Wossner Or JE Pistons

[coomo]

Did I read somewhere, that if your fitting 3.2 cylinders to a 3.0sc block/Rods Only JE make pistons with the correct fitment? Or have things changed recently.Im sure Ive seen 3.2ss engine builds using Wossner Pistons.Or did I just imagine the whole damn thing!

[jpnovak]

You are confusing two different things.

The 3.0 and 3.2 cylinders are both 95mm. By themselves this does not create a 3.2SS. To increase the capacity of a 3.0 to 3.2SS you need to increase the bore of the cylinder to 98mm. Likewise, if you increase the bore of a 3.2 from 95 to 98mm you end up with a (nominal) 3.4.

The 3.0 cylinders can not be bored to 98mm. The top of the cylinder has a sealing ring. When you cut 1.5mm off the cylinder bore wall the edge of the sealing ring is less than 0.5mm and is not thick enough to support the sealing ring. The 3.2 cylinder does not have a sealing ring. When cut to 98mm they do not have the same edge issue.

Solution. buy existing 98mm cylinders or buy 3.2 cyilnders and have them bored/replated to 98mm.

As for pistons... YOu could use Wossner, JE or CP for pistons. They all make suitable pistons as well as custom options to fine tune your compression ratio, valve pockets and target performance metrics.

[coomo]

Many thanks for that.Ive an offer of a set of 95mm from a 3.2.However 4 are marked w8 & 2 are marked w12.Im not sure what these numbers relate too?

[wildcat077]

All JE pistons have a fabrication number etched on the inside , if the numbers are still visible just call them and they will give you all the specs !

[3rd_gear_Ted]

Look closely at the nuances of the pin bosses, the skirts and ring landings.
These effect the piston weight and mass a lot.
Mass resists acceleration

[Trackrash]

Originally Posted by coomo

Many thanks for that.Ive an offer of a set of 95mm from a 3.2.However 4 are marked w8 & 2 are marked w12.Im not sure what these numbers relate too?

Keep in mind that the 3,0 pistons used a 22mm wrist pin while the 3,2s went to a 23mm wrist pin. I'm thinking you have a 3,0?

[Trackrash]

Here is what a 9.5 -1, 95mm JE piston for an SC motor looks like. Assuming you have re-usable Mahle cylinders?
BTW, be careful using used pistons, here is a link to how to check them. Evaluating UsedÂ* Pistons:Â*How to Determine if Your Pistons Are Still Good

[Walt Fricke]

Gordon - that J&E piston looks a lot like the 12:1 95 I had made for my 2.8SS maybe 10 years ago. The one which pulled apart at the wrist pin on the chassis dyno, probably because the wrist pin was in a sense too short - its ends did not extend under the side or skirt boss. This even despite the hefty looking main boss. J&E now has a better design - the side skirt is moved in to overlap the wrist pin ends.

To be sure, the disaster happened at 8,000 rpm. Maybe these will hold up at lesser rpms? I've got five of them, but can't imagine anyone using them given the history, though they could easily be recut to lower the CR and used on a modest street motor?

[Trackrash]

Here is the top view.

[coomo]

Originally Posted by wildcat077

All JE pistons have a fabrication number etched on the inside , if the numbers are still visible just call them and they will give you all the specs !

These are Mahle Cylinders not JE.

[Walt Fricke]

Gordon - your piston design looks a lot like the one which did this to me:


A better design looks more like this from the bottom:




Less leverage on the wrist pin, and compression and tension from wrist pin ends taken up by the skirt and not just the boss extending inward from the skirt.

[rkeele]

Iv'e had similar results with Wossner pistons, I was using Mahle 3.6 cylinders, all replated to original spec. not positive but suspect short light wrist pin. However It could have had a rod bearing let go, since it was rebuilt with suspect Glyco rod bearings, I also have 5 pistons and cylinders 1 hr. run time they might be fine but who wants to take a chance.