[Hib Halverson]

Intro: nitrous oxide, is an "oxygen bearing compound". When nitrous oxide along with extra fuel are injected into the cylinders, once the compression stroke heats the air/nitrous/fuel mix to 575°F, the nitrous breaks down into nitrogen and oxygen. Since the proportion of oxygen in nitrous oxide is higher than that in air, you end up with a very lean air:fuel ratio. Add extra fuel and the engine makes more power.

First, heed the advice above and run a dry system and that means the extra fuel needs to come though the injectors. A wet system on an engine like the LT5 is just asking for trouble in the form of an intake manifold explosion.

Wet systems on port injected motors can really be fun if the nitrous and fuel aren't right and the engine spits back thought the intake. A long time ago, I built a Chevy Beretta with nitrous. Back then no one had a dry system for a 2.8L V6 so I put on a wet system that NOS made. Several times during really cold weather (good air) and when I tried to use nitrous below 3000 rpm, I hit the nitrous and BANG! the motor spit back big time, the MAF quit and the check engine light came on. One time the manifold backfire was so big, afterwards, I smelled smoke, pulled over and found the filter in engine's air box on fire. Needless to say, my wet system nitrous days with that Beretta didn't last very long.

Second, for a 100 or 125 shot to work well you're likely going to need bigger injectors and how much bigger is going to be determined by how much extra fuel flow you need.

Thirdly, the extra fuel.
I've actually never done nitrous on an LT5, but I've done it on other port fuel engines. Typically, you'd apply reduced nitrous pressure to the FPR and that bumps fuel pressure up. The increased pressure increases fuel flow by an amount needed by the nitrous oxide provided that the fuel supply system can produce the extra flow. Remember, for a given set of fuel pumps, when you up the pressure the pumps' maximum available flow goes down. If the required fuel flow exceeds the maximum available flow, the engine goes lean under nitrous oxide operation and then, bad stuff happens.

Fourth, the spark calibration.
This is a challenge too because with the nitrous working, even though it's an antidetonant, sometimes the dynamic cylinder pressure gained by burning the extra fuel and oxygen from the nitrous oxide, is more than enough to overcome the antiknock qualities of N2O and cause detonation. Rather than let EST solve the problem with KR, you're better doing some testing then retarding spark in the cal by an appropriate amount such that, with nitrous enabled, the engine is for the most part out of detonation. The main reason for this is, once the engine is in detonation, it takes more KR to stop it than if the spark was retarded enough such that the engine didn't detonate. Additionally, if you currently have an aggressive spark cal, it's possible that right at the nitrous hit, if the extra fuel doesn't get there in time, you may momentarily have so much detonation that there's not enough KR to stop it. But then, the only way to do all that is have a PROM switcher, so...most people let KR keep them out of trouble.

In short, the challenges are 1) making sure you can get the needed fuel flow with the pressure increase, 2) tuning the nitrous pressure delivered to the FPR and 3) getting the spark cal right.

The last motor I did nitrous on was a 3.8L V6 in a Camaro. Wiithout the gas, the motor made about 300-hp SAE. When I hit the bottle it went to 385-hp SAE. An "85 shot" on a three-eight V6 with a stock lower end was plenty.

Lastly, nitrous works bitchin' if the system and the engine are configured and tuned right but if the system is not set-up right, nitrous is great at blowing up motors in short order. Like any "power-adder". The easy part of buying it and bolting it on. The hard part is tunning it so the engine makes power and is reliable doing it.