Purposely built racing engines differ according to their particular application requirements. Some prepped engine blocks are built with narrow power bands to provide a high RPM, while others are designed with a lower power range greatly focusing on the drivability and endurance quality.
However, assembling a typical racing engine involves lump sum amount of pre-assembly and mock-up stages. This is done to check and verify the compatibility of various internal components with the engine blocks.
Notwithstanding numerous differences, the racing engine blocks seek to achieve an optimum level of changes in fuel characteristics, volumetric efficiency and cylinder pressure. And, hence preliminary planning of engine assembly is critical for identification of problematic areas and to ensure a perfect blend of performance parts with the engine blocks.
Here are five tech tips that should be considered while building racing engine blocks.
In order to control the output of the prepped racing engine blocks, displacement limits are enforced by the racing associations. With specified displacement limits, the engine builders are free to choose the best combination of bores and strokes. Therefore, the trend of using bore dimensions with large valves and piston area is highly favored mechanism of engine building.
On the other hand, a combination of the broader power band and longer strokes are more compatible with certain layouts. Furthermore, optimum bores and stroke ratios and length of corresponding rods are essential elements for planning a specific series engine.
Though aluminum blocks are compatible with the 500-800-hp environment and run at high power levels, yet iron blocks are widely used by many builders. This is so because iron blocks are considered to be more resistant to high-stress environments.
Moreover, the block stability is helpful in promoting high levels of ring seals and reduces friction.
Limiting the combination of bore size and cylinder heads is a typical measure of cost saving. Sprint cup engines are perfect examples of bore sizing that help in retaining the desired level of thickness and stability of cylinder walls. In case the appropriate cylinder bore sized is not stated, the bore size that suits best with the engine blocks shall be used.
In some cases, stock cranks and rods are required by low-level sports organizations. These cost-effective measures are used in complementary with cylinder heads and crankshaft. Power is the limiting factor and hence stock rods and cast cranks are used.
Cylinder heads strive to limit the costs of engine block building and are accompanied with certain restrictions pertaining to valve size, material, port volumes, spark plug placement and combustion chamber size.
Therefore, a critical evaluation of these factors, permissible cylinder head configurations are helpful in easy selection of crankshaft that further assists in achieving maximum volumetric efficiency.
Exhaust systems include muffler systems, spec holders and stock exhaust manifolds that are vital to provide exhaust timing to the acid cylinders when allowed to blow down. Spec muffler exhaust systems are used for testing and pointing out the effective pipe lengt5hs and cross-sectional areas.
Like other components of racing engines, the restrictions on the exhaust systems should be critically valued for its effect on torque production and positioning of engine blocks.