as far as the idle air control I am not sure but I think I remember seeing somewhere that it is a stepper motor, a stepper motor is able to be turned a certain amount so it can just open and close a valve. It would take a pretty good stepper motor to be able to handle the temperature drop of the nitrous. As a gas goes from a high pressure area to a low pressure it takes a lot of heat with it, that is how air conditioning works and if the valve is not really strong it would freeze up. I am sure there are valves that could be used for it but the cost would probably be a lot more expensive than a standard solenoid. From the small amount of looking around the web it looks like most linear flow valves are still solenoid based. I figure there isn't much difference between the standard vavles used for nitrous systems and one of the precision linear flow valves as far as the use in a car. It looks like the linear vavles are good for varying the opening and closing of the valve where we are only concerned with going from 0-100% and not closing so there probably isn't much advantage to using one over the other.

One thing I thought of for a way to control the unit without a menu would be to have some buttons on it and you could set the rpm points by revving the engine to that point and hitting a button. would be simple and easy to use and take like 10 seconds to adjust.

One other question for you guys is how many channels would be worth using for outputs? what would be a good way to solve the wheelspin problems? Is there anything other than rpm that would be helpful to monitor?

btw the first idea I had for a controller was to raise the gas pedal an inch or so and put a spring on the cable so after wide open the pedal could be pushed about an inch farther and use that inch of pedal to control a nitrous system. When I first got my camaro that was what I planned on doing but decided to let the warranty run out before doing anything to that car, I have 33k miles now so it is time to start looking for stuff to do to it. I pretty much decided it would be very hard to control nitrous with the gas pedal. If any of the sponsors here want to give me a good deal on a nitrous system to test with I would be more than happy to take it

 

We've been toying with the linear progressive since March 04. Never got into a big rush due to the fact that the cost would be high and there would be low sales due to that. We've finished software and found good servo's. Decided it would be better to find a good valve that has built in servo control or a 0 to 12 volt actuation like stated before. Was planning on keeping it all quiet till it was finnished, but looks like there are some smart fellers out there that knew they needed somthing like this.

Is it time to replace the regular noid pulsing progressive controller? Absolutely not! Noids are a lot better these days. 20 years ago, sure, but not now.

 

If you look at the data the manufacturers of the solenoids provide some of them give flow numbers for the solenoids at different % open and I think that is where the linear valves woudl be more accurate that at 50% pwm signal the flow would be 50% instead of being a slight curve it would have a straight line for the flow. like this: http://www.engineeringtoolbox.com/45_485.html keep in mind those curves are exaggerated and are not quite as far off as what that picture would lead you to believe. also it is more than just the valve that changes flow so the fittings hoses and other stuff will make all the curves more like the quick opening style.

the only accurate way to set it to a perfectly linear system is to run the system as installed with a flow meter of some sort and graph out the flow vs % open then set the controller to open at a rate to give you linear response. So one option would be to hook a flow meter right before the jet and use that to base the opening of the solenoid on to acheive the desired flow at a desired time, this would be more independent of bottle pressure and system variances than any other way. This would probably be expensive but would give very accurate and repeatable runs no matter what conditions exist as long as there is sufficent nitrous to acheive the desired flow rate. An advantage of that system is it could set the fuel rate to match the nitrous flow so it is always a good mixture even if the bottle gets low.

all of this is just speculation on my part so I could be wrong with all of this.

 

I'm curious about the valve you found. I haven't looked at this stuff in a long time, but have used servos in hydraulic systems in the past and thought a bit about them as a linear nitrous controller. I know they could handle the pressure, but doubted they could live with the temperature drop caused by the expanding nitrous.

It seems like a linear controller would be better in the long run. In theory, PWM of a solenoid should work (think about our injectors) but I would think you would want a solenoid designed to work that way. The other thing is that the inertia and coil inductance cause an offset and some non linearity.

 

critter,
still looking for one every once in a while, we have 3 other projects we are working on rite now (and a list of 13 other to do's) and can't justify the time and effort for a low selling product. The cost of these types of valves is perty expensive due to the fact that the largest costumer base is big money industry so they get rob'd. A certain valve can make the plant say maybee $500k a year on a certain machine, so the price goes up to $500 or more cause they need it to make the 1/2 mill. Only thing that keeps it from hitting $3K is competition from other valve manufactures.

sbr,
your getting warmer! You seem like a smart guy. Play around with it in your spare time. You'll learn what u run into and what u need to do.

