Video: Steve Morris Engines Unveils Twin Turbo 481X Engine Package!

Steve Morris Engines (SME) is well known for building one-off projects that are truly works of art (Devel Sixteen anyone?), and monstrous high horsepower builds for V8 dragcar and streetcar owners all over the planet. The latest project coming out of the stables at SME is the Alan Johnson Performance Engineering (AJPE) big-block Chevy/Hemi hybrid 481X engine platform (in its twin turbo configuration), with a bunch of extra Steve Morris goodies bolted on.

The team at SME masterfully designed and assembled this beast for customer Grant Tuttle’s attempt at the Radial vs. The World drag class. In the video above, Steve Morris gives viewers an up-close and personal look at this twin turbo beast, and then makes it scream on the dyno for break-in.

Steve Morris Engines - Twin Turbo 481X

The all-billet AJPE/SME 481X engine in its twin turbo configuration.

Running a high horsepower mill on an engine dyno is an abusive task for any dynamometer, and every dyno has a limit to how much torque and horsepower it is capable of keeping loaded. So as a means to preserve their high dollar investment, when most engine builders connect a freshly assembled 3,000 horsepower mill to the engine dyno — prior to shipping it out to the customer — the engine is generally tested at a fairly conservative power output which is often nowhere close to its peak potential, or even near the same level that the customer will be pushing it to in many cases.

To better stress-test their engines at a higher horsepower, to be fair to the customer, Steve Morris resorted to designing and building his shop’s engine dynamometer himself. While Steve states that this specific 525ci 481X engine is capable of holding itself together at 90 psi, not even the SME dyno would survive a max power pull with this engine. So this 481X was instead tested to between 40 and 50 psi of boost, which is still much higher than most dyno cell operators would dare to go.

The Build

481X Billet Block Pistons

AJPE’s billet 481X engine block and SME’s custom spec Diamond pistons.

As stated earlier, AJPE’s 481X engine platform is a hybrid between the big-block Chevy and Hemi architecture. It retains the big-block’s 4.84-inch bore spacing, but utilizes mostly Hemi patterned auxiliary components. And AJPE teasingly calls this combination the “Anti-Hemi.”

Additionally, many of the parts used in this all-billet build are designed in-house by the team at Steve Morris Engines. Including the custom SME designed billet intake manifold, 90mm twin throttle body setup with a tight radius “Ram’s Horn” intake elbow (for better clearance), SME valve covers, front motor plate, balancer, crank trigger pickup, and cam sync design!

The top end includes AJPE’s lightest “stage four” 6061-T651 billet cylinder heads, weighing just 36.6 pounds each! The heads also feature 73cc combustion chambers, 50 degree valve seat angles, Trend 1/2-inch intake and 9/16-inch exhaust pushrods, 0.937-inch Jesel lifters, and a custom grind SME camshaft to time the 2.450-inch intake and 1.920-inch exhaust valve events.

Steve Morris Engines - 481X Billet Block

AJPE’s billet 481X engine and “stage 4” cylinder heads, with a custom SME billet intake manifold.

Internal lubrication is handled by a five-stage Peterson dry sump oiling system, and fueling is accomplished using an Aeromotive front mount fuel pump feeding a set of Atomizer injectors — which are both powered through a single SME belt drive assembly.

Boost pressure is forced through the 481X using two Pro Mod-spec 102mm Precision turbochargers, while boost control is managed through a pair of Turbosmart wastegates and blowoff valves. But Steve says they will most likely be downsizing the turbos to better suit Tuttle’s needs before sending it out to him.

Holding all of that boost within the cylinders is achieved through the use of SME’s custom spec Diamond pistons, while a set of MGP connecting rods handle the torsional and tensile forces, and a 4.150-inch billet Bryant crankshaft keeps it all in rotation. And engine management for this project is controlled through a FuelTech FT600 EFI system, and Steve was just recently trained by FuelTech’s own Luis De Leon when he paid the SME shop a visit.

Steve Morris (left) and Luis De Leon (right)

Steve Morris (left) was trained on FuelTech’s new EFI management system by the company’s own Luis De Leon (right), which was then used on the new 481X engine (center).

The Results

Once this accumulation of billet materials made its way into the dyno cell, Steve turned up the boost to 40 psi and went for it.

With the pull starting at 4,500 rpm, the 481X engine was producing 2,314 horsepower at 26.5 psi by 6,000 rpm, and topping out at 8,000 rpm and making a solid 3,660 horsepower and about 2,400 lb-ft of torque at 40.5 psi! In the near future Steve is hoping to use some tuning magic to make a few more pulls with this setup and break the 4,000 horsepower mark on his dyno, so we’ll just have to wait and see what tricks Steve has up his sleeve to keep his dyno alive.

About the author

Kyle Kitchen

Born and raised in Southern California, Kyle has been a gearhead ever since seeing his first Mitsubishi Evo VIII in 2003. He is almost entirely self taught mechanically, and as an inexperienced enthusiast always worked on his own vehicles, regardless of the difficulty, just to learn how to do it himself. Prior to becoming a freelance writer for the company, Kyle started his automotive performance career with Power Automedia as a shop technician, where he gleaned intimate knowledge of LS platforms and drag racing builds; then later joining the editorial team as the Staff Writer for EngineLabs And Turnology. Today, Kyle is an experienced EFI calibrator; hot rod builder; and motorsports technician living in the San Jose area. Kyle is a track junkie with lots of seat time. You can usually find him racing his Mitsubishi Evo X in local time attack and road race events.
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