84' m20 or 91m42

[TobyB]

the M42 is a far more modern engine.

Fixed that for ya...

t

[Kershaw]

it was sarcastic, but they are rated from the factory with the highest torque of ANY E30 I think haha

And it made for really fun low speed fun.

[g.ruff561]

My opinion is it depends on what your plans are for the car. I have 91 M42 and 92 M20. I prefer the M42 hands down. That being said, in this case I would buy the 318. All cars have their gremlins. The M42 just has an easier maintenance platform in my opinion.

[varg]

Yet you have presented none.

They're common knowledge to the M42-initiated. See below.

The M42 has more design and build flaws than the rest of the car around it.
-Oil pan bolts that weren't threadlocked from the factory
-Critical oil passage runs through the oil pan and when said bolts loosen can cause oil starvation
-Insufficient half-shell thrust bearing causes crank walk
-Timing chain idler gear is a common point of failure and the casting that it is mounted to is weak
-Profile gasket fiasco could have been avoided altogether by using a different cooling passage design between head and block
-Valve cover fastener design sucks, should've used bigger studs instead of weak little M6 threads in aluminum
-The under-intake hose mess
-3 piece Timing case design is very leak prone
-7mm exhaust studs

M42 has forged internals, dual cams, ability to adjust timing, timing "chain", coil and plug ignition, hydraulic lifters, headers from factory. All which the M20 lacks, sure the M20 makes about 30hp more, but that's because it has 2 more cylinders. Let's not forget, also the 318is is about 200lbs lighter then the 325is.

-The M20 also has forged rods, cast pistons. Nothing fancy in either engine.
-Dual cams, every econobox engine in the 90s had this
-Ability to degree in the cams doesn't matter much on such a low-performance engine, and it is a low-performance engine, less than 80hp/l, doesn't even rev to 7,000rpm. Nobody bothers with it this adjustability anyway.
-This whole timing chain thing is overrated, the wear parts and timing case of the M42 are troublesome and leak-prone. Comparatively, replacing a timing belt on an engine like the M20 every few years is not exactly a difficult or expensive proposition.
-Hydraulic lifters are no big deal and the M42's limit potential for high revs. NA builds looking to make decent power go solid lifter so they can rev high reliably

The only thing the 318is has on a 325is is slightly better handling. As far as I4 engines go the M42 is pretty ordinary, it doesn't really stand out in a positive manner vs any other DOHC 1.8L I4. The M42 is a buzzy, anemic turd.

[Hooffenstein HD]

M42 is going to be more fun than a B27. Until you do an I swap on the B27 and then you will laugh at M42's.

[benz-tech]

They're common knowledge to the M42-initiated. See below.





-The M20 also has forged rods, cast pistons. Nothing fancy in either engine.
-Dual cams, every econobox engine in the 90s had this
-Ability to degree in the cams doesn't matter much on such a low-performance engine, and it is a low-performance engine, less than 80hp/l, doesn't even rev to 7,000rpm. Nobody bothers with it this adjustability anyway.
-This whole timing chain thing is overrated, the wear parts and timing case of the M42 are troublesome and leak-prone. Comparatively, replacing a timing belt on an engine like the M20 every few years is not exactly a difficult or expensive proposition.
-Hydraulic lifters are no big deal and the M42's limit potential for high revs. NA builds looking to make decent power go solid lifter so they can rev high reliably

The only thing the 318is has on a 325is is slightly better handling. As far as I4 engines go the M42 is pretty ordinary, it doesn't really stand out in a positive manner vs any other DOHC 1.8L I4. The M42 is a buzzy, anemic turd.

You've never driven a properly built M42. I absolutely agree it is anemic as hell in stock form, but with the right combination of stock BMW parts, mine is as strong as any stock m20. With, much better fuel economy to boot.

[sketchkid]

Hey thanks so much guys I think im gonna go with the 1991 318i since ive had a m20 and m42 before i found the m42 to have less issues and was easy for me to work with.

[fresh_TD]

no, it does not have a forged crank. also, all engines have forged rods. there's nothing special about the M42 bottom end.

Yes it does. You should read up on it sometime and get familiar.

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[fresh_TD]

Hey thanks so much guys I think im gonna go with the 1991 318i since ive had a m20 and m42 before i found the m42 to have less issues and was easy for me to work with.

Good choice!

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[nando]

Yes it does. You should read up on it sometime and get familiar.

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yeah, no. sorry. I'm sure all the fanbois think so though.

modding an M42 is a waste of time - maybe a turbo would be fun. even a supercharger is only M52B28 power levels, barely. you're not getting 30hp with bolt on parts, either.

[fresh_TD]

yeah, no. sorry. I'm sure all the fanbois think so though.

modding an M42 is a waste of time - maybe a turbo would be fun. even a supercharger is only M52B28 power levels, barely. you're not getting 30hp with bolt on parts, either.

Cool story..

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[varg]

You've never driven a properly built M42

LOL

see sig

It's funny that I have the fastest M42 car in this thread and I'm the one telling everyone it's crap.

[Bimmerbum318]

yeah, no. sorry. I'm sure all the fanbois think so though.

modding an M42 is a waste of time - maybe a turbo would be fun. even a supercharger is only M52B28 power levels, barely. you're not getting 30hp with bolt on parts, either.

Bmw thought modding a m42 was a waste of time as well, oh wait they made an s42 that made 315hp. Hmmm and it was n/a. Is the m42 slow in stock form? After first gear I completely agree it's slow but being tuned down from the factory and given a 28lb flywheel will do that to a car.

[varg]

Bmw thought modding a m42 was a waste of time as well, oh wait they made an s42 that made 315hp. Hmmm and it was n/a. Is the m42 slow in stock form? After first gear I completely agree it's slow but being tuned down from the factory and given a 28lb flywheel will do that to a car.

The S42 has about as much in common with your M42 as a Euro S50 has in common with an American M50. Almost nothing is interchangeable.

[stonea]

Bmw thought modding a m42 was a waste of time as well, oh wait they made an s42 that made 315hp. Hmmm and it was n/a. Is the m42 slow in stock form? After first gear I completely agree it's slow but being tuned down from the factory and given a 28lb flywheel will do that to a car.

But the S42 was a race engine, it wasn't built to even see public roads. Don't get me wrong, I kind of like the M42 and as I stated earlier I would like to own one, but the S42 argument needs to die. Its like comparing the S54 to the M54.