Pontiac Supercharger Kit Installation - Double Down

The Engine
Jill's plan to showcase the Luhn Performance/Vortech supercharger kit involved the building of the sort of engine that she believed would be representative of the type that most potential customers would build. The engine would use "off-the-shelf" components wherever possible, passing up as much exotic or custom-built pieces as possible. This would also make the combination easy to replicate, if someone wished to just use this particular recipe.

Starting with a garden variety, YC-coded 400 two-bolt block from a full-sized car, the block was bored 0.030 inch to 4.151 inches. The cylinders were filled with Ross forged pistons treated with a proprietary hard-anodized coating that is resistant to heat transfer and also reduces friction. A 3-inch main, 4.21-inch Butler Performance/SGI forged crank replaced the stock cast 3.75-inch-stroke unit. Total displacement checks in at 455 ci. The rods are Eagle H-beam 6.800-inch units with ARP rod bolts.

Although it seems out of place that an engine with this much power potential would retain its two-bolt mains, that is exactly what happened here. The production caps were augmented however, with ARP studs. Since the rpm levels weren't going to be excessive, it was determined that the studs would more than compensate for any additional stress. Had this been a 3.25-inch main block, it likely would have been a different story.

The induction system is actually pretty tame, considering the power production. A set of stock 87cc Edelbrock Performer heads are topped off with a 750 Holley, modified by Tom Vaught for use in a blow-through application. For the tests, a set of 2-inch primary Hooker Super Comp headers were used without collectors, as they interfered with the dyno's exhaust ducting. The mixture is fired with an MSD Pro-Billet distributor with BOP Engineering composite distributor gear, ACCEL 8.8mm spark plug wires and NGK plugs.

Luhn did, however, go off the beaten path with the camshaft. A BOP Engineering round lobe camshaft blank was ground by Cam Motion with a revised firing order. It uses the "4-7 swap," which changes the firing order from 1-8-4-3-6-5-7-2 to 1-8-7-3-6-5-4-2, like a GM LS-series V-8. The idea is to better equalize the intake flow in the manifold, so the adjacent #5 and #7 cylinders are not robbing each other of available airflow. This change doesn't require a new crankshaft design, just a rerouting of spark-plug wires

The grind itself is a hydraulic roller with 242.3/253.6 degrees of duration at 0.050-inch lift, and 0.616/0.627 inches of lift with 1.65:1 rockers. It also features a 114-degree lobe separation angle and 73 degrees of overlap. The full specs are provided in the Engine Buildup Worksheet. Though it's a custom piece for this application, it is one that can be easily duplicated using the BOP Engineering round-lobe blank.

The Supercharger
As this was intended as a street/strip application ultimately going into a '64 GTO, the supercharger choice was critical, as ultimately, drivability and response were more important than wringing out the very last ounce of power. After all, if you're figuring on putting out more than 850 hp in a package that is docile on the street, why kill its easy-going nature in search of another 50 or even 100 hp? You already have way more than you can use on the street as it is.

The blower is an off-the shelf Vortech V-1 T-Trim unit, rated at 1,200 cfm. According to the manufacturer, it will support 825 hp at a maximum of 26 psi. With a maximum blower impeller speed of 55,000 rpm, the engine speed was kept under 5,500 rpm, due to the 10:1 final-drive ratio of the crank to the impeller.