Wiseco Piston and Hybrid Ceramic Bearings from Dominant Saws for 372XP

[blsnelling]

I realize that compression isn't everything. Hell even a 372 with 140psi runs pretty dang good. All I was saying is for the average hack it would still be a better route to stick with OEM or meteor if there is no advantage with the wiseco. If they could make them so squish is acceptable and compression is stout around 180 like you say just as a drop in I'd have to try one.

Typical compression on a stock 372XP is anywhere in the 140s. 150 would be a very good one. That's just how they're made. A lot of that is due to excessive squish. I do agree that they should raise the crown height on these about .015" and increase the dome another .035".

 

[blsnelling]

What jerk sold you a saw with a messed up case and crank?

Some PSP loser from the east side of Cincinnati No wonder he didn't want it!

 

[Mad Professor]

Brad, so it really only has 0.001" clearance on P/C?

I think I remember Leeha getting some 166 slugs and they ran 0.004-0.005"

 

[Chainsaw Jim]

I consider Meteor to be OEM quality. They're like $40-$45.

It may very well be but it isn't an upgrade like this wiseco is. I see people in my area don't like buying saws with aftermarket parts since the reputation for the chainsaw aftermarket parts world is the opposite of the aftermarket dirt bike parts world. This wiseco piston should be a different story with the reputation the name has already earned and it should help keep the 372's resale value as good if not better than if the piston were oem.

 

[Chris-PA]

I realize that compression isn't everything. Hell even a 372 with 140psi runs pretty dang good. All I was saying is for the average hack it would still be a better route to stick with OEM or meteor if there is no advantage with the wiseco. If they could make them so squish is acceptable and compression is stout around 180 like you say just as a drop in I'd have to try one.

Probably true, though in fairness that's not the purpose of parts like this. I'm interested to see if there's any actual benefit over doing the same mods with OEM or more typical AM parts. I'm actually more impressed by the bearings than the piston, but marketing is marketing - are any of these fancy parts actually removing any limitations that would be significant in a modified work saw, or do you have to be pushing things to the limit in a race engine for any benefits to be noticeable?

 

[Big_Wood]

Probably true, though in fairness that's not the purpose of parts like this. I'm interested to see if there's any actual benefit over doing the same mods with OEM or more typical AM parts. I'm actually more impressed by the bearings than the piston, but marketing is marketing - are any of these fancy parts actually removing any limitations that would be significant in a modified work saw, or do you have to be pushing things to the limit in a race engine for any benefits to be noticeable?

I know of a 372 with ceramic bearings in it and the thing has some significant run time. I've always wondered about them as well. Maybe I'll try a set one day.

 

[blsnelling]

My previous 346 has ceramic bearings in it. I used it a fair amount for several years, then sold it to an arborist who put it into full time use.

 

[Chris-PA]

I know of a 372 with ceramic bearings in it and the thing has some significant run time. I've always wondered about them as well. Maybe I'll try a set one day.

From their ad:

Overall friction is more than 10% less than an all-steel bearing of the highest quality. We've seen an increase in 500 free rpm on a Husky 357. This translates into speed in the wood, under load.

But by definition free rpm is no load - there isn't much resistance compared to when it is working, and the rpms are much higher than when it is working. Does it include a chain going around a bar? How does total bearing friction compare to a chain in the wood? What exactly does a 500rpm no load increase in rpm translate to under load?

Still, the saw already runs really well.

 

[Derf]

From their ad:

Overall friction is more than 10% less than an all-steel bearing of the highest quality. We've seen an increase in 500 free rpm on a Husky 357. This translates into speed in the wood, under load.

But by definition free rpm is no load - there isn't much resistance compared to when it is working, and the rpms are much higher than when it is working. Does it include a chain going around a bar? How does total bearing friction compare to a chain in the wood? What exactly does a 500rpm no load increase in rpm translate to under load?

Still, the saw already runs really well.

Good points all around. The ceramic ball bearings will be harder than steel, with a lower frictional surface so their "rolling resistance" is lower.

Do you have any experience on a bicycle? Think of this as the difference between pedaling on flat ground with a knobby tire vs a smooth tire, or a fatter tire vs a skinnier tire.

The second upshot is that provided the bearings are kept clean, they should last longer than steel bearings. Just theory though, not much evidence yet showing service intervals.

As to how it affects real world use with a bar and chain load, or when cutting wood, if you are making a cant racer it might help you earn 0.1 second faster cuts. Back to the bicycle analogy - if you are biking up hill towing a trailer behind you, you'll probably forget or can barely tell if you have a knobby or smooth tire.

They are claiming "more than 10% reduction in friction". That might translate to a significant reduction in drive train losses when there is no load, which might work out to 500rpm. But when there is a chain to drag around a bar, or through wood, there is a lot more friction to overcome. Suddenly the reduction of "more than 10%" in the bearing ends up as .05% of the total frictional load.

Are ceramic bearings better than top steel bearings? Probably. Are they worth their price? Debatable. Would I go out and swap my bearings and expect any noticeable improvements? No.

 

[smokey7]

I am very interested in this. I really want to know the details and limitations from using these bearings and forged pistons. I would have to bet that the piston must be undersized to give room for expansion. I would love to learn more about this and what the real measurements are. Piston to cyl clearance, crown to pin height, ring pin location, any any other info.

