BMW 330e Stage 1: from 292 to 400 HP measured on the dyno

One of the most interesting engines we have worked on recently. The BMW 330e, the plug-in hybrid homologated at 292 HP, left the Bapro dyno with 399 HP and 725 Nm measured after Stage 1. Beyond the figures, the story of this powertrain deserves to be told in detail, because almost everything about the way it delivers power is different from a conventional BMW.

This article answers a question we get regularly from 330e owners:

The car makes 100 HP in Electric, 252 HP in Sport and 292 HP in XtraBoost. After tuning, how much power will each mode make?

The short answer: almost nothing like what they imagined. The long answer is below, with a real dyno run as evidence.

How the 330e delivers power from the factory

The official homologated figure, the one shown in the CIV (the Romanian vehicle identity document) and by RAR (the Romanian vehicle registry), is 292 HP system output. How it is split across the modes, however, looks different from the way most drivers perceive it:

The first thing to clear up: 252 HP is not the power of Sport mode. It is the continuous system output in any hybrid mode (Hybrid, Comfort, Sport, all of them). The difference comes from XtraBoost, which is only available in Sport mode, and only in short windows of up to 10 seconds.

Where the +40 HP of XtraBoost comes from

This is the least understood part of the whole story, including within the tuning community. XtraBoost comes entirely from the electric motor, not from the B48 combustion engine. The combustion engine delivers the same 184 HP regardless of mode.

BMW's own arithmetic says it all:

• B48 combustion engine: 184 HP (constant, it is not "boosted" under acceleration)
• Electric motor peak: 113 HP
• Electric motor, continuous rating: ~68 HP
• Continuous system output: 184 + 68 = 252 HP
• System output with XtraBoost active: 184 + 113 = ~297 HP (BMW quotes 292)

The +40 HP from XtraBoost is exactly the difference between the electric motor's continuous output and its peak. The combustion engine does not change at all.

The conclusive proof: when the battery drops below a certain threshold, XtraBoost is disabled automatically. If the extra power came from the combustion engine, it would have nothing to do with the state of the battery.

Why is it limited to 10 seconds? Because the electric motor integrated into the ZF8 transmission has a very high power density in a small volume. At its 113 HP peak it generates heat quickly, and the power electronics (the inverter) have to be protected. After 10 seconds, the ECU brings delivery back to the continuous rating.

Why the B48 in the 330e is "choked" from the factory

Now comes the part that explains why the real gain measured on the 330e is larger than on other B48 versions. And why on the dyno we got 400 HP instead of the "estimated" 350-360.

Compared on the same B48B20 block:

Yes, you read that correctly: the combustion engine in the 330e delivers exactly the same power as a 320i, even though it is physically the same engine as the one in the 330i (258 HP), with the same turbo, the same injectors, the same block and the same intercooler.

Why did BMW do this? Several reasons that point the same way:

• WLTP targets: homologation with lower emissions and fuel consumption
• Combined thermal management with the electric motor integrated into the transmission
• Extra durability margin, given that the electric motor loads the ZF8 gearbox from a different direction
• Commercial differentiation: the 330i remains the "sporty version" as far as the combustion engine is concerned

For tuning, this means Stage 1 on the 330e is not just a modest gain. In practice it unlocks the real potential of hardware identical to the 330i's, plus the standard Stage 1 margin on top of that.

The dyno result at AMC Motorsport

The car came onto the dyno for a full evaluation: stock run, development of a custom map, Stage 1 run, final check. Both runs were made under identical conditions, on the same Bapro dyno, with the same DIN 70020 correction standard, on the same day.

BMW 330e G20 dyno overlay, stock run (thick lines) vs Stage 1 (thin lines) · AMC Motorsport, 14.05.2025

Stock run (Reference)

• 325 HP at 5619 rpm
• 494 Nm at 2096 rpm

Stage 1 run (Comparison)

• 399 HP at 5526 rpm (+74 HP)
• 725 Nm at 2776 rpm (+231 Nm)

A few important technical observations about the chart:

• The 325 HP stock figure is already above the homologated 292 HP. This is not unusual for BMW: the factory homologates conservatively, and system output with XtraBoost active is typically above the catalogue figure. The DIN 70020 correction standard also contributes to this difference.
• Torque rose by more than 230 Nm, but the useful band also moved: peak torque went from 2096 rpm to 2776 rpm. This points to more progressive delivery across the whole range, not an "on/off" type punch.
• Peak power is reached lower (5526 rpm vs 5619 rpm), and the curve stays strong towards the limiter, a sign that the map respects the mechanical margin rather than forcing it.

What tuning actually changes, mode by mode

This matters for the customer's expectations: tuning is done exclusively on the DME (the combustion engine's control unit). The electric motor, the battery and the XtraBoost logic are managed by a completely separate unit (EME, Electric Motor Electronics), which is not touched by the remap.

The most important point: in pure electric mode, the car feels exactly as it did before. You only feel the difference once the combustion engine comes in. Anyone who promises you a gain in Electric mode is not telling the truth.

Why a 330e remap measured on the dyno

On any hybrid powertrain, the chance of confusing an "attractive offer on paper" with the real result is greater than on a conventional engine. On the 330e specifically, almost anyone can say "I'll give you 400 HP", but without a real measurement on the dyno it remains just a number.

At AMC Motorsport, the result above was obtained on the same Bapro dyno on which every car we tune is tested:

• Before the remap, to establish the car's real baseline
• After the remap, to confirm the gain under identical conditions
• Both runs with the same DIN 70020 correction standard and the same atmospheric pressure

Note for 330e xDrive owners: our dyno is single-axle, so we can only actually measure the RWD version. For xDrive, we work from the calibration measured on the dyno on the RWD version, without a dyno session in the package.

Booking and a tailored quote

If you have a BMW 330e and are interested in a Stage 1 with a result measured on the dyno, contact us for an evaluation. 17 years of experience, 426 verified reviews, rated 5.0, more than 3,000 projects measured on the dyno.

Str. Carpatilor nr. 60, Brasov