BMW E21 / E30 323i Engine Comparison [M20b23 2316cc]

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.

E39 Audio: On/Off Switch for the Amp/Subs

The system remote shuts off with the ignition [see: Getting a Remote Signal for the Amp], so I've no worry about getting a flat battery, but it would be nice to have a manual On/Off switch inside the cabin so I can mute the subs while driving if I need to, without having to cut out the rest of the speakers.

While I had the back seats out I ran a wire through the bulkhead into the o/s rear footwell [see: Adding an On/Off Switch], so I got hold of a beacon-switch from a tipper at work to fit inside the cabin. The plan was to run the wires out from the middle of the seat and under the carpet on the transmission-tunnel, then fit the switch inside the armrest-compartment. Neither of these panned out. Running the wires under the carpet is doable, but to lift the carpet [and the sponge backing] up enough involves completely removing the armrest console, as well as all the side trim and clips, so I've taken a shortcut for now and run the wires under the trim below the o/s door, then under the driver's seat and through a gap in the side of the console. The wires are exposed, but they're well hidden and I've made sure to keep them well away from the seat-runners.

As for the placement of the switch, which is over an inch deep with the wire terminals on, it turns out there's just no room for it inside the centre-console. The base of the armrest-console is a solid steel tray with an electronics-module right under it and the storage-tray below the armrest angles up to fit flush with it too. I don't want to go further forward on the dash and mess up the wood so I've fitted it in the storage-slot under the rear air-vents. The plastic slot was missing anyway and the vents were hanging loose, so at least it looks complete now even if it's a pain to reach. Not a problem for people in the back though and that might not be such a bad thing if one is screaming we've missed our turn-off and we can't hear over the drum and bass. I just used a piece of thin plywood for the panel, covered in the leftover vinyl wrap from my ScoobyLab stickers. It's a bit shiny, but the vinyl gives it more of a trim look than black paint.