Your street motor should share many of the characteristics of an MMA or UFC opponent, whether it's for the local cruise, the all-out open drag nights at the track, or even the everyday haul. And you can get the job done with off-the-shelf components. The days of super-custom engine builds with race-gas compression are all but gone in the today's street cars. Virtually every part is available over the counter, which brings the cost down, making such an engine build that much more realistic. Having the opportunity to tag along on an engine build, we wanted to illustrate how easy it is to make gobs of power.
As you may have already guessed, this isn't your average 454. In fact, it's an even larger 496 with a pump-gas-friendly 10.25:1 compression. While other options could have us wringing out a short-stroke small-block till all ends of the rev band, an easier option was to piece together an existing 496 short-block for the Bel Air we had in mind. Not only will the motor live longer with fewer revs, but it will have the benefit of more inches, and power will be on tap virtually everywhere in the rpm band.
Now, with any street-specific motor build, certain perimeters must be met. It has to be easy on the budget, must run on pump gas, and must produce useable twisting actions without wringing the pumper out of breath to do so. Plus, ours had to fit under the stock hood of a very clean '66 Bel Air. All in all, when you can get it to look exactly like the factory 425hp 396 big-block it came with as a factory option, kudos to you.
We met up with John Barkley and whipped up a ground-pounding, 600-lb-ft big-block factory lookalike out of his garage. We began with an original GM four-bolt main block, an Eagle rotating assembly with a 4340 steel crank, SRP pistons and rings, a Melling oil pump, and a Moroso pan-with ARP bolts throughout. It also has the benefit of a pair of large aluminum 320cc lungs from RHS, a complete Comp Cams valvetrain with a Thumpr hydraulic roller camshaft, and lifters to boot. We even utilized faux intake bolts, making the Weiand Stealth manifold look factory. In true CHP fashion we strapped the big-block on the engine dyno at Vrbancic Racing in Ontario, California, and put the 496 through its paces. And now here's an easy-to-reproduce recipe, should you want to whip up this combination yourself.
Churn out 570 hp and 600 lb-ft from our RHS-headed 496
With a diesel-like torque curve, it's the perfect motor for the street
Our build primarily consisted...
Our build primarily consisted of adding a competent top end to satisfy the bottom. The block is a factory GM four-bolt with steel caps; however, the bore was punched 0.060 over, making it 4.310 inches.
To keep the compression low...
To keep the compression low but still take advantage of the squeeze, the deep holes were filled with domed, paint-can-sized 4.310-inch SRP forged pistons. Underneath, our crank was an Eagle 4.250-inch 4340 forged steel piece with 2.750-inch main and 2.200-inch rod journals. To handle the pounding, we used a full set of 6.385-inch H-beam rods with ARP rod bolts. For sufficient oil, we called on a Melling pump and pick-up. Our factory-style pump would allow for our Moroso oil pan to fit with clearance.
Before the RHS cylinder heads...
Before the RHS cylinder heads went on, we installed our Fel-Pro 4.580-inch-bore head gasket set, which features a wire-ring combustion seat with stainless steel for extra sealing. They are also made with a solid steel core to minimize torque loss and gasket blowout so the clamping force is maintained.
Breathe Deep Don't let the...
Don't let the orange paint fool you. These are fresh-out-of-the-box aluminum Pro Action 24-degree cylinder heads from RHS. They came complete with hardened seats and bronze valve guides. The intake valves are 2.250 inches, and exhaust valves come in at 1.880 inches (11/32-inch diameter for both). They also come with dual 1.509-inch valvesprings, 3/8-inch guideplates, and 7/16-inch rocker arm studs.
To fasten the cylinder heads...
To fasten the cylinder heads down, following the instructions from ARP, we installed the head-bolt kit. We torqued each 12-point head bolt in a clockwise pattern, starting from the center and working our way out with moly-lube on the threads and oil on the washers. We torqued each to 85 ft-lb, and let them sit for 10 minutes. We then backed off a quarter-turn and retorqued each bolt in the same clockwise pattern.
In some cases the pushrod...
In some cases the pushrod guideplates will have to be clearanced. Our situation called for relieving the outer edges of some plates to install the ARP 12-point head bolts.