As of February 2018 a 692cc proof-of-concept engine had been built. Preliminary test results show FMEP @ 1550 rpm is 0.18 Bar (using 10W-40 oil @135 degrees F). Most engines are over twice this amount of friction. Inventor Mike Brickley discussed his proof-of-concept engine on a reddit AMA (Ask Me Anything) in April 2018.