A Demon 170 Swap Turns a Charger Into a Different Car Entirely

A Charger with a Chrysler 300 SRT Demon 170 engine swap is not a stock Charger anymore — it is a high-performance machine built to order, usually by a specialty shop. The Demon 170 is a supercharged 6.2-liter V8 that produces 1,025 horsepower in the 300 SRT Demon, and when transplanted into a Charger, it delivers similar power with different weight distribution and handling characteristics. You will not find this car on a dealer lot. It exists only as a custom build, which means you are buying either a completed project from a builder or commissioning one yourself.

The price, timeline, and reliability all depend on who does the work and how thoroughly they engineer the swap. A finished car from an established shop might cost $150,000 to $250,000 or more, depending on the Charger's condition, the quality of the installation, and what other modifications come with it. A DIY or semi-professional build can cost less upfront but carries real risk: engine management tuning, fuel system upgrades, cooling, and electrical integration are not straightforward tasks, and a poorly executed swap can leave you with a car that runs badly or fails inspection.

Key Takeaways

  • A Demon 170 swap is a custom build that requires either buying a finished car from a specialty shop or commissioning one, since Chrysler does not offer this combination from the factory.
  • The total cost typically ranges from $150,000 to $250,000 or higher for a professional build, plus the price of the donor Charger and engine.
  • Engine management, fuel delivery, cooling, and electrical systems must be completely redesigned for the swap, which is why amateur builds often have reliability and performance issues.
  • Warranty coverage is nonexistent on a swapped car, and insurance companies may require inspection or charge higher premiums for a heavily modified vehicle.
  • Resale value is unpredictable because the market for custom swaps is small and depends entirely on the builder's reputation and the quality of the work.

Where to Buy a Charger With This Engine Swap

You have three realistic paths: buy a finished car from a known builder, commission a build from a shop, or purchase a Charger and have a shop perform the swap. The first option is the safest because you can inspect the completed car, test drive it, and hold the builder accountable if something fails. Shops that specialize in Mopar swaps — particularly those with experience moving Demon engines into older or different platforms — have the tuning knowledge and parts suppliers to do the job right. Look for builders with documented builds, customer reviews, and a track record of cars that pass inspection and hold up.

Commissioning a build means you choose the Charger (usually a 2015 or newer model, since older cars need more structural work), source or let the shop source the Demon 170 engine and transmission, and pay the shop labor and engineering costs. This route gives you control over the final spec but also locks you into a timeline — most builds take four to eight months — and requires you to trust the shop's judgment on parts and tuning. The third path, buying a Charger and swapping it yourself or through a local shop with limited experience, is the cheapest entry but the riskiest. Engine management alone requires dyno tuning and custom ECU work, and mistakes here can destroy the engine or leave the car undriveable.

What the Demon 170 Engine Brings to a Charger

The Demon 170 produces 1,025 horsepower and 945 pound-feet of torque in the 300 SRT Demon, but in a Charger the actual output depends on tuning, fuel quality, and whether the shop keeps the supercharger at full boost or dials it back for reliability. A Charger is heavier than a 300 sedan and has different suspension geometry, so the power delivery will feel different even if the numbers are the same. The Charger's weight distribution is more neutral, which can make it handle better than the 300 in corners, but it also means the engine is working harder to move the car, which puts more stress on the drivetrain.

The Demon 170 is a supercharged engine, not turbocharged, which means it responds when ready to throttle input and does not have turbo lag. It also runs on 100-octane fuel in the 300 SRT Demon, and most Demon 170 swaps require the same or close to it. Regular 87-octane gasoline will not produce full power and can cause engine knock. You will be buying premium or race fuel regularly, which adds to the cost of ownership. The engine is also tight on packaging — the supercharger sits high on the block — so hood clearance, radiator placement, and intercooler routing all require custom fabrication in a Charger.

Engine Management and Tuning Challenges

The Demon 170's engine control unit (ECU) is calibrated for the 300 SRT Demon's weight, aerodynamics, suspension, and fuel system. Drop it into a Charger and none of those parameters match anymore. A professional shop will reflash the ECU with custom tuning that accounts for the Charger's different mass, gear ratios, and fuel delivery, then validate the tune on a dynamometer. This is not a bolt-on job — it requires hours of dyno time and real-world testing to get shift points, boost levels, and fuel mixture right.

Poor tuning shows up as hesitation, rough idle, check engine lights, or catastrophic engine failure if the air-fuel ratio runs too lean. Some shops use off-the-shelf tuning software and call it done; professional builders write custom code or hire a tuner who specializes in supercharged Mopar engines. Ask any shop you consider whether they tune in-house or outsource it, and whether they warranty the tune for a specific period. A tune that works on day one but fails after 5,000 miles is a sign the shop cut corners.

