The B-2 lacks afterburners as the hot exhaust would increase the infrared footprint; breaking the sound barrier would produce an obvious sonic boom as well as aerodynamic heating of the aircraft skin which would also increase the infrared footprint. The wing shield the exhaust and plume from below.
Engine types:
The purpose of that cowling on the Viggen is not to hide the engine, or to help cool the exhaust gasses. Rather, it is there to house the huge thrust reverser that gives the Viggen its STOL characteristics (it uses reversed thrust to decelerate) and lets it run in reverse on its own.
versus afterburner
See 9:50 and on, for a real good look, here:
Also, there simply are no 'small air intakes' on the Viggen fuselage
When the country's ability to produce fire had now reached a degree of science and technology you everything the world's leading countries in the field. These developments are just the poor little guy the field. the tiny body positions sent off the pitch. Hes Cairo the same story! Although the final versions are introduced, but these things should not be underestimated. Should Iran by America, Russia, Japan and China compared because the Kshvray especially America from World War I to the industry, and after a few years here in the Valley of the path you are 10 years of traveling that this goes to show progress the Ministry of defense has set up the following extent.
America, Russia and China did not exist when we put the Iranian government but we Tmdnmvn Carmon now reached the point where we love ourselves just a little weak and show. Even though great progress was made in the bad I say!
(perhaps yhou could clean this up a bit, so all can read what you had to say)