'Pump it-pack it-purge it-squeeze it. Nitrous is the fast way down the track or the quickest path to boulevard stardom. The easiest way to get there is with a carbureted plate system. But who makes the best plate? That's what we're here to find out. We assembled six single-stage plates from as many manufacturers, bolted them on a small-block, and let 'em duke it out. We have average power, peak power, how much each of these plates cost, as well as a ton of other details that you won't find in any other magazine-probably because they're not crazy enough to attempt something like this.
To make it fair, we designed a test procedure where each plate would be run on the same 9.5:1 compression small-block 302 Ford (until it scattered a head gasket). To make it simple, we chose to use one set of NOS Big Shot solenoids and lines along with one 15-pound bottle for each plate. We also specified each plate to run the same-size 63 nitrous jet (0.063-inch diameter), allowing each manufacturer to spec its own fuel-jet tune-up based on a 6-psi fuel-pressure standard. This is a typical tune-up for roughly a 150hp increase.
We started out to test each plate with a full 15-pound nitrous bottle set at 900 psi. We thought we'd test each plate three times between 4,000 and 6,000 rpm and then average the horsepower for each run and combine those three numbers to create a single average power number for each plate that would indicate which plate would be quickest in the car. However, we quickly discovered that nothing stayed consistent even when we didn't change a thing in our test procedure. The runs were often so different that the testing would not have proven anything. So we changed the procedure to average the best run from each plate that could be backed up by a second test that was almost as good. That way, we had some semblance of consistency.
We also carefully monitored fuel pressure, nitrous pressure, air/fuel ratio, and a ton of other variables to ensure that the test was as fair as possible. Pay specific attention to each sidebar. We learned a ton about nitrous in this flog, and we've passed along many of those details that can help you make the most out of your nitrous system.
Nitrous-Oxide SystemsNOS, the oldest and perhaps most prestigious nitrous company in the aftermarket, chose its popular Big Shot system as its plate player. This is a 11/42-inch-thick plate with the standard spray-bar arrangement that has been in use since the early days. The Big Shot plate uses one spray bar for nitrous and the other for fuel, using 34 nitrous holes-the highest count in our test. The holes are drilled at a downward angle to direct the high-pressure nitrous over the fuel to break it into smaller droplets as both are introduced into the manifold. An interesting aside: We found an old NOS plate from the early '80s that had only two nitrous holes per side-four total for the whole plate! This latest adjustable NOS Big Shot system is designed to make as much as 400 hp.
If there were a theoretical advantage, NOS had it because this is the only test where we used the same manufacturer for the plate, lines, solenoids, and bottle. The average power numbers revealed NOS to be right there in the mix with all the plates with the exception of Nitrous Pro-Flow. We also looked at test-to-test consistency, and the NOS plate did well with a difference of only 39 lb-ft of max torque and a mere 11hp difference in peak horsepower between three back-to-back nitrous runs.
By The NumbersPlate: PN 12510NOSPrice: $125.95 (four jet sets included) at summitracing.comJet Combo: 63 nitrous, 71 fuelPeak HP: 598 @ 5,500 rpmPeak HP Gain: 198 hp (400hp baseline)Avg. HP: 559.7$/HP: 0.63Source: Nos (A Division of Holley); Bowling Green, KY; 714/546-0592 (tech); 800/Holley-1, ext. 8530 (nearest dealer); nosnitrous.com
Nitrous ExpressThis company takes a slightly different approach to plate design, using a billet-aluminum 31/44-inch plate with a plenum divider instead of spray bars. The divider incorporates individually drilled nitrous and fuel passages with only four nitrous and fuel discharge holes in each side. The goal is to create an even distribution of nitrous and fuel in the intake manifold to eliminate lean cylinders-lean is bad when it comes to nitrous. Nitrous Express claims its jets flow 35 percent more than the competition's. These jets do have what appear to be different entry and exit angles, which may affect jet flow. Note that we checked each company's 63 nitrous jets with a specific drill size to ensure they all conformed to the rules.
Testing with the Nitrous Express plate went smoothly. The plate hit the torque hard with a peak 740 lb-ft at 4,300 rpm, which was the second highest we recorded. Peak horsepower came right after peak torque-613 hp at a very low 4,400 rpm. Horsepower at 6,000 rpm was still 548. This was something we saw happen often. Maximum horsepower occurred way low in the rpm band, and horsepower trailed off at higher rpm even though bottle pressure never dropped below 860 psi.
