Wiseco Piston Pics and Comments

[blsnelling]

As most of you know, I've been in Orlando on business travel this week. So I'm just now getting around to posting about these new Wiseco pistons that came Monday.

First of all, the quality of the forgings looks excellent. They all use thin 1mm rings. The 066 rings have end gaps of .009". Piston to cylinder clearance is about .0015"-.002", as best as I can measure.

My scale can only measure in .2 oz increments, so not very accurate at this weight. The factory Mahle piston came in at 3.0 and the Wiseco at 3.4, for nearly a 15% weight increase.

I've run into a couple rather serious issues. The 066 piston is much wider between the pin bosses, leaving .180" play of the piston from side to side, allowing the needle bearing to come out of the rod by the same amount. I do not yet know if this is an issue on any of the other pistons. It looks like I'll have to have a set of bushing/spacers machined up to take up that gap. That's going to add more weight to an already heavier piston.

The 044 piston looks to have a manufactures defect, where the ring end pins are way off center. This is allowing one ring to drop into the intake and the other into a transfer port. This piston is unuseable. The pins are properly centered on all of the other pistons.


This is the 044 piston. Notice how far off center the pins are to the right.

Well right of the window.

Well into the window.

The pencil marks are where the pins are.

LOTS of metal around the pin bosses. That's where all the extra weight is.

 

[blsnelling]

This is the 372 piston.

Here's one of the thin 1mm rings. Notice how it's shaped to fit around and over the locating pins. These rings can be install either side up.

 

[blsnelling]

Here's the issue with the 066 piston. I can' see this being right, so I figure I'll have to have Nik make me up some spacers.

 

[Rounder]

Hmmm, for the money, I'll stick with Meteor - thanks for the post- Sam

 

[albert]

Spacers and and hi rpm usually not a good idea.

 

[volks-man]

i want to see one of these pistons fail.
i am not hoping for a failure, nor do i expect one.

i want to know if a forged piston melting down will leave you with an unusable cylinder more often than a standard soft piston.

 

[blsnelling]

Spacers and and hi rpm usually not a good idea.

What's the alternative?

 

[volks-man]

Spacers and and hi rpm usually not a good idea.

What's the alternative?

meteor?

 

[blsnelling]

Hopefully that's still an option, should it need to be. However, the skirts are a little wider on this Wiseco piston, and I ported the cylinder before installing it. I think I'm still ok though with a stock width piston. But I intend to make this piston work. It's just a matter of finding the right solution. A wider needle bearing would be ideal.

 

[brncreeper]

"free port" needle bearings?:monkey:

 

[blsnelling]

"free port" needle bearings?:monkey:

 

[Stihl088stock]

Wow, these are a lot "porkier" than I thought they would be.

That 066 slop is no-good at all!

 

[weimedog]

What's the alternative?

If you shim the bearing thats enough. The rod will center based on where it is on the crank. My bet is Wiseco will figure this out. The "windows" look small...will they flow? Those pins just don't want to be over a port, other than that who cares.

I've also seen needle bearings with wider shoulders to take space...wonder if thats what they had in mind.

 

[brncreeper]

Oh, I see where the play is now. OK, carry on...

 

[mtngun]

However, the skirts are a little wider on this Wiseco piston, and I ported the cylinder before installing it.

Ah ....... wider skirts..... wider ports. That's one potential advantage.

A wider needle bearing would be ideal.

Good on you for being sharp enough to notice the problem with the fit of the needle bearing. Darned, that may be expensive for Wiseco to re-engineer.

What material does Nik suggest for the spacers ? I dunno if a plastic material would hold up in a saw, but if it would, that would be ideal. Metal spacers would rattle around and perhaps cause damage unless they fit on the pin perfectly.

Thank you for the honest and detailed report.

Question -- how much meat between the top ring and the top of the piston ? I'm wondering how much could be safely shaved off to make a pop-up, since Grande Dog has yet to recognize the huge market potential for a cast pop-up piston for the 066 and 066BB (hint, hint ).

 

[Stihl088stock]

I've also seen needle bearings with wider shoulders to take space...wonder if thats what they had in mind.

If they had that in mind, they should include one with the piston!!! Something is goofy.

 

[blsnelling]

The OEM needle bearing is 12x17x13. That means something like a 12x17x17 would work. Anyone know if such a critter exists?

 

[parrisw]

Hopefully that's still an option, should it need to be. However, the skirts are a little wider on this Wiseco piston, and I ported the cylinder before installing it. I think I'm still ok though with a stock width piston. But I intend to make this piston work. It's just a matter of finding the right solution. A wider needle bearing would be ideal.

The OEM needle bearing is 12x17x13. That means something like a 12x17x17 would work. Anyone know if such a critter exists?

Brad I ended up with a bunch of needle bearings in my stock acquisition. I'll have a look, how exactly do you measure one of those? Measure on the needles or the cage?

 

[kevlar]

I don't think the space between the rod and the piston will matter, I see this in snowmobile engines all the time,once located inside the cylinder it ain't going anywhere!

 

[parrisw]

I don't think the space between the rod and the piston will matter, I see this in snowmobile engines all the time,once located inside the cylinder it ain't going anywhere!

I think he is worried about the bearing coming out of the rod slightly.