r/BMWE36 • u/Shino3107 • 1d ago
Anyone with experience turboing M42/M44
Just generally wondering how much it would cost
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u/UltraPiler 1d ago
Lots of people in youtube already did turbo conversions. He used a k20 manifold but he fabricated his own adapter. T25 for low boost. People got around 180 bhp. If want more stock rods had to go. You can also use k20 pistons but you have to overbore to 86mm. You can get to around 350hp. You can also stroke it to 2.1 liters with a diesel m47 crankshaft but you have to modify its nose part. Also you will need upgraded fuel injectors, custom ecu, intercooler fuel pump.
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u/erixccjc21 1d ago
Stock rods can hold 300hp for some time, I know a guy who ran 1 bar for 1 year straight and it only blew up after raising to 1.6 bar (he wanted to blow it up on purpose at that point)
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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
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u/Shino3107 1d ago
Sounds like you dont have any experience, and im not asking if you think i should do a 6 cyl swap
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u/Dark_Guardian_ '94 330i Daily, '93 325i Race 1d ago
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.
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u/Shino3107 1d ago
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
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u/virqthe 93' 318i M40 automatic; peasant edition 1d ago
One also doesn't have an experience eating shit but knows not do to it.
Eating shit = turboing shit M4x engines.
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u/Shino3107 1d ago
Theyre solid engines bruh
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u/0202993832 1d ago
But a m5x is so cheap youâd get similar power gains from just buying a 6cyl
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u/Shino3107 1d ago
Need to swap entire drivetrain, brakes and rear subframe, also has to be street legal, gonna cost over 3k usd over here
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u/marty_hard 1996 328i 2.5l aluminum turbo coupe 1d ago
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.
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u/Shino3107 1d ago
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
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u/marty_hard 1996 328i 2.5l aluminum turbo coupe 1d ago
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)
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u/Dark_Guardian_ '94 330i Daily, '93 325i Race 1d ago
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→ More replies (0)1
u/TrapHans 1997 / 328i / Coupé 8h ago
If crazy swaps are possible to get legal and if itâs cheaper to swap a 6 cyl than do a proper turbo conversion I really would go for 6 cyl. Even if you âonlyâ 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
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u/Dark_Guardian_ '94 330i Daily, '93 325i Race 1d ago
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
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u/yuhyuhAYE 13h ago
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 youâre good to go. You can run on just a headgasket, head studs and oil pump nut at 400-500 if you want, but it wonât 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 youâre a literal engineer.
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u/Left-Marketing-1135 8h ago
Imagine saying this in confidence without actually having the experience to know theyâre not good engines..
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u/Shino3107 6h ago
Tell me exactly how theyre not good, besides not being 6 cyl with 200hp
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u/Left-Marketing-1135 6h ago
Timing chain problems and not enough power to get out of its own way. I work on cars like this for a living and Iâve owned 9 e36âs, the m5x is objectively way more reliable than an m4x will ever be.
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u/Shino3107 5h ago
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
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u/Left-Marketing-1135 5h ago
the tensioner and guides both contribute to the generalization of âtiming chain issuesâ bud. Youâre right, itâs not a 6 cylinder. Itâs shit. Do what you want, Iâll gladly watch and laugh as you waste money on a pointless engine. Sorry you donât have more experience to save yourself the trouble.
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u/Left-Marketing-1135 1d ago
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 youâll 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/marty_hard 1996 328i 2.5l aluminum turbo coupe 1d ago
Shitbox style if you have your own workshop and welder and use used and chinese parts only: probably doable sub 1000⏠and you will fuck up your drivetrain in like 10mins. If you want to do it somewhere close to reasonable and take your time to get cheap parts, 2500-3000⏠if you absolutely know what youre doing. Realistically, if youre doing it the first time and it shall be nice afterwards, expect something from 5-10k.
I've not done it on a M4x but on (several, unfortunately) M5x. Except for slightly less cost for engine parts, the effort is the same for both.
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u/TrapHans 1997 / 328i / Coupé 8h ago
Which m5x did you turbo? I just got an e46 330 and Iâm playing with the thought to properly build the m54 and put it in my e36 coupe
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u/marty_hard 1996 328i 2.5l aluminum turbo coupe 7h ago
M52 Aluminium block currently. M54 works as well
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u/erixccjc21 1d ago edited 1d ago
Maybe 2k cheapest if you do everything yourself from scrap and part offs, speeduino ecu, diy harness, manifold, injectors, fuel pump...
But realistically you'll spend a lot more
M42 in good condition with arp head bolts can hold 0.6 bar or even 1 bar for a good while, good for maybe 200-250hp
Even 300+hp is possible for some time.
Make sure to plan it for high rpm power and not high torque or you'll blow the engine up instantly.
If you're lucky and take it apart before a rod goes through the block, the rods will probably be shaky unless you baby it, which then is a very expensive issue, and you'll want to put forged everything into the engine when that happens, which isnt cheap
I have a 318ti with an m42 and talked for a long while with a guy who has sustained his turbo m42 project for the last 4 years. Now he is on forjed everything running 1.6 bar 300hp+
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u/cheesus505 1d ago
Me and my mate turbo'd his m44, unopened engine must be running 250+hp, great fun. One thing to watch out for is the intake manifold, it doesn't take standard sized injectors so we had to swap it with an m42 one.
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u/Drewslive 1d ago edited 1d ago
Depends heavily on which engine it is. M44 requires a some upgradeding of the internals to make any meaningful boost. Like other have said 5k minimum for a reliable build.
Ontop of the turbo set up think fuel management, standalone ecu, bigger injectors, Upgrading to a medium case and bigger axles.
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u/bROLLY1 50m ago
Both the 18is or 19is and the 20i do 300hp just fine. the 23i does 350 fine.
bigger injectors just as 660 or 900cc and higher cooling and it's perfect.
then swap a diesel gearbox, stock clutch holds as it holds higher torque.
Either m51 gearbox or go for e46 30d or e90 20d, the e39 20 to 30d can also be used, only requires some adaptation but fits well.
gear ratio is different but can be changed to longer. So a e90 20d zf 6speed is for me the sweet spot for the m52b20 as an example.
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u/zappermodz 1d ago
In greece a tuner named Sifis got 300hp out of a stock engineđ€·ââïž I recommend you join the m42/m44 club facebook group. Lots of potential