Uncommon LS Swaps: Building Specialized Setups for Strange Engine Conversions

Recently, we started to deep dive into the topic of LS conversions with the help of John Potucek from Keystone Automotive. As part of the discussion, we mentioned how important proper planning is when planting an LS into a vehicle that never had this engine as an option. That advice is especially true in the conversation of uncommon LS swaps. Sure, dropping an LS in place of an existing V8 can be a little puzzling but overall, LS swaps are known for being rather straightforward, budget-friendly, and versatile. That is, until you come face-to-face with some configurations that can present knuckle-busting difficulty. Have we piqued your interest? Good, stick with us as we continue to unpack all you need to know about the LS platform—from street to track. 

Truth: the more creative you get with LS conversion ideas, the further you drift from aftermarket solutions. Admittedly, this can leave you in a bit of a dark place if you’re staring at an oddball platform with no idea where to start.

Now, you may be thinking, “Is there really such a thing as an uncommon LS swap?” I mean, people pack these things into freakin’ Miatas—along with everything else under the sun. While some swaps are certainly easier than others, it’s true that LS engines find themselves married to a wide array of vehicles.

This is good news for you.

As we always say, the first step of any good build plan is research. And with forums containing volumes of information on a variety of LS swaps—both common and strange—a lot of your plan can be based on what other builders have done. After all, you don’t always have to reinvent the wheel. Even if you can’t find a swap example that matches your exact model, just reading through the process of a similar swap can help you sort out how to mount the engine, trans, and differential if necessary.

That said, let’s break down some of the basic obstacles you’re up against when tackling an uncommon LS swap.

A Premium on Space

While swapping an LS for a front-mounted engine on a rear-wheel drive platform certainly makes things easier, there’s still plenty of work ahead.

If the vehicle you’re working with originally hosted an inline engine like a four- or six-cylinder, plan to spend a good amount of time making room under the hood. It won’t always be as simple as figuring out how to bolt the engine in place.

Removing accessories and other under-hood components may be the least of your worries. Altering or removing components like the inner wheel wells, radiator support, and even the firewall may be necessary to get the engine, radiator, and exhaust headers to fit.

In some cases, you can also run into the issue of having to alter the hood. (This isn’t always a bad thing—but if you’re building a sleeper, it’s definitely a detail to remember.)

Necessary Custom Work

Often when performing an engine swap, placement of the headers and the oil pan can be serious obstacles to overcome.

While you probably already know this, you don’t want to base the swap on how your existing equipment fits into place. Instead, you should figure out how the engine and transmission need to mount and have these pieces custom-made so you can make room where possible. If it means a little more massaging to the firewall so the headers will fit and a little bit of grinding on the K member for the oil pan, then so be it.

Trans Tunnel Chopping

“You yank your Mazda’s little 4 cylinder [sell for $1,000] and grow a set because you have to chop up your trans tunnel,” writes one Miata forum member about his home-brewed LS swap.

You won’t always be able to bolt your LS to the transmission currently in the vehicle. This is especially true if you’re planning to run an engine producing considerable amounts of power. This means that the chop saw’s meal doesn’t end with what’s under the hood.

If you’re lucky, getting a transmission mounted properly may be done with an altered/custom transmission cross member and a mallet to make room. Though, if you’re tackling a more uncommon LS engine swap, like a Miata, Fairlady, or something with a small trans tunnel, expect to cut out what’s present and make your own trans tunnel. (Or at least reshape some sections to fit the 4L80E or Tremec you’ve opted for.) It’s important to remember that the dimensions of the transmission will be a deciding factor on what work needs to be done here.

As for transmission choices, natural selection has pretty much made easy work of this.

“We highly recommend the GM 4L60E transmission over a traditional 3 speed automatic. The 4L60E transmission provides an ideal driving experience to match the price point,” says LSX Innovations, a manufacturer of US-made LS swap parts and components.

“The 4L80E and 6L80E GM transmissions are fantastic choices as well if your budget allows. Usually, they are not needed unless you have a built engine. All three of these GM transmissions can be sourced easily from a local junkyard.”

If you’re looking for a more exciting driving experience, LSX recommends the T56 or TR6060 transmissions. “With the correct flywheel and clutch (sourced from the donor vehicle of your transmission), either of these transmissions can easily bolt up to any LS engine you are using,” the company explains.

Our friend from the Miata forum opted for a T5 with his LS conversion, which shows that there is flexibility in transmission choice depending on power levels and the weight of the vehicle.

Different Differential

If you’ve made it as far as planting an LS and ripping the interior apart to fit the proper transmission, the next step is to do yourself (and your vehicle) the justice of putting power to the wheels with a stout differential.

This can be a very broad topic, as the vehicle may have an independent or solid axle differential. The best way to go about this is by seeing what already exists in the world and has either a good deal of information in terms of fabrication or even aftermarket support.

At the least, you can expect to put beefier axles in place. But if a swap is necessary, you can expect to have a good amount of work here alone. Though, luckily this part of the build will generally leave you without having to chop up or modify the vehicle dramatically.

Wiring and Plumbing

When taking on a task like this, you can easily be consumed by the major steps and lose sight of the simple tasks. The whole time you’re setting up this swap, you might underestimate the challenges that present themselves when it comes time to actually get the motor running.

Keep It Painless

In our title covering this same topic for more typical platforms, we took the time to highlight Painless Performance’s stand-alone wiring harnesses for LS engines and a number of applicable transmissions. Here, you definitely want to consider a similar unit. However, don’t forget that in many cases where you’re jamming in an LS, you may very well be left gutting the entire vehicle—which almost always exposes crummy and tired wiring that may not be replaceable through aftermarket suppliers.

To keep headaches to a minimum, you can opt to revamp the existing wiring harness with something like Painless Performance’s 21 Circuit Classic Custom Wiring Harness. A universal harness, it’s ideal for hot rod or street rod builds but can easily accommodate just about any vehicle you have in mind. Painless Performance ensures it has enough length to handle full-size and muscle cars, as well. American-made, it’s the company’s most widely used customizable wiring harness to date.

Keep It Stealthy

On that note, plumbing likely won’t be that simple either. If you’re running this system in place of a carbureted platform, you’ll likely need to swap your tank to accommodate an in-tank pump that can supply fuel to the engine. While Aeromotive’s Stealth stamped-steel reproduction tanks are an awesome go-to for LS swaps, they aren’t available for every make and model. So, if you can’t buy the tank you need, hook up a fuel cell to get you going!

The brand’s Stealth Fuel Cells are true universal aluminum fuel cells, boasting excellent performance in EFI or carbureted applications, forced induction or naturally aspirated, street driven or race-ready. An innovative baffling system inside the cell ensures that the fuel pump inlet always has a constant column of fuel, eliminating slosh issues. And, unlike a lot of other tasks throughout your build, the installation of one of these babies is super simple. Since these can be mounted anywhere, just strap in the cell and hook up your feed and return lines. That’s it.

Don’t forget though, that if space is limited, corrosion and abrasion may be serious obstacles to overcome. In this case, there’s no solution for Aeromotive’s A1000 braided Stainless Steel Fuel Line. A1000 series hose is available in AN -6, -8, and -10, and pre-cut lengths from 4-ft to 20-ft.

Have you tackled any uncommon LS swaps? Was it worth it? Let us know in the comments what kind of build obstacles you faced.