In the majority of physical experiments doing a blind test is not that helpful, since it will not change the physical data. It can happen that blind testing is helpful, but most of the time it is a sign that the protocol or equipment needs to improved.
Most of the time bias creeps in at the analysis stage. In my experience. Deciding what data to keep and what to reject, deciding which fitting algorithm is working correctly, etc.
The purpose of blind testing in medicine is to eliminate the possible effects caused by different patient-doctor psychological interactions.
If we find out that inanimate objects behave differently if the operator does/doesn't believe in their success (as patients do), then that'd be much bigger news than engine development.
