It’s crazy to think that the LS engine is now about a quarter century old, but here we are toward the tail end of its mass production. With the Gen V now in full swing and taking over every new GM engine compartment that once housed an LS, are the LS’s days as a viable swap option numbered? We certainly don’t think so, and it seems that you don’t either! 

Whether you’re starting out with a daily friendly 4.8L LR4 or going HAM with a 7.0L LS7, it’s hard to make a wrong decision when swapping or modding an LS-based engine. So, we’ve compiled the top 10 questions we’ve been asked about them and offer you some simple answers to hopefully enlighten and entertain.

1 Is the LS engine reliable?

LS engines, like most engines, are pretty reliable as long as they’ve been properly maintained, and they’re even pretty decent when somewhat neglected! They are inherently strong, partly due to their main cap and head designs, which is why it’s not uncommon to see engines with 300,000-plus miles on them with only regular maintenance. Used, high-mileage LS-based engines are seeing large amounts of boost with very minor modifications and usually survive quite a while. So, in our opinion, yes, they’re reliable!

2 Who designed the LS engine? 

It should come as no surprise that the chief engineers of the LS were not only skilled engine designers, but lifelong gearheads as well. Ed Koerner and Tom Stephens came up with the general architecture of the LS, with design team members Alan Hayman, Jim Mazzola, Ron Sperry, Bill Compton, Brian Kaminski, Jon Lewis, Stan Turek, Don Weiderhold, and Dave Wandel contributing their expertise to one of the world’s most beloved engine platforms.

3 What are the different LS engine sizes? 

If we’re including all derivatives, the various displacements that have been available over the years include 4.3L (yup, a V-6 variant released in 2014), 4.8L, 5.3L, 5.7L, 6.0L, 6.2L, 6.6L, and 7.0L engines. Each of these has been refined through multiple iterations and differed depending on the application.

4 Can an LS engine be carbureted?  

We’re of the mindset that EFI is a better option 99% of the time, but if you’re swapping an LS into a classic truck and want to keep things as simple as possible, a carbureted setup may indeed be a good choice. You’ll need an aftermarket intake manifold designed for a carb, the carb itself, and an electronic ignition controller (LS-based engines don’t have a spot for a distributor and still require an ignition source for the coils). You could install a front-mounted distributor if you really wanted to, or any other multitude of things for that matter, but that’s a lot of trouble to go through to ditch the reliability of EFI. In the end, you’ll have to run your own numbers and see if this is the right move for you.

5 Which LS engine has the most horsepower?  

If we’re talking about any LS engine ever directly offered by GM, the winner is the long-discontinued LSX454R, conservatively rated at 770 horsepower and 612 lb-ft of torque. The most powerful LS in a production vehicle is in the upcoming 2023 Cadillac Escalade V, a 6.2-liter pushing 682 horsepower and 653 lb-ft of torque!

6 What transmission can be used with an LS engine? 

Technically, you can use just about any transmission with the use of an adapter, but luckily the list of options is long, most requiring only minor modifications. Have an old Powerglide or manual 3-speed? Yup, those’ll work with the proper spacers and hardware. So will that Turbo 350 in your uncle’s shed, or even that T-5 5-speed in that Astro at the wrecking yard. There are generally multiple options to achieve any given combination.

The 4L65E and 4L80E automatics are popular choices since they are more robust than the 700R4/4L60E and are made to bolt right on to LS engines. That being said, plenty of folks have used “weaker” transmissions with success when coupled with a consistently light foot. On the manual side, T56s are the usual fare, but some opt for the beefier Tremec TKO-series transmissions.

Of course, the more power and torque your engine have, the stouter you want to go. That’s where the 4L80E and 4L85E really start looking like a good idea!

7 Which LS engines have an aluminum block? 

We thought this question would be a bit more complicated to answer, but as it turns out it’s pretty straightforward! Every LS engine that came out of a passenger car had/has an aluminum block, but trucks and SUVs usually received an iron block. Notable exceptions are the LS2-equipped SSR and Trailblazer SS, and L76-equipped Silverados and Sierras from 2007-2009 (the Avalanche kept the L76 through the 2013 model year).

8 Which LS engine is best for adding boost? 

Both 5.3L and 6.0L engines are the most popular for turbocharging since they are widely available and can support up to 1,000 horsepower with proper preparation, but we’ve pretty much seen every iteration of the LS receive boost by now, and both cathedral port and rectangular port heads flow very well under pressure. From backyard “eBay” turbo setups to high-dollar twin-charged dream builds, anything goes when it comes to forced induction on an LS!

The key is to upgrade as much as possible before you go crazy. Oil pumps and timing chains are common failure points, so swapping out the originals for

If money isn’t an object, why not look into factory boosted options such as the LSA, LS9, or even a Gen V LT5 (yeah, we know, but LTs are the future of the small-block, are they not)?

9 When was the first LS engine made? 

The engine we all know and love was first introduced in 1997 in the C5 Corvette in 345-horsepower 5.7L LS1 form, and as the 270-horsepower 5.3L LM7 in the 1999 Silverado/Sierra. Both engines would receive refinements and improvements over their life cycles, resulting in more power across the board.

10 Where is the best place to buy an LS engine? 

Well, that depends! If shopping new, you can’t beat buying an LS through any of Chevrolet Performance’s authorized retailers, but LS-based crate engines are also available from aftermarket companies such as Edelbrock.

If you’re in the market for a good used engine and want to build it yourself, your local Pick-N-Pull type place is likely the cheapest but may result in a dud unless you can inspect the engine thoroughly before buying. It may be in your best interest to purchase any available warranty on the long block.

We’ve had decent luck with used engine resellers as they can usually provide a video of the engine running and will often offer a reasonable warranty. You’ll pay more up front but will receive better service than the pull-it-yourself route.

Lastly, there’s Craigslist, Facebook Marketplace, and any of the other person-to-person websites and apps that sell everything under the sun. At a bare minimum, you’ll want to try to check the compression and the condition of the oil if possible.


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