Nitrous oxide is the unrefuted king when it comes to horsepower per dollar. Though, laughing gas needs to be treated with respect and you can’t get greedy with jet sizes. With the investment being so reasonable, it’s been a crowd favorite for over half a century. Don’t worry – your floorboards won’t fall out when using spray.
Nitrous Pro-Flow, a sister company of Wilson Manifolds, builds one of the simplest of plug-and-play nitrous systems on the market. So we began to ask ourselves, “Could we add 200 horsepower in two hours of work?
Darin’s 1966 Chevelle is super clean. It was previously a track-only car and he’s been wanting to drive it more frequently on the road. It’s fitted with a 12:1 compression 427 cubic inch big-block Chevy.
Our Test Mule
Darin Burgess’ 1966 Chevelle, super clean and previously a track-only car, was in dire need of some spray. Now ready for the road, it’s fitted with a 12:1 compression 427-inch big-block Chevy. With 350.5 horsepower and 340.6 lb-ft of torque on tap in naturally aspirated configuration, we knew there was more to be had from the small, big-block. The Chevelle was no longer fun to drive, so with the installation of a Nitrous Pro-Flow system, things were about to get interesting!
Nitrous Pro-Flow’s nitrous kits are some of the most plug-and-play systems on the market. The nitrous plate comes with an integrated plate that holds the nitrous, fuel, and purge solenoids. The nitrous and fuel solenoids are already plumbed to the plate’s spray bars, where the high-pressure nitrous sprays through the fuel as it atomizes on its way to the engine.
“Our ultimate goal is for our customers to have the best possible experience at the racetrack,” explains John Rollins of Nitrous Pro-Flow. “If we assemble and test the system before it gets to the them, it will only help in achieving a clean install, time saved and possible mistakes avoided.”
Nitrous Pro-Flow’s system comes semi a la carte but the pricing is comparable to others on the market.
All the solenoids are pre-wired to a male weatherpack connector and connects to a terminated female weatherpack. Simply wire in the included relay to an arming and window switch – viola you’re done. There’s even an option for a billet bracket that contains a window switch that’s designed specifically for 4150-style carburetors; no bending metal brackets to fit, one bolt and you’re done.
“Our solenoids are made here in the USA to our specifications,” Rollins explains. “We use high-amp coils to get the most lifting power, Teflon plungers for durability, and offer a wide variety of orifice sizes to meet the exact needs of each system.”
When it came to the spray bar design, Rollins says, “Our spray bars have a patented 360-degree spray pattern to provide the most even plenum saturation possible. It’s not uncommon for the corner cylinders to be more efficient and, in turn, have ‘tuning issues.’ NPF plate systems combined with a properly ported manifold will have similar distribution to a direct port system.”
We really like the fact that everything is pre-wired and you can also get a fully terminated female harness that makes wiring super simple.
PN 309100: Nitrous Pro-Flow Single Stage System 175-350hp 4150
PN 307515: 15-pound System Completion Kit #6 Line
PN 732101: WOT Switch & Bracket 4150
PN 307600: Safety Blow-down Tube
PN 362918: #8 Safety Blow-Off Adapter
PN 821000: 0-1500 PSI Nitrous Gauge
PN 450030: Relay W/Harness
Blowing Out Before Blowing Up
If you’ve been to a drag race, it’s quite possible you’ve seen a nitrous car backfire through a scoop or possibly send fiberglass shards 50 feet into the air like bad party poppers. Nitrous Pro-Flow offers an upgrade for their plate systems that uses their patented burst panels that are integrated into the plate. Call it insurance you hope that you’ll never have to use, as these thin pieces of metal are designed to disperse a nitrous backfire out the sides of the plate and not up. Best part? They are fully replaceable at the track.
We also made [the burst panels] the same dimensions as a quarter in case replacements are not readily available. – John Rollins
“It’s one of those things where if you have them and never need them, you’re much better off than if you needed them and didn’t have them,” says Rollins. “There are two types of events that can happen in a plenum, a backfire or an explosion. A backfire typically happens with the throttle open and an explosion is with the throttle closed. In the event of a backfire, you can pop some or occasionally all of the panels, but the carburetor or throttle body will likely survive undamaged.”
