BMW M8 S63 Performance Engine ReplacementRebuilt & Options

The S63B44T4 in the M8 is BMW's most refined hot-vee V8, but high performance demands proactive maintenance. Later revisions are significantly improved over early S63 engines.

• Rod bearing wear remains the most common catastrophic failure (55k-85k miles)
• Turbocharger failures occur, particularly with neglected oil changes
• LCI models (2022+) have improved cooling system durability
• Regular 5k-6k mile oil changes dramatically extend engine life
• The S63TU4 in the M8 is more reliable than earlier S63 iterations

A rebuilt S63 engine for an M8 costs £14,995-£23,000 supply only. Fitting adds £1,800-£3,500. Dealer prices run £22,000-£30,000 for a complete replacement.

• Used engines: £8,500-£15,000 with 30k-60k miles
• Reconditioned units: £14,000-£22,000 with factory tolerances
• Competition models (S63B44T4) cost more than standard M8 units
• Specialist supply & fit is approximately half the main dealer price
• Core charges of £2,000-£3,000 apply on remanufactured engines

With meticulous maintenance, an M8's S63 engine can reach 120k-150k miles. However, rod bearing and cooling system failures typically appear between 50k and 90k miles without proactive care.

• Preventative bearing replacement at 60k miles extends life significantly
• Cooling system overhaul at 60k miles prevents overheating damage
• M8 Competition engines see higher thermal stress than standard units
• Regular oil analysis can predict bearing wear before failure
• Many M8 engines need major work by 80k-100k miles under normal ownership

The four biggest red flags are cold start rattle (timing chain guides), deep knocking (rod bearings), blue startup smoke (valve seals), and coolant loss (cooling system leaks).

• Listen for 1-2 second rattle on cold start - indicates timing guide wear
• Any bottom-end knock means imminent rod bearing failure
• Blue smoke on startup after sitting overnight signals valve seal wear
• Check coolant level history - M8s consume coolant when stressed
• Request service records showing oil changes every 5k-6k miles minimum

Replace with a rebuilt unit if your engine has suffered rod bearing or timing failure. If caught early with top-end issues only, a rebuild may be viable. Most owners choose replacement for the upgraded components.

• Full replacement with upgraded bearings costs £14,995-£22,000 supply only
• Top-end rebuild (valve seals, timing guides) costs £5,500-£8,500
• Bottom-end failure almost always requires full replacement
• Rebuilt engines include 12-month unlimited mileage warranty
• Upgrade to coated bearings prevents the original failure point

Both use the 4.4L S63 twin-turbo V8, but the Competition gets the S63B44T4 with 617hp versus 600hp in the standard M8's S63B44B. The blocks are similar but tuning and some internals differ.

• Competition produces 617hp (625PS), standard M8 produces 600hp
• The T4 in S63B44T4 denotes the fourth-generation Competition tune
• Competition models dominate replacement enquiries due to higher sales volumes
• Both share the same rod bearing and cooling system weaknesses
• Engine swap between variants requires ECU reprogramming

Some oil consumption is normal on the S63, especially with sporty driving. Excessive consumption (over 1L per 1,000 miles) indicates worn valve stem seals, piston rings, or turbo seals.

• BMW considers up to 1L per 1,000 miles within specification
• Valve stem seals harden under extreme heat - common from 60k miles
• Blue smoke on startup is the classic symptom of seal failure
• Regular oil level checks between services are essential
• Upgraded Viton seals in rebuilt engines solve the problem permanently

2022+ LCI models are the most reliable M8s, benefiting from cooling system and software refinements. 2019-2020 early cars have the highest documented failure rates, particularly for cooling and turbo components.

• LCI (2022-2025) has improved coolant hose and expansion tank design
• Pre-LCI (2019-2021) cars show more cooling system and wastegate issues
• Final Edition (2024-2025) benefits from all cumulative improvements
• Any M8 with full service history is preferable to a neglected newer car
• Low mileage doesn't guarantee health - heat cycles matter more than miles

The engine and S63B44T4/S63B44B codes are identical across all M8 body styles (Coupe F92, Convertible F91, Gran Coupe F93). Performance figures are the same regardless of bodyshell.

• All variants use the same 4.4L twin-turbo S63 V8 engine family
• No power difference between Coupe, Convertible, or Gran Coupe
• Gran Coupe carries slightly more weight but shares powertrain completely
• Replacement costs are identical across all three body styles
• The Gran Coupe is the most common M8 on UK roads

The S63 has significant tuning potential, but any power increase accelerates wear on rod bearings, turbos, and cooling systems. Stick to stock unless you accept dramatically shorter engine life.

• Stock Competition already produces 617hp - tuning adds little real-world benefit
• Remapped cars show much higher rod bearing failure rates
• Most specialist rebuilders refuse warranty on tuned engines
• Cooling system upgrades are essential for any power increase
• A stock M8 with proper maintenance outlasts any tuned car