M30 vs. S50

[SUICIDE109]

I'm wanting to do an engine swap for the 325IS I bought a couple weeks back and I am wondering if I should do an M30 or s50... If I go M30 I'm aiming for a b34 or b35. The real question is about the pro's and cons about these swamps such as which one is easier to find, easier to swap, power specs and which one is easier to turbocharge and fit a 6 speed tranny to. Please help

[phreshkid]

I guess I'll be the r3v asshole and tell you to use the damn search button.

[Doughnut]

If you want DOHC and 6 speed go s50. If you want SOHC and sewing machine go m30.

:razz:

[Bearmw]

If you want to spend a lot of money and do it right then pick either of them. FWIW I think the true costs of a well done swap are probably the most important thing to factor but the least discusssed. Ask me how I know.
Anyway first question: What is your total budget?

[F34R]

If you go with a M30b35 you can do a solid rebuild and swap for around the same price of a s50/6spd.

But no matter what one there will always be problems and unforeseen parts that need to be replaced. But in the end you will have it replaced.

Prime example: I just tore my m50tu motor down and found a SHIT ton of things that needed to be redone. I was pissed as hell at first but, now I know everything is replaced and up to date.

Things to look for when buying a motor:

-Remove the valve cover and look for carbon build up in the head. That is a sure sign that the motor did not receive proper oil changes.

-Also look at camshaft lobe wear and rocker arm pad life.

-Pull the drain plug in the oil pan and look for metal flaking in the oil. That is a sign of damage of the internals. I found one so bad once that had chips and flaking in the oil.

Pull spark plugs and look for issues like oil and wear on the firing end.

http://www.gnttype.org/techarea/engine/plugs.html

But remember, having a budget for a motor swap always goes over. To me rebuilding the motor is one of the most important things to do on a build. I had a budget of 1,500 to buy/swap in my m50tu and minor repairs. I threw that out the window and I am now boosting while rebuilding lol. So plans can and WILL change at any moment, just in the long run do it right.

[Holland]

Kind of hard to compare an S50 to an M30. One is quite dated, and the other is more modern. M30 will be cheaper on parts, and is boost friendly, but quite incompetent to an S50. S50 is less boost friendly out of the box, but has far more aftermarket support and has seen plenty of boost. It's all down to preference, as the M30 is an old school torque monster, and the S50 has power down low and up high. If you like the old school feel of a cam then M30, if you want that linear pull then S50.

[Bearmw]

I agree with F34R that to help control costs its important to do as thorough an inspection of motor and trans or any parts for that matter before buying them. I have bought junkyard stuff that looked like a good deal but upon further inspection was not such a goood deal because of worn cam journals, hidden cracks, cylinder wear, etc.

Trying to not buy a money pit motor is a good idea for sure. I chose to go the old school M30 B35 route but because I didn't inspect as thoroughly from the get go it has cost more. Anyway when all said and done in about a month or so I will have an NA M30 with 225 WHP and 250ft/lbs that should last for many years. I know I could have gotten more power by turbo but I will drive it a lot and I'm sure my car will suck enough fuel as is:)

Part of the reason I chose the M30 is because I like lots of torque available at all RPMs. I am a fan of displacement having had a high compression 455 cutlass at one time. If I were to build another nonstock E30 I would definitely consider LS1 or similar.

[The Humjet]

Both motors are completely different.
One is pretty old school with it single cam, solid built, bags of torque and cheap to buy and maintain (M30.
The other is far more modern smoother motors with a linear powerband. Has more power out of the box and lots of aftermarket parts. But is more expensive to buy and maintain (S50).
The m30 is great for boost, take good'n'tights car for example that is as crazy as setting yourself on fire.
But that doesn't mean the s50 couldn't handle boost and make power enough to make you giggle like a little girl.
With the m30 swap your gonna find it hard to get hold of a good gearbox to match. Most of those motors came with an auto attached to it.
The s50 however comes only with a manual which is very competent. Or you could use your stock 325i gearbox which are everywhere and strong enough to handle the increase in power.
These are a few things to think about. There is also a lot more than that.

