Most sanctioning bodies, ProStar/IDBA etc requires that the NOS bottle to be supported in such way that it cannot be dropped from its bracket. This means you have to modify the stock bracket with an additional bottom support. The NOS and fuel solenoids can be mounted in any position, this isn't explained in the installation instruction but confirmed by numerous racers with long experience (Bill Vose for example). Make the fogger lines equal in length for consistent pressure to all four manifolds. Speaking of manifolds, most experienced racers put their foggers in the rubber manifold to eliminate vibrations and to keep the foggers as far away from the intake tract as possible to maximize the fuel atomization/vaporizing, so did I. You have to bend the left branch of the Y-shaped oil distributor towards the cylinder block to clear fogger #2. The use of an fuel pressure safety switch is optional but strongly suggested to prevent nuked pistons. I'm using one. Besides the WOT throttle micro switch, thumbs button on the handle bar I'm using an Suzuki GS 80-82 5 gear shift indicator that allows the NOS to be activated in 2nd gear and up. You don't want to look THAT foolish at the starting line do you?
Stuff: 2-1/2# bottles. NOS soft plume foggers. NOS shower heads. Steel braided lines. Cheater fuel. Cheater nitrous. Pro Shot nitrous safety. Powershot purge. Holley Blue pump. NOS small red regulator. Equal 32/32 spread @ 6 PSI (of ACTUAL fuel pressure, not indicated on that small "Toys-R-US" gauge). NOS fuel pressure safety switch. Schnitz Pro Street box. Thumb "go-fast" switch.
Fact: The major obstacle with a progressive nitrous
controller is that the pulsing nitrous solenoid, distribution block and the hoses acts
like a buffer for the liquid nitrous oxide so when the solenoid is opened they're filled
with liquid NOS and the metering jets at the foggers are limiting the liquid nitrous flow
escaping through the nozzles. When the nitrous solenoid is turned off, there's still
liquid nitrous in the lines etc that continues to vaporize and escape through the nozzles
even though the solenoid is shut off. The fuel however is immediately shut off since it's
not in a compressed state (to speak of). Thus leaning out the mixture to a dangerously
lean condition if the "buffer" is large enough during a progressive ramp-up.
The idea behind a progressive controller is to get an ON/OFF function of both fuel and nitrous simultaneously. You can't compress fuel and fuel doesn't expand unless it's being heated up and it vaporizes. This is not the case at a room temperature with gasoline. Nitrous however, vaporizes at room temperature. We've got a problem, but... it can be minimized!
Fix: Install a Summit (true vane type) or any other vane (gear driven) type (not pulsing) fuel pump (Holley Blue is okay) that is capable of 10 PSI or more while flowing through the metering jets. Install the NOS red small fuel pressure regulator. Set the fuel pressure regulator to 6 PSI (actual pressure, not what you're reading on the gauge - those small mechanical gauges are VERY temperature sensitive). This fuel pressure of 6 PSI allows you to use an equal spread of the fuel and nitrous jets, which means you use the same size on both nitrous and fuel. For now, don't use larger jets than size #26. The progressive modulation (pulse width) of the fuel solenoid now upsets the dead head NOS RED diaphragm fuel pressure regulator so that it delivers a higher fuel pressure when it's being exposed to pressure pulses. This makes the fuel pressure to be higher during the progressive ramp-up thus compensating for the liquid nitrous still in the lines.
Ideal: Would be to have individual solenoids directly connected to each fogger to minimize the liquid "buffer" effect on the nitrous side and to use a by-pass fuel regulator that will maintain the fuel pressure at a constant level even when exposed to pressure pulses. This however is kind of hard to achieve. That's why most Big Dog's are using a two- or even a three-stage shot of nitrous - to eliminate the liquid buffer problem. Also, barely adapt your whole setup to accommodate the largest jets you're going to use - too large solenoids, lines etc just worsen the "buffer" problem.
