LS firing order is a crucial aspect of engine performance. It refers to the sequence in which internal engine cylinders are ignited to produce power. The firing order plays a critical role in the overall performance of the engine, affecting everything from power output to fuel efficiency.
The LS engine is a popular engine platform used in a wide range of applications, from high-performance sports cars to heavy-duty trucks.
The LS engine is known for its reliability, power, and versatility. Understanding the LS firing order is essential for anyone who wants to tune or modify their LS engine for maximum performance.
Whether you are a professional mechanic or a DIY enthusiast, understanding the LS firing order is essential for maintaining the engine’s performance and ensuring optimal power output.
By understanding the firing order, you can diagnose engine problems, improve fuel efficiency, and fine-tune the engine for maximum performance.
What is Firing Order and Why Does it Matter?
An engine can’t just fire its cylinders from front to back for simplicity’s sake. Every time one of the spark plugs fires off in the combustion chamber full of air and fuel mixture, a reaction is started that rapidly develops extreme pressures in the chamber.
This expanding pressure presses down on the piston and connecting rod. All these pulses make their way to the crankshaft, and they aren’t gentle.
To protect the health and longevity of an engine, the firing pulses must be balanced from bank-to-bank and from front-to-back. Engine designers try to avoid firing adjacent cylinders consecutively whenever possible.
Properly balancing the pulses from compression not only helps protect the crankshaft, but it also results in the engine running more smoothly and produces a better overall exhaust note.
Without balanced firing pulses, the engine would run rough, wear unevenly, or even fail catastrophically. Firing order also impacts:
- Power Output: Ensures even power delivery.
- Exhaust Note: Affects the “heartbeat” sound of the engine.
- Efficiency: Improves RPM stability and fuel economy.
Understanding LS Firing Order and Cylinder Numbers
The firing order of an engine refers to the sequence in which the power event happens in different cylinders. For LS engines, the firing order is 1-8-7-2-6-5-4-3.
This firing order is a cross-plane driving rod that is equally divided by 90°, which means that the firing of the cylinders is evenly distributed across the engine.
The LS firing order is different from the firing order of other engines. For example, the firing order for a Gen I small-block engine is 1-8-4-3-6-5-7-2.
Notice that cylinders 4 and 7 have swapped, and cylinders 3 and 2 have swapped. However, the LS engine firing order is 1-8-7-2-6-5-4-3, where cylinders 4 and 7, and 3 and 2 are in their original firing order positions.
The LS firing order is designed to provide a smooth and efficient power delivery, and it does a decent job of alternating firing between banks as much as possible. However, some LS engine enthusiasts have experimented with different firing order combinations, such as the 4/7 swap.
This modification switches the firing order of cylinders 4 and 7, which can improve low-end torque and reduce vibration.
It’s important to note that changing the firing order of an LS engine requires modifications to the camshaft, crankshaft, and timing chain. It’s not a simple modification and should only be attempted by experienced mechanics or engine builders.
In summary, the LS firing order is 1-8-7-2-6-5-4-3, and it provides a smooth and efficient power delivery.
While some LS enthusiasts have experimented with different firing order combinations, it’s important to understand that this modification requires significant engine modifications and should only be attempted by experienced mechanics.
(1) 4.8 LS Engine Overview.
The 1999 4.8L LS engine is one of the first GM pickup truck engines in the LS engine list among its third-generation V8 counterparts. It was produced between 1999 and 2007 until GM ceased producing this engine.
The 4.8 LS is popularly known as 4.8L Vortec or Vortec 4800. The engine was featured in the Chevy Silverado 1500 (1999 – 2006), and the Chevy Tahoe (2000 – 2006), respectively.
The engine still remains topnotch to date and works perfectly with upgrade system kits like turbos, cams, high-flow cylinder heads, cold air intake, nitrous oxide, and superchargers.
Firing Order
The 4.8L LS engine is designed with the LS standard 1-8-7-2-6-5-4-3 firing order, starting with the 1st cylinder on the driver’s side and followed by the last cylinder on the passenger’s side.
Cylinder Numbers
The fold method of cylinder numbering with #1 facing #2, #3 facing #4, #5 facing #6, and #7 facing #8 is applicable to the 4.8L LS engine. In that case, cylinders 1,3,5 and 7 sit at the driver’s side, which is your right. Meanwhile, cylinders 2,4,6, and 8 sit on the passenger’s side, by your left.
