I received the 2.0 liter 3 & 4 BHW pistons today as the 1 & 2 were not in stock. I compared them with the .5 over ASV.
BHW on the left
The top of the ASV piston tapers in.
Above, you can see the tapering that I have heard so much about on the BHW piston. You can also see the difference between the oil cooling galleys. What is the benefit of those 2 differences?
Here is another angle
The tops side by side. Without measuring, I can't see the positioning differences in the bowl locations and valve relieve positioning if any. You can see the style differences. The ASV reliefs are a little deeper.
Here is an angled pic.
This angle reveals that the ASV reliefs are deeper.
You can also see the deep ridges above the top ring of the ASV on the right.
The BHW piston is a little taller too. Maybe not as the plank these are on are not perfectly level at all. However, the ring spacing is identical.
Seeing these two side by side for the 1st time, answers so many questions for me.
There is more meat at the top of the BHW. The start of the bowl is deeper in the BHW. Does this mean anything? Compression? I thought I read that the BHWs start at 18.5:1 compared to stock 19.5:1 for the ASVs. Is that why? More cc's at the top of the area of the bowl down to where it truly starts to taper to the in side I guess.
The bowl of the BHW is smooth where the ASV bowl has ridges. The ASV bowl agles down at a higher angle too.
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