Beginners installation: Install the NOS/Holley/NX motorcycle starter kit as described. Start off with a spread of FOUR (like #16 NOS and #20 FUEL) since the kit's fuel pump (at least the NOS) sometimes only deliver 3.5 PSI during full flow. Always use a larger fuel jet than a nitrous jet with the stock system since its fuel pump CAN NOT deliver 6 PSI which is required for an equal spread on the jets. Get the fuel pressure safety switch, if you don't... expect to burn up your motor. Set the safety switch to at least 3.0 PSI (three point zero) and wire it to shut off the NITROUS solenoid only, NOT the fuel pump or the fuel solenoid. Use a thumb switch to go-fast, don't put it on a WOT throttle switch = a bit dangerous. I'm using the starter button for the GO-FAST function. Use one heat range colder plugs, like going from JR9B to JR10B on a Suzuki Bandit 1200. If you're shooting more than 60 hp, like using fuel jets bigger than #24, put another spark plug washer under the plug. Pull any kind of ignition advancer you might have installed. If you're really concerned - retard the ignition about 1 degree for every extra 10 hp you add. For a 100 hp extra shot (for a total of 230 hp) you should be at around 28 degrees of ignition advance. If you've got an air shifter it should BANG LOUD when you shift. If it doesn't BANG it means that you're on the lean and dangerous side. If you're too rich it will blubber and stutter but it will still BANG loud when you shift. Good luck!
Beginners tuning: The first pass ever should be with the NOS bottle turned OFF. When you hit the button the bike should fall on its face due to too much fuel. If it doesn't - find the fault and test again. Now when it falls on its face you can turn on the bottle. When you hit the button (above 6000 rpm) for no more than HALF OF A SECOND it should give you an instant hit. If not, find the fault and try again. Check out Burgermans home page for even more tuning tips. That kind of information is invaluable for us deadly that aren't backed-up by a credit card and Billy Vose or one of the other nitrous guru's out there. http://dragbike.com forums is also a good place for nitrous oxide information. Most of the participants are tight lipped (trade secrets I guess) but there's a few willing to give you some advice.
Important progressive nitrous notes: Immediately retard the ignition to the max retard setting when you press the button. The progressive makes the nitrous go ON OFF ON and those "ON" pulses are 100% pulses. Even though the progressive says 50% it means that the duty cycle is 50% = the nitrous is shut OFF 50% of the time but is also turned ON 50% of the time with 100% power. Octane rating is VERY important when you're on the "juice". Detonation will occur with pump gas if the combined combustion pressure exceeds that of a 13:1 motor. That's about 220 hp with a 10:1 motor. Detonation is not the same a knock. Knock is when the mixture is ignited before the spark plug does it for you. It's a dangerous situation but not as severe as detonation. Detonation is when the spark plug ignites the mixture and the increased combustion chamber pressure creates a second spontaneous combustion and the two flame fronts collide and induces a very high pressure spike in the combustion chamber. This pressure spike will EAT aluminum off your pistons AND cylinder head. It will create a hole in your piston in less than a second! If the electrode on your spark plugs are gone/eaten off but it still runs after you've replace the plugs it's either detonation or a too lean condition. DO SOMETHING ABOUT IT before you make the next pass or you'll have to pick up pieces from your pistons from the oil pan.
Bottle temperature: You read and hear a lot about maintaining a nitrous pressure of 900 PSI. That's easy done in the Southern parts of the USA during the summer. But the thing is - that's not neccessary, just tune your system for the "average" ambient temperature where you are at. 750 PSI would be ideal for a "warm" Swedish summer day. That way you don't need to heat up the bottle before a race.
Danger! Don't ever heat your bottle with a propane torch, at least not at the same spot - that'll weaken the aluminum and the bottle will explode in your face and you're dead and history.
Purge: If you need to lower the nitrous pressure at the starting line - install a nitrous purge. It's mostly for show, but if you're concerned about 0.005 second on your ET... go ahead and waste $2 worth of nitrous. A regular Powershot solenoid works.
Refill at the track: Get yourself a cooler filled with ice. Put the small bottle in the cooler for a couple of minutes. That will lower the nitrous pressure to about 300 PSI. The pressure difference will make the liquid nitrous in the larger filler bottle (750 PSI at 22 degrees Celcius, +70F) transfer itself to the smaller bottle. Voila! Easy! Don't overfill. Get a digital kitchen scale and weight before and after and purge off any excess weight BEFORE you warm up the small bottle again.
Before the first pass of the day: Before you turn on the nitrous bottle, do a "fuel purge" and make sure you've got fuel flowing in your nitrous installation. Just rev to 1/2 the max rpm and push the GO-FAST button. The motor will bog down and sputter if you've got fuel. That means you're okay to let the nitrous juices flow!
Grade of Nitrous: Medical or Racing NOS? Performance wise there aren't ANY differences. The racing stuff just smells bad to prevent you from getting too happy at the track.