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HOT ROD magazine (March, '02). Monster Torque! GM's 383 Crate Motor: 500-LB-FT In 6 Easy Steps.

For those who do not receive HotRod magazine, here is a summary of an interesting article about tweaking GM's HT383 crate motor.

Some of this may be useful reference material for forum members who are trying to decide on their upcoming engine combinations.

Advertised specs:

325 hp @ 4,500

415 lb-ft @ 3,500

"medium-rise GM dual-plane intake with EGR provisions"

Vortec heads

4-bolt mains

Hypereutectic pistons (9.1:1 compression)

Hydraulic roller cam. 196/207 duration @ .050 with .431/.451 lift.

Forged crank w/ 3.800" stroke.

Std 4.00" bore.

Step 1

Initial Combination tested 338 hp @ 4,400 & 444 lb-ft @ 3,400

Headman Tork-Step Headers

Petronix Flame-Thrower HEI

Speed Demon Carb (625 cfm Road Demon) w/ jets at 70/76

Timing set to 34 degrees

Step 2

1.6:1 Roller Rockers 355 hp @ 4,700 & 452 lb-ft @ 3,500

Adding a set of Comp Cams Pro magnum 1.6:1 rollers gained 17 hp and 8.2 lb-ft at peak and didn't lose power anywhere in the curve.

Step 3

RPM Air Gap Intake 370 hp @ 4,600 & 466 lb-ft @ 3,700

Gained 15 hp and 14 lb-ft.

Step 4

Demon 750 Carb 379 hp @ 4,600 & 474 lb-ft @ 3,700

81/88 jetting.

Gained 9.4 hp and 7.7 lb-ft.

Step 5

Bigger Cam and thinner head gaskets 455 hp @ 5,600 & 493 lb-ft @ 4,200

Comp Cams XE282HR

230/236 duration @ .050 and .510/.520 (.544/,555 w/ 1.6:1 rockers) w/ 110 lobe separation angle. (The Vortec heads required valve guide modification for this swap due to lift) Swapping to thinner steel shim head gaskets bumped the compression ratio to 9.6:1. The larger cam gave up as much as 25 lb-ft of torque at every data point below 3,600 rpm. Also it formerly idled at 650 rpm and 19 inches of vacuum the new cam idled at 950 rpm and 12 inches of vacuum

Gained 76 hp and 19 lb-ft.

Step 6

Slippery Oil 463 hp @ 5,600 & 502 lb-ft @ 4,200

Changed from 10W30 dinosaur oil to Royal Purple's 5W30 street oil.

Gained 7 hp and 10 lb-ft.

They were so impressed with this oil that they're planning a full chassis-dyno test of Royal Purple products for the engine, trans, rearend, and wheel bearings.

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