The BMW M S63 Engine: S2 and R2 Configurations, Tuning, and Maintenance
Quick Summary
The S63 is M GmbH’s twin-turbo V8 with two turbochargers mounted in the vee of the engine block. It comes in two configurations: S2 (up to 850 hp, 555 lb-ft) for everyday driving and R2 (over 1,000 hp) for extreme loads. The main difference is piston design and how far the internal components are upgraded. This guide sorts out the technical details, common problems, and proper maintenance so you can avoid expensive mistakes.
The Problem: Tuning Without Preparation Destroys the Engine
An owner installs more capable turbochargers, raises boost pressure—and a few thousand miles later the engine needs a full rebuild. The cause isn’t poor build quality. It’s that the S63’s stock internal components weren’t designed for high boost pressure. The valvetrain and VANOS system are especially vulnerable when revved past 7,000 rpm.
Symptoms
- Power loss at high rpm
- Faults in the variable valve timing system
- Abnormal piston noise while the engine is running
- Oil leaks through gaskets and seals
- Unstable idle
- Premature wear of VANOS components
Causes
Insufficient valvetrain stability at high rpm. Above 7,000 rpm, the stock valve springs can no longer control the valves precisely. That costs power and, in the worst case, damages the engine.
VANOS oil supply problems under high load. The VANOS system needs steady oil pressure. Driven aggressively, the oil pump can’t deliver enough oil to the VANOS units, which triggers faults, cuts power, and accelerates wear.
The Fix: Proper Configuration and Maintenance
Choosing the Right Configuration for Your Goals
For tuning up to 850 hp, the S2 configuration is the smart choice—it balances performance and reliability. For more than 1,000 hp, go with the R2, but be ready for serious maintenance.
Key Differences Between S2 and R2
| Parameter | S2 | R2 |
|---|---|---|
| Pistons | Forged, offset wrist pin | Forged, centered wrist pin |
| Piston noise | Reduced | Higher |
| Head and main studs | Stock | Upgraded |
| Head gasket | Stock | Reduced compression ratio |
| Target output | Up to 850 hp | Over 1,000 hp |
Both configurations come with Carrillo connecting rods and upgraded valve springs. A modified VANOS oil feed improves oil supply under high load.
The CarBahn Tune for S2
If you own an S2 car and want more power while keeping the factory warranty, use the CarBahn tune. This software optimizes engine operation without pushing the components past their limits.
Periodic Rebuilds for R2
R2 engines need regular rebuilds: every 12,000–19,000 miles for track use, 31,000–37,000 miles for mixed driving. A rebuild includes new piston rings, bearings, and seals, plus inspection of critical components.
Refresh Kit for High-Mileage Engines
For a high-mileage S63, the Refresh Kit is the recommendation: new gaskets, seals, and O-rings. Replacing them restores sealing and prevents oil leaks.
Prevention: Buying Checklist
- Check the engine block for cracks, especially the area between the cylinders
- Inspect the cylinder head for hairline cracks around the exhaust valves
- Make sure the crankshaft has no scoring or distortion
- Check the camshaft lobes for wear and chipping
- Check the condition of the Valvetronic and VANOS mechanisms—there should be no play or noise
- Demand a complete factory engine (from oil pan to valve cover) with no backyard modifications
Bottom Line
The S63 is a great tuning platform when you approach it correctly. For 850 hp, pick the S2 with the CarBahn tune; for more than 1,000 hp, the R2 with regular rebuilds. Every engine is hand-built for specific goals, and the development draws on Steve Dinan’s expertise. Professional maintenance is the key factor in longevity. Start with a diagnosis and an honest assessment of the engine’s condition before you buy.