Need your help with a motor swap decision in my e30.

[E30beemer]

Hey guys,

It's been awhile since I've been on the forums and its great to be back. Things have been really busy for me with work and family over the past few years so I have sadly neglected my 1991 318is, 5 speed. But I recently met a few guys who were into it and it immediately sparked my interest again.

So my car is basically all original with its factory m42 motor with 155k original miles. Nothing modified to the car and I am the second owner. The M42 needs a head gasket and likely some head work so I have been thinking about doing a motor swap instead of dumping more money into it. Originally I wanted to keep the car in its original form as I know the 1991 318is is a nice model to keep that way but the time has come to consider other options.

What I would like is a nice clean car with a great motor. This will be a weekend car only. It will not be my daily and no racing or track time. I don't really want it to be crazy loud so its likely whatever motor swap I choose it will just have basic bolt ons with a "quiet "exhaust".

I wanted to get everyone's opinion on what they would consider doing if they were in my shoes. Been out of the loop for a few years so I just wanted to try and catch up quickly with the summer approacing. Naturally, the budget is important to get advice. I would still need to do the suspension, brakes and tires so I would like to be around ~8k total for the entire rebuild of my car. This includes the motor, tranny, labor, etc.

Need a little push to make a decision so please feel free to talk me into something. Thanks in advance!

[haaken675]

if budget is important, you can likely find a used m42 on craigslist for not too much...

If it's not your daily, I would swap it though. Had an i4 car before, not enough torque.

[exhaust]

Do you feel like you need more power? Given the situation I'd either rebuild and tweak your M42 or find a used one and do the same thing. A 24v swap is simple compared to other swaps but it is still complicated and can be expensive to do properly.

That being said if you've decided you want to go down the swap path, find an M52 and start from there. Don't go S5X as you'll really impact your budget

[mtech325]

If originality is important to you, then stick with the m42. Stock/minimally modified cars seem to be going up in value because most e30s by this point have been tinkered with in some form or another by.

I was in a similar boat about a year ago when my m42 ate itself. The m42 doesn't have the low end grunt that a lot people enjoy for daily driving, but by no means did I think it was not fun to drive. It's simply a a motor that needs to be revved to get the most out of it.

In my case I ended up going with a 24v swap because my friends had a complete swap laying around so it was just a matter of refreshing a few things, otherwise I would have rebuilt the m42 or found one a good running unit.

If you decide to go down the 24v route, I have to disagree that an s50 or s52 is going the "blow" the budget. To properly go through and refresh the motor without taking the head off is going to cost the same by the time you're done, so why not spend a little extra have a more enjoyable motor in the long run. Since you have a 318, you have the added expense of needing to upgrade the transmission, driveshaft, and differential because the stock m42 drivetrain isn't cut out for the torque of some of the 6 cylinders. If you just want to do a quick and dirty swap, then yes, an m50 or m52 are better options.

Should you choose to keep the m42, update the timing guide to the 94-95 e36 m42 setup which gets rid of the lower idler sprocket. You'll need the lower timing case from a 94-95 car, or just find a good running m42 from an e36 318 of those years and swap over your intake manifold and oil pan setup.

Either way, you can't go wrong. It's your car, so do what makes you happiest. The 24v is a fun setup and adds a nice dose of power, even in m50 form, but a well sorted m42 car can be just as fun.

-Joey