Over the years, nitrous has been given a bad rap. It blows motors, melts pistons, and sends the hoods of cars flying skyward. It even blew up an entire car in that Hollywood abomination, The Fast and the Furious. Come on, the stuff isn't even flammable!
The truth is nitrous can be used quite safely, and that's exactly what we are about to do here. Play it safe and you'll get power increases otherwise available only through extensive engine mods or forced induction. The rules of the game are as follows: 1. Watch your mixture. 2. Retard your ignition timing. 3. Monitor nitrous bottle pressure. 4. Use quality fuel. 5. Don't engage the system below 2500 rpm or at less than full throttle. Do all of this, and your motor will stay intact. As you'll see, the components we selected made our system virtually foolproof. Before getting to the details of our kit, one other important point that all nitrous sprayers need to be aware of is spark-plug concerns. Factory platinum plugs generally aren't nitrous-friendly because their wide gap makes it difficult to light a dense nitrous-fuel mixture. In addition, such a spark plug does not conduct heat out of its ground strap quickly enough, which can melt it and also cause a detonation condition. Bad news. The good news is spark plugs designed for nitrous use are readily available, with colder heat ranges and shorter ground strap designs to get the heat out of the plug quicker. We selected NGK's V-Power TR6, a relatively inexpensive and widely used spark plug for LS1s. The only downside to these plugs is that we'll need to change them about every 10,000 miles which, on these cars, can be a bit of a hassle.
As nitrous systems go, direct-port systems are king. Delivering the exact same amount of nitrous and fuel to every cylinder, they offer the ultimate in engine safety. This distribution issue is especially key on a typical non-symmetrical EFI manifold with the throttle body located at one end. While significantly more difficult to install than traditional "wet" or "dry" systems, the peace of mind with direct port can be well worth the time. The ZEX system tested offers a wide variety of power levels to choose from. As this Trans Am's engine is essentially stock, it was decided that 125 hp would be an appropriate value. As you'll see, our results leave some power on the table with a somewhat rich mixture. Safe may be a four-letter word, but it's music to my ears, and I wasn't about to alter the ZEX system's recommended jetting. Going to smaller fuel jets would most certainly have freed up a few ponies, but at the moment, over 500 hp at the motor is good enough for this author's daily driver. Incidentally, it turned out that with the as-installed recommended jetting, the nitrous added almost exactly the ZEX-promised 125 hp at the engine.
True, it may not sound as cool as a blower or turbo, and it can only be used during full-throttle, higher-rpm blasts, but nitrous-oxide injection is cheaper; total dollars spent for everything in this article (including the throttle body and other non-nitrous-essential items) was a bit over $4,000. And as currently jetted, this nitrous kit produced essentially the same performance increase a typical intercooled turbo or blower would.
Perhaps most importantly of all, the intimidation factor of purging a cloud of nitrous into the air is second to none.
ConclusionIn a failed attempt to assess the quarter-mile improvement had by our new parts, we managed to reduce the Trans Am's already-weak clutch to flaming dust one afternoon at Englishtown, New Jersey. Even with an incredibly soft launch from idle, the clutch couldn't handle the torque and slipped more and more in each successive gear. A new clutch was immediately installed. Check elsewhere in this issue for the track results.