Hi,
I was casually going through the thread and then came across this,i would like to add that,we never really got full TOT from russians regarding the cryo engine. The supply of tech ran dry far earlier in the development stage than we might think.
Besides unknown to many members ,india started working on cryogenic engines way back in mid 80s,that engine though was based on gas generator cycle producing 120kN of thrust or the long forgotten CE-12!- an entirely indian development effort! things were progressing rather slowly and ISRO was facing critical challenges/hurdles in the design and it was that time ,ISRO got russian cryo engine(the initial contract envisized 2 cryo engines and full TOT),which although had a little lesser thrust than the engine we were already working on,but was based on a radically new cycle "staged combustion cycle"(a cycle that had instability issues and the engine itself wasnt fully ready when it was handed over to india).However staged combustion cycle offers higher thrust at the same mass flow rate and hence a better mass fraction of the rocket. indian CE-7.5 although loosely based on russian cycle, incorporates a great deal of changes as compared to the russian base cryo engine
The bigger CE-20 that will be used in all GSLV MK-3 upper stage, is based on a gas generator cycle producing a max of 220kN of thrust.More powerful cryo engines like the one capable of delivering 600kN of thrust are still on drawing board