By The NumbersPlate: PN NP304Price: $108.99 at summitracing.comJet Combo: 63 nitrous, 63 fuelPeak HP: 613 @ 4,400 Peak HP Gain: 213Avg. HP: 557.1$/HP: 0.51Source: Nitrous Express; Wichita Falls, TX; 940/767-7694; nitrousexpress.com
Speed TechAs opposed to typical brass-tube or solid billet designs, Speedtech created a four-hole plate employing a unique central distribution that sprays nitrous and fuel from the middle of the plenum outward through separate ports. A CNC-machined two-piece stainless steel fitting using multiple holes directs nitrous past a beveled edge where the fuel is introduced. The nitrous and fuel combine to create a 360-degree spray pattern that Speedtech contends offers superior distribution over spray bars that concentrate delivery in the middle of the manifold.
As with many of the systems we tested, Speedtech's fuel and nitrous jets were close to the same diameter. The best run for this plate produced 657 lb-ft of torque at 4,300, while horsepower peaked with 601 at a more normal 5,500 rpm. We made three runs with this plate and it demonstrated the least variation in power with a mere 13-lb-ft and 20hp difference between runs. It's also the most expensive, which drives up its cost-per-horsepower rating, but it appears to be the most stable of all the plates we tested.
By The NumbersPlate: PN 252-010-00Price: $350.00Jet Combo: 63 nitrous, 62 fuelPeak HP: 601 @ 5,500Peak HP Gain: 201 hp (400 hp baseline)Avg. HP: 559.2$/HP: 1.74Source: Speedtech; Tuscaloosa, AL; 205/758-7100; speedtechnitrous.com
ZEXZEX, owned by Comp Cams, recently introduced a completely different perimeter-style nitrous plate that we had to test. The ZEX system employs an open-plenum plate without a spray bar called Perimeter Injection Technology. Each of the two plate halves feature a groove, one for nitrous and one for fuel. These two halves are bolted together with a gasket in between for sealing. Each of the 12 discharge holes spray nitrous and fuel into the intake manifold. The holes are drilled at an angle that creates a low-pressure area directly underneath the carburetor designed to increase airflow and enhance mixture distribution. ZEX says this plate can be used on both single- and dual-plane intake manifolds with a range of horsepower adjustment between 100 and 300 hp.
According to ZEX engineer Matt Patrick, one disadvantage to this design is the greater distance the nitrous must travel around the plate perimeter, which creates an internal nitrous pressure drop. This pressure loss generally requires a slightly larger nitrous jet in order for the ZEX system to flow the same amount of nitrous as its competitors.
Our test procedure required a specific jet, but ZEX decided to play anyway. As you can see, the ZEX plate with a 63 nitrous jet performed very well compared to the more typical spray-bar systems. Comparing the three back-to-back runs, peak torque values varied by only 20 lb-ft while the peak horsepower moved around by 25. This was typical of most of the systems in our test.
By The NumbersPlate: PN 82043Price: $194.39Jet Combo: 63 nitrous, 53 fuelPeak HP: 602 @ 5,400Peak HP Gain: 202Avg. HP: 559.8$/HP Gain: 0.96Source: ZEX; Memphis, TN; 888/817-1008; zex.com
Nitrous WorksThe Barry Grant nitrous company supplied the Billet Atomizer, a traditional system with a 11/42-inch billet-aluminum plate. Billet Atomizer spray bars have 32 straight-drilled 0.035-inch nitrous holes and eliminate an overlap area common in other designs that could cause pressure drops. One advantage is reduced cost; it's the least-expensive plate in this test. Nitrous Works is the only company that uses brand-specific nitrous and fuel jets with larger 0.188-inch shanks. This means that competitor's jets will not work in a Nitrous Works plate.
The Billet Atomizer's 52 jet size is the leanest of all the competitors, with the other kits hovering around 62 to 63. We watched the air/fuel ratio carefully, but the plate is obviously well engineered and was safe throughout the entire test.
The Nitrous Works plate cranked out an impressive 695 lb-ft of torque at 4,200 rpm and made 598 hp at 6,100 rpm. As was typically the case, when we pulled the second test on the plate using the same bottle, we saw a larger pressure drop than we did on the first, which reduced the power slightly.
By The NumbersPlate: PN 17000Price: $102.99 at jegs.comJet Combo: 63 nitrous, 52 fuelPeak HP: 598 @ 6,100Peak HP Gain: 198Avg. HP: 560.9$/HP: 0.52Source: Nitrous Works; Dahlonega, GA; 706/864-8544; barrygrant.com
By The NumbersPlate: PN 300030Price: $260.46 at summitracing.comJet Combo: 63 nitrous, 63 fuelPeak HP: 619 @ 4,400Peak HP Gain: 219 hp (400 hp baseline)Avg. HP: 577.1$/HP: 1.19Source: Nitrous Pro-Flow; Ft. Lauderdale, FL; 954/771-6216; wilsonmanifolds.com
Nitrous Pro-FlowThis company has come on strong in the nitrous business as an outgrowth of the Wilson Manifolds company owned by Keith Wilson. Best known for the purple nitrous plates that incorporate burst panels, Nitrous Pro-Flow sent a thinner 31/44-inch-thick plate without the burst panels to be more similar to the rest of the test subjects. Considerable effort went into this design, beginning with larger stainless steel tubes encased in a billet-aluminum plate. The holes in the bar are drilled at angles to create a radial spray pattern to improve nitrous mixture distribution, offering more even cylinder-to-cylinder balance. This technology comes at a cost, however. The basic Nitrous Pro-Flow non-burst-panel plate costs as much as $150 more than its least-expensive competitor. The higher price drives up its cost-per-horsepower rating as well.
