Here's another quick engine comparison, this time the E21 and original E30 flagship models, the 323i. BMW introduced the E30 323i in 1983 using the same M20b23 2316cc injected 6-cylinder motor as the E21 had in its top model since 1977 and displacement was not increased until the better known 325i emerged in 1985. Even with sightly more weight, the E30 323i was still billed as a quicker car than its predecessor, but I have no idea what improvements were made to the engine, so lets see how the specs stack up:
| M20 Engine | 323i [E21] | | 323i [E30 <1987] |
| Bore | 80.0mm (3.15") | | 80.0mm (3.15") |
| Stroke | 76.8mm (3.02") | | 76.8mm (3.02") |
| Capacity | 2316cc (141.3 cu in) | | 2316cc (141.3 cu in) |
| Comp. ratio | 9.5 : 1 | | 9.8 : 1 |
| Power (BHP) | 141 @ 5800rpm | | 148 @ 6000rpm |
| Power (PS) | 142.8 @ 5800rpm | | 150.0 @ 6000rpm |
| Power (KW) | 105 @ 5800rpm | | 110 @ 6000rpm |
| Torque (Lbs ft) | 140 @ 4600rpm | | 151 @ 4000rpm |
| Torque (Nm) | 190 @ 4600rpm | | 205 @ 4000rpm |
A little more compression, along with a few extra horse power and a slightly higher redline make for a harder pulling engine in the high rev range, but the big difference seems to be in the torque figures. Not only does the E30 323i have a bit more, but peak-torque is delivered 600rpm lower down than the older engine and that is clearly what makes the E30 feel quicker.
