What Is a Supercharger?
A supercharger is a forced-induction device that compresses air before it enters the engine, increasing the density of the charge and allowing more fuel to be burned — producing more power than a naturally aspirated engine of the same displacement.
Unlike a turbocharger, which is driven by exhaust gases, a supercharger is driven mechanically — typically by a belt connected directly to the engine's crankshaft. This means the supercharger spins whenever the engine does, providing boost at any engine speed with no turbo lag.
Types of Superchargers
| Type | How It Works | Common Applications |
|---|---|---|
| Roots-type | Two meshing lobes push air through the housing | Older American muscle cars; some Holden engines |
| Twin-screw (Lysholm) | Twin helical rotors compress air internally | High-performance applications |
| Centrifugal | Impeller (like a turbo compressor) spins at very high speed | Performance cars; some OEM applications |
| Electric (e-supercharger) | Motor-driven; used at low rpm before turbo spools | Modern mild-hybrid systems (e.g. some Mercedes-AMG) |
How a Supercharger Differs From a Turbocharger
| Feature | Supercharger | Turbocharger |
|---|---|---|
| Power source | Engine belt (mechanical) | Exhaust gases (free energy) |
| Throttle response | Instant — no lag | Lag while turbo spools up |
| Efficiency | Lower — robs engine power to drive it | Higher — uses waste energy |
| Complexity | Simpler (no exhaust plumbing) | More complex (hot-side/cold-side, oil feed) |
| Heat generation | Less heat than a turbo | Turbo runs very hot |
| Typical use in NZ | Rare; mostly performance imports | Very common — diesel 4WDs, performance cars, many modern petrol engines |
In NZ, turbocharged vehicles are far more common than supercharged vehicles. Superchargers are mainly found on older American imports, some speciality performance vehicles, and as part of mild-hybrid systems on newer European cars.
Supercharger Maintenance
Because superchargers are mechanically driven and don't see the extreme heat of a turbocharger, they are generally lower maintenance:
- Belt inspection: The drive belt should be checked at regular service intervals
- Oil fill (Roots and twin-screw types): These use a small internal oil reservoir that requires periodic top-up or change — typically every 50,000–80,000 km
- Seals and bearings: Supercharger seals can wear with high mileage, causing oil to leak into the intake
Signs of a failing supercharger:
- Whining or grinding noise from the supercharger unit
- Reduced power or boost
- Oil residue in the intake tract
- Bearing noise that changes with engine speed
Intercooling for Supercharged Engines
Like turbos, superchargers heat the air they compress. Many supercharged vehicles use an intercooler to cool the compressed charge — particularly common on twin-screw and centrifugal types. See our article on intercoolers.
NZ Context
In New Zealand, supercharged vehicles are relatively uncommon in the mainstream market. You're more likely to encounter them on:
- American classic and muscle car imports (Chevrolet, Ford, Dodge)
- Jaguar vehicles (the AJ-V8 supercharged engine was used across many XJ and XK models)
- Holden/HSV performance variants (LS9 and LSA supercharged V8s)
- Modified performance cars
Modern factory-supercharged vehicles are less common in NZ's market than in the US or UK, where several mainstream manufacturers offer them.
NZ Cost Estimates
Supercharger servicing is a specialist area, and costs vary significantly by vehicle:
| Service | Estimated Cost (NZD) |
|---|---|
| Supercharger oil change | $80–$200 |
| Drive belt replacement | $150–$400 |
| Supercharger rebuild/replacement | $1,500–$5,000+ |
| Centrifugal supercharger service | $200–$600 |
Finding a mechanic experienced with supercharged vehicles is important — not all shops work on them regularly. Look for workshops with experience in performance vehicles or the specific marque.
When to Book a Mechanic
Book a mechanic if:
- You hear a new whining, squealing, or grinding noise from the supercharger area
- Power has reduced noticeably, especially at low to mid throttle
- You see oil residue in the intake piping