BMW N54 · N55 · B58 — more platforms coming
Plan the build before you buy the parts.
BuildSpec turns a wheel-horsepower target into a staged, costed parts plan — with the supporting mods and reliability warnings most build lists leave out.
- Platforms
- 3
- Catalogued parts
- 40+
- Build stages
- 5
- Accounts needed
- 0
What you get
A technical plan, not a parts-shop wish list
Required vs. supporting
Every recommendation is separated into what your target demands, what keeps it alive, and what is simply nice to have.
Honest warnings
Fuel, turbo, engine, clutch, and transmission planning thresholds — flagged before you spend.
Budget reality check
Estimated parts ranges by category, with installed items removed so you see what is actually left to buy.
Fuel-aware targets
Pump 91 through E85 changes the ceiling and the fuel-system requirements. The plan changes with it.
Supported platforms
N54
N54 3.0L twin-turbo
Twin small turbos with a robust factory bottom end for its era; engine condition and torque delivery become increasingly important at higher output.
- Stock (est.)
- 255 whp
- Stock-turbo planning threshold (est.)
- 380 whp
- Stock-engine planning threshold (est.)
- 700 whp
N55
N55 3.0L single-turbo
Single twin-scroll turbo, valvetronic head. Very reliable at moderate power, turbo-limited early.
- Stock (est.)
- 270 whp
- Stock-turbo planning threshold (est.)
- 340 whp
- Stock-engine planning threshold (est.)
- 550 whp
B58
B58 3.0L single-turbo
Closed-deck block, integrated exhaust manifold, strong stock fueling. Big gains on calibration alone.
- Stock (est.)
- 320 whp
- Stock-turbo planning threshold (est.)
- 480 whp
- Stock-engine planning threshold (est.)
- 750 whp
Audi, Mustang, Corvette and Honda platforms are next — the data model is already built for them.
Know the number before you spend
Two minutes of inputs beats a garage full of mismatched parts.