Tuning Guide — BMW E46 M54 (320, 325, 330)

Naturally Aspirated Tuning

There is some power to be made, even on a stock engine - but more mods mean more gains!

• VANOS targets: optimise intake/exhaust cam timing for modifications to improve torque and drivability.
• Ignition timing: advance where safe, manage knock, optimise for chosen fuel quality.
• Fuel mixture: correct lambda under cruise and load, smooth transitions.
• Light mods: intake/exhaust manifold/cat‑back are mapped in; expect sharper response and a cleaner power curve.
• Expected gains: typically +10–20 bhp with supporting hardware and healthy baseline.

Camshaft Upgrades

The M54 responds very well to a camshaft upgrade — provided VANOS targets, ignition timing and fueling are reworked to match the new airflow / intake harmonics. Expect stronger mid‑range and better top‑end.

Lots of camshaft options out there, from Schrick, Cat-Cams, dbilas, Kent & many more!

Let us know what camshaft profile (duration and lift) you are running, and we can optimise both low end torque and high end power.

DISA is useful to keep, and can be optimised to reduce low end torque loss with a big inlet camshaft.

Turbo on Stock Internals

Using a GT30/GT35 sized turbo, in a mild configuration at 7–10 psi (boost) will typically produce ~300–360 bhp on an otherwise stock M54 when the setup and calibration are correct.

• Focus on charge temps, reliable fueling, and conservative ignition under boost.
• MAF scaling or MAP strategy as needed; keep closed‑loop behaviour stable.
• Clutch and cooling upgrades recommended as power rises.

Big Turbo

A GT35‑class (read: BIG!) turbo at 14+ psi (boost) targets around ~400/420 bhp with the right supporting hardware.

• Fuel system (in some cases), intercooling, and drivetrain need to be spec’d for the goal.
• Careful spool/response management by optimising VANOS
• MAP sensor conversion often sensible

Supercharger

Centrifugal / Rotrex‑style systems bring linear delivery and great road manners. With proper pulley choice and cooling, ~350–400 bhp is typical. Idle control and bypass valve tuning keep it civil.

Roots / Eaton-style setups give a good punch of power low down in the RPM, but can run out of 'puff' at higher RPM. Also, be mindful of the bracketry etc to install... there are some poor kits out there!! ~340–380 bhp is typical.

Forged Builds (~500 bhp)

• Internals: forged rods & pistons recommended for big power.
• Compression: drop compression; if not forging, a thicker head gasket can be used.
• ECU strategy: again a MAP sensor setup is absolutely recommended here, depending on the compression and fuel quality, conservative ignition is sensible.. Also, we must watch EGTs as at this power we are asking a lot of stock exhaust valves.