Stroker piston

[dwg86]

I was just thinking...I wonder how much material is milled off the top of Hypereutectic pistons after they are cast? If Speed Pro or Kieth Black could leave an extra .030-.035 on top of their pistons(1.592 Comp Distance), we could have a hypereutectic piston that would work with the 258 rod, get a better quech, and it would add to the cc of the piston dish. I know a hyper piston that would work with a 4.0 rod would be better, but it would call for a new mold, and that is very expensive (I've already been down that road with Kieth Black). This would be a simple change in the machining process, if there is enough material. Then you just change a p/n for the new piston like maybe a H825SP, "SP" being a Stroker Piston.

I'm just not sure I want to try to sell this idea to the manufacturers. It can get very frustrating trying to sell an idea to a large corp. I've done this too many times...trying to get 1998 and newer cam cores made, talking with scat to get a forged rod using the 304/360 rod casting they already make(258 is the same rod, just wider at the big end), trying to get a hyper piston made for the 4.0 rod.

Anyone want to take this ball and run with it????

[lafrad]

There isn't any milled out of the dish from the factory. its a cast surface. only the face is milled.

They would have to "thicken up" the dish, or re-jig their stock hyper pistons to have less milled off the squish pads... and run the milling process afterwards....selling different pistons based on compression height or something.

[dwg86]

That is what I'm talking about...not milling so much off the top face. That would also increase the dish.

[lafrad]

But it would increase the compression height... take up room in the combustion chamber. one would need thicker head gaskets to keep from making a "klunk" when spinning the engine over.

[SilverXJ]

How so? You already have to deck the block to be a reasonable quench. It wouldn't be taking up room in the combustion chamber.

[lafrad]

I suppose I was thinking about how you set the motor up to begin with.

0.020" taller of a compression height would add a little bit to the size of the dish, but it would also take up the room (that would be removed from deckingthe block). Compared to NOT decking the block, your CR would be HIGHER. As it is, the stock style pistons do end up on the high side of the CR rating without decking... I don't know if it would be worth it have 2 different product lines in this case.

[Mgardiner1]

I'm sure the molds are effecient enough to get the product relatively close to the finished dimensions, its probably just a cleaning cut of a few thousandths to make a dead flat surface.

[SilverXJ]

You won't be changing compression that much over decking. As the flat part of the top of the piston rises, the dish also deepens. It isn't adding any displacement either.

The whole point here is to get a good quench, which would raise the compression over a lesser quench anyhow. What he is proposing will have the same effects as decking the block, just a better way to achieve a good quench.

[Muad'Dib]

What so bad about decking the block?

[Alex22]

What so bad about decking the block?

The cost...

[Mgardiner1]

The cost...

Definitely! And yes it would change the compression ratio to have a taller piston, but it could be calculated if the depth or CC of the dish was known.

[lafrad]

and decking enough gets new pushrods......

[SilverXJ]

and decking enough gets new pushrods......

been there