you are full of mistakes
To start China never got the Su-27 in 1985, the Soviet Union did, the bulk of Chinese Flankers were gotten after 2000, around 2004-2007, after China bought the license.The Flakers China bought directly from Russia had a pair of Al-31 included, the 1100 engines are spares or for the J-10
If China has bought 170 Su-30s/Su-27SK, you are adding to 1100+340 engines, China also used 208 Al-31s for the J-11s built in 2004-2007 (here i mention the Al-31s used on J-11As were included in the licensed, but perhaps were signed independently)
So the numbers are 1100 minus 208 minus 340 minus 208 if you say China has not decommissioned old Flankers and China has changed engines to the original license flanker clones , that gives you roughly 760 +240 used on J-10s, however the J-10 have been built even in 2016 or 2008, trying to justify that China changes engines after a decade is blantly ludicrous,
Why is ridiculous? first limits the number of Al-31s used on J-10s to 240 and it says aircraft built in 2010 onward are changing engines after merely 4-5 years, also Flankers built in 2006 will be changing engines after a ridiculous 10 year period, there are aircraft built in the 1980s that can be used with old engines, a 2006 aircraft does not need a pair of engines since most of these aircraft fly subsonic missions.
Second even if the change engines what engine powers J-20? how are you going start low rate production and with what engine?
Has J-20 flown post stall? no it has not, has it shown TVC nozzles? is it flying on WS-15, further more the Al-31s were purchased along engines for Y-20/Il-76, close to 224 D-30KP2, so tell me how ,many Il-76s are they going to re-engine?