Speed Perf6rmanc3 on Forged Piston Reliability

[Vitamin M]

Merry Christmas everyone,


Just wanted an opinion on this section of text from their website. I always thought forged internals means reliability. What they are saying is that motor has to be rebuilt again after 20-30k .. can someone explain pls see below from their site.

"
It is very important to understand the differences between OEM and Forged pistons, and what an appropriate application to use them in is. The majority of our customers drive their vehicles daily, and therefore reliability is always a factor to consider when building a street-engine. The single best way to stay very reliable and make good "useable" horsepower, is to use OEM pistons in your build. Forged Pistons are not designed to be used in a daily driven application. Forged pistons are designed to be used in a race engine where they are checked from top to bottom and rebuilt if needed after a specified number of races. Anyone who builds a street purpose motor has no intentions of tearing it down every 10k miles just to see how things are doing.

The reliability factor between OEM and forged pistons is in the material and how it behaves. Forged pistons are made from two different alloys, 2618 aluminum alloy and 4032 aluminum alloy. The difference is that 4032 has more silicone built into the piston, allowing for LESS thermal expansion, and allowing you to run a tighter piston-to-wall clearance (PTW). Piston-to-wall clearance is the area between the piston and the cylinder wall. This clearance is built into the bore so the piston can expand correctly. 2618 aluminum alloy has less silicone and expands much more than 4032. However, 2618 has proved to be stronger and can take much more abuse (detonation). Under detonation the ring lands become brittle and crack in 4032 alloy pistons. The disadvantage to having 2618 alloy is because of the loose piston-to-wall clearance that must be run. Typically, most manufacturers of 2618 alloy pistons require a wall clearance of .0030 to .0045in. (3 to 4 1/2 thousandths of an inch). When it is this loose, there will be a considerable amount of "piston slap". When you first start the engine and it is cold, you will hear the pistons rocking back and forth in the bore, giving off a clackity sound. As the engine warms up, this sound will diminish or disappear entirely, depending on the clearance.

Imagine this event in a daily driven engine. The car is started on an average of 2-4 times a day. Multiply that by a number of days, then weeks, months, etc. What ends up happening is your blocks cylinder walls become "chaffed" and "out-of-round" which leads to improper sealing and oil consumption. All of this can happen on your engine build after only 15- 20 thousand miles. Race teams understand this and use the piston for what it is intended. OEM pistons are used in many autocross and road racing applications and should be used in your street builds. OEM pistons are used in road racing over forged pistons, because of the effective sealing properties and reliability that they provide."

Is there an option with forged internals and reliability ?

[Kdawg207]

What it says is race car makes a bad choice for a daily

[Vitamin M]

Originally Posted by Kdawg207 What it says is race car makes a bad choice for a daily

Its talking about pistons.. OEM vs forged. And I want to know if forged is a reliable option for daily ? Its says no but a lot of guys here build their motors.. Are they not daily driving their cars ?

[Matt@HTP]

Originally Posted by Vitamin M Its talking about pistons.. OEM vs forged. And I want to know if forged is a reliable option for daily ? Its says no but a lot of guys here build their motors.. Are they not daily driving their cars ?

Sure it's a reliable option as long you stay within the confines of your build. The problem engine builders have is that they design a build around what their client says their power goals are, then the client tries to push it way past that "because forged".

Their quote is just to educate on the differences in aftermarket piston material and for what to expect when using it. When you do an engine build, communicate with your builder exactly what you plan on doing. Don't lie to them and more importantly, don't lie to yourself.

[Vitamin M]

That's the reply I was looking for. Thanks Matt !