(2) 5.3 LS Engine Overview.
GM seemed to have selected a number of engines to reign between 1999 and 2007 because the 5.3 LS falls within this period. This engine was popularly known as Vortec 5300. It comprised the LM4, LM7, and L59 V8 engines.
The 5.3 LS happens to be more popular than its 4.8 LS counterpart. It also had the potential to accommodate upgrade system kits like cold air intake systems, nitrous oxide, superchargers, turbos, high-flow cylinder heads, and turbos.
Firing Order
The 5.3 firing order aligns with the LS standard. The engine is built with the 1-8-7-2-6-5-4-3 firing order. Like the 4.8 LS, the firing starts with the first cylinder on the driver’s side, which is further accompanied by the last cylinder on the passenger’s side.
Cylinder Numbers
The 5.3 LS cylinder numbering architecture also applies the fold method. Here, cylinder #1 stands opposite #2, #3 stands opposite #4, #5 stands opposite #6, and #7 stands opposite #8, respectively.
Like the 4.8 LS, cylinders 1,3,5 and 7 are on the driver’s side, by your right side. Whereas cylinders 2,4,6, and 8 are on the passenger’s side, by your left side.
(3) 5.7 LS Engine Overview.
The 5.7L LS was designed as part of the third-generation small block engine in the LS lineage. It was built for GM’s high-performance cars like Camaro, Corvette, Firebird/Trans Am, CTS-V, and GTO.
The engine was introduced in 1997 and was in production for about 8 years until it was discontinued around 2005. Like its previous counterparts, the 5.7 LS was superb in its time and still stands as one of the best LS engines of all time.
Firing Order
5.7 LS isn’t different from the 5.3 LS firing order. It is fashioned to operate in the 1-8-7-2-6-5-4-3 order. Of course, it flows with the LS standard.
Cylinder Numbers
The 5.7 LS cylinder numbers are lined up with the even numbers – 2,4,6,8 on the passenger’s side. Meanwhile, the odd numbers – 1,3,5,7 are situated on the driver’s side. This is exactly the fold method of cylinder numbering.
(4) 6.0 LS Engine Overview.
The 6.0 LS was a third-generation LS engine introduced in 1999 and ceased from GM’s production line in 2007. It was fondly referred to as Vortec 6000, and the LQ4 was a 6.0 LS engine.
GM applied the 6.0 LS to several models of Chevrolet, including the Chevy Silverado 2500 (1999 – 2004), Chevy Suburban (1999 – 2004), Chevy Express (2003 – 2007), Chevy Silverado 1500HD (2001 – 2007), and Chevy Silverado 3500 (2001 – 2007).
Firing Order
Although the 6.0L LS has some variations from other LS engines, the firing order remains standard: 1-8-7-2-6-5-4-3. The firing starts with cylinder #1 on the driver’s side and ends with cylinder #3 still on the driver’s side.
Cylinder Numbers
Again, the fold method of cylinder numbering is applicable to the 6.0L LS engine, with the odd numbers facing the even numbers. In other words, while cylinders 1,3,5 and 7 are placed at the driver’s side, cylinders 2,4,6 and 8 are placed at the passenger’s side opposite the odd numbers.
(5) 6.2 LS Engine Overview.
The 6.2 LS was released in 2000 to replace the older 6.0 LS engine. However, it reigned between 2000 and 2017. Nonetheless, this engine saw an extended appearance in GM trucks than the previous LS engines.
The 6.2 LS engines were seen in their full glory in some of GM’s luxury SUVs and pickup trucks, including the Chevy Grand Sport (2008 – 2013 models), Chevy Corvette W/Open Exhaust (2008 – 2013 models), Chevy Camaro SS convertible, and coupe (2009 – 2015 models), and Chevy SS (2015 – 2017 models), respectively.
Firing Order
The 6.2L LS engine comes with some advanced features. Nevertheless, the firing order remains 1-8-7-2-6-5-4-3. It doesn’t alter the standard firing order from 4.8 LS – 6.0 LS.
The firing also starts with cylinder #1 on the driver’s side, which is followed by cylinder #8 on the passenger’s side, and finally ends at cylinder #3 on the driver’s side as well.
Cylinder Numbers
The 6.2 LS also features the fold method of cylinder numbering with cylinders #1 opposite #2, #3 opposite #4, #5 opposite #6, and #7 opposite #8. It’s typically the odd-numbered cylinders facing the even-numbered cylinders.
