Phase 2: Freeing Up The Exhaust System
In last month's issue of OFF-ROAD, we implemented Phase 1 of Unleashing the Bronco, where we installed a K&N FIPK kit on a '94 Ford Bronco equipped with a 5.8L engine. We started by running stock dyno runs to document the increases in horsepower and torque. In Phase 2, we'll go the distance and free up the exhaust system from the engine all the way back.
We started of by contacting RV Performance in San Clemente, California, which has been our performance hub center for this project. After doing some homework researching our upgrade options, this is what RV Performance came up with. We'll start with a set of Cat 4ward headers from JBA, move to a high-flow catalytic converter from Stanley's Exhaust Tech, and then a high-flow after-cat exhaust system from Dynomax.
Since the early days of engine modifications, it has been common knowledge that headers are one of the most vital components to a high-performance exhaust system. Since its development of the first emissions-legal direct-replacement header in the early '80s, JBA Headers in San Diego, California, has been an industry player in performance headers.
The HeadersJBA's Cat 4ward Shorty headers are manufactured with heavy-duty features, such as a 1.5-inch tube size and Firecone sealing domes on the collector. The JBA headers are sure to withstand the punishment we'll through at them.
The CatBecause the Bronco was getting up there in mileage, the gang at Stanley's Exhaust Tech in San Clemente, California, opted to install one of its high-flow catalytic converters. The new cat minimizes exhaust restrictions, allowing the exhaust gases to flow easily through the system, freeing up more horsepower while improving fuel economy. And like the rest of components, Stanley's cat is emissions legal.
The After-Cat SystemFor several years, Dynomax has been manufacturing one of the more popular after-cat exhaust systems money can buy. Engineered with performance in mind, the Dynomax exhaust system comes complete with prebent aluminized pipes for smooth flow. Combine that with Dynomax's Ultra-Flo muffler, with straight-through design, and you have the finishing touch to our smog legal exhaust system.
To handle the installation of the JBA headers, Stanley's catalytic converter, and Dynomax exhaust system, the exhaust pros at Stanley's Exhaust Tech put on their gloves and went to work. In one day's time, Dave Klimuck and Ben Lang disposed of the old factory system and installed the new JBA headers, the cat, and the Dynomax exhaust kit, including a chrome tip for a custom look.
After the installation of the exhaust components, we traveled to K&N Engineering in Riverside, California, for one last dyno run. Here's what we got. Starting with the stock run, the Bronco put out 171 hp at 3,900 rpm. With the K&N filter kit installed, the horsepower increased to 177.5 at 3,800 rpm. Now, with the headers, cat, and exhaust installed, the Bronco's horsepower output jumped to 184 at 3,900 rpm. As for the torque, the Bronco produced 281.5 foot-pounds at 2,800 rpm, at stock. After the K&N filter install, the torque rose to 289.9 lb-ft at 2,800 rpm. With the new exhaust system, the Bronco now puts out 291.1 foot-pounds of torque at 2,800 rpm.
The numbers don't lie. As you can see, the stock Bronco put out some decent numbers, but with a few minor upgrades, we were able to increase the horsepower and torque, which is a necessity when you're out in the dirt in your lifted wheeler with big tires.