Nitrous oxide is a power-making tool. Drag racers at every level have realized that nitrous can be an effective way to add power and simplify e.t. tuning. We witnessed copious amounts of nitrous being used at the Fastest Street Car Shootout. You probably see it at your local bracket races, and even if you don’t see it at the street races, it’s there, too.
To put together this article, we talked to engine builders Sam Gianino, Mike Hedgecock and Bob McKray. Gianino builds Pro Modified engines and specializes in race and incredibly fast street big-block Chevrolet engines such as the one for Danny Scott’s 8.18-second street-driven ’67 Camaro. Hedgecock is the owner of Eagle Engines and has done considerable work with nitrous oxide. He also built all of Robbie Vandergriff’s 2000hp engines for his Pro Modified ’57 Chevrolet. In addition, Hedgecock built the engine in Rick Dyer’s ’69 Camaro for a recent Fastest Street Car Shootout, which enabled Dyer to run his quickest e.t. of 8.39 seconds. Finally, Bob McKray builds the engines that power Gray Baskerville’s M&V race car, and he builds plenty of street/strip engines.
Before you break out the assembly lube to build a nitrous engine, you should consider a few points. First, decide how much nitrous you will be using, and be honest with yourself. It’s much too easy to change nitrous jets, increasing the power delivered by the nitrous system, without upgrading your engine at the same time. Such shortsightedness will eventually be punished with broken parts. Decide what power level you will reach with nitrous, and limit yourself to that level. Our engine-building experts agree that, if you are planning to use a kit advertised at 150 horsepower or more on a regular basis, you need to take particular care in selecting engine parts and in building the engine correctly. Next, build the engine as if it will operate all the time at the power level you will reach when using nitrous. In other words, if you’re adding 225 horsepower to your 375hp small-block, the engine should be built as though it will make 600 horsepower all the time. Such overkill ensures that you will not have an engine failure due to weak parts. At the same time that you are building a strong engine, you can configure it to squeeze the most power from nitrous use.
Nitrous allows you to fill the cylinders with much more air than your engine normally could. For that reason, the intake tract of your engine will not need particular attention. It is crucial, however, that an appropriate amount of fuel be delivered at the same time as the nitrous to match the increase in oxygen. And you have to get all of it back out of the cylinder to make room for the next charge. Therefore, special attention should be paid to the exhaust cam timing and the exhaust tract.
At the same time, cylinder pressure and detonation are big concerns. Cylinder pressure is power, while detonation means destruction. Both test the strength of every component in your engine, and they can lead to destruction if the engine is not built properly. In addition to the parts we cover in this article, quality machine work is also critical in building a good nitrous engine.
The recommendations we make here assume that you will be using nitrous on the engine regularly, such as in bracket racing twice a month. Small amounts—100 horsepower or less—can be used infrequently without making changes to anything except the fuel system with minimum risk.
The best results are realized when the engine is overbuilt. Tune the engine well before you use nitrous. Start conservatively and work your way up in power levels. Nitrous will give you hints as you go, and if you work up gradually, you can see the signs and correct a problem before it becomes costly.
