LS Swapping a C10Last Updated October 19, 2023 | Meghan Drummond
If you have a classic Chevy C10 pickup, your engine probably has more than a few miles on it. Whether you’re worried about your engine hitting the end of its lifespan or looking for a little extra oomph, it’s likely you’ve thought about what it would take to do an engine swap. If you’re considering putting a new engine into your C10, one of the best choices is going to be a simple LS engine. This is a really expensive upgrade. If you're looking for other, cheaper ways to upgrade your truck, check out our list of 5 affordable Chevy C10 mods.
Why an LS Engine?
There are a lot of reasons why an LS swap is a particularly great engine swap plan for a C10. LS engines are classic styled small-block V8 engines. Since these engines are all overhead valve as opposed to overhead cam designs, they’re more compatible with classic trucks.
Depending on which LS engine you pick, there are versions that have a lot of power, and they all fit into a small enough package that they can easily slide into most vintage cars or trucks without substantial alterations.
Once you’ve got an LS engine into your C10, they’re easy to work on yourself. If you really care about doing your own repairs, or are learning how to and want some experience, an LS engine will offer you that opportunity. And because so many people have them and have worked on them, there are guides for basic repairs just about everywhere.
The LS has been around for so long and has been a popular choice for hot rodders for so long, that it has more aftermarket support than just about any other engine. Whether you’re really interested in finding an awesome set of headers for your LS-swapped C10 or just want a lot of options when it comes to making mods, you’ll always have a lot of choices.
Perhaps best of all, an LS engine and a C10 are both made by General Motors, meaning they have brand compatibility.
LS engine swaps are so popular it’s easy to find “engine swap in a box” style kits that will include most of what you’ll need to make your engine swap complete.
Picking an LS Engine
When it comes to engines, you can either purchase a shiny new engine or go junkyard spelunking for a moderately used one. The advantages and disadvantages here should be fairly clear. New engines have a warranty, are going to function as advertised, and you rarely encounter any unpleasant experiences. They’re also a little more expensive.
Hunting down junkyard treasures is a little more hit or miss but will save you some money.
Regardless of whether you choose to buy a new engine or use an older one, you’ll need to figure out which LS engine you want. Below, you’ll find a quick chart reviewing some of the ins and outs of most of the LS variants.
The LS4 isn’t listed because it’s not a good engine swap idea since it was changed to work for FWD cars. That means that modifying it to work on a RWD truck like the C10 is going to be incredibly complicated and generally speaking isn’t worth it.
The most powerful engine for the C10, ever, was capable of producing a mere 240 horsepower, which means no matter which LS engine you select, it’s going to be a significant upgrade.
|LS1||5.7L||305-350 hp||225-365 lb-ft||1997-2004 Corvette
1998-2002 Pontiac Firebird
2004 Pontiac GTO
|LS6||5.7L||385-405 hp||385-400 lb-ft||2001-2004 Corvette
2004-2005 Cadillac CTS-V
|LS2||6.0L||390-395 hp||400 lb-ft||2005-2007 Corvette
2005-2006 Pontiac GTO
2006-2007 Cadillac CTS-V
|LS3||6.2L||426-436 hp||420-428 lb-ft||2008-2013 Corvette
2009 Pontiac G8 GXP
2010-2013 Corvette Grand Sport
2014-2017 Chevy SS
|LS7||7.0L||505 hp||470-481 lb-ft||2006-2013 Corvette
|LS9||6.2L||638 hp||604 lb-ft||2009=2013 Corvette|
|LQ4||6.0L||300-325 hp||360-370 lb-ft||1999-2004 Chevy Express
1999-2004 GMC Savanna
1999-2004 Silverado 2500
1999-2004 Hummer H2
|LQ9||6.0L||345 hp||380 lb-ft||2002-2006 Cadillac Escalade
2003-2007 Chevy Silverado
2003-2007 GMC Sierra
|LY6||6.0L||352 hp||382 lb-ft||Some heavy-duty Silverados, Sierras, Suburbans, and Yukons|
The Engine Swap Requirements
An LS engine is a modern engine, and as such, getting it to work with your C10 is going to require a little bit more than simply plugging it in and hitting the road. The good news is that if your engine was showing its age, most of these components will be as well, and replacing them all at once will give you that dramatic night-and-day sensation that makes an engine swap so satisfying.