Continuing, Rollins explained, “When an explosion happens (typically from nitrous being accidentally fired at idle or while cranking), the purpose of the panels are to lessen the damage as there is a much greater force trying to escape since the throttle blades are closed. In this case you may need to just bend blades back straight rather than search the stands and parking lot for parts of your hood. Although they can be somewhat delicate to handle, the nitrous plate burst panels are designed and every batch is tested to breach at +/- 80psi of positive manifold pressure. We also made them the same dimensions as a quarter in case replacements are not readily available.”
Nitrous Pro-Flow ups the competition with their replaceable burst panels. If you don't have any available at the track, a quarter per hole will do.
Two Hours … Now GO!
Sixteen Minutes: The air filter and carburetor are removed. A new carb gasket, the Nitrous Pro-Flow plate assembly, another carb gasket, and finally the carb. The bracket for the arming switch is pushed onto a longer bolt and tightened to the passenger front side carburetor mounting hole. The remaining longer bolts are installed.
There's not much to it. Remove the carburetor, plop down the nitrous plate assembly, another carb gasket, then the carburetor. Make sure you have one-inch longer bolts or studs to account for the plate's height. From there we began to run the nitrous line to the trunk.
Thirty-Three Minutes: The nitrous feed line is attached to the nitrous solenoid and then ran to the trunk of the Chevelle. There’s a section of metal right behind the rear seat that makes a perfect mounting location. Four holes and four bolts later, the nitrous bottle is secured.
Eighteen Minutes: The only thing we needed to make was a fuel line to attach to a port on our Aeromotive regulator. Once made, the connection to the firewall-mounted regulator only took a matter of seconds.
Forty-Six Minutes: Wiring was the last portion of the installation. It’s by no means hard, it can just be time consuming to do it right.
Total Install Time: 1 Hour Fifty-Three Minutes
(Top Left) The window switch bracket really makes placement for the switch simple. (Top Right) Right above the fuel cell seemed like the best place to mount the large 15 pound nitrous bottle. (Bottom Left) The last bit of plumbing was making a simple fuel line to supply the fuel solenoid. (Bottom Right) Wiring couldn't have been easier with the pre-terminated connectors. No fancy electronics here - just an arming toggle switch, purge button, and a wide open throttle switch.
At Power Automedia we install a lot of parts. One of the great aspects of nitrous is that you can get a good baseline, pull timing, then do the nitrous pulls in a matter of minutes. After the team got the Chevelle strapped to our Dynojet, it was time to go.
“Ignition timing is the most important aspect to understand when tuning a nitrous engine,” says Rollins. “It’s not as simple as taking X degrees per horsepower. You must either have a good understanding of the dynamics of a given engine to successfully tune it or the patience to start small and work your way up cautiously. We’ve built a database of different combinations/tune-ups and their results that we refer to when advising someone on ignition timing starting points. But, in many cases the customers do not know the specifics about their engines.”
We made a few hits at 5.75 psi of fuel pressure and dipped into the high 9:1 air-fuel ratio range so we dropped the fuel pressure .5 psi.
The small, big-block engine cranked out 350.5 hp 340.6 lb-ft of torque with 34 degrees of timing. Timing was backed off to 28 degrees and it was time for our first nitrous pull.
It’s a good idea to purge the nitrous system free of air and warm the nitrous before making pulls.
At 5.75 psi of fuel pressure we were a bit too rich, though power jumped considerably to 537.2 hp at 6,200 rpm and 462.7 at 6,000 rpm. That’s a gain of 186.7 horsepower and 122.1 lb-ft of torque.
All said and done we averaged a very conservative 10.4:1 air-fuel ratio and still managed to pick up 192.6 hp and 124.8 lb-ft of torque.
A second run at 26 degrees was attempted but we were down on power and realized that the big-block Chevy wanted the original 28 degrees. We then adjusted our fuel pressure down to 5.25 psi and made another hit. We were rewarded with 543.1 hp and 465.4 lb-ft of torque. A gain of 192.6 hp and 124.8 lb-ft of torque. After only three hits on the spray, we were satisfied with our results.
Winning! With Nitrous Pro-Flow
We would consider this install an overall win. We were able to beat our two hour installation timeline by seven minutes and picked up 192.6 horsepower to the wheels, which equates to around 231.1 horsepower to the crank with a 20% drivetrain loss calculation through a solid axle and automatic transmission. We are looking forward to watching Darin pull the front tires of his Chevelle at his next test and tune day.