We saw the impact of this technology in the test results, with the Nitrous Pro-Flow plate creating phenomenal power numbers. What the 577 average horsepower result doesn't tell you is that this plate cranked out a killer 758 lb-ft of torque at 4,300 rpm and then followed that up with 619 hp at 4,400. Power dropped off after that, but it still made 577 hp at 6,000 rpm. The air/fuel ratio was also conservative with an average of 11.9:1. On one pull, the Pro-Flow plate made 616 hp at 5,600, which shows that the power can move around a bit in terms of where it occurs in the rpm band. These were back-to-back tests with no changes, yet peak power moved 1,200 rpm.
The Big PictureWe expected to see minimal differences in the average power numbers between our seven contenders, despite radically different approaches in the Speedtech and ZEX designs. In five of the six plates, that's exactly what happened. The Nitrous Pro-Flow plate was the high-performing exception. The difference between the average horsepower for the five other plates was a mere 3.8 hp. Compared to a standard of 560 hp, that's 0.7 of a percent difference, which is virtually invisible considering that none of the plates were consistent on back-to-back runs.
The biggest thing we learned about messing with nitrous is that even with close monitoring of bottle pressure, fuel pressure, and all the other variables, these plates would often generate vastly different results with no changes to the system. During one test, a plate produced a torque peak of 4,300 rpm and a horsepower peak at 6,000 rpm. On the next pull-with no changes-the torque peak occurred at the same 4,300, but the horsepower peak dropped to 4,400 rpm. We don't have an explanation for that.
This variability also points out that even Nitrous Pro-Flow's 16 to 17 average horsepower advantage over the other plates may not always be repeatable. But let us not detract from the Pro-Flow's performance in our test. While more expensive, the Pro-Flow plate clearly demonstrates it has an advantage when it comes to making power with a single-stage plate system.
NITROUS-PLATE TEST EVALUATION Peak Peak Avg. $/HP HP HP Gain HP Gain Nitrous Pro-Flow 619 219 577.1 1.19 Nitrous Works 598 198 560.9 0.52 ZEX 602 202 559.8 0.96 Nitrous Oxide Systems 598 198 559.7 0.63 Speedtech 601 201 559.2 1.74 Nitrous {{{Express}}} 613 213 557.1 0.51Test Procedure Nitrous is incredibly sensitive to bottle pressure. Squeezing gaseous nitrous to 735 psi (or higher) creates liquid nitrous oxide. Just because a nitrous bottle is filled to a given weight doesn't mean that bottle pressure is ideal. Study the accompanying chart and you'll see that bottle pressure is directly proportional to nitrous temperature.
Every nitrous system creates a tune-up based on a standardized bottle pressure, which is usually between 900 and 1,000 psi. Our chart indicates that if the entire contents of the bottle are at 90 degrees F, then the operating pressure will be 945 psi. The important point here is that the entire contents of the bottle must be at this temperature, not just the bottle itself-this takes time to complete. Bottle pressure is generated regardless of the amount of nitrous in the tank. A properly filled bottle has a small volume of gas "head" at the top of the tank that will create the least amount of pressure decrease as the nitrous is used. A half-full bottle fully heated to 90 degrees F will still create 945 psi but will experience a much greater bottle pressure drop for the same amount of nitrous used because of the larger initial volume of gas in the cylinder. Optimal performance demands a full bottle at its optimal operating temperature, which is why nitrous racers bring so many bottles to the track. As a word of caution, never use an open flame like a propane torch to heat a nitrous bottle in search of more pressure. Better choices are an electric bottle heater, hot water, or an electric heat gun.
PRESSURE VS. TEMPERATURE Bottle Bottle Temp. Pressure (F) (psi) 40 490 50 565 60 655 70 735 {{{80}}} 840 90 945 98 1040 PRICE LIST Description PN Source Price Bottle PN 14750NOS NOS $279.95* Bottle Blanket PN 14167NOS NOS 55.95* Bottle heater PN 415 Metal Image 319.95 *Priced at summitracing.com