 

Would a slide valve with a series of progressivly larger holes work? Make use of the coolant lines going to the Throttle body to provide a little heat to keep the valve from freezing. The rate at which the holes and how many are open would determine the flow of the nitrous. Again not practical for mass production but it would be fun to play with. I have already done similar tests myself. I used a jet to control the max amount of nitrous that could flow at 100%. The availability of the coolant to keep freezing from occuring might make it work for the LS1's.
I get good control from just pulsing the solenoids also though. There are several things that can be done with pulsing the solenoids to get good control and delivery of the nitrous. I am not at liberty to discuss the details though.
I have always been interested in a linear flow design. Ran into several road blocks along the way though.
As far as pulsing the solenoids I am still using the same set of noids for testing controllers that I started with 7 years ago and no problems so far. I have tested several thousand controllers over the years. They are the newer design with teflon instead of o-ring seal.
Bottle pressure plays a big role on the solenoid flow when pulsing them also.

 

Decatur, huh? Almost next door. Sounds like LPE territory.
I don't know if you could get enough BTUs out of the cooling system to compensate for the cooling effect of any non-trivial amount of nitrous. The slide valve would suffer the same problem as a conventional servo valve, IMHO. To keep them from leaking, the internal tolerances are tiny. If you take one apart and hold the spool in your hand for a moment, it will not go back in the body. They are (or were) assembled in oil to keep the body and spool at the same temperature. I don't know if the state of the art has change, though. It is 25 years since I last used a servo valve. I don't think $500 for a good valve is out of line.

 

How's this for simple?

Use a one shot triggered by the tach signal. Set the pulse width on the one shot for 100% at 6K RPM with a pot to adjust it. Not as flexible as a micro based soultion, but would make flow proportional to RPM and the quantity adjustable.

 

Yes thats one way, with a couple other factors involved.

 

The more I think about it the more it seems that no matter what type of valve is used the only way to get linear flow would be to use a flow meter and just control the solenoid based on what the flow meter says. This would be easy to set up in a microcontroller to give whatever shaped curve you wanted for the flow rate and using a flow meter for the fuel side could also adjust the fuel rate to match the nitrous so you could keep a set ratio of fuel to nitrous.

Even if you get a 100% linear valve the actual output of the system isn't going to be linear due to the hoses, fittings, and all the other parts of the system changing the way the nitrous flows. All this stuff will make the bottom half of the flow curve steeper than the top half of it. so at 35-40% valve opening you are probably at 50% flow.

The thing I am not convinced of though is that it really matters for a car. If it was possible to go straight to 100% nitrous flow without spinning the tires then that is what everyone would do. Basically you want to set your curve to the fastest possible without spinning so it really makes no difference what the shape of the curve is as long as the tires and drivetrain can take it and the curve is the same on every run.

 

"The thing I am not convinced of though is that it really matters for a car. If it was possible to go straight to 100% nitrous flow without spinning the tires then that is what everyone would do. Basically you want to set your curve to the fastest possible without spinning so it really makes no difference what the shape of the curve is as long as the tires and drivetrain can take it and the curve is the same on every run."

Ditto! The only time a progressive unit is of value if you are over powering the system. Or you are braket racing and you can set the controller to back the nitrous off to 70% at the end of the track. Then you install an override switch so that if you fall asleep at the line(I am known to do this) you can hit the button and get more power at the big end. This way at least you have a chance to catch back up. You can also use progressive nitrous controllers to run indexed classes. Turn it up or down to get the dial in, i.e-8.20 top gas class that we run in AMA Prostar with the bikes.

I do not work for LPE but know a few of the guys over there. I build electronics for motorcycles and a few other companies for the automotive market. By pulsing the solenoids we are able to run 7.1x with no wheelie bars at around 190 mph in the 1/4. The Pro-Mod bikes are now going into the 6.60's using the pulsed method. If we were to just throw the switch on the nitrous and it came on at 100% something would either break and/or the rider would never want to get back on a bike(if he lived through it).

 

What I don't like is that the nitrous flow is constant not matter the RPM, but the air demand of an engine is not constant. It varies with RPM. Thus it would seem like you would like the quantity of nitrous to be more or less proportional to RPM. This is why guys run two or three stage systems that they bring in extra stages as the engine can handle it. Of course, with a 50HP shot it doesn't matter. If you were trying to run a big shot, like maybe 500 HP, I can see a benefit.
Really! We ran A/G years ago with IDBA and AMA. I thought the class was gone due to lack of interest. I also didn't know they allow nitrous these days.
Yeah, my brother was running progressive on his bike after we quit A/G. I think some form of modulation is needed for serious loads.

BTW, I do embedded hardware/software.

