You might have been hearing a lot of facts about 862 heads, which makes you wonder what makes it stand out among all other cylinder heads. This article is here to enlighten you about the good and vital characteristics of 862 heads. Also, it will give answers to the frequently asked questions on 862 cylinder heads. Now, let’s know what the 862 heads are all about.
What Are 862 Heads?
The 862 head is an aluminum cylinder head used in automotive applications and other industrial engines. The 862 series cylinder heads are GM’s generation III cylinder heads.
The 862 series was a “full runner” design with high compression ratio dual-quench hydraulic lifters and mechanical valvetrain components (rocker’s arms). This allowed higher peak engine speeds with more restrictive ported intakes or dual valve springs.
The 862 heads can fit into different vehicles of various brands and makes. Some of the brands include the 1998-2008 Toyota Corolla Celica, MR2 Spyder Ma, Silverado, Tahoe, Sierra, and so on. This cylinder is popular because it is one of the car’s most affordable cylinder heads.
What Are 862 Heads Good For?
862 heads are good for high-performance engines. They have a lot of flow, which measures how much air can pass through the head. They can also be used in racing applications because they are designed to withstand higher pressures than regular street cars.
862 heads have a flat-top design, meaning the valves sit directly on the combustion chamber. They have a raised valve seat and an increased volume for better flow. The exhaust valve is also raised, allowing for a more efficient exhaust flow from the cylinder head.
The intake valve and manifold are also raised to improve airflow into the engine. The 862 is designed for use with carburetors or fuel injection systems that do not require positive crankcase ventilation (PCV) valves.
The Features OF 862 Heads
1. They are lightweight
862 heads are lightweight. The aluminum construction of the head allows for faster engine cooling and less weight than traditional iron or steel heads. The use of aluminum also means that they can be machined to have more airflow, which is ideal for engines that need to generate high levels of horsepower but don’t have room for huge cylinders or valves.
The 862 head was created specifically for high-performance applications like racing and drag racing, where speed is everything. Because it has such small valves, it can achieve excellent airflow even at high RPMs without increasing the combustion chamber size (or bore).
2. They can efficiently dissipate heat because they are made of aluminum.
The second reason is that aluminum conducts heat better than steel. This means that it can efficiently dissipate heat, which is a major advantage for combustion engines. By comparison, some other metals used in engine construction, such as cast iron and copper, are poor conductors of heat.
For these reasons, aluminum heads are usually lighter than heads made from steel and/or cast iron. They’re also less expensive to manufacture because they don’t require as much machining or labor to produce as steel or cast-iron cylinder head castings would (steel is heavier and more difficult to machine). Another advantage of aluminum over other metals is its corrosion resistance. It doesn’t rust like steel does when exposed to the elements over time (i.e., rainwater). An aluminum block won’t require regular maintenance like a rusty old pickup truck might need at some point down the road after years spent parked outside unprotected under storm clouds’ steady stream of precipitation
3. They are commonly utilized in high-performance
The 862 head is commonly used in high-performance, racing, and sports cars. It’s also found on some luxury and sports cars. The 862 is a 12-valve design that utilizes two intake valves per cylinder and one exhaust valve per cylinder. The combustion chamber volume is 84cc for the 862S, 83cc for the 862C, 84cc for the 862F, 82cc for the 862A, and 84cc for the 862B
4. They’re used in race cars because they provide superior fuel economy
The design of the 862 head is such that it provides superior fuel economy to a high-performance race car. This is because it is lightweight, aluminum, and can efficiently dissipate heat.
The 862 head was first utilized in high-performance engines in 1968 at the 24 Hours of Daytona on a factory racing team. Since then, they’ve become one of the most commonly used heads on race cars everywhere due to their ability to provide superior fuel economy while still providing excellent performance for your engine.
5. Weight savings and faster engine cooling
The 862 heads are a great choice for any engine builder who wants to build a serious high-performance engine. The 862 heads use an extra thick casting, which means they can handle the pressure and temperature of high-performance applications. This increased strength also means less chance of warping under the extreme heat generated by forced induction and nitrous oxide injection systems.
The 862 head features bigger valves than the stock LS (2.25” intake and 1.55” exhaust), so you can flow more air through your engine, giving you more power at higher RPMs, which leads to better fuel economy. The larger valves also allow faster cooling of hot combustion gases from detonation (pre-ignition), allowing you to run higher compression ratios without damaging your pistons or bore walls, boosting horsepower even further.
862 Heads Specification
| Material | Aluminum |
| Manufacturer Part Number | 12559863 |
| Intake Port Shape | Cathedral |
| Exhaust Port Shape | D – Port |
| Intake Port Volume | 200 cc |
| Exhaust Port Volume | 70 cc |
| Combustion Chamber Volume | 61.15 cc |
| Intake Valve Diameter | 1.89 in. |
| Exhaust Valve Diameter | 1.55 in. |
| Compression Ratio | 9.5:1 |
| Price | $290.95 |
| Compatibility | LR4, LM4, and LM7 engines. |
The Problems Associated With 826 Heads
826 heads are a notoriously unreliable part of the engine. They have been known to fail after only 50,000 miles and tend to leak, which can cause issues with oil pressure and lead to an expensive repair bill. 826 heads are also expensive; you may be paying several thousand dollars for new ones if your current ones break down. The 826 Head was designed for turbocharged engines, so it’s not very effective when used in naturally aspirated motors.
Also, when the head gaskets fail, they break with time, enabling coolant to leak into the oil. The problem is that when this happens, it’s not just a little coolant that gets into your engine oil; it’s a lot of coolants, and this causes all sorts of horrible things to happen. First, there’s a risk that the engine will overheat because too much heat can’t get out, and if you’ve ever seen an overheated car engine, you know how bad that can be. But what happens next is worse than overheating: seizing (the metal parts seizing together). Everything metal inside your cylinder block becomes one solid piece with no moving parts.
FAQs
Q1: Is it Necessary to Upgrade 862 Heads?
Yes, but not in the way that you might think. While the 862 heads are a good upgrade over the stock 706 heads, they’re not always better than aftermarket alternatives. For instance, if you’re looking for an all-out race build or something especially powerful and high-performance, then upgrading your 706 or other OEM head with an aftermarket part will probably be a better choice. However, if you plan to use your car for street driving and occasional drag racing (or vice versa), then upgrading to 862s may be a good option for your budget build.
Q2: What’s the difference between the heads 821 and 823?
The main difference between both of them is that they have different combustion chamber sizes. The 821 has a smaller chamber, while the 823 has a larger one.
This can affect your engine’s efficiency, which means it will either burn hotter or cooler depending on what you want to do with it. If you want to run more boost and make more power, then going for an 823 would be better since it allows for more airflow through the intake ports and into the cylinder heads themselves (which helps with turbocharged setups).
But if you don’t need that kind of power from your engine and just want something that runs well without any issues, then sticking with an 821 should work just fine as long as there isn’t anything wrong with it.
Q3: Are 862 or 706 heads better?
The 762 and 862 heads are both good. They both have different applications that they excel in, but they’re both good all around. The 862s are better for racing and high-compression applications, while the 762s are better for street use.
Read: Difference Between 4.3 and 4.3 Vortec Engines
Conclusion
862 cylinder heads are the way to go if you want cylinder heads for great performance. They have distinct qualities that make them different from other cylinder heads. They dissipate heat quickly and can be used in high-performance cars like race cars. They are also good because of their weight-saving and rapid engine cooling benefits. Now that you know all you need about the 862 engines, you can be sure which cylinder head to get the next time you need a cylinder head.