Dunno if you guys have ever heard of these things or not but i figured it is GM and also a huge part of GM'* preformance history.
Below is pictured a 2.7 and a 3.0 Pontiac SD4 4 cylinder engine while it is a very fragile motor they create insane amounts of horsepower for there time and even in todays standards. the 2.7 was the 1st generation of the SD4 putting out about 188-200HP this was the engine that was in the Dole IMSA GTU car (the car my 84 IMSA was promoting and my IMSA originally came with one) Also the Dole team Fiero car drivin by clay young was also the 1st american car ever to win the IMSA GTU series back in 84-85.
Over the years the engine evolved into the 3.0. it looked a lot like the 2.7 but putting out a total of 300HP N/A To my knowledge it was never used in any of the IMSA cars directley but was sold as an over the counter engine from pontiac but never offered as a option.
Soon after came the cosworth pontiac DOHC SD4 with an N/A setup it was putting out about 500HP there were not may of these motors made .
2.7 SD4 the 3.0 also looked like this
And this was the cosworth/pontiac DOHC.