LS Engine Swap

There’s no doubt that modern V8 engines are producing more stock power with better mileage than only a handful of years ago. The standard in light truck V8s is 380+ horsepower these days, and that has crept up from the low 300s just a few years ago. The GM LS engines are no different and have gone through an array of generations in the basic platform that is still used in the entire GM V8 line up – Corvette, Camaro, GM trucks and SUVs. Displacements change while block size stays the same, making it easy to fit aftermarket goodies. Displacements include a 4.8, 5.3, 6.0 and a 6.2, and early engines also came in a 5.7-litre version.

They all use the same basic externals, but head designs, crankshaft timing and injectors, along with truck and car intakes, cable and drive-by-wire throttles and cylinder shut-off systems, and steel and aluminum blocks, make the hunt for an engine a little more involved than – “give me that one” off the shelf.

The 6.0L and 4L80E transmission going into our project came from a reputable local wrecker of pickup trucks. Actually, they had 20+ LS-based engines on the racks, along with Hemis and Ford 5.0-litres to pick from. I went with a Gen III engine rather than a Gen IV version. The Gen III has lower horsepower but also does not have cylinder deactivation to deal with. It came both in a cable throttle and a drive-by-wire throttle version, and this engine is drive-by-wire – meaning the gas pedal needs to be purchased with the engine. The engine is a 2004; the Gen IIIs went from 1997 to 2007. The Gen IV overlapped in some vehicles and went to 2015, and the current engine line-up is labelled Gen V series.

The two versions in the 6.0L Gen III engines were the LQ4 and the LQ9. In the cars, they were labelled LS1 LS2, LS3 with the current LS9, packing 638-hp in factory supercharged form. Its MSRP on www.chevrolet.com is $25,509US, and the 430-hp LS3 “connect and cruise” all-in package with electronics is $13,856.00. In the trucks, the LQ9 is the higher-performance version commonly found in the Cadillac trucks, though the LQ9 was found in some other truck models in later years. Both were 6.0L or 364 cu.in. Heads on both are aluminum.

I’ll touch a little on the Gen IV (LS2 and up) engines as they are common swaps as well, and come with about 40 hp more than the Gen III engines. In the near future, I’ll load one onto the engine stand for a performance build to replace the Gen III engine. The power in the Gen IV motors bumped from the low 300s to the mid 300s, and they came with cylinder deactivation for better fuel economy (there is a kit to turn this portion off for retrofits) along with variable valve timing. Both steel and aluminum blocks can be found.

Keep in mind when hunting for an engine; the truck engines are far more readily available and not as sought after by the hot rod crowd as the LS-numbered Camaro and Corvette engines. If the taller intake doesn’t work for you (plus the car intakes do look better), retrofit intakes in the lower car style can easily be swapped in for better fitment. There were no issues for clearance with the truck intake in our install, so we stuck with the taller manifold.

Keep in mind, all of our mods are easily transferable between the 4.8L, the 5.3L and the 6.0L with slight changes, and all perform well and have great longevity.

Our simple mods for the 6.0L were a Comp Cams cam upgrade, the Comp Cams roller rocker fulcrum upgrade, decent flowing easy-to-fit Hooker ceramic-coated exhaust manifolds, and a Holley Terminator engine and transmission management system.

Getting a packaged engine with a documented compression and oil pressure test from a wrecker is a great way to start; just make sure you get a “dressed” engine that would be one with all brackets, accessories, starter, alternator, steering pump, exhaust manifolds, wiring harness, computer and gas pedal.  Don’t worry about what you do and don’t need; there typically is little savings getting a stripped-down version and there is nothing worse than hunting for parts. Mine even came with an air conditioning pump and engine mounts. It was $1000.00 for the engine and $800.00 for the trans with all electronics attached. I came across another wrecker with plenty of good-compression 5.3s for $800.00 dressed – also a great choice.

While the Holley computer system was a little more money than, say, an aftermarket harness and getting the computer reflashed, it gave me a lot of flexibility in engine choices, and the ability to self program as well as to laptop program, but also controlled the drive-by-wire system (no extra module needed) and the cable system in one package, and transmission control with shift point management and lock-up control. With a switch of injector harnesses, the system can run any current Gen III and Gen IV engine with a reset and relearn, and can accommodate forced induction as well.

Also, the engine can be run as a stand-alone with no trans control for stick shift transmission installs. That gives us a lot of options for future LS articles and engine swaps for the foreseeable future. I also ran the Terminator system in a throttle body configuration on my 5.0L Ford engine and it worked excellently, so no reason to really change up from what worked in the past.

We will also cover a few of the add-ons that were needed to get the engine into our frame of choice, and in the near future we’ll do a full programming article, cooling system and start-up article to let you know how everything turned out, and maybe a dyno run as well!

All-in cost for the engine less transmission has us under $5000.00 with mods, new water pump and oil pump and a re-gasket of the engine. Pretty good value for an expected 400-hp engine fully up and running.

