I have repeated this many times - 80% of technology and modelling can be reverse engineered. Rest 20% is complicated technology which needs to be done from scratch. The problem of lack of modelling, size, angles etc can be solved with reverse engineering. The alloy and other 'novel' processes have to be done by R&D.
It is lot more complex than that 20% I will explain u how. Now u get a new material which can withstand a slightly higher temperature than the previous metal alloy.
Then u will substitute that material in the inner core now your core will be 1-3%efficient. The efficiency increases from stage to next stage at the final stage gets a hike in efficiency of 5-8%.
But u cannot put the part made with that alloy to core because the alloy may not tolerate the pressure or temperature at the last stage as it will exceed it's threshold.
NOW THE CORE IS FINE BUT THE LAST STAGE WILL MELT DUE TO EXCESSIVE HEAT.
Your next step is to put that alloy to the last stage with out putting it to the core but now ur core efficiency is same but thrust may simply increase by 0.5% - 1% which may not be remarkable but it is still a progress.
Now u decide to put that new alloy to the core then in order to not melt your final stage u have to increase inlet diameter. SUDDENLY YOUR EFFICIENCY OF THE CORE DECREASES ON THE OTHER HAND YOUR CORE AND FINAL STAGE IS SAFE. IT INCREASES THE ENGINE WEIGHT AS YOUR ENGINE INLET HAS INCREASED.
Now again a lot of changes are required such as combustion, blade vibration and core itself.
In the whole saga I have never told anything thing about time for testing this....and I have tried to explain very basic things that creates havoc.
Imagine that with just 20-30 parameters which cause effect that multiplies.
The engine is really a SON OF A BITCH to be precise..... It takes a lot of time and testing.
Engines are the only things that cannot be easily modified......