432-Inch Powerhouse

The engine featured here was built by Miller to compete in the 2006 Jeg's Engine Masters Challenge, an annual engine building competition sponsored by Popular Hot Rodding. He has been a regular competitor at the event, always one to showcase the Olds' potential. As Miller relates, "It's a great chance for me to get out there and have people see what I am doing. Last year's 434ci limit worked out well. Since a .030-inch overbore 425 comes out to 432, I was able to run a stock stroke and stock bore with a .030 overbore, and I was there." In fact, Miller's engine is based on a production Olds 455 passenger car block, with a factory forged 425 crankshaft. He explains his objectives this way: "I'm not necessarily in the contest to win outright, but more to develop new products, show people what's available, and what can be done. Like the 403 engine we brought last year: most people don't think the 403s are worth anything, but we made 600 hp, and got it to live and stay together, even with that windowed main web people are afraid of."

Commenting on the blocks, Miller reveals to PHR: "At 500 to 550 hp, they are great. We have a few options in girdles: a halo girdle that connects the first four mains, a halo girdle that attaches all five mains, and then I have what I call a pan rail girdle, which attaches like the halo girdle, but also attaches to the pan rail." He informed us that the older blocks are said to have a higher nickel content, and are considered stronger from a metallurgical standpoint; but in his experience, they all hold up quite well, especially with a girdle installed. In fact, Miller said he has never experienced a block-related failure in all these years of building and racing Oldsmobiles. As extra insurance, this engine was built with premium ARP fasteners at all critical points.

For the power output anticipated in this build, the basic production components were righteously fortified, using a DMR girdle system and Miller's beefy billet main caps. Although the crankshaft was plucked from a factory engine core, Miller had Crankshaft Specialists rework the 'shaft with a custom knife-edging and lightening job, as well as hard-chroming the journals. A DMR windage tray provides further oil control and windage reduction. The stock 455 3.000 journals were retained on the mains, while the rod journals were ground to 2.200 inch, to accept the Oliver 7.000-inch big-block Chevy connecting rods. To achieve the 10.5:1 compression mandated by the rules of the Engine Masters competition, Miller had CP Pistons deliver a set of custom forged pistons in a dished configuration. Aiding in overall power production was a low-friction ring set from Total Seal, with narrow .043 compression rings used in conjunction with 3mm oil rings.

Coatings For Power

The engine made use of quite an extensive array of coatings from Polymer Dynamics. The outsides of the intake manifold and cylinder heads were coated (primarily for cosmetics, according to Miller); however, it didn't stop there, as nearly everything inside was coated, too, including the crank and rods, for oil shedding. A dry film lubricant was used on the oil pump gears, and the piston skirts received a similar treatment. The tops of the pistons were thermal-coated, as were the intake and exhaust runners, the valves, the combustion chambers, and the bottom of the intake.

Miller explains that the Olds engines build a lot of torque, but admits that the oiling systems need some work (though he has developed techniques to correct these shortcomings). Overall, he considers the Olds a straightforward engine to build. Oldsmobile uses a shallow stock valve angle (at 6 degrees), and he says: "For the cfm that an Oldsmobile head flows, they'll make more power per cubic inch than most of the other heads out there." Until recently, there weren't many choices in aftermarket heads, but now options are opening up. Miller tells us that the Edelbrock heads are similar in design to the original cast iron heads, limiting the all-out potential. For this engine, he went with the Bulldog heads, which he finds to have greater power potential. He used the offset pushrod version of the Bulldog head, which moves the intake pushrod clear of the intake runner, to offer room for larger ports, and ultimately more flow. Flow peaked at 385 cfm in fully ported form, as reported by Miller.