Which engine would you choose for a swap?

[Codym42]

How does the handling compare after the swap? Does it feel any different?

It is VERY tail happy when driven hard. Its better now that I replaced tires but it still doesn't feel like it should. A friend of mine who has an e30 drove my car and agreed with me. I'm eventually going to do either an adjustable rear subframe or riser bushings along with new bilsteins in the rear. I was also told to remove the rear sway bar completely but haven't tried that yet.

It's pretty simple. Compare the M42 to a good little I4 from the same era, the first generation Honda B16A.

1.8L vs 1.6L
6,500rpm vs 8,000rpm
138hp vs 160hp
10:1 vs 10.2:1
$21,000 car vs $12,000 car
meh vs the start of a legend

It's not that BMW couldn't do it, it's just that they didn't. A good, fun 4 cylinder revs high to make what little power it does and is ever responsive, an M42 doesn't even like to rev. 6,500rpm is plenty of revs for a 6 cylinder designed in the 70s (M20), but even in the late '80s when the M42 was penned 6,500rpm was average at best for a 4 cylinder. Look at that B16A, 1.6L, 20 more hp than the M42, revs to 8,000 rpm. The M42 on the other hand? It's coarse and noisy, and falls flat on its face after 6,000rpm. It doesn't even respond well to mods NA, with even a mere 150hp being a rare sight on M42club. Some pretty awful issues like profile gasket failure, crank walk and snapped idler tensioner bosses have also been observed in M42s. It's an engine with a lot of flaws considering what it came from; the era of BMWs being very durable, long lasting cars.

The rally engine is kind of a non-sequitur when talking about ordinary M42s, there's nothing stock left aside from the castings and they've attempted to fix every issue they can such as getting rid of the idler sprocket and putting a 180° thrust bearing set in it. It's basically a high dollar custom build, what is there to hate about that? other than getting a mere 205hp for your $10k of course. M42s are, in stock form at least, pretty much economy car motors minus the reliability.

No doubt there are better 4 cylinders out there. My m42 made it to 283k before I pulled it with no major issues and regular maintenance. I liked the fact that the whole drivetrain in the 318is is lighter. I will say that those who argue the m42 is more economical are kind of wrong. I'd rather put 87 in an m20 and get 22mpg than have to put premium in an m42 and get 26mpg. Its just not worth it.

Yes, the Honda B16 and B18 engines are impressive to me as well. In the '90s the m42 was comparable to other Japanese 4 cylinders in terms of power. The SR20DE found in the Sentra SE-R and NX2000 made 140 hp and that was even a 2 liter. The 1.8L in the Isuzu Impulse and Storm GSI made 140hp. Honda was on a different level back then. I would love to own an EM1 or GS-R.

[agent]

Why three commas? Are you a billionaire?

Would have been funnier if you didn't explain the reference. I still lol'd though.

[Motheye99]

I put 87 in my m42. There only economical to get another used one white it eventually breaks.

Also the reason they rev like shit is the 26lb dual mass flywheel!!!

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[Andrew325is]

Honda engines are transverse and have some really crappy engineering designs. I’d take a slightly less powerful BMW engine any day.

[Julien]

Honda engines are transverse and have some really crappy engineering designs. I’d take a slightly less powerful BMW engine any day.

expand on this, i'm curious to hear it

[varg]

Yes, the Honda B16 and B18 engines are impressive to me as well. In the '90s the m42 was comparable to other Japanese 4 cylinders in terms of power. The SR20DE found in the Sentra SE-R and NX2000 made 140 hp and that was even a 2 liter. The 1.8L in the Isuzu Impulse and Storm GSI made 140hp. Honda was on a different level back then. I would love to own an EM1 or GS-R.

Right, proving my point, the M42 compares with average late '80s/early '90s 4 cylinders, not with good ones. Ergo, it is not a good engine, it is about average. Just with some critical flaws. You know you're not in good company when you have to stoop to a Sentra or an Isuzu to compare favorably. Remember that the engine we're talking about came in a car that cost $21,000 new, and that SE-R was about half the price and... it was a Nissan :giggle: The Honda was also close to half the price, and somehow managed to be powered by an engine that was superior in every measure and revered to this day as the beginning of a legendary line.

