Twin Turbo LSX Engine - Baddest Of The Bad

Thomson Automotive's Twin-Turbo Lsx Engine Pushes 2,048 Hp From Only 400 Cubes.

Barry Kluczyk Sep 1, 2009 0 Comment(s)
Sucp_0909_18_z Twin_turbo_lsx_engine Turbonetics 2/24

Two of these mid-sized, 88mm HP-88 turbochargers from Turbonetics are used on the engine. Each features ceramic ball bearings for greater wear and heat resistance, as well as Turbonetics' 3.50-inch turbine wheel. Alone, each turbo supports about 1,200hp, but when used in pairs, the sky's the limit.

Capabilities notwithstanding, Alameddine spent many hours sneaking up on the turbo engine's tune. It wasn't a simple plug-and-play operation. The fuel trim was kept safely fat and both rpm and boost were initially limited, as dyno pull after dyno pull revealed what the engine was capable of handling.

Alameddine's attention to detail paid off when Thomson began making full dyno pulls, but there was something clearly holding back the engine. It was making more than 1,500hp, but was stymied by the mufflers on the dyno's exhaust system.

It was a simple matter of too much exhaust backpressure and once Thomson's technician's uncorked the system, the engine blew unrestricted and instantly hit the 2,000hp mark. Keep in mind that the performance-hampering backpressure wasn't anticipated because the dyno's exhaust system already measured a large five inches in diameter.

Sucp_0909_22_z Twin_turbo_lsx_engine Custom_plenum 3/24

The boost generated by the turbochargers is pushed into this custom plenum atop the engine. Air is funneled through it and a pair of 2,100cfm ACCEL-DFI throttle bodies, before flowing down into a tunnel ram-type intake. The entire intake system was custom-fabricated, with the lower tunnel ram section CNC-milled by GM and the upper plenum and intake tubes built by Thomson Automotive.

With the unrestricted engine blowing hard on the dyno, it recorded a peak of 2,048hp at 7,140 rpm and a neck-straining 1,507 lb-ft of torque at the same rpm level. And while the engine makes big power even at lower revs-about 700hp at 4,000 rpm-the power comes on like a sledgehammer from about 5,000 rpm onward. In fact, power jumps from about 980 horses at 4,800 rpm to nearly 1,400hp at 6,400 rpm.

Similarly, torque leaps from the merely super-strong 906 lb-ft at 4,800 rpm to nearly 1,700 lb-ft at 6,400. That's nearly 90 percent more torque in the time it takes the tach to swing only 1,600 rpm higher. Talk about driveline shock.

Thomson says there was even more power to be extracted from the engine, but the dyno sessions ceased when GM Performance Parts asked to put the engine in a '96 Impala SS they'd constructed especially for it. Of course, it's no ordinary Impala SS. It was disassembled and rebuilt was a full-frame race car.

"With more time and more boost, I think we could have seen perhaps 2,500hp," he says. "There's a lot left in it."

As we went to press, the folks at GM Performance Parts were not ready to make any passes in the car, but we've got a detailed look at it and we'll bring it to you in a future issue.

For now, contemplate the implications of a 2,000hp, 400-inch LSX engine and what the trickle-down benefits will be for street/strip engines. It's pretty heady stuff, for sure.


Chevrolet Performance Parts
Detroit, MI 48232
Thomson Automotive
Wixom, MI




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