(6) 7.0 LS Engine Overview.
GM’s constant upgrade of its product line continued the LS lineage until the 7.0L LS7 was released. The V8 LS7 became a “fresher” (new release) among all the preceding LS engines in 2006 when it featured in the Chevy Corvette Z06.
The 7.0 V8 LS engine continued until it was last seen in the Camaro Z/28 around 2014 – 2015. The engine was discontinued in 2015.
Firing Order
By now, it is obvious that the 7.0 LS engine would not come with a variance in its firing order. Just like the older LS engines, the 7.0 LS is designed with the standard 1-8-7-2-6-5-4-3 firing order.
Cylinder Numbers
Also, the 7.0 LS is configured with the fold method cylinder numbering style, with the odd-numbered cylinders facing the even-numbered counterparts. In other words, cylinders 1,3,5 and 7 at the driver’s side sit facing cylinders 2,4,6, and 8 at the passenger’s side.
Crankshafts and Camshafts
The LS engine’s firing order is determined by its crankshaft design. The LS engine uses a 1-8-7-2-6-5-4-3 firing order, which is different from the traditional 1-8-4-3-6-5-7-2 firing order used in most V8 engines.
The LS engine’s firing order is optimized for performance and efficiency, and it is achieved by using a different crankshaft design.
The LS engine uses a cross-plane crankshaft, which is different from the flat-plane crankshaft used in some other high-performance engines.
A cross-plane crankshaft has four throws that are spaced at 90-degree intervals, and it is designed to provide a smooth idle and good low-end torque.
The flat-plane crankshaft, on the other hand, has two throws that are spaced at 180-degree intervals, and it is designed to provide better high-end horsepower.
The LS engine’s cross-plane crankshaft is designed to provide a firing order that is optimized for performance and efficiency.
The crankshaft rotates twice for every complete cycle of firing, which means that each cylinder fires once every two crankshaft rotations. This firing order is achieved by using a specific camshaft design that is timed to the crankshaft rotation.
The camshaft is responsible for opening and closing the engine’s valves, which allows air and fuel to enter the combustion chamber and exhaust gases to exit. The camshaft is timed to the crankshaft rotation, and it is designed to provide the correct valve timing for each cylinder.
The LS engine’s camshaft is designed to provide a firing order that is optimized for performance and efficiency, and it is timed to the crankshaft rotation to achieve this goal.
In summary, the LS engine’s firing order is determined by its crankshaft design, which is optimized for performance and efficiency.
The cross-plane crankshaft is designed to provide a smooth idle and good low-end torque, and it is timed to the camshaft to provide the correct firing order.
The camshaft is responsible for opening and closing the engine’s valves, and it is timed to the crankshaft rotation to provide the correct valve timing for each cylinder.
Power and Performance
The LS engine family has been a favorite among engine builders and performance enthusiasts for its high power output potential. The LS firing order was changed to 1-8-7-2-6-5-4-3 to enhance power [^1].
This firing order does an excellent job of alternating firing between the banks as much as possible, which helps to reduce load and increase horsepower.
LS engines are known for their ability to handle nitrous oxide, superchargers, and turbos. They can handle large loads of nitrous oxide without any issues, and the supercharger and turbochargers can produce massive amounts of power when tuned correctly.
One popular modification to the LS firing order is the 4/7 swap, which switches the firing order of cylinders 4 and 7 [^2]. The 4-7 swap can help to reduce load and increase horsepower, making it a popular modification among LS engine enthusiasts.
LS engines are also known for their ability to handle high-performance applications. They are commonly used in drag racing, road racing, and other high-performance applications.
The LS engine’s high power output potential and ability to handle large loads make it a favorite among engine builders and performance enthusiasts.
In conclusion, the LS engine family is a high-performance engine that can handle nitrous oxide, superchargers, turbos, and other high-performance applications.
The LS firing order was changed to enhance power, and the 4/7 swap is a popular modification that can help to increase horsepower and reduce load.
Engine Components
LS engines are known for their reliability and performance, which is why they are a popular choice for many car enthusiasts. To understand the LS firing order, it’s essential to have a basic understanding of the engine components that make it all possible.
#1. Cylinder Heads.
The cylinder heads are a crucial component of the LS engine. They house the valves, which control the flow of air and fuel into the combustion chamber. LS engines have a unique head design that allows for better airflow and increased power.
#2. Cooling.
