m42 turbo or m50 turbo

[el_gringo]

Alright ladies and gents, i have been boggling my mind for months now going back and forth on what i should do. I have a '91 318is, stock, just dropped and straight though exhaust that sounds like shit.

My friend who has another 318is, picked up a wrecked e36 m3 with a perfect motor, tranny, wiring and all the parts needed from a e36 to do his s50 swap. Congrats on his part, but it got me thinking:

I want something that will take his s50 for a walk when im done. im talking i want it at least neck and neck with gut wrenching results, or damn near close. I have the m42 already, but i can not see a boosted m42 playing with a s50 which will have aftermarket bolt on goodies (cams, exhaust, ect).

i have seen a m50 turbo @ 1.4 bar getting 600+ bhp, and i have read of a m42 turbo getting 448bhp @ 30psi. now i dont know much about FI, but i see it like this:

my 318is weighs roughly: 2426 lbs without the m42
m50: 20.58 psi gets 618bhp @ 299lbs
m42: 30 psi gets 448 @ 220lbs

i understand the m50 has two more cylinders, but only weighing it down almost 80 lbs? i think its worth it, weight wise. but onto $$$ -> BHP numbers...

a local junkyard will get me a m50, wiring harness, and ecu for $600. i already have my m42, but i can turn around and sell it complete (200k mi) with tranny, wiring and ecu for almost $500. i already have the correct radiator, transmission bracket setup, somewhat decent diff, and my ride stance wont change that much... although i will upgrade wheels, suspension, sways, and mounts while im at it and its on a lift.

i dont feel like ripping my m42 down (as its my daily driver) and spending a few thousand to boost it, but not being able to keep up with what seems to be a common swapped m50. i will have the m0 on a stand, broken down, decks, cleaned, and parts replaced with upgrades... iirc, im looking ar roughly 3 to 3.5k to turbo a m50 CORRECTLY to have a dependable everyday car, but i have yet to find a number on how much a dependable everyday turbo m42 would cost me...

question is, would you do it? if you dont have a turbo m42, or m50, please dont chime in with prices, only state if youd do the m50 or 42. if you have a turbo m42 thats complete for a DD, show a spec list with prices with labor please...

[318kid]

Pros of M42: Better Gas Millage
Don't have to worry about an engine swap
Cheaper
Way Cooler
Lighter (Yes you will be able to feel 80 lbs)

Cons: Not as much horsepower as m50
Possibly lower milage m50
Some other stuff I may be leaving out!

I don't have a swapped m50, but I don't think you can get a completely swapped m50 with a turbo for 3 to 3.5k.... It's probably more around 5k if you want it to be reliable. There is a youtube vid. of an m42 running 1.5 bar with just a lowered compression ratio... he's making 333hp at the rear wheels.... A turbo m42 running around 10 psi will probably get you close to your friends power. Its basically how much money do you have, and how much time do you want your car to be down for. I don't care what you do... Either way would be awesome!

[bearsbmw]

I just finished my e36 m42 turbo bottom mount for $1700

[vagrant_mugen]

m42 for sure.  im just a 4cyl guy though.

i can give you a close estimate for the machine/parts cost of an M42 w/ turbo stuff and MSnS if you want, been pricing it out for myself.  i dont have labor costs besides machine work as i do all my own wrenching.  LMK

[halcron]

For me, I would pick M42 over M50. The reason is balance. IMHO, the balance in weight, power and handling is more important than just raw power. Afterall, its a daily driver car and not a drag car.

I am someone who prefers a Lotus rather than a Lamborghini. A light car with a small engine than a heavy car with a big engine.

If you are going for 600HP on a M50, you have to consider more than just engine. You have to ensure your differential, transmission etc is able to handle the power as well. There is also ECU, tuning to take care off. Not to mention turbo lag from using a large turbo to generate sufficient boost.

[el_gringo]

Yes you will be able to feel 80 lbs

My eta with the m20 would play with a 318is... i know what your saying, but i think 80 more lbs, but almost 200 more bhp is worth it, right?

I don't think you can get a completely swapped m50 with a turbo for 3 to 3.5k.... It's probably more around 5k if you want it to be reliable.

I meant aside from just getting a m50, to properly turbo it so its reliable would put me around 3 to 3.5 k for turbo goodies alone... so around 5k all said, done and burning rubber sounds right

Its basically how much money do you have, and how much time do you want your car to be down for.

If i go the m50 route, the only downtime will be a weekend to pull the m2 and put in the m50, hook up wires, lines, power and tweak tuning... i hope lol. record is 14 hours from first pulling of stock motor and rolling off with a swapped engine.

i dont have labor costs besides machine work as i do all my own wrenching.  LMK

I would appreciate that! i do all the wrenching myself. if i dont do it, the car doesnt need it.

I just finished my e36 m42 turbo bottom mount for $1700

thats a manifold alone? I was quoted roughly 1350 for turbo, manifold, inter cooler and plumbing. like i said, i am new to the FI side of the world, so i dont know if its good or bad. a guy localy does tig welded mandrel bent headers/manifolds. he quoted 900 if i went that route.

