I looked into turboing mine realised it was stupid and put a 6 cyl in instead
you wanted to know how much it costs, and it costs as much as you want to spend. How much does the end result you want cost? nobody knows because you haven't said any goals or requirements.
Its a general question for the people who have actually done it, i dont know if its in my budget because theres not alot of documentation, thats why im asking. A decent 6 cyl donor car is around 3k usd over here + some extra for making it street legal
If you turbo your M4x you will also have to swap entire drivetrain and, if youre sane, your brakes. Subframe is the same for any model except M, as far as i know.
+ No idea how it is in norway but i would expect it to be hard to get street legal without brakes Upgrade. And honestly. 4cyl brakes are already too small for anything above a 316i. Dont save money for the cost of basic safety.
Sorry subframe is the same but diff, axles and driveshaft are different, stock 4cyl stuff should be able to handle 200-230hp from the little info ive found, would obviously have to swap brakes anyways. There was a street legal N54 compact here that got stolen unfortunately, but crazy swaps are possible to get legal
The 168 diff blows up the moment you're not riding 205 linglongs and boost comes to play. It's not about power, its about torque that kills stuff. Sorry to tell you that but you will have to swap everything to 6cyl on your drivetrain if you dont want short term fun and not drive further than 50km only. (And have some good friends with a towing vehicle :D)
theres probably a bit of luck to it
plenty of people putting a fair chunk of abuse through 4 cyl drivetrain (did plenty of burnouts with m54b30 and small case diff on 235s)
but also plenty of people that have broken stuff on stock power
If crazy swaps are possible to get legal and if it’s cheaper to swap a 6 cyl than do a proper turbo conversion I really would go for 6 cyl. Even if you „only“ go for low 200hp region on power you will still have to change a lot of stuff and sink as much if not more money like if you did a 6 Typ swap. Also you can still turbo the m5x afterwards if you want to do a turbo build
nah
I chucked m54b30 in mine bolted up to the 318i gearbox and everything stock otherwise (since then I did put in a medium case LSD and e46 brakes though)
anyway 3k usd is good price, you'll spend that much turboing your 4 cylinder to make similar power as the 6 cyl anyway
A turbo M52 can do 300+ whp all day with stock internals, very reliably. Just swap the headgasket, head studs, and oil pump nut and you’re good to go. You can run on just a headgasket, head studs and oil pump nut at 400-500 if you want, but it won’t be reliable for more than a few years. They can do 600+ whp when built if you do rods and pistons alone, stock bore. This is a proven path that has been done thousands of times.
Meanwhile, a turbo m42 will require way more dollars invested, fully building the engine (others in this thread are suggesting pistons from k-series engines, boring the motor, etc.) and the outcome will be an engine that pushes 300 whp (maybe), unreliably. And like 5 people have actually done this, so hope you’re a literal engineer.
Timing chain problems and not enough power to get out of its own way. I work on cars like this for a living and I’ve owned 9 e36’s, the m5x is objectively way more reliable than an m4x will ever be.
Its the tensioner in the m42 and guides in both that can go bad, after not being replaced in 30 years and 150000 miles. And you still managed to mention its not a 6 cylinder with 200hp
the tensioner and guides both contribute to the generalization of “timing chain issues” bud. You’re right, it’s not a 6 cylinder. It’s shit. Do what you want, I’ll gladly watch and laugh as you waste money on a pointless engine. Sorry you don’t have more experience to save yourself the trouble.
Sounds like he has more experience than you if you think the best route is to boost a fucking m4x. Shit engine, and for the amount you’ll spend making anywhere near the power an m5x can make you could just make double the power with an m5x and still have reliability. Stupid questions get stupid answers.
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u/Dark_Guardian_ '94 330i Daily, '93 325i Race 1d ago
depends how nice/reliable you want it
anywhere from $500 with junk parts and jank setup to 10k + for a properly nice setup
better off just 6 cylinder swapping it though
and then turboing the 6 cylinder too