317 Heads: Are They Good For Your Build?
Hey guys! So, you're diving into the world of engine building, and you've stumbled upon the 317 heads – a popular choice for many car enthusiasts. But the million-dollar question is: are these cylinder heads any good? Well, let's break it down and see if they're the right fit for your project. This article will go deep into the pros and cons, the applications, and everything else you need to know to make an informed decision about the 317 heads. I'm going to cover everything, from the casting numbers to the flow rates, so you can get a comprehensive understanding of what you're dealing with. Knowing what to expect is half the battle, right?
What Exactly Are 317 Heads?
Alright, let's start with the basics. The 317 heads are a specific casting of aluminum cylinder heads often found on the GM LS family of engines. They're a popular upgrade option, especially for those looking to boost the performance of their LS-based builds without breaking the bank. These heads are generally considered a solid, affordable option. The 317 casting number is a key identifier, and it's essential to understand where these heads came from and what they were designed for. These heads were typically found on the 4.8L, 5.3L, and 6.0L engines, primarily in trucks and SUVs. That means they were designed for torque and efficiency, which gives them a unique set of characteristics. They're not the absolute top-of-the-line performance heads, but they offer a great balance of performance and value. Keep in mind that understanding the origins of the 317 heads helps determine their strengths and weaknesses. So, when someone asks you about the 317 heads, you can confidently tell them they are a good budget option with decent flow characteristics.
Origin and Application
The 317 heads found their home on various GM vehicles, including the Chevy Silverado, Suburban, Tahoe, and even some GMC trucks and SUVs. Their primary function was to provide a blend of decent power and fuel efficiency in these vehicles, meaning they were optimized for low-end torque and mid-range power. Because of this, they are great for street applications and mild performance upgrades. They were originally designed for engines that prioritized work capability and towing capacity. This design philosophy influences their performance characteristics, making them suitable for certain performance applications but potentially less optimal for others. It is important to remember the original intent behind the design. Knowing this helps you gauge their suitability for your particular project. Therefore, if you are planning a high-revving, all-out performance build, you may want to look at other head options that are specifically designed for high horsepower applications. The 317 heads are great, but they have their limits.
Key Features and Specifications
Let's dive into some specifics. The 317 heads have a 71cc combustion chamber volume. They come with a 2.00-inch intake valve and a 1.55-inch exhaust valve. The intake runners are generally around 210cc, while the exhaust runners are around 75cc. These specifications significantly impact how the engine breathes and how much power it can potentially produce. The flow rates are crucial. Out of the box, the 317 heads offer reasonable flow numbers, which can be improved with porting and other modifications. The flow numbers refer to how much air and fuel the heads can move through the engine, which directly relates to power output. The better the flow, the more power you can generally make. These heads are known for being a great starting point for modifications. So, if you're willing to put in some extra work, you can get even more performance out of them. Porting and polishing can drastically improve the airflow. Moreover, the 317 heads are a good match for several different LS engines, which makes them a versatile choice for many projects. Understanding these features and specifications gives you a better idea of what these heads are capable of.
The Pros of Using 317 Heads
Now, let's talk about the good stuff. Why would you choose 317 heads? What are the advantages? There are several compelling reasons why these heads remain a popular option. From cost-effectiveness to performance potential, the 317 heads bring a lot to the table.
Cost-Effectiveness and Availability
One of the biggest selling points of the 317 heads is their affordability. Compared to many other aftermarket cylinder heads, the 317s are relatively inexpensive, especially if you can find a used set. They were produced in high volumes, so they are readily available in the used market. This makes them an attractive choice for budget builds. The lower price point makes them accessible to a wider range of enthusiasts who may not have the budget for high-end, aftermarket options. Finding them at a good price can free up funds to use for other essential components. Availability is another key advantage. Because they were mass-produced, you can usually find them easily from local salvage yards, online marketplaces, or from fellow gearheads. This ease of access can save you time and hassle, letting you get your project moving faster. Accessibility and affordability make the 317 heads a great starting point.
Potential for Performance Upgrades
Don't let the budget price fool you – the 317 heads have plenty of potential for performance upgrades. They respond well to porting, polishing, and valve upgrades, all of which can significantly improve airflow and power output. Many engine builders and shops offer porting services specifically for these heads. They've found ways to maximize their potential. With the right modifications, these heads can support a considerable amount of horsepower. Whether you're planning a mild street build or something a little more aggressive, the 317s can adapt to your needs. The versatility and potential for modification are two of the biggest advantages. By investing a little extra time and money in these areas, you can transform them into a serious performance upgrade. So, even though they may not be the ultimate performance heads out of the box, with a bit of work, the 317 heads can become a powerhouse.
Compatibility with LS Engines
Another significant advantage is their compatibility with a wide range of LS engines. They fit various LS blocks, making them a versatile option for different projects. This compatibility simplifies the installation process and reduces the need for extensive modifications. The 317 heads are essentially a drop-in replacement for many other LS heads. This ease of installation is a massive bonus for those who want to get their project up and running quickly. They are often a direct bolt-on upgrade, meaning less work and more time enjoying your ride. The 317 heads are a great option for the LS engine family because of their versatility and simple installation process.
