How much horsepower does a supercharger add to a V8?

On a typical modern V8, a bolt-on supercharger at 5–8 psi usually adds about 150–300 horsepower (roughly 40–65% over stock) at the crank on pump gas; with supporting mods and 10–14 psi, gains of 250–500+ horsepower (about 70–120%) are common. The exact increase depends on boost level, fuel octane, intercooling, engine compression, and tuning quality.

What actually determines the gain?

Superchargers increase the mass of air entering the engine, allowing more fuel to be burned and thus producing more power. Theoretical gains track the pressure ratio (boost relative to atmospheric pressure), but real-world results are tempered by heat, mechanical drag, and fuel limits. Below are the main variables that control the outcome.

• Boost pressure and pressure ratio: Higher boost raises airflow; practical gains roughly scale with (14.7 + boost) / 14.7, then are reduced by heat and parasitic losses.
• Intercooling and inlet air temperature: Efficient intercooling maintains air density and detonation margin, enabling more timing and power.
• Fuel octane and tuning: Higher octane (or E85) supports more spark advance and/or boost without knock; conservative pump-gas tunes make less power.
• Supercharger type and efficiency: Centrifugal units build power with rpm and are efficient at higher speeds; positive-displacement (Roots/twin-screw) deliver strong low-end torque but can add more heat at high boost.
• Parasitic loss: Driving the blower can consume 20–80+ horsepower depending on size and speed, trimming net gains.
• Engine baseline and hardware: Compression ratio, camshaft, cylinder heads, exhaust, and fuel system capacity set the ceiling for safe, reliable power.

Together, these factors explain why two similar engines at the same boost can see different results, and why well-cooled, well-tuned setups on good fuel consistently make more power.

Rule-of-thumb gains by boost level

The following estimates assume a healthy, modern V8 with a quality intercooler and a safe pump-gas calibration. Actual results vary by blower type, fuel, and tuning strategy.

1. 5–6 psi: About 35–50% over stock. Example: a 450 hp engine rises to roughly 600–675 hp at the crank.
2. 7–8 psi: About 45–65% over stock. Example: the same 450 hp engine reaches roughly 650–740 hp at the crank.
3. 9–10 psi: About 55–75% over stock on pump gas; more with E85. Example: 450 hp becomes ~700–790+ hp at the crank.
4. 12–14 psi (with supporting mods/fuel): About 75–110%+ over stock. Example: 450 hp becomes ~790–950+ hp at the crank; higher on ethanol blends with aggressive timing.

These percentages reflect net gains after parasitic losses and typical heat effects. Higher boost can exceed these numbers, but reliability and fuel quality become critical constraints.

Crank vs. wheel horsepower

Most kit claims are crank horsepower (measured at the engine). Chassis dynos measure wheel horsepower, which is lower due to drivetrain losses—typically 12–15% for manuals and 15–20% for automatics. For instance, 700 hp at the crank often appears as 560–615 hp at the wheels, depending on the drivetrain.

Real-world context for popular V8s

Across common platforms, published results from reputable kits tend to cluster in similar ranges when boost and fuel are comparable.

• 5.0L class (e.g., Ford Coyote): Stage-1 intercooled kits at ~7–8 psi often deliver ~650–750 crank hp on 91–93 octane; E85 or higher boost can push well past 800 with supporting fuel hardware.
• 6.2L class (e.g., GM LT1/L86): At ~6–8 psi, intercooled systems commonly show ~650–750 crank hp; larger TVS or twin-screw units at 10–12 psi with fueling upgrades can reach ~800–900+ crank hp.
• 6.4L class (e.g., HEMI 392): Centrifugal kits around 7 psi frequently add ~200–250 wheel hp; with intercooling and good fuel, 700–800+ crank hp is typical, more on ethanol blends.

These figures assume conservative tunes on pump gas and otherwise stock long-blocks. Forged internals, upgraded fueling, and ethanol blends enable materially higher, safer power at increased boost.

A quick way to estimate your gain

If you want a ballpark number before choosing parts, you can apply a simple process that accounts for boost and realistic efficiencies.

