The N55 lives in two generations of BMW. The same 3.0-liter single-turbo six went into the E82 and E9x cars from 2011, then carried on through the F-chassis 335i, 435i, M235i and the first M2. Inside the engine that barely matters: pistons, rods and bearings are the same job either way. Outside it, the chassis decides which fuel pump, catch can and clutch will actually bolt in. This N55 forged build parts list keeps both halves in view: one sequence for the engine, with the chassis-specific parts flagged so you order the right version the first time.
Which N55 owners this list fits
It's for owners whose engine is coming out to be built stronger: you're planning more boost than the cast factory pistons were meant for, or the engine needs a refresh and you'd rather put forged parts in while it's apart. It assumes an N55B30 car (135i, 335i, 435i, 535i, M235i, M2 or similar), a machine shop for measuring and any bore work, and a bench at home for the assembly.
One thing to know before you shop: many N55 internals are sold as "N55/S55" parts, listed for both engines. The S55 in the M3 and M4 uses a closed-deck block, though, so the block-reinforcement step below applies to the open-deck N55 only. Everything listed comes from our BMW N55 collection or shares fitment with it, and every spec quoted is from the product listing.
Engine out to first drive: the N55 sequence
- Confirm the chassis, not just the engine code. Write down whether the car is E-chassis (E82/E9x) or F-chassis (F2x/F3x/F87). The internals below don't care, but the fuel parts and catch can do, and their listings name specific models and years.
- Tear down and inspect the bare block. Strip it to block and crank, measure the journals and bores, and look the casting over carefully. Reinforcement supports the cylinder tops of a sound block; EPOXY54 is not a crack repair.
- Place the slow orders. The Wagner Tuning N55 head stud set is a special-order item, so get it moving now rather than when the head is ready to go on.
- Decide piston, bore and head gasket thickness together. Manley lists its 37cc Platinum Series dish set in more than one version, including an 84.5mm-bore set for oversize blocks. The Cometic N55B30A MLX gasket comes in .044", .052" and .060" thicknesses. Gasket thickness changes compression, so choose it with your piston dish and tune, and have the gasket on the bench before the block work.
- Machine the block. Bore, hone and deck work all happen on the bare casting. EPOXY54 can be applied before or after machine work, but finishing the machining first means only one trip to the shop.
- Reinforce the open deck. EPOXY54 gives an open-deck block closed-deck strength without machining. It has 21,000 psi compressive strength and a thermal expansion rate closely matching aluminum, and it's a DIY install in 5 steps. Order the Inline 6 configuration with Partial Fill for a street car, which keeps OEM coolant capability. The coolant passages are drilled using your head gasket as the template, which is why the gasket choice came first. The N54/N55 closed deck conversion page has the platform overview.
- Assemble the short block. Main bearings, crank, forged rods with new rod bearings, then pistons, checking clearances at each step.
- Fit the head on studs. Head gasket, head, then the stud set, torqued to the manufacturer's specification.
- Renew the cooling and breather parts while you can reach them. Water pump, catch can and oil filter go on before the engine goes back in.
- Install the chassis-specific fuel and clutch parts. These go in as the engine returns to the car. Order them by chassis, using the fitment tables on each listing.
The N55 forged build parts list
Read the fitment table on each listing against your exact car before ordering. Parts marked E-chassis or F-chassis are listed only for those cars.
| Stage | Part | Why it's on the list | Link |
|---|---|---|---|
| Block | EPOXY54 Aluminum Block Epoxy Kit (Inline 6) | Supports the cylinder tops of the open-deck N55; Partial Fill for the street, Dry Block for track use only | View |
| Block | EPOXY54 Install Kit | Stir stick, drill bit and squeeze bottle; sugar or salt and masking tape not included | View |
| Head clamping | Wagner Tuning N55 OEM Head Stud Set, Burnished (P102061410.BR) | Stud set made for the N55; special order, so place it early | View |
| Rods | Manley N55/S55 Turbo Tuff Pro Series I-Beam rods (14449-6) | Manley's boosted-engine line, forged from 4340 or 300M vacuum-degassed steel | View |
| Pistons | Manley N55/S55 37cc Platinum Series dish piston set (647000C-6) | 2618 alloy forgings with tool steel wrist pins; the dish lowers compression for boost | View |
| Rod bearings | ACL N54/N55/S55 High Performance rod bearings, standard size (6B1584H-STD) | Standard size for a crank that hasn't been ground; replace while the rods are out | View |
| Main bearings | ACL N54/N55/S55 main bearings, standard size (7M1397H-STD) | Carries the crank in the block; replaced together with the rod bearings | View |
| Head gasket | Cometic N55B30A 85mm .052" MLX head gasket | Shim layer adds clamp load around the chamber on the open-deck block; also sold in .044" and .060" | View |
| Cooling | Mishimoto N54/N55 engine water pump | Direct replacement electric pump; includes hardware to replace the factory torque-to-yield bolts | View |
| Breather (E-chassis) | Mishimoto 11–13 335i/335ix/135i baffled catch can kit | Traps crankcase blow-by before it reaches the intake; direct-fit hoses and bracket | View |
| Oiling | aFe Pro GUARD D2 oil filter, N54/N55 | Direct OE replacement cartridge with the o-rings included | View |
| Fuel (E-chassis) | Radium E9x fuel surge tank, regulated (pump not included) | Billet hanger for up to two pumps with a built-in regulator; listed for the 2007–2011 335i | View |
| Fuel (F-chassis) | DeatschWerks DW400 pump module, F20/F30/F87 N55 | Listed for the 2012–2015 335i, 2014–2016 435i, M235i and 2016–2018 M2, among others | View |
| Clutch | Clutch Masters N55 Twin-Disc (Race/Street) kit with aluminum flywheel | Fitment table spans E- and F-chassis cars; works only with the included Clutch Masters flywheel | View |
Where N55 builds trip up
- Buying fuel parts by engine instead of by car. The Radium tank is listed for the E9x; the DeatschWerks module is listed for F-chassis cars. Both cars run an N55, but each part is listed for only one of them.
- Reading "N55/S55" as "same block." Shared rods, pistons and bearings don't make the blocks the same. The S55 is closed deck; block filler is an N55 step.
- Picking a gasket thickness off the shelf. With three Cometic thicknesses on offer, the choice should come from your piston dish and compression target, and it has to be settled before the coolant passages are drilled.
- Bolting a twin-disc kit to the stock flywheel. The Clutch Masters listing says the kit won't work with the OEM flywheel. Use the flywheel it ships with.
- Reusing stretched hardware. Factory torque-to-yield bolts are made to be replaced. Mishimoto includes new mounting hardware with its water pump for exactly that reason.
For the background behind this list, N55 Closed Deck Alternative covers why the N55 deck needs support, Open Deck vs Closed Deck Block explains the deck designs, and What Head Studs Fix, What Block Filler Fixes shows why the stud set and the epoxy sit on the same list. Building the twin-turbo engine instead? See the N54 bottom end build order.
Plan your N55 build
Settle the chassis, order the slow parts, pick piston and gasket as a pair, finish the machining, then reinforce the block before the rotating assembly goes in. Start with EPOXY54 in the Inline 6 configuration and add the Install Kit if you don't already have the tools. Questions about fitment for your car? Email support@epoxy54.com before you order.
Ready to order? Shop the N55 build stage by stage, with every part on one page.