Proper cooling is essential to keep an LS engine running smoothly. LS engines use a water-cooled system to regulate engine temperature. The cooling system includes a radiator, water pump, and thermostat.
#3. Spark Plugs.
Spark plugs are responsible for igniting the fuel and air mixture in the combustion chamber. LS engines use high-performance spark plugs that can withstand high temperatures and pressures.
#4. Injector.
The fuel injector is responsible for delivering fuel to the combustion chamber. LS engines use a high-pressure fuel system that delivers fuel to the injectors at a rate of up to 3,000 psi.
#5. Rod Bearings.
Rod bearings are crucial to the LS engine’s longevity. They connect the connecting rod to the crankshaft and help reduce friction between the two components. LS engines use high-quality bearings that can withstand high RPMs and loads.
#6. Intake System.
The intake system is responsible for delivering air to the combustion chamber. LS engines use a high-flow intake system that allows for better airflow and increased power. The intake system includes an air filter, intake manifold, and throttle body.
#7. Engine Builder.
LS engines are known for their reliability, but proper assembly is crucial to ensure they perform at their best. It’s essential to have an experienced engine builder assemble the engine to ensure all components are installed correctly.
#8. Gas.
LS engines can run on both regular and premium gasoline. However, using premium gasoline can help increase power and performance. Overall, the LS engine is a reliable and high-performance engine that has become a popular choice for car enthusiasts.
Understanding the engine components is essential to ensure the engine runs smoothly and performs at its best.
Symptoms of an incorrect firing order
- Engine turns over but won’t start
- Rough running or loud misfires
- Loss of power or stalling
Which Ls Engine Is Best?
To help you make the decision, here’s a list of the best LS engines:
- The GM LS3. The LS3 is GM’s most popular engine platform, and for a good reason. It’s reliable, powerful, and lightweight, perfect for street and light-duty race applications.
- The GM LSX. This engine is an updated version of the LS3, and it comes with a much longer stroke and big-block-style canted valve heads. It’s ideal for high-performance applications that need lots of torque and power.
- The LS7. This engine is a classic muscle car engine that remains popular today. It comes with lots of power, reliability, and lightweight construction.
- The LS9. The LS9 is the most powerful of the LS engines, designed to be a reliable and powerful race engine. It’s well-suited for drag racing and other high-performance applications.
What makes the LS better than SBC?
Here’s why the LS is better than SBC:
- Power – LS engines produce more power than SBC engines, which can move your vehicle faster and more forcefully. You’ll be able to get from point A to point B in no time with an LS engine under the hood.
- Durability – LS engines are known for their unwavering durability and are less prone to breaking down and requiring repair or replacement. This, in turn, can help save you money and time since you won’t have to keep maintaining or replacing your engine as often.
- Efficiency – Most LS engines are also incredibly efficient, meaning you can get the most from your fuel and get better mileage. This is especially great for those watching their pocketbook and wanting to save money at the pump.
- Cost – When looking at the total cost, LS engines are the most cost-effective option. The LS is more affordable to purchase but is also more affordable to maintain over time.
ls firing order vs Sbc
The differences between the firing orders of SBC and flathead/inline-six engines also carry through to other aspects of performance. For example, the SBC firing order tends to give the engine more bottom-end power, which is ideal for drag racing and short-distance applications.
On the other hand, the inline six has a stronger top-end power delivery, better suited for performance applications that require higher revs and RPMs.
Do all LS engines have the same firing order?
Yes, all LS engines are built with a similar firing order. The order in which power moves across the various cylinders of an LS engine is 1-8-7-2-6-5-4-3. This cylinder firing order is peculiar to engines within the LS family.
With this correct (standard) firing order, LS engines deliver optimum performance and efficiency with minimal vibrations when running.
Of course, the firing order of an engine can influence the vibration, power output, and engine life ultimately.
The LS engines’ standard firing order performs an amazing job by alternating the firing process between the banks.
LS Firing Order Vs. SBC/BBC Firing Order: Which is better?
The Small Block Chevy (SBC)/Big Block Chevy (BBC) are built with the 1-8-4-3-6-5-7-2 firing order. The process starts with the first cylinder at the driver’s side on the engine block and ends with the first cylinder at the passenger’s side.
Meanwhile, the LS engine operates with the 1-8-7-2-6-5-4-3 firing order. This was orchestrated as an upgrade to the LS family. GM decided to upgrade the traditional SBC/BBC firing order in the LS to the new standard LS firing order because of its numerous advantages.
