DaRkMuCk's GM LT3 Engine Website - LT3 Specs

LT3 Specs - LT3

The Pontiac Sunbird GT and Pontiac Grand Am GT, came with a 2.0 litre, 8 valve, single overhead cam (SOHC), and a watercooled Turbocharger (Garrett T-25). The engine code is LT3 (C20GET). 2 Versions of this engine are produced still today as the C20XE and the C22XE, by Daewoo.  

The engine is actually an Opel design but was assembled in Brazil. The bore and stroke are the same (3.386" or 86 MM) which is what you call a "square" engine - the bore and stroke are equal. An "undersquare" engine has a small bore and a long stroke for more low end torque but less high rpm power while an "oversquare" engine has a large bore and a short stroke which allows it to make power at higher rpm but sacrifices low end torque. So I guess the "square" engines do a little of both!

The first thing that really impresses you about the engine is the way it accelerates. Its 2.0L overhead cam, turbocharged 4-cyl engine with multiport fuel injection delivers 165 hp without innercooling, which translates to low 15s around 92 mph in the 1/4 mile and 0-60 in about 7 seconds. The garett T25 turbocharger features a water-cooled center bearing for extended life, and it develops a max of 9 pounds of boost at wide-open throttle. An integral knock sensor in the engine's electronics guards against detonation on either reg. or premium fuel, and a block heater is provided for quick warm-ups. The bulletproof cylinder block is still made of cast iron, and the cylinder head is aluminum. Forged low compression pistons with low tension rings are used to stand up against the turbo-charged enviroment, the crank is nodular cast iron along with the connecting rods, but they happily accept the boost. Minor changes over the years of this engine improve sealing and friction characteristics. For example, the valve covers have a new stand-off boss on the lower face that connects the cylinder head when the gasket has been crushed the proper amount for optimum sealing.

Engine Code:        LT3

Bore x Stroke:        3.386x3.386 (in)/86.0x86.0(mm)

Displacement:                121 cid, 2.0L

Firing Order:          1-3-4-2 (No.1 cylinder at timing belt end)

Rotation:                     Clockwise

Compression ratio:       8.0:1

Intake valve size:        1.69"

Exhaust valve size:      1.44"

Camshaft duration:      214 degrees at .050"

Camshaft lobe centers:      114 degrees

165 hp @ 5600 rpm at 7 psi of boost

175 ft-lbs. of torque @ 4000 rpm


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