Guide to Swapping an LS3 into your Street/Strip Chevy
The long production history of the LS engine family allows for a lot of options, and it’s best to consult the experts at GMPP or LS swap companies to help you find the motor that fits your build’s budget and horsepower demands. They can make sure you’re headed in the right direction.
To illustrate just how straightforward putting a new GMPP powerplant into a classic musclecar can be, let’s look at what’s involved in grafting an LS3 into a Chevy Nova.
The Car: 1971 Chevy Nova
The Engine: GM Performance Parts LS 376/480
Making It Happen: BRP Muscle Rods Swap Kit w/Hedman Hedders & Keisler Perfect Fit Kit w/Tremec TKO-600
Even though we’re using an LS3 backed by a manual transmission, the same process follows for any swap project of this kind. Every LS engine shares the same mounting position for both the engine and transmission, whether it’s the LS1 or the LS9. As for the transmission, swap kits exist for both stick shift and automatic options.
6.2 Liters of American Muscle
“Power, efficiency, sophistication, durability, reliability… Should I go on?” asks Dr. Jamie Meyer, head of Product Integration for GM Performance Parts, detailing the advantages of LS engines verses traditional small-block Chevys. LS engines have come a long way since 1997 – The LS3, first introduced as the base engine in the 2008 Corvette, punched out the original LS1 displacement from 5.7 to 6.2 liters and added strength to the block casting to support more power. The 430-horse Corvette mill subsequently found its way under the hood of the late, great Pontiac G8 GXP, then got the nod as the standard powerplant for the new Camaro SS. This versatile engine is a personal favorite of Dr. Meyer, and the LS3 crate motor can be ordered in a few different flavors from GMPP. You have options for EFI or carbureted setups, and the already-formidable stock internal components can be replaced with GMPP upgrades when you order.
We used an EFI version of the all-aluminum Ford-eater and opted for the variation that included a GMPP Hot Cam. Known as the LS 376/480 (where 376 is the displacement in cubic inches and 480 is the rated horsepower), it features the same solid 6-bolt aluminum block, nodular crank, high performance rods, and 10.7:1 pistons as the standard LS3, but it has one big difference – an aggressive performance cam.
The LS3 started out its production history as the base engine in the 2008 Corvette, followed by the Pontiac G8 GXP and the new 2010 Camaro SS.
The bumpstick installed in this engine features a .525” max lift on both the intake and exhaust side, and the duration is 219/228 degrees at .050” lift with a 112 degree lobe separation angle. Compared to the stock cam, the added duration packs an additional 50 horsepower over the standard LS3 crate engine. Despite the additional power on tap, you still get the peace of mind for this 480 horsepower crate engine that comes from a 24 month or 50,000 mile warranty, with service provided by any local GM dealer. One thing to note, however, is GM’s warranty starts at the time of the engine purchase, not when you first hit the road. If you’re like most of us and take your time getting a project together, it’s best to wait and buy the motor close to the time of installation.
Hidden beneath the composite intake manifold is our LS3’s secret weapon – GMPP’s “Hot Cam” that adds an extra 50 horses.
Best of all, you get an engine that is both durability-tested and dyno-proven. GM designed this engine to last the life of your car, while still being capable of delivering monster horsepower.
GMPP offers a wide range of engines, and the GM Performance Parts Catalog, PN 19243162, can help you sort through them. This catalog is GMPP’s current black book of aftermarket goodies, from big ticket items like LS crate engines all the way down to GM-branded clothing and merchandise. This can be a great reference guide on what’s new from GM, but be forewarned – it’s the gearhead’s version of the Sears Christmas Wish Book, so make sure there’s room on your credit card before you crack the cover.
