Need some help spec'ing pistons
 

When you guys have an engine built, what piston alloy do you spec? I'm spec'ing out an engine for a mild street blower build (800-ish rwhp) and after reading everything I could find online, I opted to go for 4032 alloy forged pistons. But my mechanic is having trouble finding an engine builder that will use them.

After researching, it turns out there are two commonly available alloys for forged pistons: 2618 and 4032. 2618 pistons are the gold standard as far as full on racing and detonation resistance are concerned. However, they have a couple of drawbacks - they are noisy when cold, and while it is the toughest alloy, it is also the least wear resistant.

4032 alloy is the alloy piston used by GM in the LT4 and LT5 as well as the LSX B-15 longblock. It is somewhere between cast hypereutectic and 2618 forged in terms of both toughness and wear resistance. That is, it is tougher than cast and more wear resistant than 2618. It also has the added benefit that it doesn't expand as much as 2618, making 4032 pistons quieter when cold.

So I don't understand why we're having so much trouble finding a builder to use them. I know they are marketed as a 'budget friendly' option to 2618 pistons, but for this build, they are really the superior option - I need wear resistance as much as detonation resistance. Have any of you guys had experience with both 4032 and 2618 pistons?

JE markets their 4032 pistons as SRP Professional, and Wiseco markets them as Pro Tru, although I believe many of their LS designs can be had in either alloy. Mahle doesn't market them separately from the 2618 forgings, just gives you a choice of alloys.

The Wisecos in my car are 2618 and they're not noisy at all. I don't drive the car in 40 degree weather or anything though.

I think some of the disadvantages of 2618 alloy are exaggerated, or are no longer an issue with todays manufacturing capabilities. The piston to wall clearance with 2618 pistons have tightened up over the years and the skirt coating that a lot of pistons come with now help as well. If all these engine builders are using 2618, then the 4032 may not be as superior as you think.

Wiseco does have a couple of coatings that look interesting. they have that thick skirt coating that is designed to fill the gap, and that hard anodized coating for the ring lands and the wrist pin areas. How many miles have you put on your engine?

The reason I'm going with the 4032 alloy is because I want to put about 100,000 miles on this engine before I rebuild it. If this was just going to be my weekend cruiser I would have gone with the 2618 alloy, no question. But I want the superior wear characteristics of the 4032. I was just kind of surprised how many builders seem to be afraid of them.