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Early Fabrication - Part 2

Let's Talk Motor
Are we using a SBC (Small-Block Chevy)? No. Are we using Chevy motor? Yes. Must be a big block then. No again. Are we going to have "fun" with this installation? Yes. Enough already, right?

What we are using is a Gen III (generation 3) "medium-displacement" LS1. If you know the history of the generations, you'll know that zillions of Small-Blocks were produced since being introduced as a 265 c.i. in 1955. You may also know that in 1992, GM introduced the evolutionary Gen II Small-Block LT1 and, in 1996, the Small-Block LT4. Both of these motors are configured with cast iron blocks and aluminum heads.

During the period of the LT1/4, GM was already at work on a clean-sheet-of-paper design with specific goals for horsepower/torque per cubic inch as well as weight. They achieved their goals with the introduction of the LS1 in the 1997 Corvettes. As mentioned, this motor was not based on the Small-Block but was built as the logical next step for overhead valve, two valve per cylinder technology. If the LT1/4 was evolutionary, they were building the LS1 to be revolutionary.

Out back is the 4L60E electronically (computer) controlled automatic overdrive transmission - not to be confused with the 4L60, which is simply another name for a 700R4. The transmission has a removable bellhousing and gear ratios of 1st:= 3.06 2nd =1.62 3rd =1.0 4th = 0.7.

Before we get into more details about the LS1, let's have a look at our motor as retrieved from the donor 2000 Camaro:
As you can see, there's a lot to come off the motor and a lot of cleanup to do. However...
 

About the LS1
Starting with the "case", the design team wanted the LS1 case to be both lighter and more rigid than the iron block engine it would be replacing. They achieved this through external stiffening ribs, six-bolt, steel, main bearing caps and a case skirt that extends below the crankshaft centerline. Approximately 60 lbs. was shed over the previous, cast iron, block. Additional weight savings were made by manufacturing the intake manifold from a composite material made from nylon and and glass fibre. The plenum is located beneath the air runners permitting the runners to be long with smooth curves, enhancing airflow.

The crank is manufactured out of cast, nodular iron and weighs more than previous cranks because of the larger main bearing journals and because of a "wheel" that is part of the casting used to trigger the ignition.

The rods are designated as "sintered". The manufacturing process involves filling a mold with steel powder which is compressed under extremely high pressure. Rather than using a rod bolt and nut, a capscrew is used to hold the "big-end" together. It is said that the LS1 rod is the strongest connecting rod ever used in a GM, production, mid-displacement V8.

Pistons are cast aluminum as is the oil pan, which is sealed with an o-ring verus a gasket. The motor uses a gerotor oil pump. It is driven off the front of the crankshaft. These pumps are less complex than traditional designs and require less power to pump.

You could write an entire story about the head/valve/combustion chamber design. Suffice to say the intake and exhaust efficiency is way up with better aiming of air and fuel and exhaust flow. Also, unlike Small-Blocks, the two centre exhaust ports on each four cylinder bank are not siamesed but are spaced equally. Rockers are of cast investment steel rather than aluminum.

Cooling returns to traditional normal-flow pattern as the GM engineers abandoned the reverse-flow of Gen II designs.

This is a distributor-less design with separate ignition coils for each cylinder and a short plug wire connects to each spark plug. The rationale for this is that less spark energy is dissipated by short spark plug wires so more is energy available at the plug (a lot more as it turns out) and shorter plug wires reduce radio frequency interference that plays havoc with on-board computers and sound systems.

There are many other features of this engine design but the idea here was to give you a high-level description of the main features.

Wiring the Beast
Like our roadster (with TPI fuel injection), we've decided to utilize a Ron Francis' Wire Works Advantage main panel and Telorvek injection panel system. The Telorvek panel acts as a link between the wiring harness and the computer. Our plan is to mount both panels in the trunk. This won't be a problem as the Advantage panel can be supplied with extra long wire and the Telorvek panel comes with 20 ft. of wire for each sensor.

Like the Advantage panel, the wire is printed every 5 inches with the name of the destination location and is colour coded. We've been extremely pleased with the Wire Works products in our roadster. Quality is top notch. You'll learn more about what we'll be using in the future.

Use the banner at top left to learn more at the Ron Francis' Wire Works site. Wire Works products are available through Horton Street Rod Products.