Introduction: Breathing New Life Into a Classic

The 1971 Dodge Demon remains one of the most iconic muscle cars of the early 1970s. With its aggressive styling and lightweight body, it was built to dominate the streets. Today, many enthusiasts are looking to upgrade their Demons with modern performance parts that mimic – or even exceed – the legendary Hemi power. The good news is that you can achieve significant gains without breaking the bank. This article provides a detailed cost breakdown of upgrading your 1971 Dodge Demon with Hemi-style performance parts, all while staying under $2,500. We’ll cover essential components, budget-friendly brands, installation tips, and real-world performance expectations.

Why Hemi Performance Parts for Your Demon?

Original Hemi engines are rare and expensive, but you can build a Hemi-like powerplant using aftermarket parts designed for Mopar small-block and big-block engines. Hemi performance parts focus on high-flow intake and exhaust, aggressive cam profiles, and efficient ignition systems. The result is a throaty idle, crisp throttle response, and substantial horsepower gains. For a 1971 Demon, which originally came with slant-six or small-block V8s, swapping in a performance cam, free-flowing headers, and an upgraded intake manifold can transform the driving experience. The Summit Racing catalog offers a wide range of components that fit within a budget build.

Selecting the Right Parts: A Component-by-Component Breakdown

Below we dive into the five key performance parts that offer the biggest bang for your buck. Each section includes estimated costs, recommended brands, and what to look for when shopping.

1. Intake Manifold – Opening the Airway

The intake manifold is the engine’s lung. A high-performance manifold increases airflow and fuel distribution, which can add 15–30 horsepower depending on your engine. For a small-block Mopar (318 or 360), popular choices include the Edelbrock Performer RPM (around $400–$500) or the Weiand Stealth (around $350–$450). If you’re building a big-block, expect to pay $500–$650. Make sure to choose a dual-plane design for street driving with good low-end torque, but a single-plane manifold can be used for high-rpm builds. Budget range: $300 – $600.

2. Headers – Letting the Exhaust Breathe

Factory exhaust manifolds are restrictive. Headers reduce backpressure and scavenge exhaust gases more effectively, freeing up 10–20 horsepower. For a 1971 Demon, shorty headers fit easily with the factory steering gear, while long-tube headers require a special starter or mini-starter kit. Brands like Hooker, Hedman, and TTI offer quality sets ranging from $200 to $500. Stainless steel headers will cost more but resist rust. Budget range: $200 – $500.

3. Camshaft – The Heartbeat of Your Build

Upgrading the camshaft is the single most effective way to change engine character. A performance cam with higher lift and duration will produce a lumpy idle and strong mid-range power. For Mopar small-blocks, consider the Comp Cams Xtreme Energy series (part #20-600-9 for 273–360) priced around $200–$400. Big-block cams run $250–$450. You’ll also need new lifters and possibly valve springs, which can add $100–$200 to the total. Budget range: $150 – $400 (plus optional components).

4. Carburetor – Fueling the Fire

A high-performance carburetor ensures the engine gets the right air-fuel mixture. A 600–750 CFM four-barrel carb is ideal for street-driven small-blocks. Holley, Edelbrock, and Quick Fuel all produce reliable units in the $300–$600 range. For big-blocks, you may need 750–850 CFM. The Holley Street Avenger series is a popular choice with a built-in fuel pressure regulator. Budget range: $300 – $600.

5. Ignition System – Sparking Performance

Modern ignition systems deliver a hotter, more consistent spark for better combustion and throttle response. Upgrade to an MSD 6A or 6AL ignition box (around $250–$350), a high-capacity Blaster 2 coil, and a set of quality plug wires. For a complete system, budget $200–$400. Pair this with a distributor replacement or new rotor/cap for optimal results. This investment can improve fuel efficiency and start-up characteristics. Budget range: $200 – $400.

Total Cost Scenario: Building Your Budget

Now let’s look at two realistic scenarios – a “budget build” using lower-cost options and a “performance build” using premium parts.

Component Budget Option Performance Option
Intake Manifold $300 (Edelbrock Performer) $600 (Weiand Stealth, polished)
Headers $220 (Hedman shorty) $500 (Hooker long-tube ceramic)
Camshaft $180 (Comp Cams 260H) $400 (lunati Voodoo series)
Carburetor $320 (Edelbrock 600 CFM) $600 (Holley 750 vacuum secondary)
Ignition $210 (MSD 6A + basic coil) $400 (MSD 6AL with digital timing control)
Total $1,230 $2,500

As you can see, you can build a robust Hemi-style package for under $2,500, with the budget build leaving you nearly $1,200 for additional upgrades like a performance dual exhaust or a fresh fuel pump.

Installation Considerations: Can You DIY?

Installing these parts yourself will save hundreds in labor costs. Most of these upgrades are bolt-on and can be done in a weekend with basic tools. However, cams require removing the timing chain and potentially pulling the engine if space is tight in the Demon’s engine bay. Headers can be tricky on small-block Mopars due to steering box clearance – you may need a mini-starter kit (around $50–$100). Carburetor and intake swaps are straightforward, but you’ll need to adjust fuel lines and possibly upgrade to an electric fuel pump (add $80–$120). Ignition installation is simple: mount the box, connect wires, and set timing. Allpar has excellent step-by-step guides for Mopar engine work.

Performance Gains: What to Expect

A properly tuned 1971 Demon with these five upgrades can see a gain of 60–100 horsepower over stock. A 318 small-block can go from 200 hp to around 300 hp; a 360 can hit 350 hp. Torque increases even more dramatically – expect a 50–80 lb-ft jump. This makes the Demon a real handful on the street and capable of low 14-second quarter-mile times with a good launch. The sound alone is worth the price of admission. For reference, a genuine 426 Hemi from the era produced roughly 425 hp, so your budget build is within striking distance of that legendary power.

Additional Upgrades to Consider (If Budget Allows)

If you have leftover funds after the core five parts, consider these:

  • Exhaust system: A 2.5-inch or 3-inch mandrel-bent exhaust with performance mufflers (add $200–$400).
  • Aluminum radiator: Keeps the engine cool during spirited driving (about $150–$250).
  • Electric fan conversion: Frees up parasitic drag and improves cooling (around $100).
  • High-flow fuel pump: Ensures fuel delivery under high demand ($80–$120).
  • Upgraded oiling system: High-volume oil pump ($80) and pan modifications to prevent oil starvation (optional).

Where to Buy: Trusted Sources for Hemi Performance Parts

To stay within your $2,500 budget, compare prices across multiple retailers. Jegs High Performance and Summit Racing both offer free shipping on orders over $99 and have extensive Mopar parts. For Mopar-specific components, check Mancini Racing or 440 Source for big-block and Hemi parts. Online forums like For A Bodies Only are valuable for used parts and advice. Always verify part numbers for your specific Demon year (1971 has a unique engine bay layout).

Conclusion: Transform Your Demon on a Budget

Upgrading a 1971 Dodge Demon with Hemi-style performance parts is one of the most rewarding projects a muscle car enthusiast can tackle. With a total investment of $1,230 to $2,500, you can modernize the engine’s airflow, fuel delivery, ignition, and exhaust. The result is a car that sounds menacing, pulls hard, and stays reliable. Whether you’re building a street cruiser or a weekend strip warrior, this budget-friendly package delivers exceptional value. Plan your purchases, take your time with installation, and enjoy the roar of your enhanced Demon. For more ideas, check out Hot Rod’s budget Mopar build articles for additional inspiration.