Rx-8 Ls Swap vs Stock: a 200-hp Power Gain on the Dyno

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The Mazda RX-8 has been a beloved sports car since its debut in the early 2000s. Known for its unique rotary engine and lightweight design, it offers a thrilling driving experience. However, many enthusiasts have sought to enhance its performance by swapping the stock rotary engine for a more powerful V8 engine, specifically the LS series. This article explores the RX-8 LS swap versus the stock engine, focusing on the significant power gain observed on the dyno.

The Stock RX-8 Engine

The stock RX-8 is equipped with a 1.3-liter rotary engine, known for its high-revving nature and unique characteristics. Here are some key specifications:

  • Power Output: Approximately 238 hp (at 8,500 RPM)
  • Torque: Around 159 lb-ft (at 5,500 RPM)
  • Weight: Approximately 2,800 lbs
  • Engine Type: Naturally aspirated rotary engine

While the rotary engine provides a unique driving experience, it also has its limitations in terms of power and torque delivery. Many RX-8 owners find themselves wanting more performance, which leads to the consideration of an LS swap.

The LS Swap: An Overview

The LS engine series, produced by General Motors, is renowned for its power, reliability, and aftermarket support. Swapping an LS engine into an RX-8 involves significant modifications, but the results can be impressive. Key aspects of the LS swap include:

  • Engine Options: Common choices include the LS1, LS3, and LS6 engines, with power outputs ranging from 300 to over 500 hp.
  • Weight Distribution: The LS engine is heavier than the rotary, which can affect the car’s balance and handling.
  • Aftermarket Support: Extensive options for performance parts and tuning are available for LS engines.

Enthusiasts often report a dramatic increase in horsepower and torque after completing an LS swap, making it a popular choice for those seeking significant performance upgrades.

Power Gains on the Dyno

One of the most compelling reasons to consider an LS swap is the substantial power gain it offers. On the dyno, the differences between the stock RX-8 and an LS-swapped RX-8 are striking. Here’s a comparison of the power outputs:

  • Stock RX-8: Approximately 238 hp at the wheels
  • LS Swapped RX-8: Easily exceeding 400 hp at the wheels, depending on the engine choice and tuning

This 200-hp power gain represents a significant improvement in performance, translating to faster acceleration and higher top speeds. Many LS-swapped RX-8s can achieve 0-60 mph times in the low 4-second range, compared to the stock model’s 6-second range.

Performance Considerations

While the power gains are impressive, there are several performance considerations to keep in mind when deciding between the stock engine and an LS swap:

  • Weight and Balance: The added weight of the LS engine can affect handling and balance, which may require suspension upgrades.
  • Transmission Compatibility: Swapping to an LS engine often necessitates a new transmission, adding to the complexity and cost of the swap.
  • Cooling Requirements: The LS engine may require a more robust cooling system to handle the increased power and heat output.
  • Fuel Requirements: Depending on the LS engine chosen, fuel requirements may change, impacting fuel efficiency and overall running costs.

These factors should be carefully considered to ensure that the overall performance of the vehicle meets the driver’s expectations.

Cost of the LS Swap

The cost of performing an LS swap can vary widely based on several factors, including the choice of engine, parts, and labor. Here’s a breakdown of potential costs:

  • Engine Cost: $3,000 – $10,000 depending on the LS variant
  • Transmission: $1,500 – $3,000 for a compatible transmission
  • Parts and Accessories: $1,000 – $5,000 for mounts, exhaust, cooling systems, and wiring
  • Labor: $2,000 – $5,000 if hiring a professional shop

Overall, a complete LS swap can range from $7,500 to over $25,000, depending on the choices made. While this is a significant investment, many enthusiasts find the performance gains worth the cost.

Conclusion

The RX-8 LS swap offers a remarkable power gain, transforming the driving experience from a unique rotary engine to a robust V8 powerhouse. With the potential for 200 hp more than the stock configuration, the LS swap appeals to performance enthusiasts looking for speed and excitement. However, the swap comes with its own set of challenges and costs that must be carefully weighed. Ultimately, whether to stick with the stock rotary engine or opt for an LS swap depends on individual preferences and performance goals.