Video: Steve Morris Engines’ “Mild” Turbo LS3 Tickles 1,200 HP

Our friends over at Steve Morris Engines have developed some of the world’s most powerful turbo- and supercharger-based engines, using their extensive research and development over hundreds of hours on the dyno to craft engine solutions for their customers. Their newest design is an engine targeted toward the late-model crowd; an LS3-based engine crafted to accept the customer’s choice of power-adder.

Steve's personal Trailblazer SS

Steve’s personal Trailblazer SS

Stories abound on the internet about LS engines that were pulled from a junkyard, placed behind a turbocharger or supercharger and abused to death – literally. In this case, SME started with a GM crate LS3, but made extensive changes to the block and heads to help them live at these power levels.

“The original idea behind this was to design a custom rear-mount turbo kit for Steve Morris’ 2006 Trailblazer SS. We spent some time building the piping for this kit while we made the enhancements to the LS3 engine. Once completed, we tested with the rear-mounted turbo. As we began testing, we decided to also make a quick front-mounted turbo kit and see how far we could push it safely for our customers,” notes SME’s Alex Esnaola.

The LS3 block and cylinder heads have proven to be durable; the engine began life as a brand-new LS3 crate engine from Chevrolet Performance, but Morris and the gang put their own custom touches on it, upgrading many of the internal components substantially to handle the extra power.

“This engine package was designed to offer a quality, viable alternative to junkyard engines with low-quality (and rather questionable) components,” says Esnaola.

Stealth is the order of the day on this build. If you didn't know what you were looking at, chances are you'd pass right by this thing at your local car show or cruise-in.

Using the same stroke and compression ratio as the stock LS3, SME upgrades the connecting rods (the downfall of the stock engine) with a set of forged H-beam rods and ARP 2000 bolts. Included in the rotating assembly is a set of custom 2618 forged pistons from Diamond Racing. These upgrades ensure that the engine will handle up to 1,200 horsepower.

Depending upon customer requirements, the engine is also outfitted with one of Morris’ custom hydraulic roller camshafts, a valve spring upgrade, ARP head studs, hardened pushrods, and a set of MLS head gaskets.

The development engine in the video wears a single 75mm custom SME-spec turbocharger, manufactured exclusively for SME by Bullseye Power. They’ve also engineered an air-to-water intercooler, use the stock intake manifold and in this particular instance, a set of flipped Hooker 304 stainless-steel exhaust manifolds. The rest of the exhaust was constructed from 304 stainless material sourced from Stainless Works, including one of the company’s mufflers.

Two different views of the moneymaker. With 1,200 horses on tap, someone's going to get a beating.

Not only does the platform perform well with a turbocharger – as you see in the video – but it can also be customized to use whatever form of power-adder the customer wants, from a different turbocharger, a positive-displacement supercharger, or a centrifugal supercharger.

“ We ran seven different “popular” camshaft profiles, along with our own in-house design. We made the changes so frequently, that it became a contest to see just how quickly we can go from a running engine to a running engine – just under 35 minutes, by the way. This level of development and testing is yet another example of how we differentiate ourselves from ‘one-man band’ operations. It comes from many years of engine development and optimizations – not from theory or speculations,” Esnaola says.

Fueling is provided by a custom in-tank twin-pump fuel system, and the engine’s fuel and timing curves are controlled by a complete Holley Dominator EFI system. Esnaola raves about the Holley’s configurability and ease of use in changing and controlling engine parameters – SME uses the system in the majority of their high-end builds due to this.

“The Dominator controls all of the engine functions, boost control, and transmission controls. The touch-screen display allows for speedy tune-up changes on the fly,” says Esnaola.

Owing to its budget-friendly roots, this LS3 engine has been developed to make max power low in the powerband; doing so keeps the engine stresses down, allows the use of the hydraulic roller camshaft design, and promotes durability. Don’t think it hurts power production, though – the engine pumped out 1,160 horsepower at 5,700 RPM and 1,189 lb-ft torque at 5,500 RPM in the video.

morrisdyno

“We engineered sensible upgrades for reliability on pump gas. After the camera stopped rolling, we upped the boost to 19.5 pounds and made 1,218 horsepower,” says Esnaola. This is simply an insane amount of power for a vehicle that will see actual street use – and regularly – on the roads in Western Michigan, where SME is located. We’re sure a fair amount of track time will also be on tap, as the company works to find the limits of the Trailblazer’s performance.

The bullet on the dyno.

The bullet on the dyno.

In this instance, Morris has the engine set up to use a boost curve topping out at 18.3 psi to prove out his development process, but the team achieved a bigger number later on during the testing phase.

“This truck also features more than meets the eye. The truck received a custom-built 4L80E transmission, custom-stall torque converter, and a Borg Warner 4485 transfer case from K&M Transmissions in St. John, IN. SME designed and machined a custom intermediate shaft for the front differential, custom front and rear driveshafts, and performed a refresh of the front differential,” says Esnaola.

Amazing to see how much horsepower the stock block and cylinder head castings will support – on pump fuel, no less – with the right internal upgrades and external supporting parts.

“It is interesting to note that during the development of the turbocharged version of this engine package, we ran numerous camshaft profiles, a variety of turbochargers, turbine wheels, housings, etc. This little engine package saw over 100 engine dyno pulls with no issues whatsoever!” says Esnaola.

About the author

Jason Reiss

Jason draws on over 15 years of experience in the automotive publishing industry, and collaborates with many of the industry's movers and shakers to create compelling technical articles and high-quality race coverage.
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