The Holley kit comes with...
The Holley kit comes with a single wideband Bosch oxygen sensor and a weld-in bung for it. You can mount it on either cylinder bank if you are running true dual exhaust. DC Performance mounted ours right at the passenger-side header's collector. As an option, Holley offers an NTK sensor that can handle nitrous or leaded race gas. Since we weren't running either of those and the NTK sensor is considerably more expensive, we went with the Bosch unit.
One of the last things to...
One of the last things to bolt down was the plenum and 58mm billet throttle body Holley provides. An air filter is not provided, but Holley recommends calling K&N to request an air filter for a factory GM TPI engine.
This is the wideband controller...
This is the wideband controller used in the closed-loop EFI system. A narrow band (open-loop) EFI system is set at stoich (14.7), and does not compensate for climate change. A closed-loop system like the Holley Stealth Ram kit uses a wideband and Bosch O2 sensor capable of readings from 10:1 to 16:1 to try to maintain the target air/fuel ratio of 14.7:1. It can account for altitude, pressure, and temperature.
Chris Jensen, DC Performance's...
Chris Jensen, DC Performance's tuning master, inserted the Commander 950 CD-ROM and hooked his laptop up to the ECU. With the truck sitting on the dyno, Jensen was able to program the EFI system at idle and at speed under load. No matter how good at tuning you are, don't try and tune your truck while you drive.
To protect the EFI controller...
To protect the EFI controller from dirt and other elements, Jensen drilled a hole in the firewall and brought the wiring harness through to the unit, which he mounted in the back of the glovebox. Jensen tuned the unit and made sure everything was working right before he bolted the controller down.
It was exciting to be almost...
It was exciting to be almost done, but we had to stop here to get new throttle and tranny-kickdown linkage, as the factory stuff will not work with the new Stealth Ram. We picked up some Lokar cable linkage at the local auto parts store and adapted them to the side of the plenum and the throttle body.
The throttle response was improved, as were the driveability and fuel economy. But did we make more power? DC Performance tuned the engine prior to the teardown so it would be running as well as it could with the carburetor on it. Once they were done, they pulled off initial dyno numbers and proceeded to remove the top end of our stock 350. When the kit was finished, DC Performance strapped our test truck back on the dyno for its final numbers.
Before
Peak Horsepower - 147.50 hp
Peak Torque - 216.50 lb-ft
After
Peak Horsepower - 154.90 hp
Peak Torque - 221.47 lb-ft