This guide will walk you through the basics of what you should know before attempting an LS swap, but it’s obviously not step by step nor does it account for every individual situation. An LS swap guidebook is a great idea for anyone who has never done an engine swap before.
The basics that you’ll want to think about in addition to the engine are going to be:
No surprise. Every engine needs something to literally mount it into the engine bay and the LS engines are no exception. You will need a set of engine mounts to successfully complete your swap.
Transmission and Driveshaft
The C10 transmissions aren’t rated for nearly as much horsepower as the LS engine is capable of producing, so it’s recommended that you go ahead and install a new transmission at the same time. Though this is optional, if you choose to stick with the stock transmission you won’t be able to use the LS’ full power without destroying your transmission.
Naturally, if you’re replacing your transmission, you’ll also need to replace your driveshaft with one that will accommodate the new transmission to rear axle difference.
There are a lot of transmissions that will work. If you’re looking for a manual, the transmission of choice for most is the T56, a relatively powerful and easy-to-find transmission. The T56 has a lot to recommend it by, depending on the T56 you’re able to locate, they have a substantial torque capacity rating. They also have overdrive gears, a hydraulic clutch, and aluminum bellhousing. They also have brass synchros, which improves their longevity substantially.
If the T56 isn’t your cup of tea, you could also purchase one of the newer Tremec T5s. You most likely won’t want to get an older T5 since they had a reputation for being overly sensitive to torque outputs and were easy to break, but the newer ones have substantially improved torque capacities. The reason that a lot of people prefer the T5 to the T56 is that it’s easy to work on, and is absolutely riddled with aftermarket support.
If you’re more interested in an automatic transmission then you’ll be looking for a 4L60E, or any other others in that series, like the 4L70E or 4L85E.
If you’ve already decided to grab a junkyard engine, you can also grab a transmission. The LS has been paired with a lot of transmissions through the years, so you’ll have plenty to choose from.
Clutch and Flywheel
If your transmission doesn’t include a clutch and flywheel, you’ll want to get a new clutch assembly to accompany it. There are a lot of differences between clutches, but which one is right for you will be determined primarily by how you intend to drive your C10 after your LS swap is complete.
The other big determiner will, of course, be the spline count of your transmission.
Once you’ve picked your transmission, the spline count will narrow down your clutch options, then you’ll want to think through clutch materials. For driveability, you’ll want an “organic” material clutch. Though these discs can’t handle the heat of street racing, they offer a comfortable pedal feel. Metallic is the most durable in terms of heat, perfect for race applications, but it can generate a lot of “chatter” which makes for uncomfortable daily driving.
Intake and Exhaust System
The respiratory system of the engine is attached to the engine, so when you’re replacing the engine, you’ll need to replace your intake manifold as well as your exhaust. Some people take the opportunity here to upgrade a few things as well, whether that means installing a cold air intake, or perhaps some LS-specific headers.
This is perhaps the most optional but also the most recommended. When you increase your horsepower, you should also reevaluate your brakes and their stopping distance. More power means that the truck is harder to slow down, so you’ll likely want to improve your brakes as well to match.
More engine power means more heat, and you’ll need a way to cool it down. You will need a proper cooling system that’s designed to work with an LS engine. This isn’t a place you want to cheap out, few things will destroy an engine as quickly as an overabundance of heat.
The radiator is one area where you may need to consider an aftermarket option even if you’ve managed to junkyard together everything else.
Most stock LS radiators had their inlet and outlet passages on the passenger’s side. Rerouting these to the driver’s side of the engine presents a challenge that requires substantial fabrication and some hose contortion. It's also a good idea to install a coolant overflow tank.
Or you can just get an LS engine-specific cross-flow radiator.
Oil Pan or Crossmember
It’s recommended that you try to fit your LS engine in first. While the oil pan is usually able to clear the crossmember without any problems, there is a distinct possibility that it will not and that you’ll have to buy either a new oil pan or a new crossmember.
