Everything You Need To Know For Your LS Swap

You could say that we’ve been around the block a time or two when it comes to all things LS. If we had a nickel for every time that we’ve built or swapped an LS into a car we’d have… well a lot of nickels. And when you work with the LS as much as we do, you learn a few things along the way that just might make your life a bit easier when performing one. With that in mind, we and the guys over at Jegs decided to bring you a little somethin’ to make your life a easier when it comes to your next LS swap.

Why Choose The LS

If you’re reading this, you’re probably pretty well aware of the LS’s benefits. They’re compact, simple, reliable, and just so happen to produce a lot of power with very basic mods. And while the power production is great, the main reason people love to use them for swaps is their simplicity. It’s this facet that’s really driven the platform to new heights.


With the help of a huge aftermarket that’s sprung up around the engine, you can bolt an LS into almost any platform without a ton of fabrication. The support for the LS is nearly unrivaled by any other engine in history.

Part of what drives the popularity of the LS is also its availability. You are only a junkyard away from picking one up for dirt cheap. Even if you decide to go with a block—either short or long—from a vendor, they can still be had for relatively small change. But what’s the first thing to consider when attempting your swap?

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The first concern when installing an engine in a car is obviously the mounts—where it will sit. Luckily for us, there are tons of companies out there making LS swap kits for everything from a first-gen F-body to a Mazda Miata.

For example, take the TransDapt Swap-in-a-Box kit we spotlighted in the video. It comes with everything you need to get an LS sitting between the fenders of your favorite ride. The kit includes headers, oil pan, oil pick up tube, engine and frame mounts, the transmission crossmember, and the transmission mount for almost any gear box GM makes.

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And TransDapt isn’t the only one making kits for LS swaps. There’s an LS swap kit out there for virtually any combination that you’d like to put together. Once the engine and trans are in, it’s time to think about how you’ll route the exhaust.


Sourcing a set of custom headers used to be one of the main concerns of any swap. But these days, there is probably a purpose-built set for your swap sitting on a shelf somewhere ready to go. That’s because brands like Hooker have done the hard work for you and have already plumbed a set of pipes to clear the engine bay on your project car.

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They even offer them for imports. Want to put an LS in an S13 240SX? They’ve got you covered. Not only do they most likely have a set of headers for your application, they typically offer them in multiple coatings, making what was once a pain in the neck a breeze.

Transmission and Torque Converter

One of the main questions we get around these parts is whether an old school transmission, like a TH350 or 400, will mount up to an LS. The answer is yes. While the bolt patterns are slightly different, older Turbo transmissions will in fact bolt right up to an LS engine without any adapters. The torque converter on the other hand is another story.

When it comes to the torque converter on an LS swap you have a few different options. You can get a custom torque converter made for your particular swap, which changes the spacing and mounting locations, or you can just use a spacer.

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The spacer makes the install very simple as it moves the flex plate out toward the transmission, allowing it to properly mesh with the torque converter. Typically, you only want the torque converter to come toward the engine 1/2 of and inch from being fully seated. Any further and you risk the converter not aligning with the trans pump and input shaft correctly.

The spacer simply corrects this geometry by bolting between the flex plate and the crankshaft flange, eliminating the need for a custom piece. Obviously, this is the cheapest way to go as well.

Keeping Your Cool

Next up is how to keep your transplanted LS cool under the collar. Most think that they’ll just find some conversion hoses and utilize their stock radiator. This is not always feasible in every application. Swapping out a radiator, like the all-in-one kit from Be Cool is a sure fire way to make sure that your LS not only has the correct routing it needs, but that the setup is up to the task of cooling as many ponies as you plan on making.

The kit also makes for a cleaner installation as it comes with the pre-molded hoses as well as the fan and shroud. This keep everything neat and tidy and ensures that your new LS will look like it came in that engine bay from the factory.

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Throttle Control

Another question we get asked frequently is how to run a cable operated throttle body on an application that didn’t already come with one. There are many routes to overcome this, but some are more simple than others.

If you intend to run an engine that originally came with a drive-by-wire throttle body (anything Gen IV and above, and some Gen III applications), it is often easiest just to buy a pedal position sensor and mount it. Not only is it an easy way to do it, but it can really clean up the engine bay. Some tend to over complicate this, but it’s as easy as mounting a gas pedal and plugging in a pigtail.

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Other routes include re-flashing the PCM with an operating system that originally included a drive-by-cable throttle body in the original application. Typically this can only be accomplished with Gen III engines that were installed in vehicles both ways. The ECM has to have an IAC driver in it to be able to operate the idle air control valve, which most Gen IV controllers didn’t come with.

Our recommendation is to just stick with what ever the vehicle came with in the first place. Both routes are fairly straight forward so their is no need to over complicate it with swapping out controller operating systems.


This is arguably the most daunting of tasks when it comes to an LS swap. Modern day electronics are vastly more complex than ever, and that becomes a serious factor when swapping any modern mill into your ride.

Luckily, brands like Chevrolet Performance and Holley have gone to great lengths to ensure that swapping an LS into your project is basically a plug-n-play ordeal. Their complete stand alone wiring harnesses will allow you to run an LS without any serious wiring know-how.

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MSD’s Atomic EFI kit actually gives you everything you need to get an LS up and running from a wiring standpoint and includes all of the plugs, connectors, and controller built into the fuel rails—making for a super clean install. Tuning it is easy and requires just a few parameters to be input via a hand-held module, but requires no extensive tuning knowledge.

And if you’d rather not run EFI all together, brands like MSD make full kits that allow you to run a carburetor instead of port fuel injection to retain that old-school look but retain modern coil-near-plug ignition—giving you the best of both world if that’s the route you choose.

Fuel System

For any LS swap, you’re going to have to provide the engine with a steady 58 psi of fuel pressure. This can be accomplished several ways. Mounting an external in-line fuel pump is probably the easiest. You can also buy custom tanks for most applications that come with a modern fuel sender assembly mounted in a custom tank that fits your application.

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Feeding The Beast

One of the final consideration in any LS swap is the air intake. Many vendors offer LS swap air intake kits, or you can go universal like the piece mentioned in the video from Spectre Performance.

One thing to be sure to consider is if you will be running the car with a speed density tune or will be retaining the mass airflow sensor. If you’re going with the speed density setup, you can realistically put any filter you choose directly on the throttle body, or just a straight or 90-degree pipe with a filter on the end.

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If you are retaining the MAF, it maybe a good idea to use a piece like the one we chose from Spectre. It has the MAF slot already built in and retains a clean look for the install.

Wrapping It Up

As we mentioned before, LS swap are much more straightforward than almost any engine swap has ever been. From the intake to the oil pan, there are multiple vendors out there that most likely supply any part that you will realistically need to complete your swap without any fabrication.

Jegs carries every part we mentioned here, so head over to their site and check out all of these great components and more. So what are you waiting for? Get out there and get wrenching.

Article Sources

About the author

Chase Christensen

Chase Christensen hails from Salt Lake City, and grew up around high-performance GM vehicles. He took possession of his very first F-body— an ’86 Trans Am— at the age of 13 and has been wrenching ever since.
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