Little bit of random thought but bear with me....

Davecara

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Jul 8, 2023
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My current daily is an E90 320i gutless N43. I love the thing to bits and when I get a new car I'm keeping this as its worth naff all.
A friend of a friend has an S55 engine that needs a home.

My stock ECU is an MSD81.2, the N55 runs an MSD81. I haven't opened up a spare to check YET but in theory, could I add the mosfets and injector drivers to my MSD81.2, relevant wiring and a reflash and have it run the S55? I know its a daft idea but I want to play with the car as its got no resale value really as Its been crashed a rebuilt twice and it'll keep me out of the pub!

I'd like to keep it all within the BMW family if that makes sense rather than go aftermarket management and have things not work because of it etc
 

Davecara

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Jul 8, 2023
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nope cant be done and cheaper just to replace the car
Who's ever been into modified cars and just chinned it off because its cheaper to buy something higher performing? Is it not part of the fun trying to make things work that wouldnt normally?
Some n54's run MSD81, but not N55 - that runs Bosch MEDV 17.2
Helpful thank you. Looks like either an MEDV ecu kit used then or look into an aftermarket management that can be fully integrated into the car. I'll start watching Copart for a written off 335i or something with the N55/S55 engine.
 
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Davecara

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Jul 8, 2023
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Just the motor unfortunately. It spun a shell and because he's got more money than sense he bought a crate engine and just took this one out. Its been stripped and there no visible damage to the crank or rod so hopefully give it a refresh, measure everything and go from there
 
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martymil

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With an aftermarket ecu it shouldn't be a problem on LHD fitting one.

There are lots of things you will need to make this work and I think you are underestimating the amount of work
that will need doing especially on a 320i platform.

I done a few transplants now and what you are doing is daunting for a very experienced mechanic.

The amount of money this will cost you will buy you a brand new car but good luck because you will need it.

An LS swap would be a lot better for your base and still cost you less than just rebuilding the s55 motor.
 
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wheela

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With an aftermarket ecu it shouldn't be a problem on LHD fitting one.

There are lots of things you will need to make this work and I think you are underestimating the amount of work
that will need doing especially on a 320i platform.

I done a few transplants now and what you are doing is daunting for a very experienced mechanic.

The amount of money this will cost you will buy you a brand new car but good luck because you will need it.

An LS swap would be a lot better for your base and still cost you less than just rebuilding the s55 motor.
You had me till LS swap. Gotta stick with BMW for the power plant!!!
 
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Davecara

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Jul 8, 2023
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With an aftermarket ecu it shouldn't be a problem on LHD fitting one.

There are lots of things you will need to make this work and I think you are underestimating the amount of work
that will need doing especially on a 320i platform.

I done a few transplants now and what you are doing is daunting for a very experienced mechanic.

The amount of money this will cost you will buy you a brand new car but good luck because you will need it.

An LS swap would be a lot better for your base and still cost you less than just rebuilding the s55 motor.
I'll be staying with a BMW engine whichever way I go, LS's aren't that easy to come by over here! Selling the S55 and buying an N54 might be an option I suppose.
I've not been into BMW that long really but I've built a lot of cars from scratch, fabricated a hell of a lot and I make wiring harnesses in my spare time (I hate the term 'milspec' but that's kinda what I make)
The more I look, the more a crashed 335 seems a sensible purchase and sell the S55.
Id love the M engine though!
The problem is the E and F series electronics are not compatible.
Would the 335 ECU not work with a flash?
 

martymil

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I'll be staying with a BMW engine whichever way I go, LS's aren't that easy to come by over here! Selling the S55 and buying an N54 might be an option I suppose.
I've not been into BMW that long really but I've built a lot of cars from scratch, fabricated a hell of a lot and I make wiring harnesses in my spare time (I hate the term 'milspec' but that's kinda what I make)
The more I look, the more a crashed 335 seems a sensible purchase and sell the S55.
Id love the M engine though!

Would the 335 ECU not work with a flash?
Nope the injectors are the issue and so is the hpfp, no chance it will work.