I fill this is a grate example of how a long rod make less side wall pressure.
Yes we can pick the details a part but ...........................it's a good simple explanation.
the other advantage of the long rod is to keep the piston up in the bore, that the longer stroke it trying to pull out the bottom
mendelmax wrote:Muad'Dib wrote:How long did your last stroker run (or still running)? Miles?
It was built for my buddy, I don't know how many miles he has now, probably around 2000-3000. It's pretty new engine.
And I don't want to replace it, this time I'll be building mine
I spent some time doing a simple drawing. I regret I used so small scale, since it's not as accurate as I would like it to be, but it shows my point. To make things clearly visible I used 60mm stroke and two extremely different rods: 70mm and 140 mm. I made drawings for 45, 90 and 135*, if someone is more ambitious I encourage to draw it larger with more angles. It clearly shows why longer rod leaves the bottom part of the cylinder earlier and stays at the top longer. Sorry for poor scan, the parts drawn with pencil are not too well visible, but everything is clear.
This drawing also shows why cylinder walls are wearing less in long-rod stroker- the angle between vertical axle and actual rod position is smaller, thus piston is supported more on the rod, less on cylinder wall. This wall pressure is a wasted energy, which also robs power from our engine. Not much, but little differences added together may make a real power.
To me the biggest drawback of using long rods seems to be the high ring position on the piston. They get close to the top, which in the long run may lead to seizing from overheating. Not a big deal on low duty applications, but for someone who wants to floor it often, use NOS or turbo this gets important. It can be somewhat solved by using ceramic piston coat. We did it on our last stroker and we hope it will help somewhat with excessive heat caused by propane (burns hotter than gasoline).
P.s. if you click on the pic, it will enlarge enough to get the idea