Re: M42 question (archive)

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In Reply to: Re: M42 question posted by austin on February 13, 2000 at 00:24:28:

The M42 engine is based on the 318i M40 cast iron block fitted with an alloy 16V TC head (with a history back to the M1 engine) and modified cranks and pistons. It is a classic pent head with the spark plug centred between the valves. 80% of the compbustion chamber is in the head and runs a highish compression ratio of 10:1. Hydraulic tappets and duplex chains are used in the head. The the engine has a problem with the profile gasket failing but most cars at this stage will have had them replaced.

Motronic fuel/ignition management is used with distribtorless HT. There is a coil for each cylinder.

The engine is well balanced and smooth. Unlike other 16V of the time, the engine has a good spread of torque but really shifts after the torque peak @ 4000rpm. 0-60mph of ~9.5 seconds masks the need for a shift to 3rd at 50-55mph but the lowish 3rd and 4th are good for pace on back roads.

The engine basically is responsive to professional tuning as so many of the basics are right. Cheap upgrades are chipping and air filters. The stock exhaust is ~2" right thru' so is superbly functional is not so resonant.

The 318iS also contains the 325iS suspension and brakes. This means you get an M-Tech set up with -15mm springs, frimer shocks and beefier anti-roll bars. Rear discs are included which are a world apart from the usual drums. Some cars have PS, some have ABS, some have sports seats.

Although not as fast as the 325iS, many prefer its more balanced handing as the M42 engine is lighter.

Finally, only ~36,500 were made (targeted at markets in Ireland, UK and Italy with penal taxes on engine size) so it is a collectable (as echoed recently in BMW Car magazine) - however the specialised parts compared to a "normal" 318i are more expensive and harder to track down. For me, I have never had a problem but trying to find technical manuals for it has so far been unsuccessful (Bentley nor Haynes don't cover the TC).

Finally, finally, the M42 engine was modified slightly and fitted to the E36 318iS. The E36 doesn't accelerate as fast as the E30 (up to ~80mph) but its top speed is higher.

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