Nitrous Oxide Properties and NOS Systems 1

[fatdumbnhappy]

Hello All,

This is my first post, so bare with me... I would like to know if anyone has found any useful NOS websites or NOS specialist in the LA area. I am considering a NOS system for a 2 stroke motocross bike. I also had a couple specific questions, so here goes.

1. Has anyone found a pressure vs. temperature graph of N2O that includes its phase? I'm trying to find something like a P-T diagram for steam.

2. Are there any ideal points to inject or mix the NOS into the intake of a 2-stroke? I haven't found too many companies that deal with 2-strokes aside from snowmobile applications.

Any advice would be great. Thanks for you help.

fatdumbnhappy

 

[R1100S]

Just out of curiousity, why put nitrous on a motocross bike?

 

[StefanHamminga]

For your application a can of methanol/nitro/premix-oil (RC-car fuel) sure sounds a lot more practical (instead of dragging that bottle along). And your bike will appreciate the cooling properties of methanol.


Stefan Hamminga
Mesken BV
2005 Certified SolidWorks Professional
Mechanical designer/AI student

 

[patprimmer]

The all or nothing nature of nitrous, as well as the problems of mounting the bottle, and the safety issues of an exposed bottle in a collision would cause me some concern if it was on a motor cycle. I would be astounded if your racing association would allow you to expose fellow competitors to the risks associated with a broken bottle or valve.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[fatdumbnhappy]

Thank you for your replies. Now where should I start...

Why NOS on an MX bike: I'd like to have a sleeper. If I got a '95 or so bike nobody would think twice about shooting the hill with me. I could run with the brand new bikes and make them wonder if their bikes are slow. Aside from that, NOS wouldn't do me much good. I'm not an MX racer or a drag strip racer. It's just a thought at this point.

StefanHamminga: Thanks, I like your idea. It sounds like a lot less hastle. I could get about a 10% boost from switching to methanol (if i'm not mistaken), but what about nitro-methanol premix? What could I hope to get from that?

As far as racing association, i'm not really doing this for money or sponsorship, so nobody but my wife can tell me not to. Besides, if I hid the bottle well the competition wouldn't even know it's there. Then the'd feel really slow.

Anyone else out there have some NOS or nitro-methane websites they have found useful?

Again, I appreciate the input. Cheers,

fatdumbnhappy
CPP ME

 

[BigWallyB]

Besides Pats excellent input. Another 2 dinars worth.
1) I would be concerned. Before I put nitrous in my boat I did quite a bit of research. The biggest problem I could discern with it is you get exactly what you want, heat (power) generation. Makes sense, considering the Hp increases one can get with a proper setup on and SI engine. In a I/O boat, with the whole river for cooling, this was not a problem. On a 2 stroke, air cooled or even a 4 stroke, water cooled bike this appears to me to be a major difficulty to overcome.

2) As Pat said, its all or nothing, and you better have a heavy bike with soft, fat, heavily cleated rear tire if you want to stay locked to the dirt. I can't even handle my extended swingarm 78' YammerHammer 500 4 stroke, oil cooled monster any more. I'd be a red blotch on a rock or stick in a tree, if I had to handle double that torque.

Life is what happens while we're making other plans.

Wally

 

[patprimmer]

Raising the compression to about 15 or 16:1 and running on methanol will give a significant power boost and will let it run cooler.

As methanol uses about twice the amount of fuel as petrol, you will need a bigger fuel system from air vent in the tank to fuel lines, carby jets AND internal passages etc.

You will need to flush the system as methanol laying around in contact with metal will cause corrosion, especially with aluminium or magnesium.

Nitromethane is a whole new ball game, and gives even more power, but about doubles the fuel requirements again over methanol. The exhaust fumes are very toxic and corrosive.

Unless you are a professional racer, with the required equipment and knowledge on to handle the fuel, I would not recommend nitromethane.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[turbocohen]

1/2% nitromethane will smell strong enough to get noticed. It will also be enough to wreck your 2 stroke if spark retard is not adequate do to more flame speed. Steel oringed head to bore is a must and head to crankcase bolts need to be upgraded.

As stated earlier, you have to flush with straight gasoline/oil after using nimeth or corrosion will be what is listed on the coroners report.

 

[Metalguy]

Turbocohen,
I doubt you could smell such a low % of nitro, but in any event nitro requires MORE spark advance than gasoline.

