Crankshafts

Race Engine Crankshafts

A major part of the overall performance of an engine is the internal balance achieved between all the moving parts. The forces generated by an engine at high RPM are truly awesome. When you start to exceed the designed rev limit or designed power characteristics these forces will ultimately threaten the integrity of the engine itself. Also, there are significant benefits to be gained from reducing unnecessary mass. This will reduce avoidable power losses and make the engine more responsive and free revving. An engine which is balanced properly will be more efficient, reliable and will tolerate much higher RPM.

We’ve made a big commitment in this area because it is fundamental to the performance and race winning sucess of our engines.

We focus on 2 areas of engine balance. 

The first is matching the amount of power released by combustion in each cylinder. A dominant factor here is the flow through the cylinder head. Our gas flowed cylinder heads flow identically across the cylinders. Compression ratio of cylinders and camshaft wear is also a major factor here. Matched fuel injectors/carbs also dictate balanced power across the engine. These factors together with inlet and exhaust manifold design ensures that combustion between cylinders is correctly matched.

The second area of balance is mechanical. Here, we look closely at the major moving parts of the engine (flywheel, piston and rings, con rods, pins and crankshaft). The piston rod assemblies are blue printed and mass balanced. We also employ race quality heavy duty or coated bearings to match the predicted loads. However, with the crankshaft we have a number of options.

Custom made crankshafts

If we have reason to believe that the standard or existing crank in an engine will have problems handling the power we are aiming at, we can manufacture a custom made crankshaft. Likewise if we wish to alter the stroke of the engine we can also design a crank with the desired stroke length.

Again, this is achieved with the help of simulation software. A machined crankshaft made from billet will be stronger than a cast or forged crank as it is not subject to the heat cycles and pressure associated with those manufacture techniques. A custom made crank can also be lightened substantially to reduce its rotational mass and then fitted with custom counterweights to help balance the rotation of the shaft.

Crankshaft Balancing

The other option we have is to balance the existing crankshaft, flywheel a piston/rod assemblies. In this process we are looking for accuracy with very low tolerances. We match the crank to the rod/piston/bearing assemblies.

To do this we have invested in state of the art CNC machinery. Our new CWT Multi-Bal 5000HD heavy duty balancing machine gives us total control over the balancing process. A process which we previously found difficult using 3rd party balancing firms.

Custom made crankshafts

If we have reason to believe that the standard or existing crank in an engine will have problems handling the power we are aiming at, we can manufacture a custom made crankshaft. Likewise if we wish to alter the stroke of the engine we can also design a crank with the desired stroke length.

Again, this is achieved with the help of simulation software. A machined crankshaft made from billet will be stronger than a cast or forged crank as it is not subject to the heat cycles and pressure associated with those manufacture techniques. A custom made crank can also be lightened substantially to reduce its rotational mass and then fitted with custom counterweights to help balance the rotation of the shaft.

Software also offers unlimited data storage for bob-weight information, part numbers, and part description:

The analysing electronics built into the balancer are state-of-the-art, which allows our machine to give extremely fast and accurate analysis of a crankshaft or rotating part. This allows “real time” updating of the correction requirements before you cut the first chip. This single feature will allow us to quickly and accurately correct the unbalanced crankshaft.

The machine itself weighs 4090 pounds. The base, filled with a special resin material, eliminates any residual vibration. The entire casting is encapsulated with steel to give it a long and durable life. Each bed is cured for six weeks and all mounting registers are machined in our CNC machining centre. This construction insures perfect mounting of our stanchions and optional drill platform.

Using this fantastic tool, we are able to deliver the accuracy and consistency we need to build great race engines.

Check out how the crankshaft balancer works in this video from the manufacturer. It’ll take about an hour to get through but it is an interesting insight in to the process and how accurate the results are.

Click on the video screen to go to YouTube and see the playlist. There are 6 videos in the series.