mountain_mod_viper
New member
I've got a 780 viper with wiseco 72.9mm pistons. The guy that does my porting cut some notches, windows, or whatever you want to call them on the bottom of the piston skirts on the intake side. My question is this:
Aren't the pistons balanced so there's equal weight on both sides of the wristpin and if one side was heavier than the other, it would cause the piston to rock back and forth at 9000 rpm? I'm just wondering whether or not to have him do the same thing when I put new pistons in.
Thanks
Aren't the pistons balanced so there's equal weight on both sides of the wristpin and if one side was heavier than the other, it would cause the piston to rock back and forth at 9000 rpm? I'm just wondering whether or not to have him do the same thing when I put new pistons in.
Thanks
no ,they are not balanced that way, you can mod the intake sides of them and they will run just fine. If you would see what I have done to vmax4 pistons your jaw would drop, theres nothing left when done with them, and they run at 10,200rpm!
All 3 pistons should staticly weight the same when done though, meaning overall weight with pin and circlips would be the same, so all 3 rods have the same load.
All 3 pistons should staticly weight the same when done though, meaning overall weight with pin and circlips would be the same, so all 3 rods have the same load.
mountain_mod_viper
New member
Thanks Mr Viper! I won't be as worried now! I have about 1500 miles on the cut pistons without any troubles, until last weekend when I lost a cylinder skirt, intake side on the mag cylinder. I know that it was probably detonation, but also wondered about the piston thing. Millenium says they can fix it.
yammerhammer
New member
Pretty common mod that started back with the 485 Phazer engine. They do
it to un-shroud the transfer port. More commonly know as the "SX" mod. Just
had to do it on a MM. Blew it up on a long weekend trip, called a guy to bring
up a new piston. Fired up the dremel and went to work. Took a long time to
do with a dremel. I think a mill would be a better choice but when you are miles away from one in an enclosed trailer...
Many of ported engines run it.
it to un-shroud the transfer port. More commonly know as the "SX" mod. Just
had to do it on a MM. Blew it up on a long weekend trip, called a guy to bring
up a new piston. Fired up the dremel and went to work. Took a long time to
do with a dremel. I think a mill would be a better choice but when you are miles away from one in an enclosed trailer...
Many of ported engines run it.
yammawolf
New member
what exactly does this do for performance? , what does the finished product look like? can it be done to stalk pistons? does it affect the reliabilty?
