How to Build a High-Torque 383 Stroker
- 1). Plan the engine build with careful consideration to what design features will make it as thermodynamically efficient as you can. Areas that require detailed attention are reduced frictional losses, cylinder head/combustion chamber design, compression ratio and valve (camshaft) timing, among other things.
- 2). Select internal rotating components -- crankshaft, pistons etc. -- that will rotate freely in the engine. Proper bearing clearances are key to allowing the crank to rotate, but controlling oil "windage" with streamlined counterweights and oil "scrapers" is beneficial. Special coatings on the piston skirts can also reduce piston-to-cylinder wall friction.
- 3). Install cylinder heads with modern combustion chamber designs. An example of a "new technology" chamber design would be the 5.7-liter Vortec heads, compared to old-style GM performance heads of the late 1960s and 1970s. Vortec heads were designed for late 1990s GM trucks, vans and SUVs, and they have airflow and combustion characteristics that produce far more torque and power. Many aftermarket head manufacturers have emulated this design.
- 4). Combine the proper piston head shape with the volume of the combustion chamber of the head to achieve the highest compression ratio possible while still operating on lower-octane fuels. Camshaft timing is an important factor here as well. The objective is to reduce the combustion space -- the area where the actual explosion of the air/fuel mixture occurs -- to as small an area as possible to promote rapid combustion. With the 64cc combustion chambers of the Vortec-style heads, choosing a piston with a smaller dish can increase the compression up to an acceptable level.
- 5). Determine which rpm range the engine will be used most, and select a camshaft with valve-timing events that optimize that range. A cam with relatively short duration and valve-timing events can help increase cylinder pressures, which in turn increases torque. This is one of the most important components, so seeking the recommendations of a cam manufacturer's tech support help desk or a custom camshaft designer is suggested. Provide as many details as possible about the engine specs and design, and the vehicle in which it will be used.
