BenzUnited Parts
M278 2-Piece Billet Aluminum Pulley Set – E550 / CLS550 / S550
M278 2-Piece Billet Aluminum Pulley Set – E550 / CLS550 / S550
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Precision billet upgrade that reduces belt slip, eliminates noise, and gives smoother, sharper response on every tuned or hard-driven M278.
Why This Billet Pulley Set Makes a Real Difference on the M278
CNC-machined for zero flex and maximum strength under boost.
Ultra-quiet, high-speed bearings that eliminate belt chirp and last for years.
Direct replacement using factory brackets — no modifications, installs in under 60 minutes.
Real-World Results Owners Report
- Smoother revs and noticeably sharper throttle response
- Eliminated belt squeal and improved belt tracking under load
- Better consistency when the turbos are spooled on tuned cars
- Zero vibration even at redline • Made in USA quality you can feel
“The difference in smoothness and belt noise is night and day on my tuned E550. These pulleys are the first thing I recommend after downpipes.” – Alex R., 2015 CLS550 • 512 whp
What You Get (Complete 2-Piece Kit)
- ✔ 2 × Precision CNC Billet Aluminum Pulleys (hard anodized)
- ✔ High-Speed Nachi ZZ Bearings pre-installed
- ✔ All necessary stainless hardware + install guide
Fits These M278 4.7L BiTurbo Models
| Model | Chassis | Years |
|---|---|---|
| E 550 • CLS 550 | W212 / C218 | 2012–2016 / 2012–2018 |
| S 550 • CL 550 | W221 • W222 • C216 | 2011–2017 |
| SL 550 | R231 | 2013–2018 |
| GL / GLS 550 • ML / GLE 550 | X166 • W166 | 2012–2019 |
✅ Confirmed for all M278 4.7L BiTurbo engines • Message if unsure
Frequently Asked Questions
Do I need a tune for these?
No. These are a direct replacement for the factory pulleys — no ECU changes required. They're a supporting/reliability upgrade rather than a standalone power adder.
Will this fix my belt squeal?
That's one of the main reasons people buy them. The high-speed Nachi ZZ bearings and zero-flex billet construction address belt chirp and poor belt tracking under load — common complaints on higher-mileage or tuned M278s.
How long does the install take?
Under 60 minutes. It bolts on using the factory brackets — no cutting or modification, and all necessary stainless hardware plus an install guide are included.
How do I confirm it fits my car?
Confirm your car has the M278 4.7L biturbo V8 — the engine code decides fitment, not the badge. Covered chassis are listed in the table above. If you're unsure, message us your year, model, and VIN and we'll confirm before you order.
What's in the kit?
Two CNC billet aluminum pulleys (hard anodized) with the Nachi ZZ bearings already pressed in, plus all required stainless hardware and an install guide.
Install in under 60 minutes • Bolt-on using factory brackets • No cutting or mods
BenzUnited Parts • Mercedes Performance Specialist • Ships from USA