Transmission, Cooling, and Fuel System Upgrades

The Demon 170 in the 300 SRT Demon pairs with an eight-speed TorqueFlite automatic transmission. That same transmission can handle the power in a Charger, but the Charger's driveshaft, differential, and suspension components were not designed for 1,000 horsepower. A proper swap includes reinforcing or replacing the rear differential, upgrading the driveshaft, and often installing a limited-slip or locking differential to put power to the ground without spinning one wheel.

Cooling is another major system. The Demon 170's supercharger generates heat, and the Charger's factory cooling system is not adequate. A professional build includes a larger radiator, upgraded fans, and often a separate intercooler circuit to cool the supercharger's intake charge. Without this, the engine will run hot, lose power, and risk detonation. The fuel system must also be upgraded — the Demon 170 demands high-octane fuel delivered at precise pressure, so the factory Charger fuel pump and lines are replaced with a high-flow pump and braided steel lines. Some builds add a secondary fuel tank or fuel cell to may support consistent supply under hard acceleration.

Warranty, Insurance, and Inspection Issues

Chrysler will not warranty a swapped car, and neither will any aftermarket shop unless they explicitly state otherwise in writing. If the engine fails at 10,000 miles, you own the repair cost. Some shops offer a limited warranty on their labor — typically one year or 12,000 miles — but not on the engine itself. This is a real financial risk on a car that cost $200,000 to build.

Insurance is another complication. Most standard auto policies exclude or heavily restrict coverage on modified vehicles. You will need to contact your insurer and disclose the swap before you buy; some will refuse to cover the car at all, others will require an inspection and charge a higher premium. A few specialty insurers cover high-performance and custom builds, but they are more expensive and may require the car to pass a safety inspection or be registered as a custom vehicle in your state.

Vehicle registration and inspection vary by state. Some states allow custom-built cars to be registered as long as they pass emissions and safety inspection; others require a special custom vehicle title or inspection by the state. A Charger with a Demon 170 swap will almost certainly fail a standard emissions test because the engine management is tuned for performance, not emissions compliance. Check your state's rules before you buy — you might not be able to legally register the car where you live.

Resale Value and Market Reality

A custom Demon 170 swap holds value only if the builder is known and the work is documented. A car built by a respected shop with photos, dyno sheets, and a clean service history might sell for 70 to 80 percent of what you paid. A car from an unknown builder or with questionable work history could sell for 50 percent or less, or not sell at all. The market for these cars is small — there are far fewer buyers for a $200,000 custom Charger than for a stock one — so you are betting on finding the right buyer when you want to sell.

Documentation matters enormously. Keep all receipts, dyno printouts, tuning files, and service records. If you ever sell the car, a buyer will want proof that the engine was installed correctly, tuned properly, and maintained. Without it, they will assume the worst and offer accordingly. Some builders provide a build book or certificate of authenticity; if yours does not, ask for one anyway.

Frequently Asked Questions

How much does a Demon 170 engine cost by itself?

A used Demon 170 engine pulled from a 300 SRT Demon typically costs $15,000 to $25,000, depending on mileage and condition. A new or rebuilt engine from Chrysler or a performance supplier costs more. You will also need the transmission, which adds another $3,000 to $5,000. These are just the core components; installation, tuning, and supporting modifications add significantly to the total.

Can I do this swap myself?

Mechanically, yes — the engine and transmission bolt in. But engine management tuning, fuel system integration, and cooling system design require specialized knowledge and equipment. A DIY build often results in a car that runs poorly, fails inspection, or damages the engine. Unless you have professional tuning experience and access to a dynamometer, hire a shop.

Will a Demon 170 Charger pass emissions testing?

Probably not. The engine is tuned for maximum power, not emissions compliance. Some states allow modified vehicles to be registered if they pass a visual inspection, but emissions testing is a separate hurdle. Check your state's rules before you commit to the build.

What Charger model year works best for this swap?

2015 and newer Chargers are the best candidates because they have modern electrical systems, better cooling capacity, and more room for the supercharger. Older Chargers require more fabrication work and often need frame reinforcement. A 2015 or newer also holds value better if you decide to sell.

How often will I need to service a swapped Demon 170?

More often than a stock engine. Supercharged engines run hotter and work harder, so oil changes, coolant flushes, and spark plug replacements come sooner. Plan on annual service at a shop familiar with high-performance Mopar engines, which costs $1,500 to $3,000 per year depending on what needs attention.