Lightened and Underdrive Crank Pulley

Here is another enhancement that I am considering. Someone in the forum did his research and came up with a working model of the lightened crank pulley. Crank pulleys are not new in the market. Daisy had them long ago to underdrive the water pump and power steering. She even had a lightened crank pulley but I decided to take it off because the lightened crank pulley was not dynamically balanced unlike the stock crank pulley. I did not want the risk of wrecking the engine for a meagre increase in power(?). Daisy did run better with the underdrive pulleys and till today, they have not given any problems whatsoever.

Several Japanese tuners have also been selling underdrive pulleys either for the crank, water pump and even alternator. They are relatively inexpensive to purchase but more than the price, they must be doing something useful. I was never convinced until I saw the results of what a lightened underdrive pulley can add to the efficiency and power output of the Swift engine. Here's a quote from the guy who made the pulley.

"I know there are many schools of thoughts about lightweight crank pulleys. Based solely on physics, number one there isn't lose of torque at the wheels, number two there will not be any harmful resonance (the stock crank pulley isn't dynamically balanced to tackle resonance anyway). Instead you get better throttle response and on a track you get better rev matching while up shifting, much like installing a lightened flywheel."

It all sounds good but unlike others who only talks, this guy went all the way and custom-made a crank pulley to prove his logic. He took another step forward by conducting a dyno test to make sure it really works and this is the result.

"The black curve you see is my Swift Sport in stock form. 110ps at the wheel amounts to about 126.5ps at the crank, very close to the 125ps stock on paper.

The red curve is with the underdrive crank pulley. 114ps at the wheel is about 131.1ps at the crank. All in all a gain of about 4.6ps. I was more for the torque gains and was pleased to see the jump in the torque curve."

Would you not buy this product when so much painstaking work has been done to prove that it works? I would buy it in an instant. There is only one problem. It will take him about 4 to 6 weeks to make one for me because the machine used to produce the pulley is being used for something else. The cost of the pulley is $400. For a proven gain of 4.6ps, this is a fantastic product. With some extrapolation, I figured the increase will be much more once it is installed on Nickie. I would very much want one as soon as possible so that it can be installed together with the Greddy camshafts and Remus exhaust. Thereafter, one more round of ECU tuning to maximise the enhanced components and Nickie is ready for another long run up north. Here are some pictures of the crank pulley.

Stock Crank Pulley

Lightened & Underdrive Pulley

Comparison between stock and enhanced puley

Final Product Anodised in Red

The question that begs to be answered is this; when will this enhancement exercise end? It seems that there is always something new to pop into the car. Its a difficult question to answer but I am consciously aware that each enhanced part has proven its worth individually. As a complete package, Nickie no longer drives like before. The car has grown up considerably. It would be unfair to stop unless it is proven that any change or addition of parts will not increase the efficiency and is no longer economically viable. In short, when it does not make sense to do more, the enhancement exercise will stop.