 

LOL, ditto again. There is no real advantage that you would get out of a valve controlled setup. You can do more with adjusting the duty cycle around then u could opening and closing a valve. If pefect ramps is what you wanted, you could tune the controller to the noid just like you tune a EFI system. Add a little more here, take a little out there............., not important.

Cost would be outrageous for nothing gained. $300 to $1000 for just a valve, then you need a servo or valve controller board designed, software writing, chart out the flow maps for N2O and fuel, hope the PSI are the same for every bottle and every fuel system of every vehicle it goes on, add the cost of saftey noids on top of it in case eithor the N2O or fuel valve stick open. You are seriously looking at a $2000 +/- system by the time it hits the market for NO REAL GAIN, other then "well my noids don't bang." Most folks complain the Maximizer is $600. Noids can take it, if your worried, pull em off every winter and send them in to get a check up/rebuild. It's a lot cheaper and easier to just order a spare set of noids.

Step 1: Pick up phone.
Step 2: Dial Nitro Dave's #.
Step 3. Say "Hey Dave(or Steve)! I would like a spare set of noids.
Step 4. Give CC and shiping info.
Step 5. Wait for UPS.

Way cheaper and easier with lots less problems.

 

7.1X's and no bars, kinda sounds like Street Bike Shootout. Helped out on a team for 1 season in that class. Lot's of fun.

 

Outlaw Street actually

I work for Schnitz Racing in Decatur. We sponser one race per year with AMA Prostar and multiple races at Rockingham and MIR. Ryan Schnitz rides for Muzzy Kawasaki and will be running the NHRA Races this year on a S&S Powered Buell. He is also running a Turbo ZX-10 in the AMA Prostar Streetbike Shootout series.

Any of you experimentors and or Engineers interested in a Microchips DSPic Eval board and ICD2 In Circuit Debugger? I have both new in a box from a promotional training course. 16-bit MCU with built in DSP processor. I use Freescale (Motorola) and was not persauded to switch by thier presentation. You can use thier eval C compiler and I found that if you just set the Date back on your PC it keeps running past the eval period. I did kick out half of the cost for the course so it is not free. However $100.00 for a $249.00 eval board and a $159.00 debugger is a good deal. I also have three of the DSPic chips for your own design. This has all of the workshop training material with it and CD's with software and examples. If someone can make use of it let me know. I do not usually post items for sale in a thread like this, however, maybe somebody here will actually use the stuff.

Oop's, I just got the thread all off from subject. Well I will quit gabbing now.

 

I personally use the atmel avr series of microcontrollers so other than curiosity about that devel system I would have no real use for it.

On a side note I have been playing with a basic progressive controller and have something more or less put together, I should be able to finish it up in the next day or so. When I get it working I'll post it so everyone that is wanting to tinker can try and build one. I ended up using an atmega32 chip and a 16x1 lcd with 2 buttons to set the points on it(stuff I had laying around). If I can keep it simple enough it can probably be built on prototyping board and will not need a board etched. If I get left alone the rest of the weekend I should be able to finish it. As much snow as there is out right now I should have lots of free time.

if anyone has any idea how to do it without using a display or having to program it with a computer let me know, the display is going to need 8 or so wires connected so it is by far the biggest part of wiring this thing together.

 

Ahh Schnitz, I remembor running into them in Gainsville. That was in 00. If I remembor rite, they had a turbo bike in 00 also.

I'm a Microchip fan and user. Don't think I need what ya got though.

 

Well I have something put togehter and working, at least as far as running on a frequency generator and outputting to a scope

running the PWM at 1Khz seems to work, anyone got a preference for what frequency a normal nitrous solenoid likes best to run?

The actual circuit is pretty simple so it would probably take an hour at most to put it together on a breadboard, the circuit to program the device is more complicated than the rest of it. I will see what I can dig up as far as a simple circuit to program this thing so everyone can start making one.


This is the circuit used to program the controller:


Does it look easy enough or would you guys want me to try and find something simpler?

 

Just a post from someone who generally just lurks, but I'll toss in 2 cents and say that looks like about as simple as a programmer could get. Would it be simple to add window switch ability to the controller? Just a thought. I'll watch this thread with interest.

 

one quick comment I found while browsing the web:
http://www.diy-nitrous.fsnet.co.uk/nitrous-solenoid.htm
not sure how accurate that information is as I just saw it and haven't really put much more thought into it. It seems reasonable though.

btw for the code for the controller I just finished debugging it and I have 3 things to set: start rpm, full power rpm, and cutoff rpm. so that takes care of the window switch. I am trying to draw the circuit in eagle layout but I suck at that program so as soon as I get it I will zip it all together and put it somewhere for everyone to dl.