When working on hi-performance engines, there are many components to keep track of. But keep in mind, even the people who build and repair engines for a living are always learning new things, in an effort to make these engines as efficient and powerful as possible.
To be better equipped to handle engine assembly, check out these useful hi-performance engine building questions from Automotive Training Center. We’ll provide the all-important answers, too.
Is a 4-Bolt Main Better than 2-Bolt?
Main caps hold the crankshaft in place, and the crank bearings sit in here. A 2-bolt cap will be fastened to the block with two bolts, while the 4-bolt cap carries two bolts on each side. Two-bolt main bearings on small- and big-block engines are good for performance, but generally, a 4-bolt main will provide extra strength and work better in high-power applications.
Engines with factory 4-bolt mains are rare, but some vehicles come new with small- and big-block castings featuring a 4-bolt main. A 2-bolt block can also be machined to handle aftermarket 4-bolt main caps, in some older castings.
What’s the Installed Height of a Valve Spring?
Installed height is the height of the valve spring when the valve is closed. This is measured from the spring seat to the bottom of the retainer. Each spring features a recommended installed height, and it needs to be correct, for the right amount of spring pressure.
If there isn’t enough pressure, it can cause valve float at a high RPM. Too much pressure, meanwhile, can end up wearing the camshaft.
Why Are Forged Parts More Expensive than Cast?
The raw materials can be similar, so what makes forged parts more expensive? A cast part is made when molten material is put in a mold. There isn’t as much follow-up machining to take care of. Forged parts, meanwhile, are made by forcing the material into a shape. This requires more steps and is more labor-intensive, with more finish machining. The alloys are also of better quality.
What Is Align Honing?
Between the crankshaft and main bearings, the oil clearance needs to be perfect. When the engine was first built at the factory, it was set up as intended. However, if rebuilding or working with a new block and main caps, align honing will need to be done.
This will guarantee that the main bearing saddles in the block, and main caps, are perfectly round and in alignment. This allows the crankshaft to rotate within the bearings, and ensures the engine runs smoothly.
Are Aluminum Heads Higher-Performing than Iron Heads?
If all things are equal, including head designs, chamber volumes, and valve sizes, there isn’t an airflow advantage with aluminum. Aluminum is capable of dispersing heat faster than iron. This can allow for more aggressive ignition timing, enhancing performance with better chamber designs.
A higher compression ratio may be used with aluminum heads. Overall, aluminum heads are lighter, which can increase performance and vehicle balance.
Our Hi-Performance Engine Program
Learn all about vehicle engines and engine performance at Automotive Training Center. Our hi-performance auto school is designed to help students develop a skillset that prepares them for building and repairing hi-performance engines.
Take a look at this exclusive video from the ATC team regarding engine performance.