For me, I would pick M42 over M50. The reason is balance. IMHO, the balance in weight, power and handling is more important than just raw power.

i cant have my cake and eat it too! lol

you have to consider more than just engine. You have to ensure your differential, transmission etc is able to handle the power as well. There is also ECU, tuning to take care off. Not to mention turbo lag from using a large turbo to generate sufficient boost.

i understand. like i said, if i am going to dish out money, im going to throw it in the corrected manner at the parts to guarantee a flawless ride once completed.



guys, keep in mind that i am not saying "when the motor is swapped in i want it at 600+ bhp with a great amount of tq under my ass". i just want a turbo project that will get my feet wet and hands dirty to know my ups and downs, and go from there. Although my goal is 600+bhp (when boost is turned up), it will take awhile to get there. little things can rob power, and it will take awhile to plug & play and see what combo works best, right?

[rob_e30]

As the saying goes, there's no replacement for displacement.  An M50 turbo should beat an M42 turbo every time, all else being equal.

Now, if you want to spank your friend and his S50 you can do it with a turbo M42.  We did back to back comparisons on a Dyno Dynamics with our turbo M42 race motor and a slightly enhanced S50 (upgraded MAS, software, injectors, exhaust) and at 14psi we were more than 80rwhp more with the M42 turbo.

[kowalski]

As the saying goes, there's no replacement for displacement.  An M50 turbo should beat an M42 turbo every time, all else being equal.

Now, if you want to spank your friend and his S50 you can do it with a turbo M42.  We did back to back comparisons on a Dyno Dynamics with our turbo M42 race motor and a slightly enhanced S50 (upgraded MAS, software, injectors, exhaust) and at 14psi we were more than 80rwhp more with the M42 turbo.

is yours still a 1.8L though? I can't remember...

Oh, and what exactly are you putting down with that thing?

[Boosted E30]

i just got my turbo m42 running good and im hoping to get on the dyno somtime next week so i will post up numbers but as of right now on 10psi its probably just as fast as a e36 m3

[318kid]

is yours still a 1.8L though? I can't remember...

Oh, and what exactly are you putting down with that thing?

I think he's just a few cc under 2L....

and el_gringo if you hope to swap engines in around 14 hours you better have EVERYTHING there, and know what you are doing....I think it's a lot more labor intensive that what you make it out to be.

[George77]

I would go m50,actually I bought a 525 from 92 for the engine and it's gonna be my next project M50 turbo.As you see ,you have to push to much in m42 to get some power.I mostly drive the car on the streets so the handle offered by the m50 swap I think it's enough.

[George77]

I feel bad to do  this swap cos the m42 proved to be a very strong engine.The thing is that a want to make power as cheap as possible and reliable as well.The thing that saves me a lot is that a can do all by my self .

[rob_e30]

is yours still a 1.8L though? I can't remember...

Oh, and what exactly are you putting down with that thing?

It's a bit under 2L in order to meet BMW CCA Club Racing rules.  Custom pistons, stock rods and stock head.  Tec3R custom ECU, and upgraded just about everything else.  Power depends on the boost level but between 280 on the low end and 320 on the higher.  Dynojet numbers would be quite a bit higher (they tell me).  Peak torque and HP are about the same but at different rev levels.

One reason we decided to go 4 cylinder versus 6 was in the cost savings...  You only have to purchase 2/3rd's of your engine components.  Valves, valve guides, lifters, springs, pistons, rods, bearings, all that stuff there is less of making it cheaper and lighter.

[el_gringo]

As the saying goes, there's no replacement for displacement.  An M50 turbo should beat an M42 turbo every time, all else being equal.

Now, if you want to spank your friend and his S50 you can do it with a turbo M42.  We did back to back comparisons on a Dyno Dynamics with our turbo M42 race motor and a slightly enhanced S50 (upgraded MAS, software, injectors, exhaust) and at 14psi we were more than 80rwhp more with the M42 turbo.

Oh i am aware of this, i have seen a few things about your car, but you also need to look at that your race engine is well over the price range of this build i am looking into... see below statements for a suprise

I think he's just a few cc under 2L....

and el_gringo if you hope to swap engines in around 14 hours you better have EVERYTHING there, and know what you are doing....I think it's a lot more labor intensive that what you make it out to be.

My buddy who is doing the s50 swap is having me (the only local guy with bmw brains) to help him out... so i will make sure i have EVERYTHING and some extra laying around... i wont do it solo, but i will have everything set up to just go in and start connecting, bolting, and tightening... although i need to find a off the shelf manifold that will have a suit a m50T e30

I feel bad to do  this swap cos the m42 proved to be a very strong engine.The thing is that a want to make power as cheap as possible and reliable as well.The thing that saves me a lot is that a can do all by my self .

i am the same way, but if i dont end up selling the m42 setup, i will keep it and build it up slowly... a 318is is great for a e30 with looks... i have d.schwartz, thats a automatic win in my book. i am thinking of going blacked out, mtechII, deep dishes, and low.

so hopefully when i can actually start saving money, i will get things going...

PS: Christmas is coming!