Technical Are valve reliefs on pistons actually needed?

As a general rule, 4 valve relief pistons are stock or lower performance, while 2 valve relief are higher performance pistons.
The lower performance stuff has no need for deep valve relief......at least that's the original stock design criteria.

This is another reason the stock and low performance pistons have 4 releifs.....so that even though they have an offset in the piston pin location, the same piston can be used on either bank. Therefore, one piston blank can be machined to fit either side of the engine. Makes it cheaper to produce.
The offset pin in low performance pistons makes them quieter when they are cold.

2 valve relief will require two different piston blanks to make a complete set for a V type engine.
More expensive to produce.

 

This would be me…….

 

Off set pins do more than keep pistons quiet https://www.theengineerspost.com/piston-pin/#What Is Piston Pin Offset?

 

She could give me advice on anything she wants !

 

Potvin only uses steel pistons, 'cause that's what Henry used!

 

They should make valves with U-joints for guys like you.

 

One thing about the stock four relief pistons, if you change heads to an aftermarket or increase valve size in your c urrent heads you must check valve clearance. Aftermarket heads, often have larger valves than the stock heads and the valve relief in stock pistons are for the smaller stock valves and will not provide enough clearance for large valves. The diameter of the relief must be appropriate for the valve.

 

Not a big fan of this, but sometimes it’s necessary when swapping to a different brand of cylinder heads.

 

I was only joking on both accounts.

Well, duh. Steel pistons are traditional, everybody knows that!