If you increase the length of the rod 1mm how do you determin the placement of the piston pin? Would you just move it the same amount?

ie: To destroke, shorten the rod 2mm would you then move the piston pin down 2mm?

I don't know if I made myself clear but I am having the 12pack haze.[img]i/expressions/face-icon-small-happy.gif[/img]

 

I know this is long but once I started it was hard to stop, sorry ( and I should be answering my 65+ e-mails right now ) If you lengthen the rod, you only need to shorten the pin height ( raise the location of the pin hole in the piston ) that same amount to get back to TDC. If you lengthen the stroke by moving the big end of the rod further out on the crank wheel you will find yourself with a larger displacement engine ( good thing ). If you are stroking the engine there will be a number of things that will have to be accounted for. First to get the piston back to TDC you will have to either shorten the rod or raise the location of the pin on the piston. I prefer to lengthen the rod ( better angle ) and shorten the pin height ( lighter) for performance reasons, Why you ask! Well depending on the length of the stroke change allot of things are going to have to be redesigned now, because we are changing the size of our engine. One thing that will change is the rod ratio ( this will effect rod angled ) I like to keep a rod ratio around 1.70 to 1.90 depending on the characteristics of the engine we are developing. So we will have to lengthen our rod sometimes to get this to work out. This means we will have all kinds of other things going on at this point, deck height changes, cam chain problems, all of the fun stuff to work out. The other thing that you will have to do is set up a new compression ratio for our now larger engine, and don't forget to flow the head again so we can support the larger displacement, or it will all be for nothing. Now you get an idea why people pay performance companies to do all of this for them. BECAUSE IT'S A LOT OF WORK. I hope I didn't get to far off subject here, but by the way you posed the question I wanted to cover all of the bases.

 

Thanks alot.