Forced Induction: Turbo vs Supercharger
Turbochargers, superchargers, and what you actually need to know before adding forced induction to your car
Adding a turbocharger or supercharger to a naturally aspirated engine, or upgrading the factory forced induction setup on a car that already has it, is one of the most transformative things you can do to a car's performance. It's also one of the most involved projects, with the most ways to go wrong if the supporting work isn't done correctly.
The power gains are real. So are the risks and the supporting costs that most people don't fully account for before starting. This guide covers what you need to understand before committing to a forced induction build.
Turbo vs Supercharger: The Core Difference
A turbocharger is driven by exhaust gases. Hot exhaust spins a turbine, which drives a compressor that forces air into the engine. Because the energy comes from exhaust heat that would otherwise be wasted, a turbocharged engine can produce very high power relative to fuel consumption. The downside is turbo lag: there's a delay between pressing the accelerator and when the turbo spools up enough to produce meaningful boost pressure.
A supercharger is mechanically driven by the engine's crankshaft via a belt or gear. It produces boost from the moment you press the throttle and gives a very linear, immediate power delivery that many drivers prefer for street use. The tradeoff is parasitic drag from the mechanical drive and generally lower peak efficiency than a comparable turbo.
Twin-screw superchargers (Whipple, Harrop) produce boost more efficiently than older Roots-style blowers and are common on American V8 applications. Centrifugal superchargers (Procharger, Paxton) act more like a mechanically driven turbo in their boost characteristics, with power building as engine speed increases.
For street cars, both work well. Turbos dominate in high-output applications and in the import and European markets. Positive displacement superchargers dominate on American V8s where hood clearance favors a unit that sits on top of the intake. The right choice depends more on what's available and proven for your specific engine than on which technology is objectively better.
Upgrading a Factory Turbocharged Car
Most of the performance vehicles sold today come with turbocharged engines from the factory. For these cars, the question isn't usually whether to add a turbo but how far to push the existing setup.
Factory turbos have known limits. On most platforms, a Stage 1 tune on the factory turbo is where the easy power lives. Stage 2 adds supporting hardware (downpipe, intake) that lets the factory turbo breathe better. Both stages work within the turbo's design range and rarely cause reliability issues.
Going beyond that means upgrading to a larger turbo, and that's where things get more complex. A larger turbo needs supporting fuel system upgrades (bigger injectors, sometimes an upgraded fuel pump), reinforced engine internals to handle elevated cylinder pressure, a proper intercooler to manage the increased intake air temperature, and a fully custom tune built for the specific combination of parts.
Turbo upgrades on popular platforms (BMW N54/N55, Subaru EJ/FA, Audi EA888, Mitsubishi 4G63) are well-documented in the enthusiast community. Proven kits from companies like BorgWarner, Garrett, and platform-specific specialists like Pure Turbos or ETS exist for most common applications. Starting with a proven bolt-on kit reduces the risk of compatibility problems and gives a tuner a known starting point.
Adding Turbo or Supercharger to a Naturally Aspirated Engine
Building a forced induction system on an engine not designed for it is a more involved project than upgrading existing factory forced induction. The key consideration is the engine's compression ratio.
Naturally aspirated engines are built with high compression ratios (often 10:1 to 12:1) to extract efficiency without boost. Adding boost to a high-compression engine creates high cylinder pressures that dramatically increase the risk of engine knock. Running low boost pressure mitigates this somewhat, but for any serious power numbers, lower compression forged internals are advisable or the power limits need to be conservative.
Other supporting work that's required or strongly recommended for any forced induction conversion on an NA engine includes: upgraded fuel injectors and fuel pump to supply the additional fuel needed at boost, an intercooler to cool intake air, an upgraded radiator or oil cooler in most cases, reinforced head bolts or studs on engines known to have head gasket issues under boost, and a full custom tune calibrated specifically for the setup.
Drivetrain is another consideration. A big power increase on an engine that was never designed for it can expose weaknesses in the clutch, transmission, or axles. Budget for these potential failures or upgrade them proactively.
