SIDE
TOP
Features of Note:
- This is the Federal Mogul/Speed Pro # H471P for the Buick V6 4.1L.
- It has long skirts, but the skirts do not continue under the pin as on the GM piston.
- It does not have the oil drippers from the lower ring to lubricate the pin.
- It is has material under the pin much like the TRW forged piston.
Features of Note:
- This picture shows the top of the 4.1L hyper piston.
- It does not have the steel support to the top ring like the GM piston.
- It has a slot in the lower ring goove which drains inside the piston.
- The GM piston does not drain inside the piston. The TRW forged has small holes and all the cast pistons seem to have this slot.
- The top of the piston is fully machined.
- The notch in the top of the piston is to be placed toward the front for installation.
BOTTOM
- This is the bottom of the 4.1L hyper piston.
- It does not have the full skirt of the GM piston.
- It does not have the side support plates around the piston pins.
- It does have support ribs from the pin to the skirts and to the bottom of the piston crown.
- It has a single hole drilled for pin lubrication on eash side. It goes from the pin hole to a point between two of the ribs to the crown. They are not visible in this picture.
- The skirt walls seem to be thicker than those on the 3.8 hyper pistons. And this appears to be a stronger piston than the hypers offered for the 3.8.