Big-Block Nitrous Engine Build - Southern Heat, Part 1

We Build A Nitrous-Ready 496ci Big-Block For Super Chevy True Street Competition

Thomas J. Lyman Dec 28, 2007 0 Comment(s)
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With all the hype surrounding backyard-built, pump gas monsters these days, we here at the magazine figured we'd try something along those lines ourselves. There's absolutely no denying that these cars are popular-Hot Rod's Pump Gas Drags has been going strong for years now, and SC upped the ante earlier this year with the introduction of the Super Chevy True Street Challenge, a competition held at select Super Chevy Shows. With the increasing popularity of this "in-house" race, it only seemed prudent that we go out and find someone who would be a test mule for some wild motor-trans combo, and we found that person by way of Atlanta, Georgia, in Stephen Loflin. His '72 Nova was ready for a power upgrade; and, after some research, we decided to throw a big-block in the sea-foam green machine.

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Here's the block, after coming back from the machine shop. It's been cleaned, decked, bored .060-over as per Eagle specs, and line honed.

The decision to use the big-block didn't come overnight. We spent countless hours with Technical Editor Dan Ryder discussing our options. After burning the midnight oil for many nights, dreaming of sub-10-second passes, and speaking with Stephen down in Atlanta, we found a used 1970 marine-grade 454 block, and decided to go with it. The marine-grade blocks contain a higher nickel content, and are thus much more durable. Furthermore, we picked up the block for just $500-a typical aftermarket big-block can run anywhere up from $2,000 and up, so we definitely pinched a few pennies in that department. From there, we needed to find some components to make this thing fast-for a conservative estimate, we decided that 600 hp on motor should be the goal (we're not claiming any ridiculous numbers here, nor do we care to. We're just testing the waters in the most popular segment of street/strip cars today).

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Truthfully, after all the machining, it's hard to tell that this is a '70 block.

We spoke with a friend of Stephen's, Mikey Curtis, who runs a small racing operation out of his business, East Hiram 4x4. Mikey has run a '66 Corvette in all sorts of Outlaw 10.5 classes for years now, and knows what it takes to turn a car from a strictly street machine into a true strip-devil. After a few conversations with Curtis, we called on Edelbrock for one of its famous Top End Kits. The Power Package Top End Kit (PN# 2094) contains just about everything necessary to get the power we're looking for: Victor Jr. intake manifold, Victor Jr. 24 cylinder heads, hydraulic roller camshaft, timing chain and gear set, head and intake bolt kits, as well as a complete gasket set. Edelbrock claims that when this kit is thrown at a 502ci block, it has seen 611 hp and 573 lb-ft-this is precisely what the Nova it will be installed in needs. Edelbrock also suggested a 800-cfm Thunder Series carburetor and, the crowning jewel, a Victor Jr. nitrous kit (plate-style).

With all of the above parts, we didn't see any reason why the 496 wouldn't make somewhere around 600 hp on motor, and with the 250hp shot, upwards of 800 hp. From there, we needed a rotating assembly to complete the short-block. Summit Racing suggested an Eagle stroker kit (PN# ESP-B11012060), complete with everything necessary to take the cubes of the big-block up to 496. This kit features a 4.250 stroke, .060 domed pistons, and a forged crankshaft that comes balanced straight from Eagle. We looked to MSD for the sparks, and they sent out a Digital 6 box, along with an HEI billet distributor to keep things working properly.

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Mikey Curtis, our engine builder, sets the block on the floor to begin the build, and adds some Clevite assembly lube to the mains. He swears by his "floor" method for big-blocks, something he learned from Bob Glidden back in the day. Mikey mentioned that this helps deter distortion to the block.

For our dyno tests, we went to Al Moody Racing Engines in Mableton, Georgia. We're happy to report that Edelbrock was spot-on-even conservative-with its assessment of our power production. We saw 606 horsepower and it was still climbing when the operator stopped the pull at just 5500 (at the request of the car owner, who wanted to double check everything before going higher into the rpm band). Torque checked in at 598 lb-ft at 4900.

After this article, the car will be ready to receive the motor, along with a TCI Turbo 400, complete with a trans brake and torque converter. Immediately after the install, we plan take the car out to a Super Chevy True Street race later this year, if time and money allow (isn't that always the case). Regardless, this motor is truly a backyard-builder, cost-is-a-factor mill, with the grand total in parts just touching the $10k mark. Keep tuned in for next month's follow-up article, when we actually get the Nova out to the track, complete with a transmission from TCI and headers from Hedman Hedders.

Sources

TCI Transmissions
Ashland, MS 38603
888-776-9824
www.tciauto.com
Summit Racing
Akron, OH
800-230-3030
SummitRacing.com
Hedman Hedders
Whittier, CA 90602
562-921-0404
www.hedman.com
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