How To Build A 525ci Big-Block - Big-Inch Punch
How to Build 1,700-Plus Horsepower with a Blown 525ci Big-Block
From the December, 2011 issue of Chevy High Performance
By Henry De Los Santos
The last time you saw our Dart-based 454ci big-block, we generated 965 hp and 877 lb-ft (“Off-The-Shelf Steam” Apr. ’11 issue). For induction duties we used a pair of Brodix CNC oval-port BB-3 332 Xtras and a Brodix HV 2000 manifold, while a Vortech YSi supercharger added the artificial atmosphere. Fueling the copious amount of air was a Carb Shop–modified Holley 750 carburetor.
For round two of our build, Vortech Engineering offered to let us try out its latest line of superchargers, namely the all-new V-28 123. This wild piece of hardware is good for impeller speeds up to 70,000 rpm (rumors say significantly more), it features a 123mm billet impeller, and the peak power level is still yet to be determined. Knowing it would take a fairly stout bottom end, we decided to transform our 454ci into a 525ci stroker, using a complete Lunati bottom end consisting of a Pro Blower series crankshaft with their 4340 fully machined I-beam rods, and a set of JE pistons. For induction duties, we once again turned to Brodix and after a lengthy conversation, stepped up to the larger BB-3 380 Xtra cylinder heads. At the heart of the beast is a COMP Cams–built solid roller that we had spec’d out by Steve Morris Engines in Muskegon, Michigan. At The Carb Shop’s advice, we also stepped up to its 950-cfm carburetor with the dual needle and seat assembly.
For our second rendition,...
For our second rendition, we reused our 9.8-inch Dart Sportsman Big M block with a 4.250-inch bore. Handling the machine work, we went to Rocco Acerrio of A.R.E. Performance & Machine in Simi Valley, California, who overbored ours to 4.500 inches. He removed nearly 20 pounds of material and says, “If you’re starting from scratch and need the larger bore, keep in mind that it’ll be much more cost effective to buy the 4.500-inch bore block from Dart to begin with.”
The amount of power this gem was going to produce was seriously anyone’s guess. In our minds, we were shooting for anything over 1,500 hp and even scoured the ’Net looking for similar combinations. The truth is, at the time there were very few people with access to the V-28 123. If you recall, back in the July issue, we featured Chris Kephart and his ’62 Outlaw-classed Impala. Kephart has been at the forefront of testing the V-28 123 and is the first person to eclipse the 200-mph zone. Following suit, Chris Alston Jr. recently installed one into his ’64 Chevy II and shocked the doorslammer scene by becoming the first Vortech-powered car to dive into the 6s, running 6.71 at 213 mph right off the trailer!
It’s pretty evident to us that Vortech is onto something here, and we wanted to produce our own real-world evaluation, continuing with the off-the-shelf premise: no one-off components, no proprietary cylinder head porting, and—to challenge ourselves a little more—we wanted to generate a lot of boost through a single 4150 carburetor. It may have sounded like we were asking for trouble, but in all reality, it turned out to be one of the easiest big-horsepower combinations we’ve ever put together. Ridiculous? Even a bit arrogant? But it really was that easy. That’s not to say we didn’t run into our own issues, but these were things that were easily overcome; all of which we’ll go into greater details in the following pages.
Since we were planning to...
Since we were planning to buzz our big-block into the 7,000-plus rpm range, we relied on ARP main studs for added insurance. We also used a set of Federal-Mogul’s Sealed Power competition main bearings with its Duroshield coating.
Now, if there was one idealistic theme we wanted to stick with, it was to use the same manufacturers from the previous build with the addition of T&D shaft-mount rockers for valvetrain stability and Component Drive Systems’ geardrive to eliminate any belt issues. You have to hand it to our aftermarket; they offer top-notch components to support everything from a mild street package to dedicated track-only applications.
At the end of the day, we surpassed our goals and have to wonder, is this not enough power? Doubtful. Is this more power than most will know what to do with? That’s probably a bit more true. There’s nothing wrong with either answer, but chances are, our 525ci isn’t much different than what’s powering your street/strip project. However, it’s pretty amazing how easily a supercharger can conjure up a Jekyll and Hyde shift in demeanor on demand. Even better, everything shown here is currently available and only a phone call away.
Our choice of rods were Lunati’s...
Our choice of rods were Lunati’s 6.385-inch 4340 I-beam rod set that comes with ARP cap bolts. Given the conditions we were planning to subject them to, this is definitely a part of the build where you want to only use quality pieces.
When it came to the rod bearings,...
When it came to the rod bearings, we opted for Federal-Mogul’s Speed-Pro line and ordered up the Duroshield competition rod bearings.
For the rings, we installed...
For the rings, we installed a set from Total Seal’s TNT series. The top and second rings are 1/16-inch thick with a 3/16-inch-thick oil ring. The top are gapless, while the second ring has a 0.028-inch gap.
For this combination, we decided...
For this combination, we decided against the conventional spiral locks and ordered up the pin buttons. One of the advantages is ease of service, however, the most important thing is that these are more reliable in a high-horsepower racing application. If you’re running the fine line between the perfect tune or completely missing it, detonation will try to knock the spiral lock out of the groove. Imagine being at the upper rpm in this situation, and there’s a good chance you’ll end up shoving the pin through the cylinder bore.
Our JE Pistons were ordered...
Our JE Pistons were ordered with a slight inverted dome, a single valve relief, and weighed in at 663 g. As you can see, in this setup the oil ring intersects with the wristpin. Where you would normally need an oil rail before to complete the oil ring land, now the pin button acts as the bottom of the oil ring land.
To create the larger 525 ci,...
To create the larger 525 ci, we combined the 4.500-inch bore with a Lunati 4.125-inch Pro Blower series crankshaft. These 4340 certified steel crankshafts are stout, featuring dual keyways, your choice of 1/2- or 7/16-inch drilled flanged, and 7/8-inch lightening holes in the number 2, 3, and 4 rod journals. And if you didn’t already know, Lunati offers a choice of 4.000- , 4.125-, 4.250-, and 4.500-inch stroke crankshafts off the shelf and ready to go. We should also point out, if you’re looking to do a complete custom built-to-order program, Lunati offers an impressive short turnaround time of four to six weeks from the initial order; that’s starting from scratch!