CHP: How high can you raise the compression and still be safe with nitrous?RS: We have successfully run nitrous in motors with 17:1 compression, but many factors must be considered before this can be attempted. The camshaft must be profiled to reduce static compression at low rpm. If using a torque converter, the stall must be above the peak torque of the engine. The only enrichment fuel acceptable for large doses of nitrous at this level is methanol or ethanol.
CHP: What is the ideal compression ratio for nitrous usage in a competition engine?RS: Years of experience have taught us that 13-14:1 is a very good place to be.
CHP: What is the ideal compression ratio for nitrous usage in a street engine?RS: The limiting factor on a street engine is the availability of quality fuel. Using 92 pump gas, about 20 hp per cylinder is max using factory stock compression on your engine. However, if you have access to the new E85 fuel, the sky is the limit!
CHP: Is there an easy way to control the huge amounts of torque and horsepower produced by nitrous?RS: We have a variety of progressive controllers that'll allow you to digitally control the power output of your nitrous system through a laptop computer. The Maximizer II incorporates a window switch, delay timer, wideband O2 option, bottle pressure controller, bottle opener, and built-in MAP sensor for automatic turbo reverse ramping, both time- and rpm-based power curves.
CHP: Is it best to have an automatic transmission or a standard shift?RS: Either will work great, but an rpm-window safety switch is recommended on all nonautomatic applications. The safety switch will prevent nitrous engagement below a preset rpm.
CHP: What bottle pressure will produce maximum performance?RS: All of our systems are calibrated for 1,050 psi; any pressure below this will produce an overrich condition, which decreases power. Through our own extensive in-house testing, we've learned that any pressure in excess of 1,070 can cause a similar overrich condition that can also result in a power loss.
CHP: What fuel pressure do you recommend for peak performance?RS: Fuel pressure in itself does not affect nitrous system performance. Our systems are factory calibrated for specific vehicles and their respective factory fuel pressure setting. Higher fuel pressure requires a smaller metering jet to maintain the proper nitrous/fuel ratio and a lower pressure would dictate a larger jet to maintain the correct ratio. A higher fuel pressure will not result in better fuel atomization.
Q&A #2Q&A Session With Kevin Gass Of NOS/Holley CHP: Will nitrous oxide hurt my engine?Kevin Gass: Not directly. The use of a properly designed nitrous system will not have an adverse effect on engine reliability. If you are realistic in the engine's construction and choose the right nitrous kit, engine dependability is excellent.
CHP: How much bottle pressure should I use?KG: We recommend 900-925 psi as a baseline.
CHP: How much should I change the jetting of my carburetor?KG: We advise that our customers should not rejet their carburetors when using nitrous.
CHP: Can I use any type of plate with any size solenoids?KG: No, they need to be properly matched and we always recommend not to deviate from manufacturer-recommended solenoid sizes and plate types. They won't all work together due to orifice sizes. Properly matched components will result in maximum reliability.
CHP: How long will a bottle last?KG: This depends on the power level and duration. A general guideline is that when a 125hp system is sprayed for 12 seconds, a 10-pound bottle will last 7-10 full runs.
CHP: How does a plate system compare to a fogger?KG: The plate system provides ease of installation and low cost. The disadvantage to a plate system is that you have to make tuning adjustments from the leanest cylinders. A direct-port fogger system has the advantage of being able to tune each individual cylinder to maximum efficiency. A fogger system also hits the tires much softer than a plate, which in some applications is an advantage. The disadvantage to a fogger is that the manifold must be drilled and tapped, and lines bent for installation. Fogger systems also cost more than plate systems. Whenever maximum efficiency is desired and rules allow, a fogger is recommended.
CHP: What is the most common system NOS offers?KG: The most common street/strip system is the NOS Cheater plate system, PN 02001NOS, which sells for $476 and is available through summitracing.com. This system is adjustable from 150 to 250 hp and is upgradeable to a dual-stage system and into a Big Shot system.