How to Select a Crankshaft

The crankshaft is a mechanical part in the engine that is able to convert the reciprocating motion of the piston to rotational motion to propel the vehicle. With its one side connected to the big end of the conrods to do work, it plays an important role in the function of the engine, especially at high speeds, which makes choosing the right crankshaft critical for the high performance racing experience. Now I will give you some suggestions on how to select a proper one for yourself. Take a look!

Due to the extreme forces applied to the crankshaft, the first thing you need to consider when selecting a crankshaft is its strength, that is to say, you need to know what material and manufacturing techniques used to make it. Basically, there are three types of manufacturing techniques used to make crankshafts-casting, forging and machining from solid billet with which iron and steel are made into the products.

The basic cast iron used for crankshaft production has a tensile strength of around 80,000 psi. Rather brittle, isn’t it? Well, nodular iron is slightly improved, with a tensile strength of 95,000 psi. However, due to its higher carbon content, it has nearly twice the elongation characteristics of standard cast iron, giving the nodular iron crank increased fatigue resistance. Moreover, there is still another option in cast crankshaft, that is, a cast steel one. Cast steel has a tensile strength of about 105,000 psi and greater carbon content than the nodular iron, namely, even better elongation characteristics so that many companies offer cast steel crankshafts as entry-level performance pieces.

Forged steel crankshaft, having a tensile strength of 110,000 psi and an elongation of 22 percent, are the most popular choice for performance engines. So, if you want to go for a hot street racing, maybe the forged steel one is a good choice, for it is strong and durable and can handle horsepower from a few hundred to 1500-plus hp.

At the very top, at least in terms of tensile strength, are the forged billet crankshafts at around 165,000 psi. Since the steel used to make a forged billet crankshaft cost many times than that used to make a forged one, it is more expensive. However, the top racing drivers tend to utilize the forged billet crankshaft, because by just changing the CNC programming, they could get the most suitable crankshaft for their engine, giving them a competitive edge over the others.

Apart from the two points mentioned above, another thing you deserve to know is that all you need is a proper crankshaft. Choosing a proper crankshaft depends on a host of factors, such as horsepower, rpm range, and whether the engine is naturally aspirated or turbo-charged. Once you have determined the specifics of these things, you can make a purchase. After all, choosing a crankshaft that is not strong enough for a particular application is as much a waste of money as choosing one that is stronger than needed.

Well, that’s all for the topic. Hope you enjoy it.

Auto Novice

Auto Novices is a blog, that was set up in November 2011, which tries to help inform new & old automobile owners about various subjects from keeping their car in good working order right through to tips on buying a new & used motorbikes. GUEST POSTS: If you would like to produce a guest post for this blog then please contact us via the link in the navigation menu at the top of the page.