LS Swapping – The Prep Work
Making an engine fit properly can be an issue if you don’t have the right parts, especially when mating a chassis and powerplant three decades apart in design. To make this job a bolt-in, we picked up a BRP Muscle Rod Swap Kit. This kit is a complete package with everything needed to hard mount the engine and transmission under one part number. It even includes 1 7/8” diameter long-tube Hedman Hedders, specifically designed for the LS3 in the Nova. It uses the OEM points for the frame mounts and transmission crossmember so it can be installed in under an hour, using nothing more than some simple hand tools and an engine hoist.
We spoke with Marc Lewis of Hedman to learn more about the different Hedder options available for LS swap projects. The Hedman Husler Muscle Rod line includes applications for ’67-’92 F-Bodies, ’64-’72 A-Bodies, ’55-’57 Chevys, ’58-’64 X-Bodies, ’78-’87 G-Bodies, and even the ’92-’96 Impala SS as well as many full size trucks and S10’s.
For our car in particular, Lewis told us that Hedman manufactures its LS Swap Hedders for 1968-74 Novas in three different tube sizes and both mid-length or long-tube configurations. “Hedman has been making stepped tube Hedders for decades, and they widen the engine’s power band,” says Lewis. “The 1 3/4” segment at the port keeps back-pressure up during low RPM conditions, then the 1/8” step up to 1 7/8” creates scavenging and reduces back-pressure during higher RPM conditions.”
Included in the BRP Hot Rods Muscle Rod LS Swap Kit:
• Engine Mounts
• Frame Mounts
• Transmission Crossmember
• 1 7/8” Long Tube Hedman Hedders
We all know that LS engines can make big power. When you compare them to the stock engines you may be swapping out, that point becomes even more clear. Many small block Chevy engines struggled to make over 300 horsepower, while a new LS like ours makes 480.
Dr. Meyer reminded us, “Don’t forget to take a serious look at upgrading the rest of the drivetrain. GM Performance Parts has transmission adapters to help you use your classic Chevy transmission with a new, modern LS crate engine. Talk to your GMPP dealer to get an idea of what you need. Clutches, transmission, drive shaft (and hardware), as well as the rear end should all be upgraded to handle the increased power.”
These days there are countless options for transmissions, even for swap projects such as our Nova. Before jumping up and buying just any old transmission, keep a few things in mind. First, do you want manual or automatic? LS engines are capable of working with both manual or automatic transmissions. Which one to choose is more dependent on your car and your personal preference. Just about any GM muscle car transmission can be bolted to the back of the LS engines, as long as you have the correct bellhousing.
Secondly, how much room do you have for the transmission? For example, first-gen Camaros and Firebirds will accept a 6-speed without any modifications to the floor plan, but the Nova is another story. If you want to go with a T-56 in a Nova, you’re going to have to widen the transmission tunnel before installing the drivetrain.
The same goes for the 5-speed TKO. While it might sound intimidating, adapting the transmission tunnel to fit both options is an easy process that stock carpet will cover after you’re finished. However, many late model GM and GMPP automatic transmissions will slide right in with no alteration to the factory floorpan for those seeking a clutchless experience.
“We have multiple transmissions that you can choose from. The new SuperMatic 4L85-E will take a pounding,” Dr. Meyer explains. “We tested this behind the ZZ572/720R, so when you match it to the right converter, your LS/LSX engine will put max power to the ground.”
The TKO-600 included in our Keisler Perfect Fit Kit is rated by Tremec to withstand 600 pound-feet of torque, more than sufficient for even our stout LS3.
We wanted a manual transmission for our Nova, and we chose a brand new Tremec TKO-600. Included in the Keisler Perfect Fit Kit we were using to mount the transmission to the underside of the car and adapt it to the older car, the TKO is Tremec’s follow-on to the TR-3550, with lots of significant upgrades. The Keisler kit included everything we needed to not only mount the transmission, but also the clutch, clutch assembly, pedals, the bellhousing to make it work with the LS3, and a template to show us exactly where to modify the floor.
