1. Internal Engine Components:
* Cylinder Head Selection: The heads are arguably the most significant factor. Stock 327 heads severely restrict airflow. You'll need high-performance aluminum heads designed for high RPM operation. Look for heads with larger valves, improved porting, and a suitable combustion chamber design. Consider aftermarket options from Edelbrock, Dart, AFR, or similar manufacturers. The specific choice depends on your budget and desired RPM range.
* Camshaft: A performance camshaft is essential. The cam's profile significantly impacts horsepower and torque output. You'll need a camshaft with a larger lift and duration than a stock unit, matched to your cylinder heads and intended RPM range. Consult a camshaft selection guide or a reputable camshaft manufacturer to choose the right profile.
* Pistons & Connecting Rods: Stock pistons and rods may not withstand the increased stress of a higher-horsepower engine. Forged pistons and stronger connecting rods are highly recommended, especially if you plan on using higher compression.
* Crankshaft: The crankshaft needs to be strong enough to handle the increased power output. While a stock crankshaft *might* be okay with careful selection of other components and tuning, a forged crankshaft is strongly recommended for reliability.
* Compression Ratio: Increasing the compression ratio boosts power, but requires higher-octane fuel. This often involves pistons designed for a higher compression ratio. Higher compression ratios can also lead to detonation if the engine isn't properly tuned.
2. Induction System:
* Intake Manifold: A high-performance intake manifold is crucial for optimal airflow. The manifold should be matched to your cylinder heads and camshaft. Different designs offer varied performance characteristics across the RPM range.
* Carburetor or Fuel Injection: A larger carburetor (if using carburetion) or a performance fuel injection system will be necessary to deliver the fuel required for the increased power output. Fuel injection offers better control and efficiency than carburetors.
3. Exhaust System:
* Headers: Long-tube headers are vital for optimal exhaust scavenging, significantly improving power output. Shorty headers are less effective.
* Exhaust System: A free-flowing exhaust system (with appropriate diameter pipes and mufflers, depending on your needs for noise level) will help further improve engine breathing.
4. Other Considerations:
* Valvetrain Components: High-performance valve springs, retainers, and pushrods are necessary to handle the increased valve lift and RPM.
* Ignition System: A performance ignition system (e.g., electronic ignition) will ensure consistent and reliable spark under load.
* Cooling System: A high-capacity radiator and possibly an upgraded water pump will help keep the engine cool under stress.
* Oil System: A high-volume oil pump and possibly an oil cooler are also important for engine reliability.
* Professional Tuning: After installing all the parts, professional dyno tuning is absolutely essential. This ensures the engine runs properly and efficiently, preventing damage and maximizing power. Improper tuning can lead to engine damage or poor performance.
In summary: Achieving 340hp from a 327 requires a substantial rebuild and significant investment in high-performance parts. This is not a project for beginners. It's best to consult with experienced engine builders to plan the build and ensure its success. Attempting this without sufficient knowledge and tools could result in a damaged engine. The cost could easily reach several thousands of dollars, depending on the quality of parts and the labor involved.