BMW knew how to make a good engine, we all know them. M42? Not one of the hits.

Also the reason they rev like shit is the 26lb dual mass flywheel!!!

Yeah that big chunk is definitely partially responsible for its lackluster throttle response. Even with the M20 clutch setup you just won't find the M42 particularly responsive for a small I4 though.

Honda engines are transverse and have some really crappy engineering designs. I’d take a slightly less powerful BMW engine any day.

Care to elaborate? Especially in light of how many well known flaws the M42 we're discussing has it's interesting that you'd call honda engines flawed in comparison. As far as 4 cylinders go, Honda's are universally acknowledged to be among the best out there.

[JimmyP]

I know you guys dont like the M42 / M44, but an 8lb flywheel with a light clutch is a game changer on an M44, I assume the same on an M42.
Similar to CodyM42, my M44 has 217K on it, gets 32 MPG at 90 mph on the highway and uses less oil than my E46 325T with 1/2 the miles.
Im ok with it for what it supposed to do, just general driving around. Its not super sporty, but the lightweight flywheel is a real character changer along with some stiffer driveline mounts. Feels a bit more like a sportscar now.

[agent]

I think it sounds awful, at least that rasp. M54 sounds so much better than an M20... M44 sounds better too IMO.

:loco:

[e30austin]

I think it sounds awful, at least that rasp. M54 sounds so much better than an M20... M44 sounds better too IMO. (S54 sounds the best of course)

Gonna have to disagree with all of this, bud.

M20 makes beautiful, beautiful noises, especially at 6500rpm. M54 isn't a bad sounding engine, but the M20 wins - all day long.

S54 is a horrible sounding engine; if you don't like rasp, i'm not sure how you like the sounds of an S54.

[digger]

id say m42 stroker but done properly i.e. 200whp ish not 200 bhp

https://www.youtube.com/watch?v=gE0Y5tFnt2c

maybe a bit smaller cam than this one though....

[E30 Wagen]

I still think it boils down to what car you're starting with and what you're going to use it for. If you've got a slicktop 318is then I'd say definitely stick with the m42/m44. Delete the A/C, PS, and all the SRS crap and you've got a lightweight weekend warrior that's a ton of fun to drive at the limit. How cheaply can you source all the parts for a stroker build? Compare that with the cost of any worthwhile 24v swap and it's probably not far off?? I don't know. And for me I think less about power:weight ratios and more about how easy it is and how much space a bunch of swap parts are going to take up in my garage, and then having to get rid of the old engine.

[Andrew325is]

I know you guys dont like the M42 / M44, but an 8lb flywheel with a light clutch is a game changer on an M44, I assume the same on an M42.
Similar to CodyM42, my M44 has 217K on it, gets 32 MPG at 90 mph on the highway and uses less oil than my E46 325T with 1/2 the miles.
Im ok with it for what it supposed to do, just general driving around. Its not super sporty, but the lightweight flywheel is a real character changer along with some stiffer driveline mounts. Feels a bit more like a sportscar now.

Do you get any chatter and excessive vibration with the lightweight flywheel?

[Andrew325is]

Gonna have to disagree with all of this, bud.

M20 makes beautiful, beautiful noises, especially at 6500rpm. M54 isn't a bad sounding engine, but the M20 wins - all day long.

S54 is a horrible sounding engine; if you don't like rasp, i'm not sure how you like the sounds of an S54.

You’ve got to be kidding me, haha. The S54 on the dyno to 8,000 RPMs sounds glorious.

[e30austin]

The shop next door to me builds race cars and dyno tunes them all day long. Not a great noise, IMO

[nando]

24v exhaust is pretty raspy, yeah. I do think M20s sound better overall. Actually, I don't really like loud exhausts at all - induction noise is where it's at IMO. The S54 with the CSL airbox is the best sound ever (except maybe the S70 V12).

The popular mod with new BMWs is muffler deletes. Literally, people cut off the muffler on their mom's old 328i. It sounds horrible, probably what people are thinking of when they say the newer cars sound like crap. Then they pay extra for a tune that makes them backfire, or if it's new enough, to "enhance" the fake engine sounds coming through the speakers. God, BMW sucks these days...