Scorpio is the second strongest XB engine available for Android after ExChess. The current compile was prepared for arm5 which is by default, the most compatible.
Now we can run an arm7 compile of the same source thanks to Jim Ablett. This one should perform slightly better than arm5.
Normally 30 to 40 ELO more can be expected but the theory is not always fully working, depending on how efficiently the source benefits from the instructions specific to arm7. Don't be surprised to see that the difference is barely noticeable.
Once again, the package comes with scorpio.ini but i must state here that i could never ever obtain any effect with the settings. No matter how i rename the file, Scorpio.ini or scorpio.ini, the engine does not seem to access it and uses default values.
As usual, Scorpio needs Chess for Android, the only Winboard compatible GUI for Android.
Erratum on 19-Dec-15: No. It can use scorpio.ini very well but the file must be named scorpio.ini and not Scorpio.ini. I've checked today once again and after reinsralling the file, the engine can use all four cores as well as 256MB hash. This explains why during the last rounds of Rapidroid Scorpio performed ~200 elo lower. Now it should be okay because all rounds will be repeated with the arm7 compile.
One thing will remain unknown anyway: why did i decide that SMP and hash don't function while the old logs prove the search depths were high enough?
Finally, with single core and without hash, 3 minutes thinking result is around 235kNps while quad core and 256MB hash boost the performance to 830kNps on Exynos 4412. Indeed the SMP scaling of Scorpio is very good.
Download Scorpio 2.7.7 for arm7: HERE