Turbo Spooling Nitrous Oxide System Basics

[Alky V6]

Bottle Pressure Maintenance

Let's cover bottle pressure maintenance next.

The pressure of a nitrous bottle will change with the temperature of the bottle. This will be closely tied to the temperature of the day.
The importance of the bottle pressure is that a steady and on-target n/f ratio is very dependant on the supply pressure of both the fuel side and the nitrous bottle side.
950 psi bottle pressure is a good middle ground to set your jetting of the nitrous system too. As bottle pressure rises, as on a hotter day, the n/f ratio will lean out. As the bottle pressure drops, as on a colder day, the n/f ratio will richen.
Using an automatic heat blanket on the bottle is a good way to warm up a cold bottle. On a hot day, you can use a white colored towel soaked in water, or ice water, depending on how hot the day is, draped over the bottle to cut the temperture and pressure fairly quickly. There are also some electronic devices on the market that will cool a bottle. I don't know how affective those devices are, and maybe someone can give us some feedback on that.
The type of electric heating blankets that tie into the car electrical system (12V) can drain the battery pretty good, so it's preferred to run the heating blanket with the engine running and the charging system doing its job. A 110V DC heating blanket is also available so that you can plug the blanket into a generator in the pits for quicker heating of the bottle without worrying about draining the car battery.
It seems to take about 15-20 minutes to heat a bottle on a cold day with a 12V heating blanket. I don't have any experience with the 110V blankets.

Since it's important to keep a certain bottle pressure with your system, you will need a bottle pressure gauge so that you can monitor it. The gauge can be mounted near the bottle valve, or you can remote mount the gauge on the dash so that you can easily monitor it while driving.

Next, I'll tell about the time I learned about real high bottle pressures.

 

[Alky V6]

Before I continue, I should mention the importance of routing the blowoff valve on the nitrous bottle outside of the trunk or passenger compartment.
If a bottle should overpressurize, as might happen if a bottle is overfilled (yes, they can be filled beyond the rated poundage, and I don't recommend it) and the bottle has been sitting in a hot trunk on a very hot day, a blowoff disc is incorporated into the bottle valve. This disc is rated to rupture at a certain psi to safeguard against the bottle itself exploding (not a good thing). A fitting and hose can be attached to the blowoff valve so that the contents of the bottle will be routed outside the car if the disc were to rupture.

 

[Alky V6]

My Overpressurized Bottle Experience

This happened at Pinks All Out time trials at Bakerfield CA, 2009.

Temps that day were 101 degrees F. Inside the car? I don't even want to guess. It was freaking hot in the driver's suit.
My bottle is mounted next to the driver's seat so that I can control the bottle valve by hand and monitor the bottle pressure. The gauge is mounted off the bottle valve.
In the staging lanes, the sun was beating on the bottle through the rear window. If someone was searching for a way to heat up a nitrous bottle as much as possible, we were doing it.

Let me explain something first about my system. I'm using methanol fuel with the nitrous, and methanol has a very wide tuning range so I wasn't worried about how the bottle pressure was affecting the n/f ratio. All I knew was that the bottle pressure was the highest I had ever seen it at, and that the hit was going to be the hardest I had ever felt up to that day. The hit was going to be on the lean side. Since I run the system at rich burn limit, the leaning out of the system was only going to make more in-cylinder power, but still safe.

The bottle pressure was over 1200 psi. Why the blowoff disc didn't give up the ghost, I don't know.

When it was my turn to drive up to the burnout box, I attempted to purge some nitrous to relieve some bottle pressure and cool it down. I have since learned that at 1075 psi bottle pressure, all of the bottle content has turned to a somewhat gaseous state. So even if I did manage to purge the bottle, there would be no liquid nitrous in the bottle to boil off and help cool the bottle.
Back to the story. As I pressed the purge button,... no purging.
Hit the side of the switch panel,... press the purge button again,... no purging.
Turn the switches off, then back on,... hit the switch panel again,... press the purge button. No purging. I wonder if some of you can imagine how I was feeling.

This was Pinks All Out. This was my chance to spotlight the car with the new 91mm turbo and,... no nitrous. You can imagine how that pass went.

Back at the pits, we checked the elecrical to the nitrous system. All good. I closed the nitrous bottle, bled off a little of the pressure in the feed hose at the bottle, tried the purge valve and it worked.
OK. We just learned an important lesson about bottle pressure and the pressure limits of the nitrous solenoids. Too much pressure on the nitrous solenoids and they won't open.

We then soaked a towel in the ice chest and layed it over the bottle. The bottle pressure dropped pretty quickly. The rest of the weekend, we ran with a wet towel draped over the nitrous bottle.

 

[Alky V6]

Next we'll cover basic operation and safety controls and procedures.

 

[Alky V6]

Next we'll cover basic operation and safety controls and procedures.

OK, borrriiiiiiing, but I wouldn't feel right if I didn't cover it.

The general rules are:
Do not activate the nitrous system below 2500 rpm.
Activate only at wide open throttle, under a load, and not on a transbrake.

