LS1 Dirt

Increasing Gen III Block Displacement on a Budget

Ro McGonegal Feb 9, 2004 0 Comment(s)
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...A Goodson installation fixture attaches to the reluctor wheel and to the flywheel bolt hole.

Differences Between All Gen III LS1 and LS6 Blocks

Federal-Mogul provided the following values, the differences between camshaft-bearing od and the corresponding housing bore (id) in the cylinder block. As you can see, block clearances are not created equally. (All dimensions are measured in inches.) LS1 cam bearing set (1888M)

Position; Min. Shaft; Max. Shaft; Min. Housing; Max. Housing

1 & 5; 2.1650; 2.1669; 2.3276; 2.3295
2 & 4; 2.1650; 2.1669; 2.3177; 2.3197
3; 2.1650; 2.1669; 2.3079; 2.3096

LS6 Cam Bearing Set (1898M)

Position; Min. Shaft; Max. Shaft; Min. Housing; Max. Housing

1 & 5; 2.1650; 2.1669; 2.3675; 2.3476 (GM 12574413)
2 & 4; 2.1650; 2.1669; 2.3276; 2.3295 (GM 12574414)
3; 2.1650; 2.1669; 2.3079; 2.3096 (same as LS1)

Engine Prep and Dyno Results

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Vector (HTC) harmonic balancers with 17 percent underdrive for the LS1 Camaro and Corvette (far left). The others are 7 percent underdriven for the same engines.

Talk is cheap. We wanted a graphic demonstration and some hard numbers to back up the babble. For that round, we went to Glen Elsberry and a 351ci LS1-block-based engine that he'd taken fresh from the dyno cell. Glen arrived at the displacement with an HTC Budget Kit featuring a 0.010-inch overbore and a 0.030-inch-longer stroke (3.905 inches). The Speed-Pro hypereutectic pistons were installed 0.005 inch above the deck surface and cohabit with some port-tweaked 5.3L cylinder heads. The compression ratio is about 11.0:1 with a 63cc combustion chamber that Glen massaged to meet the outer limits of the bores.

Elsberry poured the bumpstick to his LS1 freak: a GM ASA road-race cam (0.525-inch lift, 219/236 degrees duration) with corresponding valvesprings. To feed the thing, he plopped on an LS6 intake manifold, attached an 87mm throttle-body, tapped in 30-lb/hr fuel injectors along with a 60-psi Mallory fuel pump, and used an ambient air temp sensor rather than the MAF. The primary pipes on the special dynamometer headers were 17/8 inches in diameter. Fuel was 91 octane. With the mild ASA cam, the gritty LS1 produced 479 hp. The torque curve was flat from 3,000 rpm.

What It Costs

Speed Pro hypereutectic pistons: $224.00
HTC main caps and ARP studs: $599.00
Reworked OE connecting rods: $190.00 (labor with customer rods)
ARP 8740 connecting-rod bolts: $84.00
ARP 2000 connecting-rod bolts: $120.00
HTC/Carrillo A-beam rods: $1,250.00
Reworked OE LS1 crankshaft: $575.00 (labor with customer core)
BHJ bolt-stretch gauge: $158.69
Vector harmonic balancer: $325.00


CP Pistons
Irvine, CA 92614
Mahle Motorsports
Fletcher, NC
Winona, MN 55987
Automotive Balancing
South Gate, CA 90280
Vector Dampers
South Gate, CA 90280


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