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.