 

[Marshy]

I am very interested in this. I really want to know the details and limitations from using these bearings and forged pistons. I would have to bet that the piston must be undersized to give room for expansion. I would love to learn more about this and what the real measurements are. Piston to cyl clearance, crown to pin height, ring pin location, any any other info.

These specific bearing are rated ABEC-5 for extreme running accuracy. The manufacturing tolerances of the races and rolling elements are more strict when compared to lesser ABEC-1 rated bearings that you buy on eBay or from your dealer. What that means is they have higher running accuracy and a higher speed rating as well.

http://www.skf.com/us/products/mrc/precision-abec-5-and-abec-7-bearings/index.html


The silicon nitride hybrid bearing was created primarily as a way to isolate rotating equipment that have the potential to conduct electricity. Things like armatures in motors and generators or shafts. Traditional steel bearings have the potential to conduct electricity and cause damage to the race surface and breakdown of the lubricant. The silicon nitride acts as an electrical insulator. The hybrids also have longer service life, generate less running heat and can sustain operation with a thinner lubricant film. They are more tolerant to solid particle foreign material contaminants and the list goes on...

http://www.skf.com/us/products/mrc/hybrid-ceramic-ball-bearings/index.html


Regarding the forged piston... Their web site says less expansion due to increased silicon but what they didn't say was if that is compared to other forged pistons or cast pistons. In general, forged pistons expand more than cast so there's not enough info provided IMO.

I have first hand experience with Wiseco ****ing up their piston redesign and miss judging the expansion of their pistons. It took about 5 people and a dozen pistons and and equal number of damaged cylinders to convince them it was something they did and not us. It took nearly a year and a half to resolve it and we all were out the cost of our wrecked cylinders. They claimed to of found the issues and corrected it and comp'ed us new corrected pistons... Feel like taking a guess if I've used them since?

 

[blsnelling]

Here it is with an additional .035" popup and a proper tune. It still 4-strokes when pulled out of the cut even with it tuned to 14,900. That's very surprising without any porting!

 

[stihlaficionado]

Here it is with an additional .035" popup and a proper tune. It still 4-strokes when pulled out of the cut even with it tuned to 14,900. That's very surprising without any porting!

Almost as fast as my 261

 

[Marshy]

Almost as fast as my 261 headed into the garbage

Fixed

 

[stihlaficionado]

Fixed

Now why would I want to get rid of that beast?

Nice saw Brad. Me like Red & Black

 

[Chris-PA]

Here it is with an additional .035" popup and a proper tune. It still 4-strokes when pulled out of the cut even with it tuned to 14,900. That's very surprising without any porting!

rpm

Around 0:30 it's turning about 11k, and around 1:30 it's turning 12,780rpm. Kinda scooting right along.

 

[CR888]

I have always liked Wiseco pistons and ran them in dirt bikes. Does anyone know the difference in wieght between the OEM 372xp piston and the Wiseco? My only concern in a chainsaw application would be that their may be good reason the oem's use light pistons in chainsaws. Modern saw design favours a wide bore short stroke high rpm design. A piston changing direction 10-15000 times a minute maybe does not benefit from a heavy piston as it may reduce power. They sure do look nice though with the muffler removed with the 'Dominant' logo on display. I wonder how well they dissapate heat in comparison to OEM. All I am 'suggesting' is there maybe good reason Wiseco has no contracts supplying pistons to the OhPeEe industry (if I write O P E it gets censored, funny that on a site discussing O*P*E).

 

[blsnelling]

These are lighter than the OEM piston by about 7 gram.

 

[blsnelling]

Around 0:30 it's turning about 11k, and around 1:30 it's turning 12,780rpm. Kinda scooting right along.

I didn't have my tach on it in the cut, but I figured it was up there pretty good.

 

[blsnelling]

The silicon nitride hybrid bearing was created primarily as a way to isolate rotating equipment that have the potential to conduct electricity.
http://www.skf.com/us/products/mrc/hybrid-ceramic-ball-bearings/index.html

Regarding the forged piston... Their web site says less expansion due to increased silicon but what they didn't say was if that is compared to other forged pistons or cast pistons. In general, forged pistons expand more than cast so there's not enough info provided IMO.

I have first hand experience with Wiseco ****ing up their piston redesign and miss judging the expansion of their pistons. It took about 5 people and a dozen pistons and and equal number of damaged cylinders to convince them it was something they did and not us. It took nearly a year and a half to resolve it and we all were out the cost of our wrecked cylinders. They claimed to of found the issues and corrected it and comp'ed us new corrected pistons... Feel like taking a guess if I've used them since?

I've always understood forged pistons to expand more than cast pistons as well. That's why you have to size the bore a little larger for a forged piston, otherwise they'll scuff and/or seize.

I also noticed they mentioned "hypueretic" as well. I thought that was a higher quality cast piston, kind of the strength of forged without the expansion concerns.

Were you referring to the Wiseco pistons from Baileys? I had multiple issues with those myself. I ended up pitching them in the recycle bin. Those obviously weren't speced right. I'm not going to pin that completely on Wiseco.