CHP: What advice do you have for tuning a system?
JW: Always do your initial jet on the rich side, meaning use a larger fuel jet. It's easier to cut back than to go bigger. Also, be sure to change the heat range of plugs; if it's too hot, you can have detonation issues. We recommend that you retard the timing 2 degrees for the first 100 hp, and 2 degrees per 50 after that.
CHP: That sounds pretty straightforward.
JW: It's easy to get carried away with overexpectations, letting your eyes overwhelm your senses. Don't outrun your fuel system; start slow and ease your way into it. On the dyno, we start with small jetting. Like all modifications, it's about air/fuel and what the engine can stand.
CHP: Can we assume you recommend dyno tuning?
JW: If you have the ability to run on a chassis dyno, it can save some time and agony. In the scheme of money we spend on these cars, it's worth it to be able to tell when things go sideways
Q&A: Brandon Switzer, Speedtech Nitrous
CHP: How long has Speedtech Nitrous been in business?
Brandon Switzer: We're about three years old; we were involved with Shannon Jenkins and Mike Castellana, helping them on their race teams, and one day at the track just decided to open. Most companies start at the street level and try to work up; we started the opposite way, in the most premier nitrous class (Pro Mod), and are working our way to street.
CHP: Does the race experience apply to the street/strip realm?
BS: It applies directly. It may not be one-to-one, but there's a huge trickle-down effect, improving manufacturing and how to make cars better. What we learn helps with feedback to our customers in different areas.
CHP: So where is Speedtech doing most of its business?
BS: We primarily sell to racers, because that's what we do-we're out there with them every weekend. Most of these systems are direct-port setups, but we're working to expand into the street market, so we sell a lot of plate systems too. Our Diffuser Plate System has two inserts, so it sprays a 360-degree cone of nitrous at a 45-degree angle. It's an equal umbrella, creating perfect distribution around the plenum.
CHP: What should our readers know about nitrous?
BS: One of the major things is that nitrous is a two-phase gas. If you incorrectly size any area of the system, it changes phase (or boils) and you lose all metering capabilities. The second it changes, it loses density. Area calculation is one of the biggest things to look at when creating a nitrous system.
CHP: How do you know this is happening?
BS: Nitrous gets cold when it expands; it's ambient until then. All you have to do is turn the system on and run it. Anywhere it freezes, from the bottle to the nozzle, it's changing phase.
Installing a WOT switch in vehicle without a mechanical throttle linkage, aka drive-by-wire (DBW) system, used to be problematic. NOS has addressed the issue with its DBW/Wide Open Throttle window switch. Designed primarily for use with nitrous systems on DBW vehicles, it features adjustable low- and high-rpm set points to turn the system on and then off, and throttle position sensor (TPS) activation. Don't have a DBW vehicle but still want an rpm window switch? Hook up the power and an rpm signal from your ignition, and you're good to go.