A B47 remap is one of the best-value upgrades in UK motoring: typically ~235 bhp and 450 Nm from the 190 bhp 320d/520d/X3 20d, from £150 at FLR with diagnostics included. BMW sells this same engine at up to 224 bhp, so Stage 1 works within proven factory territory. ZF8 automatic cars should take the from-£275 engine + gearbox bundle — the shift calibration is half the transformation. Every map keeps DPF, EGR and AdBlue fully active. Full brand picture: BMW remapping guide.
The Short Answer
Should you remap your B47? If it is healthy — yes, and more confidently than almost any other engine we work on. The B47 replaced the N47 from around 2014 and fixed most of what haunted its predecessor. It is strong, common and conservatively calibrated: BMW ships the same basic engine at 150, 190 and 224 bhp outputs, which is a factory admission of how much headroom the software holds back.
At Finish Line Remaps, Stage 1 from £150 includes diagnostics, a custom-written file for your exact engine and software version, a permanent factory backup and post-flash verification. What a Stage 1 actually changes: our full explainer.
Typical Stage 1 Gains by Model
Figures are typical results on a healthy, standard car. Software versions vary, so we confirm from your VRN before booking:
| Model | Stock | Typical Stage 1 |
|---|---|---|
| 318d / 418d (B47 150) | 150 bhp / 320 Nm | ~190 bhp / 400 Nm |
| 320d / 420d (B47 190) | 190 bhp / 400 Nm | ~235 bhp / 450 Nm |
| 520d (B47 190) | 190 bhp / 400 Nm | ~235 bhp / 450 Nm |
| X3 xDrive20d | 190 bhp / 400 Nm | ~235 bhp / 450 Nm |
| 125d / 225d (B47 224 twin-turbo) | 224 bhp / 450 Nm | ~260 bhp / 510 Nm |
Notice the pattern: the 150 and 190 bhp versions converge towards what the 224 bhp twin-turbo version proves the platform handles. That is the honest logic of a B47 Stage 1 — we are not inventing capability, we are using calibration room BMW left on the table for product-range reasons.
What It Actually Feels Like
The dyno figure is not the point on this engine. The point is the mid-range: the 1,750–3,500 rpm band where a 320d lives its entire life. After a Stage 1 the car stops needing third gear for overtakes that used to demand second, motorway slip roads stop being an event, and the ZF8 holds higher gears up hills it used to kick down on. Most owners describe it as the car finally matching the way it looks — effortless rather than frantic.
Economy on a sensible right foot typically holds steady or improves slightly, because the engine reaches cruising load with less throttle. Drive it like you stole it and economy drops — physics still applies. The honest detail is in our economy remap guide.
The ZF8 Pairing — Half the Transformation
Most B47s in the UK carry the ZF 8-speed automatic, and it deserves equal billing. The factory gearbox calibration is built around the stock torque curve: shift points, clutch pressures and kickdown logic all assume 400 Nm. Feed it 450 Nm without recalibration and it works — but it shuffles, hesitates and short-shifts around the new delivery.
A ZF8 gearbox tune raises the box's torque limits to match the engine, sharpens shift speed and holds gears intelligently. The engine-plus-gearbox bundle from £275 exists for exactly this pairing, and on an automatic 320d or 520d it is the configuration we recommend without hesitation. The deep technical story: TCU tuning deep dive.
Known B47 Checks Before We Flash
The B47 is robust, but it is still a modern diesel that lives a British life of short trips and long service intervals. Here is what the included diagnostics looks at:
| Item | Why it matters | How we check |
|---|---|---|
| EGR cooler and valve | EGR coking is the classic modern-diesel restriction — and B47 EGR coolers have documented recall history | Live data flow analysis, fault memory, recall status review |
| DPF health | A filter already struggling from short-trip life needs fixing before more torque arrives | Soot load, regeneration history, differential pressure — see DPF regeneration guide |
| Turbo and VNT actuation | Boost stability underwrites every figure in the table above | Boost trace on road test — see turbo health before a remap |
| Timing chain | Vastly improved over the N47, but high-mileage cars still get a listen | Cold-start listen, service history review |
| ZF8 adaptations | A gearbox with degraded fluid or harsh adaptations should be addressed before more torque | Adaptation values, shift quality on road test |
Who Should NOT Remap Their B47
- Cars with active EGR, DPF or boost faults — fix first, then tune. Diagnosis is what diagnostics from £40 is for.
