850 HP HELLCAT KILLER!
"We're calling it The Hellcat Killer", says Mike Petralia, owner and chief engine builder at Hardcore Horsepower & Dyno in Franklin, TN. "It's a BBC designed for your classic GM muscle car or truck to run down those pesky late model tug boats. And it'll beat 'em with a carb, or EFI, on pump gas, and without the need for any boost or chemical power adders". This daily drivable-engine will be the new King of the Streets because of its hydraulic roller cam too. And it'll fit in just about any old iron with maybe just a small hood scoop. Trucks and Tri-5s are no problem.
For this build Petralia relied on the proven strength of a Dart Big M Sportsman block. It features Ductile Iron splayed 4-bolt main caps and vastly improved oiling over factory GM blocks with a true priority main oiling system. It has stepped oil galleys to increase flow to the crank at higher rpms and a front oil crossover that eliminates internal oil leakage around the distributor. No need to worry about distributor shaft o-rings with these blocks. Blind head bolt holes keep water from mixing with the oil. And a 2-pc rear main seal makes oil pan selection plentiful. Dart performed all the machine work on the block including boring it to 4.600-inch followed up with a torque-plate hone finished for Plasma-Moly rings. They also finish-milled the decks true and parallel to 9.800-inch for a Mr. Gasket Co. composition-type head gasket. And they installed all the cam bearings, brass freeze plugs, and locating dowel pins for the oil pump and timing cover too.
Petralia then installed a stout rotating assembly including a 4-3/8-inch (4.375) stroke, 4340-foged steel crankshaft that was zero-balanced to run with a Neutral balance, (aka "Internal Balance"), harmonic dampener and flexplate or flywheel. Factory GM 454s and 502s were all external balanced, but many consider internal balancing an improvement so he likes to stick with that when he can.
The pistons are custom made slugs from AutoTec Pistons in Huntington Beach, CA. They're forged from 4032 aluminum with a small dome profile that gives this engine 10.85:1 compression. Which is fine on 93-octane unleaded when combined with the very efficient CNC-finished combustion chambers in the Air Flow Research heads. The slugs hang on 4340-forged steel rods with 7/16-inch ARP2000 capscrews. King Racing HP-series bearings cushion the blows.
This is the largest displacement BBC engine Petralia will build with a standard Chevrolet deck height, which makes it easier to fit under hoods. The 9.800-inch deck also fits practically all the muscle car headers on the market today. He said he could add a little more stroke and make 598cid if a customer really wanted it. But that limits connecting rod length which affects rod/stroke ratio. It would also shorten the piston compression height (the distance from the pin centerline to the flat, top surface of the piston). And the extra 16 cubes really wouldn't make that much more power either.
"The power potential is in the heads and cam"
Choosing the right cylinder head for the application is critical. But Petralia is secretive about his head selections, allowing only that they are CNC-ported castings from Air Flow Research. Runner volume is shared only with the customer. And sometimes not even then. He was willing reveal that the heads are rectangular port and came equipped from AFR with a modified spring package he specc'd out to work with the custom-ground hydraulic roller bump stick from Comp Cams. "It's basically the same cam I ran the last time, with a tweak to lobe sep angle, and a 4/7 firing order swap". As you've probably guessed by now, he won't share cam specs either except to say that it's just about .700-inch lift w/ a 1.7:1 rocker arm ratio.
When installing aluminum roller rockers on big-block Chevy heads there are 2 rockers that will cause problems with some valve covers. This rocker arm set from Erson cams includes 2 rockers with added clearance just for these spots, which are the intake rockers for cylinder numbers 1 and 8. You can also see the rocker arm stud girdle made exclusively for AFR by Jomar Racing Products.
The 582ci BBC also made over 800 ft/lbs of torque from 4800 to 5200rpm and never made less than 700 ft/lbs from 3400 to its 6000rpm redline. There's no need to rev this bad boy up. And it makes enough grunt to move any street car or truck into the stratosphere.