Question about aftermarket rod lengths

[UnderPSI]

I am looking in to replacing my rods and I have seen 3 different brands that sell them and they are all 3 different lengths. Full throttle speed sells 2 of them. The CAT h beam rods are 5.965 in length, and the K1 h beam rods are 5.960 in length. I also found a set of scat rods that are 5.970 in length. Why all the difference in rod length? What is the best size to get for a mild rebuild? I plan to use stock crank and shelf forged pistons. Thanks

 

[Mike Licht]

Stock rods are 5.960. A different lenght can be used to move the piston up in the bore or thee block can be decked. A 5.970 rod may require a custom piston depending on the block deck height. Any reputable engine builder should be able to sort it out for you. If you need help give me a call.
Mike

 

[UnderPSI]

Cool thanks. I just don't understand why three different manufactures use three different lenghts. I'm sure that the k1 are the best of the three budget rods but how do the other two stack up? I assume they would be better than stock right? Any one know if the cat or scat use arp fasteners? Thanks Jeremy

 

[Mad_Trbo]

Rod Stroke Ratio

Look into that and that will help you answer some of your questions. This is another dynamic many engine builders consider when putting together combinations.

When a lower rod ratio is employed angles can create accelerated wear on piston and associated walls. Dwell is another factor, depending on the rod ratio the dwell of the piston will change. These are all factors that i have a slight understanding of but with a little research wil help you in understanding why different rod lengths are offered.

Much success in your research.

 

[charlief1]

A longer rod will change the "dwell" time of the piston to allow different charging of the cylinders. I've got some that are 6.675" so the piston will be lighter and give me more bottom end torque. Using a shorter rod will have the opposite effect. Hope this helps.