- Short-trip-only cars already fighting DPF regeneration — a remap does not fix a lifestyle mismatch; our short-trip diesel guide explains the real options.
- Cars under BMW warranty where goodwill matters more than pace — understand the TD1 flag in our warranty guide before deciding.
- Anyone unwilling to declare the remap to insurance — non-negotiable.
How We Tune a B47 at FLR
- VRN quote. Registration in, exact engine version and gearbox identified, honest expectations and price out.
- Diagnostics first. Fault memory, live data, boost behaviour, EGR and DPF assessment, ZF8 adaptations where fitted. Included with every Stage 1.
- Custom calibration. Factory file read and archived for life, then a file written for your exact software version — never a generic download. See custom tuning.
- Verification. Post-flash live data, road test on the hills we know, written handover and aftercare advice.
Next Steps
A healthy B47 plus a custom Stage 1 — and on automatics, the ZF8 tune — is the best pound-for-pound upgrade in BMW diesel ownership. Related reading: the full BMW remapping guide for the N47 era and B58 petrol, the best cars to remap in the UK to see how the B47 ranks, and is Stage 1 worth it on a daily diesel if you are still weighing it up. Ready? Send your VRN via the contact page or call 01706 404 357. Workshop in Haslingden, mobile across Lancashire and the North West.
BMW B47 Remapping — Common Questions
On the 190 bhp B47 in the 320d, 520d and X3 20d, a custom Stage 1 typically reaches around 235 bhp and 450 Nm on a healthy engine — roughly 45 bhp and 50 Nm over stock. The 150 bhp 318d-spec version typically reaches around 190 bhp and 400 Nm. We confirm expectations for your exact car from the registration.
On a healthy example, yes. The B47 is a robust modern diesel sold at outputs up to 224 bhp from the factory, so a careful Stage 1 on the 150 or 190 bhp versions stays well inside what the platform supports. The key word is healthy — we verify turbo, EGR and DPF condition in the included diagnostics before flashing.
Stage 1 is from £150 at Finish Line Remaps, including diagnostics, a custom-written file for your exact engine and software version, a permanent factory backup and post-flash verification. ZF8 gearbox tuning is from £150, and the engine-plus-gearbox bundle is from £275.
If your B47 has the ZF8 automatic, it is the best-value addition on the menu. The gearbox calibration raises torque limits to match the engine, sharpens shift speed and improves kickdown logic. The from-£275 engine-plus-gearbox bundle is what we recommend for most automatic 320d and 520d owners.
The engines respond similarly, but the B47 carries far less reliability baggage. The N47's documented timing chain history means extra checks before tuning; the B47 largely resolved it. If you are choosing between a late N47 car and an early B47 car to buy and tune, the B47 is the easier recommendation.
A properly written Stage 1 keeps every emissions system active — DPF, EGR and AdBlue all work exactly as designed, and the car remains MOT-compliant. What we do check first is that those systems are healthy, because adding torque to a car mid-DPF-struggle helps nobody.
Dealer tooling can detect modified software and apply the TD1 flag, which can affect goodwill on powertrain warranty claims. We archive your original file for life and can return the car to stock for dealer visits, but detection of past flashes is possible. If the car is under warranty, read our warranty guide and decide with eyes open.
Yes. A remap is a material modification in the UK and must be declared. Undeclared tuning can invalidate the policy. On a 320d the premium change is usually modest — far better than discovering you had no cover.