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The Mazda RX-7 is a beloved sports car known for its lightweight design and rotary engine. However, many enthusiasts are now opting for LS swaps, replacing the stock rotary engine with a powerful LS V8. In this article, we will compare the performance of the stock rotary engine with a 550 HP LS V8 setup.
Understanding the RX-7 Rotary Engine
The stock rotary engine in the RX-7, known for its unique design, offers a lightweight and compact powerplant. This engine has a few key characteristics that define its performance:
- Displacement: 1.3 liters
- Power Output: Approximately 255 HP in the RX-7 FD model
- Torque: Around 217 lb-ft
- Engine Type: Twin-rotor Wankel rotary engine
The LS V8 Engine Overview
The LS V8 engine is a popular choice for swaps due to its reliability and performance potential. A 550 HP LS V8 setup typically includes the following specifications:
- Displacement: 5.7 to 6.2 liters (varies by specific LS engine)
- Power Output: 550 HP
- Torque: Approximately 500 lb-ft
- Engine Type: V8, pushrod design
Performance Comparison
When comparing the stock rotary engine to a 550 HP LS V8 setup, several performance metrics come into play. Below are key areas to consider:
Power-to-Weight Ratio
The power-to-weight ratio is critical in determining the performance of a vehicle. The RX-7 is known for its lightweight body, which enhances its agility and speed. Here’s how the two engines compare:
- Stock Rotary: Approximately 8.5 lbs/HP
- LS V8: Approximately 5.5 lbs/HP
Acceleration and Speed
Acceleration and top speed are significant factors for performance enthusiasts. The LS V8’s higher power output translates to impressive acceleration numbers:
- Stock Rotary: 0-60 mph in about 5.5 seconds
- LS V8: 0-60 mph in around 3.5 seconds
Handling Dynamics
While power is essential, handling dynamics play a crucial role in overall performance. The RX-7’s lightweight rotary engine contributes to its nimble handling. However, the LS V8’s weight can affect balance:
- Stock Rotary: Excellent handling due to low center of gravity
- LS V8: Increased weight can lead to understeer if not properly balanced
Cost Considerations
When considering an LS swap, cost is a significant factor. The initial investment and ongoing maintenance can vary greatly between the two setups:
- Stock Rotary: Lower initial cost, but can require more frequent maintenance
- LS V8: Higher initial cost due to engine swap, but generally lower maintenance costs over time
Conclusion
In summary, the RX-7 rotary engine and the LS V8 offer distinct advantages and disadvantages. The choice between the two largely depends on the driver’s priorities, whether they value the rotary’s lightweight handling or the raw power of the LS V8. Each setup has its own unique appeal, making the RX-7 a versatile platform for performance enthusiasts.