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LS Engines: Dream Swap Or Nightmare?

Posted in How To: Engine on February 1, 2012
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Sometimes the stuff we dream about turns out to be a nightmare. Like chasing after that hot cheerleader only to realize that she’s high maintenance or the football coach in drag. That often can happen to us as we pursue components for our 4x4s that we think will make us the cool kid on the block, and can easily be the case with engine swaps. The search for more power, lighter weight, and cool looks can be very costly, and being fully educated before you make up your mind on the right powerplant for your off roader is one of the smartest things you can do.

Right now, the hottest engine swap people are talking about are GM LS engines. They’ve been around for more than 10 years, they can make sick horsepower and the most desirable versions are all-aluminum, giving you a weight savings on the nose of your truck or Jeep. And it’s a Chevy engine, so it is an easy swap, right? You might think that if you already have a small-block Chevy in your 4x4, an LS will bolt right in. That’s where not being completely educated can turn this dream date into a painful and costly experience.

While the LS family of mills is produced by GM, the company that faithfully kept the small-block Chevy interchangeable for 50 years, there’s nothing that is going to unbolt from your old 350 V-8 and install on an LS engine. It’s every bit as different from your favorite old small-block as a Toyota Tundra V-8 would be. Want specifics? The bellhousing bolt pattern is different, the motor mount location and attachment is totally different, not a single piece from an older Chevy accessory drive will bolt up, the intake manifold is different and there is no distributor.

To be fair, if you don’t have a small-block Chevy under your hood and you’re considering a motor swap, the LS is just as viable as any other V-8 you might consider. But you’ll still do well to look carefully at everything that an LS swap will entail. Compare to your other options. Buying a salvage yard Corvette LS3 and all the parts you’ll need to install it in your 4x4 can easily set you back more than $10,000. Want a new engine and top-notch parts? Better apply for a Platinum American Express card.

Why are LS engines such hot motors to swap into a 4x4? There are two key reasons people like the LS series. One, it’s a Chevy engine (okay, really it’s a GM engine). That means that there are tons of them in the salvage yards, and they are relatively easy to find parts for. The aftermarket has completely embraced the engine, making upgrades as well as required swap components fairly easy to find. Second, they make good power in stock form and can make sick power without too much trouble. However, do not confuse the word trouble with cheap – most upgrade parts for an LS engine are expensive compared to what you might be used to spending for older V-8 engines. There’s one more element that contributes to the engine’s popularity – the cool factor. For some people, having a Corvette engine in their Jeep or 4x4 is worth the trouble despite the power/dollar ratio. And we admit that the ability to have a complete, fuel-injected engine out of a production performance car is pretty desirable.

However, here’s a rundown of what we wish people had told us before we embarked on our first LS swap. Choose your donor engine carefully. The wrong one will drive up cost with the need for an oil pan and accessory drives. The cheapest donor engines have a lot of miles – skip these as you’ll need to rebuild them. Using the factory fuel injection will require a stand-alone wiring harness and ECM or you’ll need to be a whiz at wiring to follow the very intricate directions you can find online for adapting the factory wiring harness. You’ll also need a wiring harness and controller for the ignition – this is sometimes incorporated into the fuel-injection controller, but not always. There are only a couple of carburetor intake manifolds available if you’re thinking you’ll skip the fuel injection, and they are expensive. Aftermarket accessory drives are horrendously expensive. There were quite a few variations in harmonic dampers and water pumps, so you generally cannot take a truck accessory drive and install it on a Corvette engine. If you use an adapter bellhousing, you will probably need to convert to a hydraulic clutch system. You can’t use a mechanical temperature gauge because the sensor won’t fit anywhere in an LS engine, and you’ll need metric to SAE adapters to use your electric aftermarket gauges.

Is an LS swap right for you? That depends on what you are starting with and how badly you really want it. If you’ve already done a Chevy V-8 engine swap, you’re probably money ahead to build another Gen I engine that makes the power you’re looking for and skip the hassle of an LS swap. If you have nothing that connects to the engine, then this swap is worth considering along with all of the other viable swaps for you 4x4.

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Favorite LS Picks
With LS engines coming in everything from Camaros to pickup trucks, what specific engine you start with dictates if this swap is worth it or not. Before you decide you’re going to do an LS swap, look at what engines you can get, how much they cost, and what kind of power they make. It’s very important to look at the torque curve of an LS engine compared to others that you might consider. The advantages of the LS engine really boil down to the cylinder head design. Some of them make good torque in stock form, but the engine really comes alive with higher-rpm horsepower.

The most popular salvage yard swap candidates are the 5.3L truck engines, also called a Vortec engine. These have iron blocks and produce around 300 horsepower and 350 lb-ft of torque, depending on the year and model of the truck. They are plentiful and not too expensive. They also come with an oil pan and accessory drive that will work in most 4x4 trucks. The all-aluminum F-Car (Camaro and Firebird) and Corvette LS engines have two very desirable qualities. They are lightweight and they make much better power. However, they do not have an accessory drive or oil pan that will fit in a truck or Jeep, so you’ll need to factor in the cost of changing these. Most 4x4 swaps can use the exhaust manifolds from these cars, however, so you’ll be money ahead on that front.

The L92 may be the Holy Grail for a truck swap. These are all-aluminum 6.2L engines that came in ’07 and newer Cadillac Escalades and other over-priced derivatives of the Suburban and Tahoe. They make 403 horsepower and 417 lb-ft of torque and come with the right accessory drive and oil pan.

The alternative to the salvage yard is buying a brand-new crate engine from GM Performance Parts (GMPP). The good news is that GMPP figured out that the LS series was going to be a hot swap engine. The company offers nine, count ’em, nine versions of the LS engine. They range from a 315 horsepower 5.3L (LS327) engine up to the most drool-worthy 638-horsepower, carbureted LS9. Most of these start off as assembly-line Corvette or Camaro engines, so they do not include an oil pan or accessory drive that will fit in a truck. And none of them include the controller for the fuel injection or the accessory drive system – both of which can be purchased from GMPP. The advantages of a GMPP crate engine are that the engine is brand new and it comes with a 24-month/50,000-mile limited warranty. But make sure you get out your calculator to tally up what swapping in a new LS will really cost.


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