The shifter is also a Keisler piece, and they ship these swap kits with the shifter already installed in the correct location (out of 8 possible on the TKO) to match your muscle car’s OE shifter position. This lets you save your OE interior, and it avoids the expense of having to make a custom interior to fit the transmission.
Included In The Keisler Perfect Fit Kit:
• Shift Kit
• Hydraulic Clutch
• Clutch Kit
• Drive Shaft
• Transmission Tunnel Template and Sheet Metal
To see just how comprehensive the Keisler Perfect Fit Kit really is, check out our installation video:
Getting our GMPP LS3 engine into the engine bay of this classic GM was quick and painless because we turned to BRP Hot Rods’ LS Swap Kit to make it happen. This kit includes the engine bracket, frame mount, crossmember, and transmission mount (although we were already using the parts included in the Keisler kit) with all the hardware needed to make it stay in the car. The only thing we had to do was bolt it all on.
Included in the BPR Muscle Rod Kit:
• Two Bolt-In Frame Mounts
• Two Motor Brackets
• Energy Suspension Transmission Mount
• Transmission Crossmember
• Two Crossmember-to-Frame Brackets
• Optional Hedman Hedders
The frame mounts use the OEM three-bolt pattern to allow for a straightforward install. It’s best to have the engine bay cleaned and prepped for the new motor at this point. Take advantage of the engine being out of the car before continuing your installation.
One hint when installing an LS engine is to remove the composite intake manifold before attaching your chain. We found out the hard way and were left with a few small marks on the intake, despite taking precautions to cushion it. Nothing major, but just something to watch out for. The intake comes off with a couple 10mm bolts and features reusable gaskets for a quick reinstall later.
Here is the engine just seconds before we bolted it in.
With the Nova and the LS3 both prepped with the frame and engine mounts, we were ready to mate the two together. In addition to hooking up the frame mounts, it’s a good idea to have the transmission bolted on the engine before installation. After a quick dance with the engine hoist, two bolts can be slid through the engine mounts to lock them into place on each side just like installing an SBC.
Our Keisler Kit performed flawlessly as we enjoyed the same bolt-in luxury as the BRP Kit gave us with the engine. We placed the bolts through the holes in the crossmember once they were lined up, and we tightened everything down to spec.
Our Hedman Hedders feature 3/8″ flanges for improved sealing, and a ceramic coating that will help keep exhaust velocity up and underhood temperatures down.
With the engine installed, the next step was installing the Hedders. Hedman offers seven Hedders for all the popular GM muscle car swaps, ranging in size from 1 3/4” to 2” primaries for any LS build. For this swap, 1 7/8” ceramic-coated Husler Hedders were chosen with 3 inch collectors and thick 3/8” flanges to prevent warping. Since the Nova was already sitting on the lift, it was a quick slide-in to attach the outside bolts on the flange. We repeated this on the other side, then secured the rest of the bolts.
These LS-swap Hedders are designed to provide the best fit possible, and there’s plenty of clearance between the tubes, frame, and running gear.
But Wait, There’s More!
We know it takes more than just a set of motor mounts to make a swap like this happen. Here are some helpful hints and parts that can make the rest of your LS swap project go as smoothly as ours did.
GM Performance Parts LS Controller
It looks complicated, but the GMPP wiring harness actually makes an LS swap far easier than using a salvaged harness or trying to wire it yourself.
Don’t let the fact that the LS engines are computer controlled scare you. To handle engine management, a GMPP LS Controller kit is one the best ways to go. “This is a complete kit: harness, controller, custom GMPP calibration, fuse box, and gas pedal. Everything comes in this kit. It’s all GM, all brand new, and it plugs into the stock engine sensors, allowing you to run one of these sophisticated engines in literally anything,” says Dr. Meyer.
This one kit contains everything you need to give your new LS crate engine the command to fire up. The LS Controller kit is a major help as it saves you the time of hunting in the junkyard for a stock computer and trying to salvage and adapt it to your car.
