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Holley's Wet Nitrous System - Wet Scream
Holley's NOSzle Wet-Nitrous System For The Two-Valve 4.6 Will Wake Up Your Sleeper
Horse Sense: A dry-nitrous kit supplies only nitrous and relies on the factory fuel system for any additional fuel, while a wet kit contains the hardware to supply both nitrous and supplementary fuel.
If you like your strength to flow from a bottle, we have good news. The giggle gas gnomes at the Nitrous Oxide Systems division of Holley Performance have introduced their NOSzle wet nitrous kits. One is specifically engineered for '96-through-present 4.6 Two-Valve Mustangs and will be shipped with two full sets of nitrous and fuel jets for your choice of a claimed power boost of either 100 hp or 125 hp. The primary distinction of this revolutionary design is that it feeds both nitrous and extra fuel almost directly to the combustion chambers without requiring the intake modifications of a typical race-fogger system. This design, claims Holley, also avoids the backfire threat caused by the poor mixture distribution and fuel puddling of wet systems that simply add fuel at or near the throttle body.
On this topic of backfires and other untimely explosions, the NOSzle system encompasses a number of electronic safeguards designed to ensure a long and peaceful relationship with your engine. As with most nitrous systems, it is shipped with master arming and wide-open-throttle switches, so that it can only engage when switched on and with the gas pedal nailed to the floorboard. But it also features a black box that limits operation to a window between 2,600 and 6,000 rpm. The reasons for this? Nitrous injected at too low an rpm can be damaging, and on the other end of the rev scale, if N2O flow isn't shut off before the factory rev limiter begins to cut back on fuel delivery, it can be even more destructive. Lastly, a pressure switch is incorporated, preventing system engagement if fuel pressure drops below a preset limit. That, an explicit instruc-tion manual, and color-coded and clearly labeled hardware fittings make the system about as idiot-proof as possible.
Going beyond the specific Mustang kit for a moment, Holley says the basic NOSzle design lends itself to being configurable as either a one-stage wet system of up to 500 hp or a two-stage dry system for up to 1,000 hp, and the NOSzle fits all fuel injector brands.
Sean Hyland Motorsport received one of the first available production Mustang kits and promptly installed it on one of its in-house '01 GTs, with us peering over the shoulder of technician Mike Lester. Installation was fairly straightforward, and the result was peak-to-peak rear-wheel power gains of 91.5 hp and 144.6 lb-ft on this otherwise completely stock modular. Check out our dyno sidebar for the complete power story.
On The Dyno
Our test vehicle was a Sean Hyland Motorsport show car, a prettied-up '01 GT that was mechanically bone-stock right down to its exhaust system. In this form it produced 221 hp and 269 lb-ft on SHM's Dynojet. Afterward, these peaks had jumped to more than 312 hp and 414 lb-ft. The system seemed to particularly favor the 3,500-rpm mark, where power was up by 101.9 hp and no less than 153 lb-ft.
We had to leave before the car was buttoned up for the street, but Sean Hyland reports that it drove like a supercharged car, with a smooth and progressive power delivery, and a fat and juicy torque curve.