Fatdumbnhappy,
You can run N2O-just start with a TINY hole for it. Replace your main jet with something a LOT bigger, and keep increasing the hole for the N20 until it quits 4-stroking at WFO. Don't use a bigger hole than that. The hole/jet will be very small-only a few mils. The N2O is under ~800 psi. I'd try to inject it directly into one of the cyl. transfer ports rather than run it thru the crankcase.

You will probably need to retart your timing a little and use a COLD plug.

The bike will run fine until ~1/2 throttle w/o the N2O because the needle jet will be controlling the mixture, not the main.

Once you get it sorted out the N20 hit will be IMMEDIATE!

 

[turbocohen]

Metalguy, Take a look here for more info about nimeth.

http://ntp.niehs.nih.gov/ntp/roc/eleventh/profiles/s123zntm.pdf

and here is the MSDS:

http://www.jtbaker.com/msds/englishhtml/n5740.htm

There is a lot of oxygen in the form of no2 blended into the fuel. And yes in open air the fuel does burn slower than gasoline.. but.. since more O2 and fuel can be trapped in a cylinder, more heat can be produced and several times more psi are generated during the power stroke. The burn rate increases with increasing compression pressure and cylinder temp using blends but pure nimeth will cool things off when a high rpm cammed engine is throttled and misfiring at low rpm.

A small amount of nimeth adds a small amount of oxygen and that will maybe add enough chemical supercharging for Fatdumbhappy's application without the risk of adding an NOS bottle. I wouldnt want Nimeth in a tank under my crotch though.

Hope this clarifies my earlier statement.

 

[Metalguy]

There are thousands of cars with N2O bottles in the US, and I'm not aware of any significant number of problems--except of engine problems caused by over-eager users.

Having run both nitro and N2O for many years, it's no big deal if you use your head.

 

[patprimmer]

A nos bottle in the boot or trunk of a car, over the axle and between the chassis rails is fairly well protected from being ruptured in a crash. I know of no such secure mounting site in a motorcycle.

What part of the nitromethane MSDS sounded safe for amateur use.

Also, a fuel cell in a race car has a much greater degree of separation from the driver than does the fuel tank on a motor cycle.

Stay Fatdumbnhappy, not Fatdumbndead.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[turbocohen]

Metalguy, here is a pop quiz.

If a puddle of pure nitromethane (no fuel mixtures) is on a cement floor

A. smashing a hammer
B. dropping a lit match

on the puddle WILL cause it to burn violently (detonate) and likely leave a crater.

Here is a clue, One will and the other will not result in boom. There is only one right answer.

 

[dgallup]

I did a N20 2 stroke injection project for my senior lab independant study project. It was just on a dyno so there were no issues with mounting & safety like on a motorcycle. We were able to easily double the stock horsepower. We just injected the N2O upstream on our airflow meter orifice and manually adjusted the carb for best power at each speed/load/N2O point. Without sufficient enrichment the exhaust temp will go through the roof and sieze the piston.

It is going to be real tough to get a carburated system to properly meter fuel if you want to be able to run both with and without N2O. You have to have some form of supplemental fuel when you turn on the gas. You are also going to need more of an electrical system for the solenoid than most MX bikes are capable of. But the biggest problem is that it is going to be totally unrideable! You won't be able to modulate the power at all. I think you are much better off going with alcohol/nitromethane for a bike. That is what all the top hill climbers use.

 

[Metalguy]

turbocohen,
Where to begin? (sigh)

"Pure" nitro is somewhat shock sensitive, but not overly so.

I hard hammer blow *might* make it detonate.

Besides running it in a AA/FC and many model airplane engines, I've also worked with it in an industrial setting-for non-burning uses. Many years ago someone fired a high-power rifle bullet at a RR tank car full, and it did detonate. That incident set off a big effort to find out just how sensitive it is. You probably aren't aware of this test, but they've intentionally dropped 55 gal. drums full of BOILING nitro onto concrete pads from ~50' (IIRC)-surprise, no detonation. The "official" position on pure nitro is that it requires confinement in a relatively thick-wall vessel and a severe shock in order to detonate.

There are chemicals which can make pure nitro either more of less shock sensitive. There is also a different form of "ordinary" nitro that is real bad news, esp. from a health POV. I won't say anything more about these last items and hope no one else will either.

But I think Don Garlits is living proof that a near-lifetime of nitro exposure doesn't condemn someone.

 

[carnage1]

I would look into a sneeky pete system or similar. very small can so you should be able to find somewhere to hide and protect it, it is a dry system so simpler to setup, it shouldn't give you so much power that it will be obvious that something is wrong, it shouldn't immeadiately melt your engine, and last it is relitively cheap.