Proven Horsepower Engine Combinations - 500hp Engine Combos

Mopar 440ci
Since the mid-'60s and the introduction of the RB engine (raised block), Mopar guys have had it pretty good. The venerable 440 has always been a relatively cheap, reliable source of horsepower and torque. Enthusiasts devoted to other brands have to pay extra for things that are stock on the Chrysler big-block, such as an external oil pump and shaft rockers. The skirted block, although heavy, provides a very stable bottom-end platform, and the cavernous crankcase lends itself to the addition of various stroker cranks without much fuss. However, since stroker engines can be expensive, do you really need the extra inches to make 500 street-friendly horsepower and 525 lb-ft of torque? That's the question we put to Mike Johnson at JMS Racing Engines in Monrovia, California. Johnson says, "No problem, with modern cam profiles and cylinder heads, 500 hp and 525 lb-ft should be relatively easy, and it shouldn't cost too much, either."

Johnson suggests the use of Edelbrock Performer RPM cylinder heads. Used in conjunction with stock replacement KB Silvolite hypereutectic pistons, the closed-chamber design of the 84cc heads provides a great quench area to deter detonation and puts the compression ratio at 10.3:1 when the pistons are at zero deck height. The heads can be used right out of the box with a Performer RPM manifold.

Johnson tells us the LY connecting-rod forgings are plentiful, inexpensive, and reliably capable of handling much more than 500 hp when equipped with quality hardware. Pre-'73 440s all have forged cranks that also will handle the load, so we used these essentially stock components.

Lunati ground the cam using some lobes designed specifically for the Chrysler lifter. As most Chrysler guys know, the large 0.904-inch lifters allow for faster ramp rates and higher lift without the penalty of long duration times, and Johnson planned to take advantage of this. He wanted the torque curve to be flat, with peak horsepower coming in below 5,800 rpm, so he chose a solid flat-tappet cam with 239/243 degrees of duration at 0.050 and 0.536/0.547-inch lift. The exhaust flow of the Edelbrock head is good enough that a larger split between intake and exhaust duration isn't necessary at this power level. The cam was ground with a 110-degree lobe separation and an intake centerline of 106 degrees.

A 454 core is going for almost $1,000 in California. Soon it will be cheaper to build 540s with aftermarket stuff.

On a dyno, this combo made 527 hp and 557 lb-ft. The peak horsepower was achieved at 5,600 rpm, and the peak torque occurred at 4,100 rpm, making over 500 lb-ft from 2,900 rpm all the way to 5,500 rpm. In fact, the average torque throughout the entire pull was 529 lb-ft. Even with all that power, it still pulled 12 in-Hg at an idle, just perfect for the street.

JMS Racing Engines
Monrovia, CA
626/357-2718
jmsracing.com

Big-Block Chevy 496ci
See if you follow this logic. If you are going to make 500 hp with a production iron-block 454, you have to change the pistons, and that means you are going to have to tear the engine down. If there is any machining needed on the rods, including shot-peening, bushing, or repair, it costs almost the same to buy a good set of I-beam connecting rods with ARP bolts. In other words, you should. While you are there, a cast 4.250-stroke crank, instead of the stock 4.000-inch, is available for $259, and since the Rat is externally balanced, you are going to have to pay to balance the rebuilt engine anyway. The block notching should run about $125 in labor.

That gives you a 496 instead of a 454, and the guys at Coast Performance say combine that with a good set of aluminum heads, and it isn't 500 easy horsepower anymore, it's more like 600. Low cost is the beauty of building a Chevy. At $1,700 completely assembled, the Edelbrock heads are getting to the point where they are cheaper than rebuilding iron ones. But, if you knew what you were doing, you could rebuild a set of oval-port heads and do a little pocket porting to get the iron to flow like the aluminum. Assuming a core charge of $200 for factory iron, the price for parts and labor is around $1,200 total. So in this case, we would use the Edelbrock Performer RPM 454-0 heads. They are oval-port heads that take on some of the characteristics of a big rectangular port head without the loss of low-end torque.

Speaking with Chris Huff at Coast, we found that customers want the biggest engine they can afford, so Coast tries to find the late one-piece main-seal-style blocks and bores them 0.060-over. With the Edelbrock heads' 110cc chambers, a low-dome forged piston will give you around 9.5:1 so you can run it on pump gas.

At this horsepower level, you don't really need to give up low-end torque and driveability and run a single-plane intake. So Coast also recommends the Edelbrock RPM Air Gap 2-0. It offers a broad torque curve without giving up too much high-rpm horsepower.

Using a roller cam is an expensive proposition on a big-block, so the recommendation is an Elgin flat-tappet hydraulic with 234/244 duration at 0.050 with 0.553/0.578 lift ground on a 112-degree lobe separation angle. Coast always uses Probe Industries 1.7 roller rockers to enhance the valveguide life and tops the combo off with a Speed Demon 750-cfm carburetor.

Coast High Performance
Torrance, CA
310/784-1010
coasthigh.com