It’s not hard to find an LS engine in the auto wrecker, but prices vary a lot, so it’s worth shopping around. Also, truck LS engines tend to cost far less than car LS engines. The main difference is cam profiles and the taller truck intake, which does develop better low-end torque. Our 6.0L engine fully dressed with all brackets, pump, alternator, starter, air con pump, pedal, computer etc. Was $1000.00, and a 4L80 trans to match was $800.00.

The aftermarket is ripe with LS parts, and converting your LS to a classic carburetor, or buying a truck engine and swapping to a car style intake is easy. These two examples from Holley are just a sample of what you can buy.

Typical configuration is the alternator up high on the driver’s side and steering pump below it. The air con pump runs off its own belt, lower passenger side. Our frame was tight with a high-mounted steering gear, so some changes were needed.

As we had to move around a few accessories to fit into the frame, we turned to Goatbuilt and their anodized bracket kit.

The Goatbuilt brackets move the alternator to the passenger side up high and the power steering pump high on the driver’s side. The air con pump stays in the stock location.

While you can use the stock mounts, we picked up a set of conversion motor mounts from Novak Conversions to fit our donor frame. The mount material is a little stiffer, so there is a chance of more engine vibration, but they also are stronger with a bolt that passes through the mount, solidly holding the engine to the frame.

The frame mounts for the engine were welded in place, and this particular set offsets the engine to the passenger side for better steering clearance.

The stock manifolds flow well enough, but they are pretty darn ugly and covered in heat shield.  These Hooker cast manifolds package really well in tight frames and come ceramic coated in several colours to prevent rusty exhaust manifolds being part of your future.

I went a little further than needed for the cam upgrade, cleaning up the engine and checking all the electric components like the twin knock sensors under the intake manifold. Glad I did it, because it seems some little critters made a nest under the intake. Thankfully the wiring was not chewed.

On inspection, the knock sensor bores had some oil seepage past the gaskets, so the valve plate was removed and cleaned, and new gaskets installed.

All back together ready to reinstall the intake manifold.

We are working on a budget build, but adding a cam, timing set and a rocker fulcrum upgrade add a good dash of power and gives some confidence that your valve train in your donor motor is in good shape. Unlike small blocks of the past, the internals of the LS engine are pretty stout and can handle large-lift camshafts with ease.

One of the largest lift cams I’ve ever installed in a small block. I chose this cam after spending time with the Comp Cam techs, and they assured me this fat .610-lift intake .617-lift exhaust would be just the ticket this 6.0L needed to wake it up.

Nothing too exciting looking at the old cam beside the new cam, but here they are!

One of the strangest things was installing the cam without removing the heads and lifters. All you need to do is spin the old cam around a few times with the rockers and pushrods removed and the lifters held up in the bore, and you pull the old cam out, grease the new cam and slide it back in. It’s best to shoot a light down the cam bore to make sure all the lifters do stay up, though. It’s not unheard of to have one drop back down. Worst case, you need to pull a head off one side.

The Comp Cams timing set is single roller but has slotted bolt holes, uses a Torrington bearing behind the upper gear, and can be adjusted both advanced and retarded a few degrees with an Allen key.

The timing set from Comp Cams allows for fine adjustments to timing with a small cam that can be turned with an Allen key prior to tightening the upper cam gear bolts.

The LS comes stock with roller lifters, however they are prone to needle bearing failure.

Comp Cams sells a rocker fulcrum upgrade kit with better bearings and new fulcrum shafts.

The kit comes with a cool tool you use in a vice to press out the old bearings.

The same tool with an added bearing press portion is used to press the new bearings into the rockers.

I have used Proform starters on almost every engine I’ve built and have had great success with them in performance engines. Not only are they gear-reduced for less starting effort, they can also be rotated for better fit around headers. An inexpensive insurance upgrade that also went along with a new oil pump and new water pump of OEM quality for the same reasons.

There are many ways to get your LS engine fired up. There are instructions on-line on how to mod a stock harness, aftermarket harnesses that use a stock re-flashed computer, and companies that will take your mailed-in computer and make the mods you require to work with your transmission and performance upgrades. I stepped up here and went with a Holley LS Terminator system. The computer works with all LS versions with the appropriate injector harness plug-in and will control your transmission and shift points. The kit works with both the cable and drive-by-wire system without the pedal module. The best part is, it’s self-learning as well as laptop-programmable, and is capable of managing turbos and superchargers. This makes it a very flexible set-up for future upgrades as money allows, without computer re-flash costs.

The Holley system uses OEM-type plugs for all connections, for a nice factory look.

If you are using a stock-type harness and computer, you will need the TAC module to go with your drive-by-wire gas pedal. Holley’s Terminator injection system controls the pedal directly, but you need to make sure you get the right serial numbered pedal suggested by Holley.

The computer doesn’t need to be installed in the cab – and on my last TBI Terminator install I installed the computer under the hood. This time, though, I’m trying to keep as many components out of sight.

What you choose to monitor your engine is up to style. Holley has a digital dash that will plug right into the fuel injection, but for a classic look, nothing beats the flexibility of using a Dakota Digital dash. They have a wide array of styles and this is their classic all-in-one 7-inch round gauge pod.