The Cons of Using 317 Heads
Alright, let's get real. While the 317 heads offer many benefits, they aren't perfect. Like any cylinder head, they have their drawbacks. It's essential to understand these limitations so you can make an informed decision. Here's what you need to know about the potential downsides of using 317 heads.
Stock Flow Limitations
Out of the box, the 317 heads have some limitations in terms of flow. Although they offer decent flow numbers for their intended applications, they may not be the best choice if you're looking for extreme high-RPM power. The stock intake and exhaust ports can restrict airflow, especially at higher engine speeds. This can limit the overall horsepower potential of your engine. For high-performance builds, you might find that you need to invest in extensive porting and valve work to achieve the desired airflow. If you are looking to make big horsepower numbers, you may need to look at different head options. The stock flow is good for street applications but may not be optimal for racing or other high-performance scenarios.
Need for Porting/Modifications
While the 317 heads respond well to modifications, the fact remains that you'll likely need to do some work to maximize their potential. Porting and polishing can be expensive, and they add extra time to your project. This means additional costs and potentially a longer wait time before you can get your engine running. You might need to have the heads professionally ported or, if you're a DIY enthusiast, invest in the tools and learn the skills needed to do the work yourself. The cost of porting can quickly add up, potentially negating some of the cost savings of using budget heads. So, if you're not prepared to invest in modifications, you may not see the full benefits of the 317 heads. Keep in mind that while they are good, you still need to put in some effort to get the most out of them.
Not Ideal for High-RPM Applications
As mentioned earlier, the 317 heads aren't always the best choice for high-RPM applications. They were designed primarily for torque and mid-range power in trucks and SUVs. This design philosophy may not align with the needs of a high-revving, high-horsepower engine. The stock valve springs and other components may not be suitable for extreme RPMs. This can lead to valve float or other mechanical issues. If you are building an engine that needs to make power at high RPMs, you may want to consider other head options. The 317 heads can perform well in many applications, but they might not be the best fit for every type of build.
Who Are 317 Heads Best For?
So, who should consider using 317 heads? They are an excellent choice for certain types of builds and may not be the best option for others. Here's a breakdown of the ideal applications and who might benefit most from using them.
Budget-Conscious Builders
If you're on a tight budget, the 317 heads are a fantastic option. They offer a great balance of performance and value, making them perfect for budget builds. The lower purchase price and availability make them a smart choice for enthusiasts who want to maximize their dollar. When your budget is a primary concern, the 317 heads are hard to beat. They allow you to make significant improvements without breaking the bank.
Street Performance Enthusiasts
For those building a street-driven car, the 317 heads are a solid choice. They offer excellent low-end and mid-range torque, making them ideal for daily driving and spirited street use. The torque characteristics of the 317 heads provide plenty of power off the line and strong acceleration. This makes them enjoyable for street driving. If you want a fun, responsive car that's still capable of cruising comfortably, the 317 heads are a good bet.
Mild Performance Upgrades
If you're planning a mild performance upgrade on your LS engine, the 317 heads can be an excellent starting point. They provide a noticeable improvement over stock heads without requiring extensive modifications. You can pair them with a cam swap, intake manifold upgrade, and other bolt-on modifications to achieve significant performance gains. This makes them a great option for those who want to improve their engine's power without going overboard.
How to Maximize Performance with 317 Heads
So, you've decided to go with 317 heads. Awesome! Here's how to get the most out of them and make sure you're getting the best possible performance.
Porting and Polishing
One of the best ways to enhance the 317 heads is through porting and polishing. This process smooths out the intake and exhaust ports, improving airflow and increasing power. You can send your heads to a professional porter, or you can tackle the job yourself if you have the necessary tools and skills. Porting can significantly improve the flow characteristics. It allows your engine to breathe better and produce more power. The results can be well worth the effort and investment.
Valve Upgrades
Upgrading the valves can further improve the performance of your 317 heads. Larger valves can increase airflow, while better valve springs can handle higher RPMs. You can also upgrade to performance valve seals to help improve reliability. When upgrading valves, make sure you choose components that are compatible with your heads and overall build goals. Proper valve selection is crucial for maximizing power and reliability.
Camshaft Selection
Choosing the right camshaft is essential for maximizing the performance of your 317 heads. The camshaft controls the timing and duration of the valves, which significantly impacts airflow and power output. Consider your build goals and choose a camshaft that complements your 317 heads and other components. You should consult with an experienced engine builder to find the perfect cam profile for your application. The right cam can unlock a lot of potential in the heads, making your engine run much better.
Conclusion: Are 317 Heads Right for You?
So, are 317 heads good? The answer is: it depends. They are a good option for budget builds, street performance, and mild upgrades. The 317 heads are a good choice, as long as you know their limitations. They offer a great balance of affordability and performance, making them a popular choice among LS engine enthusiasts. Just be sure to consider your specific needs and goals. If you are looking for an affordable upgrade with good potential for improvement, the 317 heads are a good choice. If you are looking to make big horsepower numbers, you may want to look at other head options. At the end of the day, with a little knowledge, you can make an informed decision on whether the 317 heads are right for you.