1991 318is Turbo S50US VS Turbo M50

[BigMoneyWastersE30]

Hello everybody,


Excuse the noob question as well as the noob name. I created my account years ago and then just fell out of it. Now that money is a bit better and not a daily driver. I've officially decided to do an engine swap on my 1991 318is E30 M42. Not necessarily on time crunch either, since E30 now has a perm spot in new garage. Question is which one would be the most "FUN" swap. I've seen here on the thread a lot of people going M50 then upgrading, cause they get tired of it. Also, I see people going N/A S50, complain about price. Is it really worth the swap or should I be looking at other engine all together? A) What do you think the best swap would be? B)Have you done this swap or ridden in a car with this swap before? C) Price? D) Swap thread if you have one would be awesome!. I've read through the Comprehensive 24 as well as the Wiki, pretty good info on there, just want to know which is funner/reliable before pulling the trigger on buying parts... The E30 after swap again, will not be a daily driver. More a fun weekend car. Not really and tracks or mountains around me....sooooooo, yeah....

[CMBusch]

First things first, what would you consider fast? I.E. what cars have you driven/ridden in?
What kind of driving do you consider fun? Highway pulls or just cruising?

More importantly, what type of driving do you expect to do in a fun weekend car? Blasting around town or going places on a highway?

My reason for asking is that an M50 with a 3.73 may be more fun at low speeds than an S50 with a 2.93.

Most complete M50s can be had for $500 while S50s run around $1,500.

If you're looking to go turbo, spending all that extra money on a S50 would be wasted. Using a M50 would be a better option if you're going turbo. However a turbo M50 will still cost more than a N/A S50. You'll be spending more than that leftover $1,000 on turbo things if you plan to do it right.

Depending on power goals, it's going to be necessary to remove the head. While these 24V engines are pretty strong, do you really want to find the limits? The extra stresses from boost will definitely find the limits. Depending on power goals, you'll want to do the essentials(head studs, MLS head gasket, etc.). Once you start digging into the engine you'll find yourself replacing everything.

[e30davie]

You are talking about a custom turbo setup on an engine that never came turbo and putting it into a car that never came with that engine. The reliability of your end product is going to be directly dependent on how good of a job you do on your conversion. And id say weather it is m50 or s50 wont make much difference in that respect.

Reliability issues in crazy engine swaps tend to be things that are over looked, such as dodgy wiring, poor piping routing, and of course poor tuning. Things done to "get the car on the road quick" rather than doing it properly will inevitably cause reliability issues.

As CMbush aluded to there is alot more to making a car fun than adding horsepower. You might get 300hp out of a turbo m50 relatively easily. but if you dont have a suitable diff ratio and LSD, suitable brakes and suitable suspension its going to be a whole lot of power you cant do anything with.

Years ago we put a ca18det into an ae86. It was rocket ship fast but after a while we decided that for the most part is was just too much power for the chassis. The CA was a bit sad so we swapped it out for a stocko 4age with less than half the power and it was more "fun" as you could drive around flat out rather than wrestling with the CA trying to put the power to the ground.

[CMBusch]

Years ago we put a ca18det into an ae86. It was rocket ship fast but after a while we decided that for the most part is was just too much power for the chassis.

Haha rarely do I see "ca18det" and "too much power" in the same context. However, having driven an ae86 I completely understand what you mean.

OP, build your car to what your idea of fun is.