We just got the results back from our latest reader survey (hey, don't ask us why it took a year), and they confirm something we already knew: Nitrous oxide is the Car Craft reader's favorite power adder. Maybe it's the low initial buy-in, the undisputed bang-for-the-buck potential, or the simplicity of flipping a switch for an extra couple hundred horses. Whatever the reason, nitrous oxide topped the list of choices, easily eclipsing blowers and turbos in popularity.
We hate to give any credit here, but the success of the bafflingly popular movie The Fast and the Furious has driven sales of "noss" through the roof. That's been a good thing for everybody who makes nitrous kits, because the huge profits they reap from fools who want to blow the intake welds on their Hondas means more cash in the coffers to develop and market high-quality, low-cost plate and fogger systems for real musclecars like ours. So there. Now you've got at least one positive thing to say about the import scene.
There are many types of nitrous systems to choose from, ranging from inexpensive plate systems to megabuck fogger-style systems that look like miniature oil refineries mounted to the top of an engine. Plate systems, which mount between the intake manifold and carburetor like a spacer, are definitely the easiest to install, because all you have to do is lift the carburetor, mount the plate, and bolt the carb back on. Run a few fuel and nitrous lines, mount the bottle, and crimp a few wires, and you're done--easy extra horsepower. In the case of Wilson Manifolds' Nitrous Pro-Flow plate nitrous systems, the work is really easy, thanks to the unique solenoid mounting plate that comes with the solenoids, wiring, and spray-bar plate pre-assembled. It's relatively pricey, but it's also a work of art, and definitely worth the cost if you want a state-of-the-art setup.
We've had this particular system for quite some time. In fact, we've been intending to install it on our '86 Mustang project car for over a year now (hey, we've been busy compiling the results of our reader survey), but we finally couldn't wait any longer and bolted it onto a small-block Chevy we had at our dyno shop to see how it worked. The test engine, which we chronicled in "530 hp From Spare Parts" (Dec. '02) is equipped with Edelbrock E-Tec 200 aluminum cylinder heads, a rumpity Lunati solid flat-tappet camshaft (254/259 degrees duration at 0.050 and 0.562/0.561-inch lift), and a stout bottom-end consisting of Probe forged pistons, Probe 6-inch forged I-beam rods, and a GM forged crankshaft. We knew it could take a stout hit of laughing gas, and the smallest set of jets in the Wilson system, which is adjustable from 175 to 350 hp, looked like a good place to start.
All it took was one pull to find the answer we were looking for. We poured in some good gas (Wilson recommends race gas for any engine running more than 9.0:1 compression; our 350 has 11.25:1 so we ran Union 76 114-octane leaded racing fuel), dialed back the timing 10 degrees from 36 to 26 total degrees (Wilson recommends retarding timing about 3 degrees for every 50 hp of nitrous), cracked open the bottle valve, and whacked the throttle to wide-open. At about 4,000 rpm, we manually hit the nitrous button and cackled as the engine practically leaped off the dyno stand. The results were impressive: 706 hp at 6,300 rpm and 637 lb-ft of torque at 5,500.
We still had a handful of jets that could have taken us to even greater heights--750, 800, maybe more. But why get greedy?
The Fuel System
Whenever we talk about power adders, it's important to also discuss the fuel delivery system, because all that extra power needs a reliable source of fuel to feed it. With nitrous systems, this is important for two reasons. First, since the ratio of gaseous nitrous to the enrichment fuel is a critical part of the "tuneup," the volume and pressure of fuel delivered to the fuel solenoid must be accurate and controllable. If there's too much enrichment fuel, the mixture is rich or "fat," and you'll lose power. If the mixture is too lean, you can get into big trouble with detonation or a backfire, which is the biggest cause of broken parts when using nitrous.
A good fuel system not only ensures adequate delivery of fuel, it also allows you to fine-tune the nitrous system by independently regulating the fuel pressure. Wilson recommends setting the flowing fuel pressure to the fuel solenoid between 7.5 psi for race gas and 8.5 to 9 psi for pump gas, with higher pressure being on the safer rich side and lower pressure leaning to the lean side. Ideally, the nitrous system should be plumbed so you can regulate fuel pressure to the solenoid independently from the fuel pressure to the carburetor. Depending on your setup, the best way to do this may be to run a separate pump and regulator to the nitrous system from the fuel tank.