Intercoolers: Why They Matter
Compressing air raises its temperature. Hot air is less dense and contains less oxygen per unit volume, which limits power and increases knock risk. An intercooler cools the compressed air before it enters the engine, increasing air density and reducing inlet temperatures.
Air-to-air intercoolers work like a radiator, using ambient airflow to cool the compressed intake air passing through them. They're simpler, don't require maintenance, and work well in most applications. Placement matters: front-mounted intercoolers (FMIC) see better airflow than side-mounted units, which is why front mounts are preferred for performance applications.
Air-to-water intercoolers use a water circuit to absorb heat from the intake air. They can be more compact and can be placed closer to the engine, but they require a reservoir, pump, and heat exchanger to function, adding complexity and maintenance requirements.
For most street-driven builds, a quality air-to-air front-mount intercooler is the standard choice. For track use where sustained high-throttle operation is common, air-to-water systems with ice water for pre-cooling are used to prevent heat soak.
Upgrading the factory intercooler on a production turbo car is one of the best supporting modifications before a tune. Most factory units are undersized to keep costs down and heat soak quickly in spirited driving.
Finding a Shop for Forced Induction Work
Forced induction builds require a shop that can do the fabrication work (if running custom piping or mounting), the mechanical installation, and a proper tune. Finding one shop that does all three well, and has experience on your specific platform, is the goal.
For bolt-on turbo upgrades on common platforms, many shops can handle the install provided they work on your car regularly. The tune is usually done separately on a dyno, and for this part specifically, platform experience matters enormously. A tuner who has done 200 tunes on an N55 BMW understands the platform's limits and quirks in a way that a generalist simply doesn't.
For custom builds, look for shops with fabrication capability in-house. Intercooler piping, turbo manifolds, and wastegate placement all involve custom metalwork. Shops that do this work regularly produce cleaner installs with better fitment and fewer clearance issues.
Ask to see completed builds on the same or similar platforms. Dyno graphs before and after are helpful, but also ask about real-world reliability after the build. A 600whp number on a freshly tuned car is less meaningful than knowing that car is still running strong at 30,000 miles.
FIND A SHOP
4 vetted shops in our directory offer this service.
EuroWise
Charlotte, North Carolina
4.9 ★ (183)Repasi Motorwerks
Stratford, Connecticut
4.9 ★ (72)Fairfield County Motorsport
Fairfield, Connecticut
4.9 ★ (197)BUTZIGEAR - The Porsche Shop
Milford, Connecticut
4.9 ★ (76)Frequently Asked Questions
A bolt-on turbo upgrade for a production turbocharged car ranges from $2,000-$6,000 for the hardware plus $500-$1,500 for a custom dyno tune. Full custom turbo builds on naturally aspirated engines start at $5,000-$8,000 for simple setups and can exceed $20,000 for high-output builds with supporting internal work.
On a production turbocharged car, a bolt-on larger turbo with supporting modifications can add 100-200+ whp over a Stage 1 tune on the stock turbo. On a naturally aspirated engine, a conservative low-boost setup typically adds 25-50% power. High-boost builds with internal work can double original output, though reliability tradeoffs increase significantly at extreme power levels.
It depends on the engine and target power level. Many modern factory turbocharged engines can handle moderate power increases on stock internals. For naturally aspirated conversions or builds pushing past the engine's known limits, forged pistons and connecting rods reduce the risk of catastrophic failure under the higher cylinder pressures forced induction creates.
At minimum: a custom tune calibrated for the setup. Beyond that, most builds require upgraded fuel injectors, an improved intercooler, and often a fuel pump upgrade. Higher-power builds also need clutch, transmission, and drivetrain attention. Turbocharged cars running E30 or E85 fuel blends also need flex fuel sensors and compatible injectors.
Done correctly with proper supporting modifications and a conservative tune, a forced induction build can be reliable for tens of thousands of miles. Done poorly (undersupported fuel system, inadequate cooling, poorly calibrated tune) it shortens engine life dramatically. The tuner's conservatism matters as much as the hardware choices.
Find a Trusted Shop
Browse our curated directory of performance and aftermarket shops.
Browse Shop Finder