In addition to the all-important ECU, the GMPP kit contains other necessary components like oxygen sensors and the throttle-by-wire pedal assembly.
LS Controller Kit Contents:
• MAP Sensor
• Two O2 Sensors
• Pre-labeled Wiring Harness
• Pedal Assembly
Everything comes pre-labeled, so there’s no degree in electrical engineering required. Just match the connectors to the plugs and you’re ready to burn some rubber.
Oil Pan Prospecting
The LS3 ships with a C6 Corvette oil pan that can be a tight fit in older GM applications. The Nova has rear steering which makes it an even tighter fit behind the subframe. Fortunately, there are a lot of different factory pans available for the LS family, and each GM vehicle platform has a GM pan that works best. For the Nova, a popular option is the LH8 oil pan. This is the pan off the 2007 H3 Hummer, so finding the right filter is as easy as asking for a H3 Alpha application from any local parts store or GM dealer.
Switching from the supplied Corvette oil pan to the LH8 provides a better fit around the front crossmember and steering rack in the Nova.
Other cars, such as classic Camaros and Chevelles, are better suited to other pans such as the 4th gen F-Body oil pan, but the LH8 is the best option for our Nova. You can get these direct from GMPP (PN 19212593) where it is known as their Muscle Car Oil Pan.
The finishing touch to our LS3 swap is front accessories. Once again, everything needed can be found right off the shelves, either from GMPP or the aftermarket, such as Billet Specialties’ Tru Trac System. We like the Tru Trac because it comes with options for AC and power steering, and offers a choice of different finishes. Be sure to check out the complete feature article on installing the system.
We went with a polished finish on our Billet Specialties Tru Track accessory setup to match our ceramic-coated Hedders, but the system is also available in a more subdued black anodized version as well.
Tru Trac Serpentine Systems Include:
• ATI Super Damper – SFI 18.1 certified
for race use
• Polished PowerMaster 105 amp one-wire alternator
• Billet aluminum one-piece alternator fan & pulley
• Cast finish Edelbrock water pump
• Billet aluminum water pump pulley
• Billet aluminum bridge bracket
• Patent-pending billet aluminum tensioner
• Billet aluminum tensioner pulley
• Billet aluminum crankshaft pulley
• Polished ARP 12-point stainless steel fasteners
• Goodyear Gatorback 6-rib serpentine belt
• Comprehensive installation manual
• Select pulleys are hard-coat anodized for increased durability in high wear areas
Kits With AC Include:
• Polished Sanden SD-7 AC compressor
• Billet aluminum AC compressor clutch cover
• Patented billet aluminum AC compressor manifold
Kits With Power Steering Include:
• Cast finish Maval power steering pump with AN fittings
• Billet aluminum power steering pulley
Using the Tru Trac kit takes all the guess work out of choosing the front drive system. Billet Specialties has taken the time to research the different platforms the engine is used for. They look at things like steering box location, the amount of belt wrap needed for each pulley to prevent slipping, and how much room is available in the engine bay in order to select the right type of components for your project. Even the size of the factory pulleys and what kind of RPM they are running at are considered before designing a kit to ensure it will spin like it was designed to do.
The Billet Specialties’ Tru Trac Kit we installed moves the AC compressor up and out of the way.
One thing to keep in mind for the Nova swap is the position of the A/C compressor. The standard low mount contacts the frame in this application, but most other GM cars and trucks can run the low mount A/C compressor without a problem. Nova guys have two options – notch out the frame and weld in a filler plate to allow clearance for the OEM compressor and lines, or use an OE or aftermarket top mount kit such as the one offered from Billet Specialties that relocates the compressor to the top side.
Now It’s Your Turn
With more and more swap kits and performance parts being developed for the LS family, replacing that tired, worn-out old small- or big-block doesn’t mean spending months making it fit or sacrificing horsepower. You don’t have to break the bank either. Now all it takes is a little time to plan it all out and getting your hands on the right parts.