belize1334
Well-known member
I was looking at my Wiseco stroker pistons and I noticed that the wrist pin offset is backwards from what I expected. My understanding of offset is the following. If you offset in such a way that the rod is more vertical while the piston is rising, then at TDC the rod has a slight angle so that it can exert torque on the crank and you ultimately make more power. If you offset the other way then there is less side loading during the burn and you get quieter operation and less piston slap. Now, according to Wiseco, they offset the same way as OEM to ensure quiet operation. But on these pistons the offset is toward the front, which would be for more power and more slap. Apparently, Mitsubishi was more interested in a motor that felt spunky than in one that had quiet operation.
Anyway, why do I care? Well, I'm building a stroker and I've been thinking alot about the unfavorable rod angle and the increased chances of piston slap due to the shorter skirts... and it occured to me. If I flip these babies around, then the offset will be more conducive to quiet operation and during the burn portion of the cycle the rod will be more vertical so there should be less side loading. Of course there are issues though. The valve recesses would have to be machined on the intake side, and the cam timing might need to be adjusted due to the altered effective TDC. But I put the question to you. What do you think about flipping pistons around to change the wrist pin offset for reduced piston side loading?
Anyway, why do I care? Well, I'm building a stroker and I've been thinking alot about the unfavorable rod angle and the increased chances of piston slap due to the shorter skirts... and it occured to me. If I flip these babies around, then the offset will be more conducive to quiet operation and during the burn portion of the cycle the rod will be more vertical so there should be less side loading. Of course there are issues though. The valve recesses would have to be machined on the intake side, and the cam timing might need to be adjusted due to the altered effective TDC. But I put the question to you. What do you think about flipping pistons around to change the wrist pin offset for reduced piston side loading?