Has there ever been a 11–1 in the Primera Argentina?

Yes, 3 times.

The first time: September 8, 1905, Alumni beat Lomas Athletic (Alumni 11–1 Lomas Athletic).

The last time: March 11, 1971, Independiente beat Platense (Platense 1–11 Independiente), 55 years ago.

Home wins: 2. Away wins: 1.

Nearby scores

1. 12–0 4 times
2. 12–1 1 time
3. 12–2 Never
4. 11–0 4 times
5. 11–1 3 times
6. 11–2 Never
7. 10–0 6 times
8. 10–1 7 times
9. 10–2 3 times

All games

1. March 11, 1971 Platense 1–11 Independiente
2. June 7, 1942 Boca Juniors 11–1 Tigre
3. September 8, 1905 Alumni 11–1 Lomas Athletic