[Bearmw]

Lots of E34 535i M30s in my neck of the woods have 5spds according to Craigslist.

[dannyyisntt]

M30 is an old school torque monster, and the S50 has power down low and up high. If you like the old school feel of a cam then M30, if you want that linear pull then S50.

I'll agree with holland on this one. Do you want an old school torque monster or a newish age 24v linear feel?

I myself opted for the old school torque monster and being a good friend of yours, I'd personally vote m30 swap for you too. Not only are m30's MUCH easier to find in our area and can easily be had for $200-$400, the swap itself will cost less. Figure by the time you spend the $2000-$3000 on the s5x you could have the m30, transmission, driveshaft, better geared differential, the right motor mounts and several other swap items for the m30 swap and possibly have money left over to start a light refresh on the engine.

[dannyyisntt]

With the m30 swap your gonna find it hard to get hold of a good gearbox to match. Most of those motors came with an auto attached to it.
The s50 however comes only with a manual which is very competent.

Humjet you've got some misinformation there. Some of the s50s/s52's DID come with auto's, though are less prevalent than the manual transmissioned cars. Also, while the m30's did largely come in automatic form, the manual transmissions aren't hard to come by. Even so, you can match the m10's manual transmission up, the s14's and I believe the s38's, so if your not able to find a transmission that spent it's life hooked up to an m30, you've got other options.

Whichever one you choose, Dom (suicide109), I already know where to find transmissions and other swap parts locally.

[Wanganstyle]

I've been on both boats. Manual transmission both cars, Original BMW car with M30 and S50/52 in the chassis designed for it. Both Last model run of the engines also, the best OEM spec:

M30b35 1990 spec with 3.64 with cable throttle, 1989 535-5 with cable throttle and 3.46 and 1997 spec s52b32 x2 with mechanical throttle and 3.23 and 3.38.

have driven all chipped, BPU modded and stock.

e32 735i-5 speed manual 1990, 1997 5 speed manual e36 m3.

M30 engine is paired with Getrag 260-6, same gearbox as my e30 325 but with a m30 bell housing instead of a m20 bell.

M30 is HEAVY and TALL. BUT is BIG, and has OEM turbo parts avail (M102 engine parts bolt right on). M30 is great for +big turbo and Freeway/drag racing.

M30 problems ? heavy, turn in suffers, weight bias shift. M30 pros? inexpensive, very strong, HUGE displacement in comparison, bolt on nice size turbo set avail. only common gearbox option is Getrag 260-6 with overdrive. 6 speed is euro only and quite rare $,$$$.

S50/52 family is shorter in length, lighter weight than m30, more common gearboxes in 5 speed overdrive, 5 speed non overdrive "close ratio", and 6 speed.

S50 is cammed better, has better modern options. costs more. more hp on top end, will be more "fun" for trackwork use in an e30

[Bearmw]

No doubt the S50 is more track worthy. How much track/hi rev use is anticipated?

I am a street driver but I attempted to make my m30 more revvy however by using an early 533i flywheel, lightening the rod big end by about 30 grams, and running custom Paul Burke pistons that are a lot lighter than stock. Also using Miller MAF and WAR chip to further increase responsiveness. Another thing is I can store an economy tune in the WAR setup if I'm taking a long highway trip and tying to conserve fuel.

Also I moved my battery to the trunk and got a super deal on a used CF bolt on hood to offset some of the added mass.

[SUICIDE109]

Ok, well the price range is 5k for now... Yes I do love the old cam feel, but I dont want to suffer in the corners with that big m30. Well I cant say it will always be on the track but it will be treated like it is. The big keys are cheap(but well done) corners, lightness and hairyness... Dannyisntt gave me a swap book for the m30's but i'm on the other side of the world and just cant walk into my room to pull it out and read it. Didn't they make a 6speed mated to the m30b34 for the e24? If I just end up swaping bellhousings for the m30, how much will I have to move the tranny back? Looks like I'll have to go yard picking on R&R

[Bearmw]

Good luck man.