I have seen these rules broken. Well,... I may be guilty on one,...maybe two counts, but just remember these rules are meant to keep your money in your wallet. Not dumped under your hood.

The bottle pressure gauge is your friend. It can tell you a lot about the health of your system, other than just the bottle pressure.
For instance;
You climb in the car after having it sit for a week and you notice a pressure reading on the gauge. You could have sworn you closed the valve after the last track session. The bottle valve may be leaking, or you may have forgotten to close the valve. Either way, nitrous has been pressurized in the nitrous system supply line for a long time. Most systems are not perfectly sealed, so you may want to check the weight of the bottle to see how much nitrous you may have lost.
Another important thing to consider is whether any of that nitrous slowly leaked past the nitrous solenoid and filled the intake manifold with grade A oxidizer. You might want to let the engine air out a bit before trying to start it. If you can crank the engine around with the fuel and ignition system off, you can pump any suspected nitrous out of the engine before you try to start the engine with fuel and ignition on.

When ever you close the bottle valve, pay attention to the gauge. It should hold pressure even after the bottle valve is closed. It will drop over time, but at the moment that you're closing the valve, you should not see the pressure drop at all. If it does, it's telling you that you have a leak in the supply system and you need to find out where it is and correct it, NOW!!! The worst scenario would be that it's leaking past the solenoid into the engine. If that's what you find, be careful with the next engine startup.

If you have a purge valve, and you're done for the day, close the bottle valve and purge the supply line until all the pressure is gone. Check your gauge. The pressure should not come back. If it does, the bottle valve is leaking.

 

[Alky V6]

I'm pretty cautious about startup. Being that methanol likes to intake-backfire on start-up real easy as it is, I don't need any help from nitrous that may have leaked past the solenoid into the intake ports.

After climbing into the car, I check the bottle valve to make sure it was closed. I then check the pressure gauge. If it's been awhile since last starting the car (over a day), I wouldn't expect to see any pressure in the nitrous system.

I should clarify something right now. Typically, nitrous pressure gauges are reading the pressure in the supply line after the bottle valve. They are not reading the bottle directly as would be if the gauge was mounted before the bottle valve.

If I've started the car earlier in the day, I would expect to see the gauge reading a pressure slightly lower than the bottle pressure. If it's a lot lower, I would have to suspect a leak somewhere, and I would need to hunt it down first.

If I'm real careful that day, I'll crank the engine over 15 revolutions with the fuel and ignition off. Then, I'll start the engine. If I'm pulling out from the front of the staging lanes to the burnout box, I'll go ahead and open the nitrous valve. If I notice a change in the engine behavior when I crack the bottle valve open, it's time to close the valve and head back to the pits. The nitrous solenoid is leaking. If the engine idles normally, I'll take a quick look at the bottle pressure. The target is 950 psi. I'll also arm the nitrous system control electronics and the purge solenoid circuitry (one switch). The master arming switch is still off.
After the burnout, I'll pull up to staging lights and purge the nitrous system with three spaced purge solenoid activations. The spacing between the purge solenoid activations is to give the nitrous time to sit in the supply line and absorb the heat from the lines to cool them. Cool supply lines will do a better job of getting liquid nitrous to the nozzles rather than having the liquid nitrous boil to a gaseous state in the lines before exiting the nozzle(s).
The last thing to do before staging is to turn on the MASTER NITROUS SYSTEM ARMING SWITCH. (Said with a deep echoing voice)

When's the next racing date. DANG I'M PUMPED!!!

 

[garyk1970]

subscribed...great info/topic

 

[Alky V6]

OK. I guess if we're past the basics, and no one has anymore to add, or any questions not pertaining to control systems, we can move forward to the whacky world of controlling the nitrous system.
Some have already added some good information on ways of controlling the activation of the nitrous system. The flood gates are now officially open.

Some methods just involve simple electrical systems while others involve specialized programming of an ECM or programmable settings within an ECM using software. I'm sure there are litterely thousands of ways to accomplish the task.

I'd like to go over a basic electrical control system with all the safeguards first. That will give everyone a good foundation for what is needed. Then we can move into how many of these controls and safeguards can be accomplished using the help of an ECM.

 

[Alky V6]

Nitrous Factoid Sidetrack

A particular volume of liquid nitrous, that then expands to a gaseous nitrous state can result in an increase in volume by a factor of 679.
This is why it is so advantageous to port inject nitrous. If you can intake liquid nitrous into the cylinder, taking up little volume of the total nitrous/air/fuel charge, and then have it expand in the cylinder after the intake valve has closed, the result is a much larger mass of nitrous taken into the cylinder per intake stroke.

The nitrous, in liquid or gaseous state, will replace some of the air intake volume during intake, but because of the cooling effect of the nitrous which results in an increase in charge density, mass air flow gains of up to 10 percent can actually be realized.

Vapor pressure of nitrous is zero psi at the boiling point of -128F.
Vapor pressure of nitrous is 1070 psi at 97.9F.
Pressure will continue to increase as temperature increases above 97.9F, but the complete contents of the bottle will be in a gaslike supercritical fluid state, which has far less of a cooling effect when injected into the engine.

