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Should You Use 4032 Aluminum Forged Pistons or 2618 Aluminum Forged Pistons in your High Performance HEMI Engine?

We decided that it would be good for our customers to understand why they may use one piston over the other in their stroker motor. In this article we want to explain the difference between these 2 alloys, to help you make the best choice that fits your applications needs.

2618 Aluminum Alloy Forged Pistons

2618 forged pistons are a low silicon based material. They expand and contact much more than their 4032 siblings. In most cases these pistons are used in extreme racing applications like NASCAR and NHRA. 2618 Pistons require a greater piston to bore clearance due to their tendency to expand when heating up. This process can be heard during a cold start and is known as piston slap. The primary reason they are used in high performance applications is their forgiving nature under high impact situations such as detonation. However, their flexibility means you sacrifice longevity, as they distort much quicker than a 4032 forged aluminum piston. So, if you plan on putting a lot of stress on your HEMI and going to the strip often you may want to consider the benefits of a 2618 piston.

4032 Aluminum Alloy Forged Pistons

4032 forged pistons are a high silicon based material. This means that they expand much less than 2618 pistons. The tendency to expand less means that the piston can have a tighter piston to bore clearance. The tighter clearances create a quitter overall operation of the motor. 4032 is a very stable allow that resists distortions such as ring integrity. The alloy’s strength and stability also lends its self to a longer life cycle capability. However due to its less ductile nature we do not recommend using this type of piston if you’re planning to build your HEMI stroker motor for a boosted application. If you’re looking to build a naturally aspirated HEMI stroker engine and don’t plan on abusing the motor every weekend you should consider a 4032 piston for you build.

HEMI Performance Parts

A2Speed has every HEMI upgrade you could imagine. Search through a catalog of our favorite performance upgrades for each engine platform.

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HEMI Supercharger

Superchargers are the most cost-effective way of adding horsepower to a modern HEMI engine. We carry many different brands and types of superchargers.

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HEMI Crate Engines

HEMI crate engines are a great addition to any “Resto Mod” project. We can find a way to HEMI swap just about any vehicle!

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The Home for Ray Barton Racing Engines built GEN III HEMI’s

A2Speed is now providing the HEMI community with the best of the best in regards to engine building companies. Our motors are found in some of the highest horse power GEN III HEMI’s around the country, and are proven to work, and work reliably.

About A2Speed
Quality Products and Services
  • About Us
  • What We Do
  • How We Do It
  • Our Quality
A2Speed is an employee owned automotive performance parts company, specializing in the Gen III HEMI engine and the cars & trucks it powers. Just like you we are Hemi enthusiasts, and like you we are only interested in proven performance solutions. Good enough isn’t. People who invest in performance modifications want parts that last decades, not years. The effort is only valuable if the result is better than good enough, and frankly these days that’s hard to do.

A2Speed’s GEN III HEMI Background

Many of us at A2Speed have been working on the Gen III since its inception. As a team we are immersed in the Hemi world. We own, drive, modify, race and occasionally…break them. We use this experience to create SOLUTIONS, not just parts. Automotive engineering has advanced such that it is often difficult to improve on the work done by the OEMs. Difficult, not impossible. Utilizing advanced 3D modeling, CFD and stress simulations coupled with rapid prototyping, allow for the development of specialized parts that would be impractical at OEM volumes. Solutions validated with real world testing. Craftsmen level quality; and because we don’t have the layered overhead, our prices are often at or below the OEM price.

Advanced Aerospace Grade Machining

Production manufacturing is performed by partner companies that have proven track records for quality and timely deliveries. We look for certifications such as ISO-9001 and AS-9100 along with ITAR and GIDEP registrations. Several of the companies we work with regularly supply major aerospace firms and the DOD. Why use outside machining services? So that you get a better part at a better price. By utilizing only the machine cycles we need, and leveraging the superior skills and years of experience, A2Speed can give you exceptional quality at truly affordable prices.

Our company is guided by a set of core values and beliefs


  • We know that we are a community, not a “market”.
  • We recognize that we serve this community at the pleasure of its members.
  • We understand the passions, challenges and rewards that drive the enthusiast.
  • We believe that function drives form, improved performance improves appearance.
  • We know that one company can’t do it all, therefore we value partnerships.

How This Applies to Our Customers


  • We never settle for anything less than perfection.
  • All of our parts are put under intense testing before being released to you
  • You can feel secure because we use both our closest partners and our own cars to test A2Speed’s products
  • Finally we know that just having a great product isn’t enough, thus we strive to offer superior customer service, and the lowest prices. Giving you the best experience possible from start to finish.
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