LS engines are designed to be fuel-injected, which means a whole new fuel system for your C10. This will be a huge improvement over the carbureted systems of old though, with a better fuel-to-air ratio for your truck. Some people have managed to keep the carbureted system, but you’ll need to keep this in mind when you work on your PCM.
The first choice you’ll have to make for your fuel system is whether you would prefer an in-tank or an external fuel pump. Obviously, retrofitting an in-tank pump into your C10 will increase the overall cost of your engine swap, but it will also last a lot longer and will likely run better.
It’s also more complicated to install an in-tank pump though, and if you have your heart set on doing all of the wrenching yourself, you may prefer to instead do an external pump. In addition to the pump, you’ll need wiring, with well-connected grounds. A common mistake some C10 owners make is not removing the paint from the metal that they’re using to ground their wiring. Clean metal is essential.
LS engines also use a return-style fuel system, which means connecting return lines. It can be complicated to run a single-line fuel rail that also handles returns, but you can instead run a dual-line fuel rail. In addition to being less prone to failure, this style of system will also ensure a little more power.
Perhaps the most important and crucial component is the electronic control unit. This oft-forgotten component allows the engine and the car to communicate. You might be wondering how to make sure you get the right ECU for your engine. If you’re buying used, you should make sure that you get the original computer, harness, and sensors.
If you aren’t able to get everything though, you may find yourself in a bit of a conundrum. There are a lot of ECMs, and they’re all just a little bit different. Some require a transmission control module, some are driven by wire and others are driven by cable. The good news is that once you have an ECM you can reprogram it to work with your specific setup.
There are also aftermarket controllers designed specifically for LS swaps that can help you make your engine behave exactly the way you would like it to. Though this seems like perhaps the least exciting choice, it’s one of the most important and the most customizable.
With pretty much all of these parts you’ll run into the same question as you had with the LS engine of whether you want to try to scrape what you need together out of the junkyard or just purchase new. The great news is that you don’t have to pick all one way or the other. If you want to purchase a new engine but install an older fuel system with it, that’s up to you.
Some junkyards will even guarantee their parts.
Prepare Your C10
The first step of any engine swap is preparing your vehicle. That means removing the old engine and all of its parts. It’s best to be gentle during this step and get an idea of where everything is. Depending on where the engine ends up sitting, it’s possible you’ll need to replace additional components, but for now, treat everything like you plan on keeping it in perfect condition.
Fortunately, LS engines are prized for their small size, so you should be able to fit it into the space opened up by removing your old engine.
Some people have even managed to make a little money back on their engine swap by selling their old engine and transmission, as long as they’re in okay shape, there’s no reason not to.
Prepare the Engine
In the same way that you need to prepare your vehicle, you’ll also need to prepare your engine, installing its new flywheel and clutch, and making sure its engine mounts are in place.
Try to lower the engine in with its existing oil pan, and if that doesn’t work then make a choice as to whether you’d rather replace the oil pan or the crossmember.
Once the engine is in place and the transmission is connected, then it’s time to begin the actual challenging process of getting everything operating together.
Getting Everything Up and Running
Once your engine, transmission, driveshaft, and fuel rails are connected to the body, it’s just a matter of getting everything operating together. You’ll need to hook up and program your ECM, make sure that your throttle system is fully operational, and make sure that there is proper clearance for all of the other engine components.
You can really do things in any order you want, as long as you stay focused and systematic. The best way to approach it is to think of each item as an entirely separate install and to complete it in full before moving on to the next.
You can work your way through upgrading the exhaust system, improving the brakes, installing the new fuel rails, and finally installing the ECU, which is best left for last. Once you’ve finished installing your new engine, all that’s left is to test it out.
Testing Your Engine
As tempting as it might be to floor it out of your garage and feel the instant power of your new and improved engine, that is not recommended. Instead, take it slow. When you first drive out, keep your windows down and listen in case there are unusual noises.
Completing an engine swap is a lot of work, and you deserve the opportunity to enjoy your work for a long time, so get everything started on the right foot.
You’ll want to break in your new engine the same way you might break in a new Mustang, making sure that your first maintenance checks are thorough and complete.
With a new transmission, engine, exhaust, and brake system, you’re essentially driving a brand new C10, and hopefully you’ll enjoy it for years to come.