They have hit 88 HRs in 52 games or about 1.69 per game. If they do that for the entire season, they will end up with 274 HRs, beating the record of 264 held by the 1997 Mariners. There is still a long way to go, of course. But so far this is very impressive. They also have 123 doubles to lead the league. At the pace of about 2.37 per game, they will hit 383 this year, beating the record of 376 held by the 2008 Rangers.
Also impressive is their team isolated power (ISO) of .227. ISO is slugging percentage (SLG) minus batting average (AVG). It is a better measure of power than SLG since it is extra bases per AB. The Blue Jays have a .471 SLG and a .244 AVG. That gives them a .227 ISO. If they finished the season with that mark, it would also be an all-time record.
The table below shows the top ten in team ISO in AL & NL history. The Blue Jays are way ahead of the record right now. Just imagine how many runs they would be scoring if their team on-base percentage was not 20 points below the league average (.310 vs. .330). They are second in runs with 271.
The next table shows the top ten in team ISO relative to the league average in AL & NL history. The 1884 Cubs had a .165 ISO while the league average was .097 (they were actually called the White Stockings at this time). Since .165/.097 = about 1.69, they get a rate of 169. The AL ISO this year is .148. So the relative ISO for the Blue Jays is 153. That would rank them very high.
In 1884, balls hit over a fence of the Cubs park that was only about 200 feet away were called HRs instead of doubles as they were in other years. So Ned Williamson hit 27 HRs that year. I think some other Cubs hit over 20.
The next table shows only the top ten since 1900.
Sources: Lee Sinins Complete Baseball Encyclopedia & ESPN