 

[Alky V6]

I'm not going to get into the wiring of a nitrous control system. Someone else can feel free to do that explanation. I'd like to cover the other main electrical components that should be part of the system, and what they should accomplish.
Wide open throttle switch. It should be a normally open switch that closes and completes a circuit only at wide open throttle. This should allow nitrous to flow only at wide open throttle. This normally is a microswitch.

Main nitrous system arming switch. This is a normally open switch that must be flipped on to close a circuit that will allow the nitrous solenoids to be activated, independent of any other system control devices. This is the last line of defense switch. NITROUS and FUEL DOES NOT FLOW TO THE NOZZLE(S) WITH THIS SWITCH IN THE OFF POSITION. PERIOD!

Intermittent switch. This switch is a normally open, manually operated switch, typically a button, that is controlled by the driver. Closing this switch will allow the driver to bypass certain other controls in case there is the demand for nitrous like right now.

RPM switch. This switch will only allow the nitrous solenoids to be operated above a user picked, predetermined engine rpm. Minimum being about 2400 rpm. You can also have another normally closed rpm switch that will open at or above a certain rpm to turn the nitrous off when the engine rpm has reached a certain level.

MAP switches. These switches follow the same thinking as the rpm switches. A normally open map switch would close and allow nitrous flow only at or above a certain map level, while another normally closed map switch would open at or above a certain map level to shut down nitrous flow.
It's not a bad idea to have systems that can back up another to ensure that a control command is carried out.
For instance, I use a map switch that will shut down the nitrous soleniod at 16 psi. I also use a delay timer that can shut down the nitrous after a preprogrammed amount of time has passed after the release of the transbrake. With the present engine/turbo configuration, the shut off point of the nitrous system is before the map reaches 16 psi. The timer takes care of that point. The 16 psi map switch acts as a backup if the timer happens to be misadjusted or not work.

 

[Alky V6]

Nitrous system control electronics switch. I have my 'nitrous system control electronics' on a separate on/off switch, intead of putting it under the control of the 'main nitrous system arming switch'. This way I can power up the 'control electronics' and make changes, or do tests without the danger of the solenoids accidentally being activated, since the 'main nitrous system arming switch' could be left in the off position for those changes or tests of the 'control system electronics'.

Relays. Since some nitrous solenoids can draw a lot of current, it's best to have the 'system controls' command relays to supply the heavy current to the solenoids.

Fuses. Make good use of fuses where ever you can. Very important.

Wires and terminals. As with all your other electrical components, make sure the wire and terminal sizing will handle the amount of expected current in the circuit.

Other switches. Some other types of switches can be used to cancel nitrous activation if proper oil pressure is not present, or if proper fuel pressure is not present.

 

[Alky V6]

My particular controls system is a mix of basic electrical devices and electronic controls. I'll outline that system next.

 

[streetknight]

This is some great info...I have an old school "time Bomb" I guess.

I welded a bung in the up pipe 1 inch upstream of the alky nozzle. Used the smallest dry nozzle that NOS made. For fuel, I just ramped up the alky knob "hoping it would work" LOL...

Controlled it with a button. Bring the car up on the converter at the line, throw it on the floor and grab the button "INSTA SPOOL"

Never had any trouble, this was a stock engine with a 61 turbo.

Anyone remember Molly Hatchet "Flirtin with disaster!"

 

[Alky V6]

Instead of me duplicating an explanation of how my nitrous system controls are layed out, I'll just refer you to another thread that contains a thorough explanation. 'Advancement of Fuel Delivery?' in this same section on this site. It's a long thread, and the explanation is in there somewhere.

Let's talk about the advantages of using nitrous oxide injection to quickly spool a turbo.

What kind of engine/turbo configuration changes can be made to help better the overall performance of the car when nitrous oxide injection is brought into the picture?

What sort of gains have people experienced after adding nitrous oxide injection to their turbo tuner's tool chest?

How has it affected the selection choices for turbochargers and torque converters?

Has it made component selection more, or less critical?

 

[liquidh8]

subscribed! I have a NOS cheater kit I am taking off my V8 car and puting in my Buick car. Got info here.

 

[porsches4lunch]

Any Updates

 

[Alky V6]

During some testing today at the track, I found a direct correlation between the 60 foot and the amount of nitrous purging before staging the car. The more purging, the better the 60 foot by as much as .06 sec, so far.

New bests for the car and the 91mm. http://www.turbobuick.com/forums/tu...-ams1000-operation-dummies-5.html#post2509400

 

[charlief1]

Simple reason is because the cooling effect to the line Donnie. It would allow for a more dense charge.

 

[Alky V6]

Simple reason is because the cooling effect to the line Donnie. It would allow for a more dense charge.

Yes, you're right. I wanted to post a number to highlight the advantage of a good purge versus a poor purge.

 

[Alky V6]

So, what can actually be done with a nitrous shot, and how large of a turbo might you be able to spool using nitrous oxide injection?

YouTube - Spooling a 91mm Turbo