Until recently, I had absolutely no experience with nitrous. Scratch that, I did go for a ride in a squeezed C5 Corvette a while back, so I'd at least know what it felt like. The kick was subtle, but it was cool; I could understand the attraction. On the other hand, I had yet to employ nitrous on a vehicle-or engine-of my own. That changed during our Sept. '06 3-Way Small-Block Showdown. With Henry involved, it was a sure thing that the juice would show up at some point, and I wasn't disappointed. Hearing my 383 bellow while under the influence, churning out almost 600 hp and gobs more torque, was intoxicating. Could I help but try it again?
The answer to that one, of course, is no. After looking over the options, I decided to give Zex's Perimeter Plate System a whirl. To be honest, the technology incorporated into this setup intrigued me. Rather than injecting nitrous into the manifold via spray bars, the Zex system, using something called Perimeter Injection Technology, injects the nitrous through 12 points surrounding the intake-manifold opening. It sounds good, but I called Zex's Matt Patrick for further explanation, and he was happy to oblige. "There's a tremendous amount of kinetic energy present when nitrous is injected, in the area of 900 to 950 psi," he began. "We figured, 'Let's aim it, let's focus that energy and utilize it.'"
This approach yields several benefits, theoretically, but how does it work in practice? Quite well, actually. First of all, I never intended that the 383 I built these several months ago be a nitrous motor. But as it turned out, the cam that had the specs I was looking for happened to be from Comp Cams' Nitrous HP line. These cams work well with any engine that has "good heads, and higher compression," according to Comp Cams engineer Billy Godbold. It worked great on this engine, helping it make 458 hp and 470 lb-ft of torque in our Sept. '06 test. With a single-plane intake installed and on the Zex squeeze, well, it worked even better.
Our first tests, in which we sprayed a 100hp shot through both dual-plane and a single-plane manifolds, showed gains of almost exactly 100 hp each time. When we worked our way up to a 150hp shot, however, the investment was returned to the tune of 648 hp and 694 lb-ft...which turned out to be more like a 180hp shot. Zex's Patrick was mildly surprised. "Our systems are usually very consistent," he said, "but some parts really work with it. Your particular combo just liked it." Indeed...and so did I. This could get addictive, to be sure.
|’ROUND THE OUTSIDE |
|383 STROKER SPECS |
|Displacement ||384.6ci |
|Bore x Stroke ||4.040x3.750 |
|Rotating assembly ||Speed-O-Motive cast crank and forged rods |
|Pistons ||Mahle forged |
|Compression ||10.30:1 |
|Heads ||Dart Iron Eagle Platinum, 215cc |
|Chamber volume ||72cc |
|Carburetor ||Holley 750-cfm Street HP |
|Camshaft ||Comp Cams hydraulic-roller |
|Valve lift ||0.520/0.540 inch intake/exhaust |
|W/1.6 rockers ||0.555/0.578 inch, intake/exhaust |
|Duration at 0.050 ||236/248 degrees, intake/exhaust |
|Intake centerline ||108 degrees |
|Lobe separation ||113 degrees |