This thread got me curious, so I did a deep dive into Purdue football history.
No National Championships
tied for 1st in B1G in 2000, went to Rose Bowl. finished 2nd in '66, tied for 2nd in '79 and 2nd in '80.
'Best' seasons: 9-0 in 1943 - finished 5th in AP. //8-0 in 1929 // 7-0-1 in 1932
best sustained success:
1966 to 1969 - including 9-2 in '66 and Won Rose Bowl - 7th in AP. Bob Griese QB '66 & '67.
(MSU won B1G in '66 but did not go to Rose Bowl due to B1G "no repeat" policy)
1978-1980 under Jim Young. 20-3-1 in conference games. went 10-2 in '79, won Bluebonnet bowl
---(in '79, one of Purdue's 2 losses was to....MN)
1997-2000 under Joe Tiller. Tied for B1G title in 2000, finished 13th in AP. Drew Brees at QB
since 2003, Purdue has not finished a season in the AP Top-25.
Gophers certainly have more Natty's and big years, but from '66 to 2000, Purdue arguably had more success than MN during that time period.