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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > N54 to N55 Swap



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      09-20-2021, 08:41 AM   #1
TheBlownE92
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Question N54 to N55 Swap

Hello Fellow E9X owners.

Have any of you done a n54 to n55 swap. I bought my car for 1k with a supposedly seized engine. With little effort I got the car started but I now am hearing a knocking noise. I have already checked the power steering pump pulley and have ruled that out as a possible issue. The engine had lots of oil when I started that. If worst comes to worst, once I pull the motor and asses if I have thrown a rod. I will most likely swap in another motor as the price to refinish the head and buy a Piston and rod setup will cost almost the same price as a sub 100k kilometre n54 or n55. If anyone has done the swap. What was necessary. Whether it has a different ecu or motor mounts will all play an role in my decision.

Thanks for taking you time to read through this. Thanks
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      09-20-2021, 09:31 AM   #2
ab987
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I would first verify that it is indeed the motor, pull the belt off and see if it goes away.

If you do verify it is the motor and really want to endeavor, the mounting points will be the same, they never changed the subframe. So it will fit in the car. What are your plans for a turbo? Of course you'll probably have to use an n55 turbo because there is only one oil/coolant feed and oil drain, and the DME is also different (MEVD70 vs MSD80/81) so prepare to find one of those. If you can verify that the new ECU will be able to communicate with some of the older modules (which it probably can), and you really want to do it, I think it'll work (get an e9x n55 if you wanna be safe). Don't expect everything to go smoothly though, you may find small incompatibilities.

But in my opinion if you want an N55, it will be much easier and probably cheaper to part out this car or sell it, and buy an N55 car. That's what I would do. Or find a used N54 from car-part or the likes and throw it in.
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      09-20-2021, 09:47 AM   #3
TheBlownE92
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Quote:
Originally Posted by ab987 View Post
I would first verify that it is indeed the motor, pull the belt off and see if it goes away.

If you do verify it is the motor and really want to endeavor, the mounting points will be the same, they never changed the subframe. So it will fit in the car. What are your plans for a turbo? Of course you'll probably have to use an n55 turbo because there is only one oil/coolant feed and oil drain, and the DME is also different (MEVD70 vs MSD80/81) so prepare to find one of those. If you can verify that the new ECU will be able to communicate with some of the older modules (which it probably can), and you really want to do it, I think it'll work (get an e9x n55 if you wanna be safe). Don't expect everything to go smoothly though, you may find small incompatibilities.

But in my opinion if you want an N55, it will be much easier and probably cheaper to part out this car or sell it, and buy an N55 car. That's what I would do. Or find a used N54 from car-part or the likes and throw it in.
Thanks for the input. I have found both an n55 and an n54 for sale in my area. I was leaning towards the n55 just for the reliability. I'll definitely pull the serpentine belt this week and try that. Thanks for your input
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      09-20-2021, 11:04 AM   #4
C.Pop
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You're trading one set of problems for another going to N55. I'd either put another N54 in there, or most likely sell the car. The resale value of these cars is not high, the level of effort to change engine type will be high, so the only way I'd do a non-native swap is if it holds some emotional appeal (i.e. LS swap, something cool like that). Otherwise just sell the car and buy something more to your liking.
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      09-20-2021, 11:19 AM   #5
TheBlownE92
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Quote:
Originally Posted by C.Pop View Post
You're trading one set of problems for another going to N55. I'd either put another N54 in there, or most likely sell the car. The resale value of these cars is not high, the level of effort to change engine type will be high, so the only way I'd do a non-native swap is if it holds some emotional appeal (i.e. LS swap, something cool like that). Otherwise just sell the car and buy something more to your liking.
I'm definitely leaning towards throwing another n54 in and then flipping the car. I bought it for 1k so anything above 5k would be profit. The blue book value for the 09 335i Drive sits around 10-11k. If I do decide to swap it would you recommend going up to an n55 car for reliability or just stay with the same car and fix the kinks?
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      09-21-2021, 12:23 AM   #6
ab987
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Quote:
Originally Posted by TheBlownE92 View Post
Thanks for the input. I have found both an n55 and an n54 for sale in my area. I was leaning towards the n55 just for the reliability. I'll definitely pull the serpentine belt this week and try that. Thanks for your input
E series N55 is no more reliable than the N54 really, same injectors, same HPFP, same water pump, turbo problems, vacuum issues. It's not much of a difference unless you are looking at F chassis EWG cars. Good luck, keep us updated
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      09-21-2021, 02:17 AM   #7
whyzee125
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Quote:
Originally Posted by TheBlownE92 View Post
I'm definitely leaning towards throwing another n54 in and then flipping the car. I bought it for 1k so anything above 5k would be profit. The blue book value for the 09 335i Drive sits around 10-11k. If I do decide to swap it would you recommend going up to an n55 car for reliability or just stay with the same car and fix the kinks?
N55 swap would be a massive downgrade that would cost as much as you could ever hope to get for the car or more. N55s are notorious for spinning rod bearings and as a result, used ones are pricy.

Throw in a used N54 with a warranty and call it a day.
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