Step By Step
The key to any strong engine package is the careful combination of compression, cylinder heads, and the camshaft. Coordinate these three critical components and your engine will make great torque and excellent horsepower.
Hydraulic-roller cams promise tremendous overall power without the sacrifice of poor part-throttle driveability. If you can handle the cost upgrade, hydraulic-roller cams have much to offer.
Piston selection is important. For budget engines, hypereutectic pistons will work just fine, but for power above 400 hp, wed recommend forgings. These Federal-Mogul pistons offer a D-shaped dish to create a tight piston-to-head clearance and still keep the compression within pump-gas capacity.
Heres an idea: Build a mild 400 with Vortec heads and the GMPP Hot cam and make 500 lb-ft of torque and 400 hp. Thats low 12s with a stock idle.
Rat motors were the 60s version of super-sizing. Everything is bigger and heavier, which means theres no reason to really build a 396 when a 454 is just as heavy but will make more power. It starts with ensuring that all clearances are right.
The key to intake manifold selection is to select the manifold that will deliver the best overall power curve. Single-plane intakes (left) tend to sacrifice power below peak torque and increase power around peak horsepower. Milder engines respond better to dual-plane intakes (right) that improve power at peak torque and below.
Serious big-inch Rat motors of 500ci or larger can sacrifice some low-speed torque in search of more peak power because they make so much power to begin with. Its possible to make well over 600 lb-ft of torque, but it would probably be tough to get the tires to hook!
Boil it all down to this simple formula: Spend your money on the cylinder heads. Thats where you can expect to gain the most overall power for the money spent for normally aspirated engines.
Our giveaway GM Performance Parts 502 Rat falls in between our mild and wild big-block combos. With McKenzie pocket ported GM Performance Parts rectangle-port heads and a dual-plane intake, this Rat made 608 lb-ft for torque at 4,000 and 553 hp using the 502/502 hydraulic-roller cam. By the time you read this, Brain Hoverson of Bloomington, Minnesota, should have that fat Rat sitting in his garage. Congratulations, Brian. It pays to read Chevy High!
Powerits what makes the world go round. The politicians and business tycoons can have their world stage and corporate mergers. All hot rodders want is more torque and horsepower. And were going to show you how to get it. These power plans are simple. Weve assembled five muscle-building small-blocks and two Rat-tastic big-blocks to cover the bases from mild to wild street engines. For the mild motors, we aimed at street powerplants with excellent idle quality, great torque, and an emphasis on mileage and throttle response. As you climb the ladder toward wretched excess, weve added some suggestions for more torque and horsepower that comes at the cost of a lumpier idle and reduced fuel mileage, but will give your engine a nastier disposition. The baddest combination will focus on all-out normally aspirated power with a single four-barrel induction system. Well save the nitrous, superchargers, and turbos for some other day.
For this story, well stick to the classic combination of parts that aim at horsepower heaven. These combinations will detail displacement, compression, cylinder heads, camshaft, intake manifold, carburetor, and header recommendations that will get you where you want to go. These arent the only combinations available. These are just ideas that weve seen tested or we know would make great power.
The power levels included in each category are ranges. You could make more or less than that depending upon your specific combination. A simple cam change could make a 20hp difference if you dial in the right grind. There are probably a dozen camshaft companies, not to mention numerous producers of cylinder heads, manifolds, headers, and exhaust systems. Our goal here is to outline a few suggestions and then let you decide on your own favorite parts proliferation. Our readers are some of the sharpest engine people out there. Let us know what you think.
Car guys are all the same. As soon as you finish building the engine, youre already planning the next one. Thats what makes all this so much fun. Build it on paper a few times before you do it for real. So pull on your Bow Tie engine-builder gloves and dive right in to our seven hot engine combos in the sidebars below.