Eight Four Suited vs Ace Three Offsuit

At the flop:
Winning 30.8% of the time
Tied 0% of the time
Losing 69.2% of the time

At the Turn:
Winning 38.34% of the time
Tied 0% of the time
Losing 61.66% of the time

At the River:
Winning 44.09% of the time(15.72% with trips or better)
Tied 0.6% of the time
Losing 55.31% of the time(2.59% with trips or better)