1. Compute pressure ratio: PR = (14.7 + boost psi) / 14.7.
2. Apply an efficiency factor: multiply by ~0.80–0.90 to reflect heat and parasitic losses on a well-intercooled setup.
3. Multiply by your stock crank horsepower to estimate boosted crank horsepower.
4. Convert to wheel horsepower by subtracting typical drivetrain losses (12–20%).

Example: A 450 hp V8 at 8 psi has PR ≈ 1.54. Using 0.85 efficiency: 1.54 × 0.85 ≈ 1.31, yielding about 590 hp at the crank net—plus an additional bump if tuning and fuel allow more spark. Well-optimized builds at the same boost often land higher; conservative tunes lower.

Reliability and safe limits

On stock internals and pump gas, many modern V8s tolerate 6–8 psi reliably with a conservative tune and robust intercooling. Beyond ~9–10 psi, consider forged pistons/rods, upgraded fuel systems, stronger clutches/transmissions, and, where available, E85 for knock resistance.

Bottom line

A supercharger typically adds 150–300 hp to a stock V8 at modest boost (5–8 psi) and 250–500+ hp with higher boost and supporting mods. Choose the blower type, intercooling, fuel, and tune to match your power goal and reliability target.

Summary

Expect roughly a 40–65% horsepower increase from a well-matched, intercooled supercharger on a stock V8 at 5–8 psi, translating to about 150–300 added horsepower at the crank. With stronger hardware, better fuel, and 10–14 psi, gains of 250–500+ horsepower are common. Final numbers hinge on boost, intercooling, tuning, supercharger efficiency, and whether you’re quoting crank or wheel horsepower.

Is it better to turbo or supercharge a V8?

Neither turbocharging nor supercharging is universally “better” for a V8; the choice depends on your priority: superchargers offer instantaneous, linear power at the expense of efficiency, while turbochargers are more efficient by recycling exhaust gases but introduce some power lag. Superchargers are simpler, easier to install, and ideal for drag racing, whereas turbos are more efficient for daily driving and can allow for engine downsizing. 
Choose a Supercharger if:

• You want immediate, lag-free power: Superchargers provide a wide, linear boost from low RPMs. 
• Simplicity is key: They are less complex and easier to install than turbochargers. 
• You prioritize a predictable power delivery: The boost is consistent and matches throttle position more directly. 

This video explains the benefits of superchargers, including their ability to provide immediate power: 1mEngineering ExplainedYouTube · Feb 4, 2018
Choose a Turbocharger if:

• Fuel efficiency is important: Opens in new tabTurbochargers recycle wasted exhaust gases, making them more efficient and better for everyday driving. 
• You need greater potential power: Opens in new tabA well-tuned turbo system can often achieve higher boost levels than a supercharger. 
• Engine downsizing is a goal: Opens in new tabTurbochargers allow smaller engines to produce the same power as larger, naturally aspirated engines, helping with fuel economy and emissions. 

This video explains why turbochargers are generally considered more efficient than superchargers: 1mOVERDRIVEYouTube · Feb 18, 2022
Key Differences Summarized

• Power Source: Superchargers are belt-driven by the engine, while turbochargers are powered by exhaust gases. 
• Efficiency: Turbochargers are more efficient as they use otherwise wasted energy, whereas superchargers consume some of the engine’s “naturally aspirated” power. 
• Power Delivery: Superchargers offer instant, linear power with no lag, while turbos have a “boost threshold” and can suffer from lag. 
• Complexity & Installation: Turbochargers are more complex to install, requiring more supporting components like oil and vacuum lines. 

How to add 400 hp to a car?

How to Increase Your Car’s Horsepower

1. Swap in a Performance Air Filter. Performance air filters are designed to increases air flow through your engine.
2. Install a Performance Exhaust System.
3. Install Performance Throttle Bod(ies)
4. Implement Forced Induction.
5. Remap your Car’s ECU.
6. Use High Octane Fuel.

How much horsepower does a supercharger add to a 5.7 Hemi?

Dyno testing showed that a stock 5.7 HEMI Dodge Charger produced 320 rear-wheel WHP. After we installed a RIPP Supercharger, we safely made 528 WHP! and 504 ft/lbs torque.

How much horsepower does a supercharger add to a V8?

On average, adding a supercharger will give you a supercharged horsepower boost of about 46 percent with 31 percent more torque. That’s some neck-snapping gains!