Turner homered to lead off the top of the eighth to give the Phillies a 4-3 lead. Reliever Cory Abbott was still in the game when Turner came up with two outs in the inning, and his 14th homer of the season completed the big outburst.
In between Turner's homers, Bryson Stott smacked a three-run shot. Turner became the third player in Phillies history to hit two home runs in the same inning and the first in 38 years.
Nick Castellanos drilled a three-run home run with two outs in the seventh inning to put the Phillies on the board and tie the game at 3. Jake Cave led off the ninth with a homer.
The Phillies won for the second time in their last six games. The rubber game of the three-game series is set for Sunday night in Williamsport, Pa., as part of the MLB Little League Classic.
Riley Adams drove in two runs with a pair of two-out hits, but the Nationals had a three-game winning streak snapped and lost for the second time in their last eight games. Abbott (1-2) allowed all eight runs in the eighth and took the loss.
Seranthony Dominguez (3-3) was the winning pitcher with one shutout inning of relief.
Castellanos' 21st home run of the season was only the seventh hit of the game for the Phillies, who finished with 16. He was the first batter to face Washington reliever Andres Machado.
Nationals starter Jake Irvin logged six shutout innings, allowing five hits and two walks with seven strikeouts. It marked only the second game in his last 10 starts that he didn't surrender at least one home run.
Castellanos drove in four runs and J.T. Realmuto had three hits for Philadelphia.
Phillies starter Cristopher Sanchez gave up three runs (two earned) in six innings with five strikeouts and no walks.
The Nationals scored twice in the fourth, first on Joey Meneses' run-scoring single and another when Adams doubled with two outs.
Adams made it 3-0 with a two-out RBI single in the sixth.
Meneses and Lane Thomas joined Adams with two hits apiece for Washington.
—Field Level Media