374 Olds 350 stroker build
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I am planning on these pistons, if the block cleans up with a hone, the 4.065" in the top row.
2618 asymmetricals equates to short life span.
2618 is a race piston material for SEVERELY high boost or NO2 application. Not for a daily driver. Piston to wall will be a minimum of .004", but most likely .005-.0055". This means that when it's 30 degrees outside it will rattle like a bearing is out of it - ask me how I know.
A 4032 alloy will run with a standard piston to bore clearance like an OEM cast or hyer piston. Yes it's more brittle and no where near as tough as a 2618, but you will not be able to abuse a 4032 to the point of needing a 2618 alloy in a NA sub 800HP build. And the balancing of the asymmetrical will not be cheap - they are silly light weight.
2618 is a race piston material for SEVERELY high boost or NO2 application. Not for a daily driver. Piston to wall will be a minimum of .004", but most likely .005-.0055". This means that when it's 30 degrees outside it will rattle like a bearing is out of it - ask me how I know.
A 4032 alloy will run with a standard piston to bore clearance like an OEM cast or hyer piston. Yes it's more brittle and no where near as tough as a 2618, but you will not be able to abuse a 4032 to the point of needing a 2618 alloy in a NA sub 800HP build. And the balancing of the asymmetrical will not be cheap - they are silly light weight.
My CP Bullets are 2618 and held up great until valve pieces got where they weren't spoda be. Had 12k miles on them at 10.56:1
Find me a modern 4032 piston with bigger than a 5cc dish in 4.065" or larger and at minimum a 1.5mm ring pack in a 1.55" compression height and .927" pin, I will consider them. The Mahle have a 1mm file fit ring pack. Mark figured .004" to .0045" would be the clearance, he warned me on the noise cold. No worse than the old junk Speedpro pistons and way lighter with a massively better ring pack.
Yes the 2618 pistons will be noisier. Just be aware narrow rings will use more oil. I used Mahle pistons with the 1.5/1.5/3mm ring pack in the last 496 I built for a customer. This was in a drag car. My last 565 had .043/.043/3/16 rings but had vertical gas ports as well to help it seal on the power stroke.
This has been my experience as well.
Nothing wrong with them, but you won’t get the same mileage that a hyper would give.
You see the recommended clearance? It's more than .005" piston to wall. If these are too tight, then mayhem will ensue in a moment. If the skirt swells to within .0005" of the bore, then .....oofa.....do over.
What are the spec of the block : deck height and bore? What's the rod length? And how many cc's are your head?
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