Chevy Caprice Nitrous Kit - Acceleration And Dyno Testing

Our Caprice had a large black plastic sheathing that was probably once occupied by numerous power wires for sirens and lights. It now serves as a safe place for us to route our nitrous feed line. Then we simply followed the wiring harness to the trunk area and secured everything down with the factory wiring mounts.

Our Caprice had a large black plastic sheathing that was probably once occupied by numerou

Just for shifts and giggles, we drove our Killer Whale from the track right onto the Dynojet 248c over at Crazy Horse Racing in nearby South Amboy, New Jersey. Once the dyno rollers were stopped, we were pleased to find 346 horsepower and 407.3 lb-ft of torque at the wheels from our nitrous-enhanced LT1.

This sounded a little low to us on both the horsepower and torque, considering that we used the 125-horse jets. The torque question was easily answered because we did not activate the nitrous until 3,500 rpm, which was well past the torque peak that normally occurs at 2,900 rpm. To compare apples to apples, we should look at the torque at the same engine speed at, say, 3,800 rpm. This was where torque was up by 87 lb-ft. But it still didn't explain why we weren't making much power. A quick peek at a borrowed nitrous pressure gauge revealed that we had only 750 psig of nitrous pressure, which was well below the minimum recommended 900-1,000 psig. This explained the power difference between the advertised numbers and what we got on the track and dyno. It also reminded us why no nitrous kit should be installed without a bottle warmer and gauge. When we get more time, we'll go back with a full head of nitrous and get you a better number. But the results from this exercise are certainly incredible.

In the end, we've proven that nitrous is indeed an irresistible power adder. Its simple installation does not require any special tools, trick computer tuning, or big-dollar support items such as massive fuel pumps, injectors, and ignition upgrades. Installed at home with just a few tools, we were able to drop our Caprice solidly into the mid-13s.

There are three wires coming out of the Zex management unit. Two come into the interior (black and red), and the white one stays in the engine compartment. The black wire goes to a good ground, and the red goes to the supplied arming switch, which we mounted to the headlight switch assembly. We then tapped the other side of the switch into a circuit in the fuse panel that was hot with the ignition on and was rated at 20 amps or more.
There are three wires coming out of the Zex management unit. Two come into the interior (b
Thankfully, we had plenty of nitrous line (16 feet of it) to go from the front all the way into the trunk. To mount the bottle brackets, we had to drill four holes in the floor pan while making sure we didn't drill into an inaccessible area above the framerail. With the bottle filled (Zex ships the bottles empty because of shipping constraints), we opened the valve and checked for leaks. None were found.
Thankfully, we had plenty of nitrous line (16 feet of it) to go from the front all the way
With all the hoses and lines connected, we started the car to make sure it still ran like it did before we broke out the wrenches. We also made sure there were no lines rubbing against anything while the engine was running.
With all the hoses and lines connected, we started the car to make sure it still ran like

We traced the TPS output wire all the way from the throttle body to the PCM. To make sure we had the right wire, we used a voltmeter to watch the voltage vary as we opened and closed the throttle. We then tapped into the TPS wire with the white signal wire from the Zex management unit. Because every car is different, the WOT output voltage is anywhere from 4-5 volts; you need to program the Zex management unit to your particular car. Once it's all set up, it will always look for that peak output voltage from the TPS and use it to activate the nitrous system.
We traced the TPS output wire all the way from the throttle body to the PCM. To make sure
Back at Old Bridge Township Raceway Park, we attacked the right lane with our former Iowa State Highway Patrol unit and were rewarded with a stout 13.522 at 98.7 mph. For a 4,200-pound behemoth (with driver), it sure is a runner.
Back at Old Bridge Township Raceway Park, we attacked the right lane with our former Iowa
With the nitrous flowing on the dyno, we realized 346.0 rear wheel horsepower and 407.3 rear wheel torque. If we were able to activate it earlier, we would have seen even stronger torque numbers, but because our car is equipped with an automatic, we can't test at 2,800 rpm because the tranny will simply downshift. Besides, we don't have enough cajones to tag the nitrous that low, as it would probably hurt something. We later discovered a less-than-ideal bottle pressure of 750 psig. Had we been up to the recommended 950 psig, we could have seen better numbers.
With the nitrous flowing on the dyno, we realized 346.0 rear wheel horsepower and 407.3 re