The LS firing engenders a power boost and increased torque output. It also minimizes irregularities of the crash shaft and increases the possibility of engine durability, as well as better heat management.
These and a few other factors are the reasons why the LS firing order is better than the SBC/BBC firing order.
What Happens if Firing Order is Wrong & How to Fix It
Once an engine is built and running, firing order issues most often seem to crop up when someone is doing maintenance or some type of repair and pulls the plug wires without paying enough attention to where they came from.
Then they get reinstalled in the incorrect order and the next thing you know; you’ve got a misfire.
How to Troubleshoot:
- Verify the firing order against the manufacturer’s specs
- Use numbered spark plug wire markers for accuracy
- Test cylinder firing with an infrared thermometer
The solution is as simple as to make sure your plug wires are always properly labeled. And never remove the wires off the distributor unless absolutely necessary. Just in case, use a sharpie to mark the number one terminal on your distributor.
And a simple plug wire marker kit is a more reliable way to permanently label plug wires in a clear, easy-to-read way than a marker.
If you do get a couple of wires crossed and you’re trying to figure out which ones are in the wrong place, start by looking up your engine in the firing-order table above to find the correct firing order and distributor rotation.
If, for some reason, you’re still having trouble, a simple solution is to use a mini laser thermometer to find the cylinders that aren’t firing. With the engine running, use the thermometer to read the temperature on the exhaust close to the cylinder head.
Cylinders that are firing correctly will heat up at approximately the same rate while cylinders that are misfiring will stay relatively colder.
If you find two bad cylinders, try swapping out the plug wires. If you’re still running an older ignition system sometimes a set of good spark plug wires will do the trick!
Of course, there’s no guarantee this will be the cure every time, but it’s always a good idea to start with the simplest fixes first. Good luck!
FAQs.
Do all LS engines have the same firing order?
Yes, all LS engines are built with a similar firing order. The order in which power moves across the various cylinders of an LS engine is 1-8-7-2-6-5-4-3. This cylinder firing order is peculiar to engines within the LS family.
With this correct (standard) firing order, LS engines deliver optimum performance and efficiency with minimal vibrations when running. Of course, the firing order of an engine can influence the vibration, power output, and engine life ultimately.
The LS engines’ standard firing order performs an amazing job by alternating the firing process between the banks.
Can you change the firing order of the LS engine?
All LS engines are built with the same firing order; hence, the 1-8-7-2-6-5-4-3 firing order is a standard for the LS family lineage. Although the traditional Chevy small block/big block engines’ firing order can be changed, the same operation may not be possible for the LS firing order.
Swapping the old SBC/BBC firing order may not be a worthy venture in the end. Therefore, you may want to find out the pros and cons of swapping out your engine’s current firing order before opting for a new firing order.
What is the best firing order?
A clockwise 1-8-7-2-6-5-4-3 firing order is best for a vehicle, especially GM’s product lines with LS engines. This was a result of various simulations with the old small-block Chevy and big-block Chevy that had a 1-8-4-3-6-5-7-2 firing order.
The LS firing order provided solutions to most of the limitations of the old SBB and SBC. The good news is that swapping up the traditional small-block Chevy and big-block Chevy engine firing is possible. However, ensure to contact an expert auto mechanic for professional advice.
What is a 4/7 firing order swap?
A 4/7 firing order is an operation that switches the positions of both cylinder #4 and cylinder #7 such that they replace each other. In other words, the swap is meant to move cylinder #4 from its position to occupy cylinder #7’s position.
The same applies to cylinder #7, which is also moved to occupy cylinder #4’s initial position. Swapping firing orders can offer a couple of benefits; however, ensure to seek professional advice from an expert mechanic before making a final decision about the operation.
Does firing order change the sound?
A vehicle’s engine firing order may not directly affect its sound. However, an incorrect firing order can trigger other components within the engine to vibrate and give off unpleasant noise while the engine is running.
Like every other operation in a vehicle, the firing order is very important to the smooth running and durability of the engine.
Final Words
After a thorough review of the different LS engines across various generations, it is an established fact that all LS engines are built with a similar firing order. The same is true for the cylinder numbers as well.
However, the LS firing order isn’t there for decoration or uniformity. For example, the Chevy Silverado 5.3 Vortec firing order is designed to offer power and torque boost, enhanced engine durability, better heat management, as well as a harmonious engine performance at large.