2 vs 3 ring pistons for inline crossflows

[xmen3]

I am trying to decide what pistons to get for my '86 115.
It has 3 ring pistons now but I have found that 5 of them have some deep grooves scored into the skirts.
My machine shop wants to put in Wiseco forged pistons with 2 rings but that is contrary to what I heave read here and in other forums.
A lot of people seem to disagree with my shop and say to get the old 3 ring cast by persan and not use the forged. Some say 2 rings are better.
Anybody have any experience with these?
Also has anyone tried the Pro and Pro V?
What about the GLM and Vertex pistons?
Are there any others that anyone can suggest?
I want to get the best fuel economy so I will be running this thing as lean as is reasonably possible.
I am not building a race motor and will tend to run @ 3500 rpm as my fuel computer/gps tells me this is the best mpg.
Thanks in advance.

 

[WillyBWright]

Re: 2 vs 3 ring pistons for inline crossflows

I prefer factory replacements. Wiseco is okay, but the factory recommends going all Wiseco if you do any Wiseco. Three ring pistons use simple basic rings. Two-ring pistons use keystone rings which are wedge shaped and seal better, believe it or not. The gasses trying to escape past them force them against the walls better and form a better seal. But when doing compression tests, it's not unusual for them to show a little less compression than three-ring pistons. In fact, expect that. You can run both types of piston in the same powerhead, mix and match.

Don't run it lean to save gas! It'll be at the expense of the powerhead. A fat motor is a happy motor. A lean motor is a Dead motor.

My experience has been that factory pistons work best. If you go Wiseco, have the cylinders bored to the large side of tolerance. I have no exerience with the others you mention.

 

[Clams Canino]

Re: 2 vs 3 ring pistons for inline crossflows

DO NOT USE WISCO IN AN INLINE!!! I've done a few posts on this as to the why's - they are many.

The 2 ring semi-keysone resist coking (carbon clogging) the best. The Pro-V (Pro-V is Vertex) are the same and just as good as the Mercury 2 ring ones. I use the Pro-V in my own inline. I use the Pro to do single replacements of the older 3 ring type. And don't run it lean.

-W