The Top End
Cylinder head selection is vitally important in a performance engine, so Speed-O-Motive chose Brodix original B-1 heads for their build. These heads offer huge 2.30-inch intake valves and giant port volume, which can equate to very high flow numbers. Mark Hyla, Speed-O-Motive's cylinder head porter, ground away even more material from the heads to correct for core shift and to optimize port flow. In fact, a pound and a half of aluminum was removed from each head during porting. Comp's No. 948 valvesprings were utilized to keep everything stable at rpm. Rocker arms were 1.7 ratio roller units from Koffel's Place and were modified for a cup-style adjuster so double-ball-ended pushrods could be used. Valvetrain geometry problems dictated the rockers be shimmed 0.200 inch for reliable high-rpm use. A single-plane, 4500 flange intake manifold was placed atop the B-1 heads and topped with a 1050 three-circuit Holley Dominator. Three additional horsepower were gained by running a 6-inch-tall K&N air filter on this engine. While B-1 original heads are generally more suited to higher-compression, higher-rpm engines, we feel Speed-O-Motive did a great job adapting this head to run on pump gas at less than optimal rpm.
On The Juice
Nitrous oxide brings two thoughts to the mind of the automotive enthusiast. First, nitrous is a great way to make inexpensive power. Second, nitrous is a great way to blow up an engine. In our opinion, there's truth to both as we've seen properly tuned nitrous engines make tons of reliable power. When applied to an improperly tuned engine, however, nitrous oxide can be disastrous. So when Speed-O-Motive and ZEX teamed up to test a 300hp nitrous kit during our engine challenge, we thought it was a no-lose situation. Either we'd see big power or a big explosion, and either makes for a good story. Fortunately, thanks to a solid engine built by Speed-O-Motive, a great nitrous kit manufactured by ZEX, and a little tuning help from the guys at CFM and ProMax, the engine performed flawlessly and set Comp's "unofficial" dyno record in the process.
So what did we learn by spraying the juice to Speed-O-Motive's big-block? First, we learned properly-tuned nitrous oxide is a very cost-effective way to add power to the big-block Mopar. Second, and contrary to popular belief, we learned a factory block can withstand the strain of nitrous oxide without damage (at least for a little bit). Third? Well, third, we learned that using nitrous is just plain fun. We'd like to thank Comp, ZEX, Speed-O-Motive, and everyone in attendance for playing along.