Watch out Hellcat Charger owners (and BMW M3s), there’s a 4-door sedan sleeper with 600-plus AWD horsepower on the streets — and it’s a Ford!

Just one month after the sixth-generation Taurus was introduced, Ford revived the performance-minded SHO option to the lineup. It features a 3.5L EcoBoost twin-turbocharged engine that produces 365 horsepower and 350 pound-feet of torque. All that grunt is funneled through an all-wheel-drive platform, making the highest-performing SHO ever a reality.

Twin turbos and a stout aluminum block, coupled with direct fuel injection and the 6F55 six-speed automatic transmission is performance gold for four-door lovers. But when a company like Livernois Motorsports gets its hands on one of these cars, with an intention of building the baddest SHO they can conceive - well, the rest of the 4-door performance sedan segment better look out.

The engine is built around one of Livernois Motorsports’ Pro Series shortblocks and their in-house ported cylinder heads.

The machine, built for Livernois customer “Mike,” features one of the company’s Pro-Series shortblocks and a Stage 1 cylinder head upgrade to handle the airflow and manage the extra power. Based on prior experience with these engines, Livernois has developed proprietary head studs to retain the boost within the chambers. On this particular engine, the turbochargers have been upgraded with a new set of ATP snails to improve boost and flow capabilities.

“We’ve got our own Livernois rotating assembly that uses a forged steel crankshaft, an exclusive forged I-beam connecting rod and forged pistons,” says Livernois’ Mike Schropp. “We went right to the I-beam rod design because we knew the power levels that we were dealing with would be on the outer extremes of what the H-beam design would support. The cylinder heads require some work in the valve job area, and we pull the port back in a little bit, but there’s not a lot of work required to get to this level and you can gain quite a bit.”

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The shortblock requires some unique touches to be able to support the power level, also. Preparing the mains to the correct tolerances, along with the hone finish on the cylinders, file-fitting the rings and setting the bearing clearances are important, but the aluminum EcoBoost block requires a couple of extra operations. The company also deburs the block and radiuses some of the oil passages that they’ve found critical to supplying the engine with lifeblood at the power levels it supports.

But most importantly, the block itself is modified to another level entirely through the use of cylinder sleeves, which not only make the overall assembly stronger, they also permit the use of larger cylinder bores to help unshroud the valvetrain in the heads. As the company has increased power levels in the EcoBoost configurations, issues arose with bore shift under load, head gasket retention and bore sealing when the boost is turned up.

Special attention is paid to all machining and blueprinting operations, as avoiding tolerance stacks is critical in an engine making this type of power.

“We have a new special block brace that stiffens the top of the bore and takes out the open-deck configuration. Those haven’t been released to the public yet, and aren’t in this engine, because the system was still in development when this engine was built. They’ll be on the market very shortly. We’ve had a lot of success and significantly strengthened the stock block using the combination of these two items,” says Schropp.

To make this sort of power, and make it livable, PCM calibration is particularly important. Livernois offers their own MyCal tuning device for the EcoBoost platform, and the tunes have been developed in-house with extra attention paid to specific parameters that they’ve discovered are vital to engine longevity.

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“The base tuning is complicated and not the easiest thing to do in comparison to vehicles that are more commonplace. With the variable valve timing and the turbochargers in these engines, there are a lot of elements that come into play. It’s a bit more difficult than just going in there and tuning for an air/fuel ratio and for power. Those items are where we’ve spent years on to develop the tunes we offer. Pushing some of these cars out there on the power levels has given us plenty of insight into what it takes to make them live and perform at the same time. If you don’t know what you’re doing in the calibration and miss it, you’ll basically turn the pistons into molten aluminum. There are certain tables to be in, and certain things to turn off and on, you can very quickly annihilate one of these engines,” explains Schropp.

Left - Livernois' own forged I-beam connecting rods and coated forged pistons are used in the build. Right - Sleeving the block is also an important operation for this engine, as it helps to maintain bore strength when the boost numbers go up.

It looks that the Livernois team has figured out what’s possible with these engines, as the one in this video pumped out 617.3 horsepower and 608.1 foot-pounds of torque during an engine validation test with unreleased boost numbers. The standard high-boost, race-fuel tune yielded 525.6 horsepower and 506.9 foot-pounds - all from a 3.5L V6 engine. Stellar numbers, and currently the world’s highest-horsepower Taurus SHO. Livernois is not known for sitting back and waiting to be caught by the competition, and Schropp tells us that they are continually developing new products and more horsepower all the time.

So it looks like the deal is to buy a used EcoBoost Taurus (they can be had for well under $20K on AutoTrader), send it to Livernois, break off a chunk of wallet, and turn the SHO into a 4-wheel-burning Hellcat Charger killer - for far less money and with a car that didn’t need a bailout to end up on the showroom floor.

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