Nitrous vs Cylinder Heads - Bolt-Ons Vs.The Bottle

The problem-or challenge-associated with improving the power output of a motor with a set of performance cylinder heads is creating the proper combination. Given the dynamic equation that is an internal combustion engine, it's necessary to have not just sufficient head flow, but optimized head flow. When the optimized head flow is combined with the proper induction system, cam timing, and compression, you have the makings of one efficient powerplant. Eliminate any one of the idealized components from the combination, and you no longer have a harmonious symphony. Instead, you're stuck with a bunch of top-quality instruments simply clanging together to make noise.

The same scenario is true of an otherwise- stock motor. Adding a set of cylinder heads to a stock motor may result in little extra power, since the heads were not a major restriction to the total airflow of the motor with a stock intake, cam, and exhaust. Despite the exemp-lary head flow, the stock induction system, cam timing, and even compression will ultimately limit the power potential. This is why you see head tests where even the best flowing set of heads unearthed little power. Please resist the temptation to select cylinder heads by advertised airflow alone. Big flow numbers may or may not correspond to big power numbers. Remember, the combination is the key, and all that flow can be detrimental if the combination is not up to the task of utilizing it.

To illustrate the two different routes of enhancing power production, we took a mild 331-inch stroker assembly and sub-jected it to the dyno. The stroker was sup-plied by Coast High Performance. The 331 featured a late-model (5.0) 302 block stuffed to the gills with a cast-steel 3.25-inch stroker crank, forged connecting rods, and matching forged pistons. Tucked inside the CHP stroker assembly was a Comp Xtreme Energy hydrau-lic roller cam. The XE274HR cam offered a 0.555/0.565 lift split, a 224/232 duration split, and a 112-degree lobe-separation angle. The cam profile is a popular choice of street Mustang owners, offering excellent power through the entire rev range, especially on the larger 331 stroker (compared to a standard-displacement 302). Additional go-fast goodies on the test motor included a Barry Grant 750 carburetor, an Edelbrock Performer RPM Air Gap intake, and a set of Hooker Super Comp headers. Also present was a CSI water pump, a complete MSD ignition system, and a TCI Rattler balancer. For this test, the 331-stroker motor was equipped with a set of stock 5.0 iron cylinder heads. The only mods to the heads were valvetrain-related to allow use of the high-lift cam.

The 331 stroker motor was first run in with 5W-30 Lucas conventional oil and then tested with the good stuff (full synthetic). Only minor jetting was required, and the stock-headed motor responded best to 35 degrees of ignition timing. Equipped with the stock heads, the CHP 331 stroker produced peak numbers of 347 hp and 398 lb-ft of torque. By no means a wild combination, the 331 stroker would be right at home in the engine bay of any Mustang, offering plenty of torque and over 1 hp per cubic inch. While respectable, what the motor could really use was another 100 hp.

To provide just that, we installed a Super Powershot plate nitrous system from the nitrous experts at NOS. Once installed, we had an extra 100 hp (the jetting was adjustable up to 150 hp) literally at our fingertips. After heating the bottle to ensure an optimum 900 psi, we were rewarded with almost exactly 100 extra horsepower. The peak power numbers jumped from 347 hp and 398 lb-ft, to 451 hp and a stump-pulling 526 lb-ft of torque. Nitrous never fails to impress on the dyno. Want to transform your small-block into a big block? Just push the button.