ETA vs M42 Daily Hoonmobile

[Nesset]

Alright so, im building a car from the ground up. Basically just a shell with no motor. I either want an M20 or a M42. I drive a 2002 and really like the lightness the M10 has up front compared to the E30's i've driven with ETA motors. Would you go for a M20b27 or an M42b18? The motor would be going into a 84 ETA Coupe..

[roguetoaster]

If you will be okay with the limited power of the M42 down the road then of course the M42 is the right choice.

That said, the ETA M20 is not bad chipped, it's just not the revvy type of engine that I prefer. The M20 did feel slightly heavy in comparison to the 318, although they did not have the same suspension, so maybe a bit apples to oranges. Perhaps a better way to say it is that the M42 always felt on, in the track car, high strung kind of way, whereas the M20 always felt a bit more plodding, but always certain to have some pull away torque when you hit the throttle.

To illustrate, at one point I had a '76 2002, '86 325es, and '91 318i in the lineup. Guess which two I still have.

[Nesset]

To illustrate, at one point I had a '76 2002, '86 325es, and '91 318i in the lineup. Guess which two I still have.

As I daily a 2002 with an M10 and a 32/36 webber I am plenty fine with limited power. I actually like a low power car more because you can push it more, harder pretty much everywhere lol.

But I would hope the 2002 and 318 :)

The 2002 is one little fun car for sure!

[roguetoaster]

As I daily a 2002 with an M10 and a 32/36 webber I am plenty fine with limited power. I actually like a low power car more because you can push it more, harder pretty much everywhere lol.

But I would hope the 2002 and 318 :)

The 2002 is one little fun car for sure!

Yep, clearly I ditched the 325, and put a new 32/36 on the 02 as I was being lazy about rebuilding the old one.

From what you said above you sound like the ideal M42 owner.

[bmwman91]

The M42 is a great engine for hooning. It revs to 7200RPM all day long (with a chip) and it's a very easy engine to drive the dogshit out of.

Beware though, it has its reliability quirks and it is more costly to maintain than an M20. At this point, based on how many miles are on all the E30 M42's, I would say that your first order of business should be to overhaul the timing chain system and to swap in a later-model M42 timing case that uses a slipper rail instead of the notoriously unreliable deflector sprocket. That little bastard sprocket tends to snap off of the casting in the timing case...and you're gonna have a bad time if that happens.

The one other thing to watch out for is in the oil pan. Drop the lower pan and make sure that all of the upper-pan-to-timing-case bolts are secure and not stripped. You may very well find a couple of them sitting in the oil pan. You can do a helicoil repair without removing the upper pan if you are careful and contain the metal chips. Use red Loc-Tite. Other goodies that you will often find in the oil pan are: plastic chunks from broken chain guides, pieces of hardened steel chain rollers, small aluminum mystery pieces from (???) in the engine which are usually related to the previous 2 items and that $treefiddy you needed the other day. Invest in a magnetic oil pan drain plug.....

[tak7]

Sounds like m42 is right for you, I love mine.

[Nesset]

I guess I will have to start planning out a M42 build... I'm pretty exited to finally be apart of the E30 hoon squad lol. But I've wanted an E30 for the last, three or so years. Got a 2002 instead, love that car but I feel guilty tossing it into corners at 40 sidways...

[Thehemiman]

+1 to the m42. I've been daily driving mine for a year now and it's been great. I drive pretty easy which can make it feel underpowered but it gets along just fine in the upper rpms. I've never calculated the fuel mileage but it's noticeably better than my m20b25 in terms of how often I refuel.

[redlightpete]

Is the m20b25 not an option? Or a '2.7i'?

[FL318is]

I have had my 91 318is since 2006 and my 76 2002 since 2011. Love them both for the go-karts they are. My 2000 E46 has been the neglected one.

[Nesset]

Is the m20b25 not an option? Or a '2.7i'?

Oh no it is, I just like keeping things original. And if not, I would want something I really do want. I like buzzy little 4 pots. I like the b25 too but the torque curve of the ETA does it for me.. Dunno why.

[Hooffenstein HD]

Ask this question in the M20 section and you'll get a completely different response. M42's are incredibly slow. You can't hold more cornering speed if you don't have the power to get there.

Assuming we're comparing an M20b25/M20b27i and not a standard eta motor.

[M42Power]

Ask this question in the M20 section and you'll get a completely different response. M42's are incredibly slow. You can't hold more cornering speed if you don't have the power to get there.

Assuming we're comparing an M20b25/M20b27i and not a standard eta motor.

If you keep them in their rev happy zone m42 powered cars can keep up with more muscular stuff in the twisties!

[eur04lif3]

If you keep them in their rev happy zone m42 powered cars can keep up with more muscular stuff in the twisties!

I've done this plenty of times. In the twisties, I prefer the M42. Straight line, m20 will take the cake.

OP, there is a reason why they put a high reving 4cyl in the M3. Now I know that m42 is not exacly an s14, far from, by even haters of M42's will admit that a proper m3 is with the light weight s14 in it. Sometimes its not about your top HP, its how you use your top HP in the corners.

[Nesset]

I've done this plenty of times. In the twisties, I prefer the M42. Straight line, m20 will take the cake.

OP, there is a reason why they put a high reving 4cyl in the M3. Now I know that m42 is not exacly an s14, far from, by even haters of M42's will admit that a proper m3 is with the light weight s14 in it. Sometimes its not about your top HP, its how you use your top HP in the corners.

Exactly why I am considering one anyways. I love how light the 2002's front end feels. And the six cyl e30's I've driven feel heavy...