Technical Need Help Figuring out parts to replace in engine rebuild


New Member
Sep 20, 2023
Southern California
2008 135i
Hello, I'm Nick and I am currently trying to figure out everything that I will be needing to rebuild my engine(N54 2008 135i 8 Bolt Manual @174,XXX Miles) to OEM Spec. I am Planning to get Hydra HP650 Turbos and aim for 550hp with headroom. To my understanding, the stock n54 motor with no internal upgrades can handle 600hp without upgrading any internal parts as long as it is a healthy motor.

I currently plan to Take my motor out and send the Head to get pressure tested, 3 way valve job and get resurfaced. After that send the block to the shop to get cleaned and to hone the cylinders, and finally getting the crank polished.(So far most of my rebuild knowledge is coming from whatever I see on the forums and my co worker who has many years over me working on hod rods and trucks.)

So far My List For main Replacing is as follows:
Valve Guides
Valve Seals
Piston Rings (I figure out what size from machine shop)
Main Bearings and Rod Bearings - Going with Kings
Head Gasket-VAC motors
Connecting Rod Bolts
ARP Headstuds
Gaskets: VCG/bolts, OFHG/bolts, Coolant Flange Gasket, Oil Pan Gasket/Bolts, Front and Rear Main Seal(A lot of this is already FCPEURO Warranty)
Freeze Plugs? (Co worker mentioned these)
Non Return Valves(FCPWarranty)
Timing Chain Kit
Oil pump Chain and bolts
Oil pickup tube
Crank Hub, Hub Bolt, Pulley bolts, washer, sprocket, Harmonic Dampener
Injector Seals, Retaining Rings and Kit
Alternator(Never Replaced)
Starter(Never Replaced)
335is Clutch and Dual Mass Flywheel(will this work for 550-600hp? I have this on FCP EURO Warranty)
Oil Squirters

In Terms of Upgrading I only plan to upgrade with
ARP Head Studs
M18 Valve Cover
M18 B58 Coil Upgrade
B58 Coils
Radium External PCV VTE
Plug Head Ports <--- Just found out about this today
Integrated Oil Pressure Kit
Aluminum Water Pump(Maybe I have warranty on the plastic one but wouldn't mind just getting this one)

Going with all New Coolant and Oil Feed/Return Lines/Gaskets with the Hydra HP650 Turbos

Is this everything I should need,? Is there anything I am overlooking? Is Porting the head for my Hp goal 550-600 worth it?
I'm in no rush of rebuilding the motor but my goal timeframe is it being all set and in the car 6 months from now
I'll be trying to do most of the work myself so if there are any tools I need, by all means please let me know.
I plan to try to track this vehicle a few times a year and daily drive it if need be.
I'll be documenting my Rebuild process.

Picture of my Car Included :D

These Are Currently The Supporting Mods I Own on the car and off the car right now):

Engine Bay:
PR Relocated Inlets
Upgraded Outlets (Will be replacing with Hydra's HP650 Outlets)
VSRF Aluminum Chargepipe
Vader Solutions Manifold Tap
Tmap 3.5 Bar Sensor
7.5" Mad Stepped Intercooler
Turner Relocated Coolant Expansion Tank kit
CSF Radiator
Aluminum Coolant Flange
PR Ignition coils (Gonna go with B58 Coils and let my friend have these or sell them)
Cat-less Downpipes
Replaced all Vacuum Lines with Silicone ones
VSRF Oil Catch Can
PR Stage 2.5LPFP
PR Upgraded Fuel Lines

I'm still researching if I should go with an upgraded hpfp or Port Injection

BC Racing Coilovers(Will be eventually Upgrading to KW v2/3s
M3 Front Swaybar
M3 Front Control Arms

Will be Swapping in a M3 Rear Subframe, Diff, Control arms etc after the engine rebuild.


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Jun 17, 2020
What is your aim in terms of output and how will the car be used?