This is what happens when u fit NOS to a pocket bike

[mech_eng_matty]

You CAN use nitrous oxide on a 2 stroke engine ! Nitrous oxide injection (aka chemical supercharging) works by freezing the intake air , making it super dense so that more than normal passes thru the inlet manifold and into the engine . And being more dense , it expands at a greater rate when combusted ~ shoving with a lot more force on the piston ! Because the air is a lot denser than normal , extra fuel needs to be supplied to prevent leanout damage to the engine . Obviously that extra fuel would need to have two stroke oil mixed in with it to add extra lubrication and IF the nitrous does happen oxidise the oil - then a synthetic 2 stroke oil would solve that problem !

MX 2 stroke engines are supercharged via the expansion chamber in combination with a reed valve - limit them to a standard pipe like what's on a Suzuki JR50 - GTMX80 Yamaha - 2 stroke step through etc and they're no better than a naturally aspirated 2 stroke lawn mower , outboard or whipper snipper motor !

Howstuffworks "Why is there a bulge in the exhaust pipe of my dirt bike?"

Le Espansioni

Cactus Jack,

Thanks for that, you make a very valid point in your argument.

It would be my assumption that quite a lot of Nitrous Oxide would be required in a 2 stroke as compared to a 4 stroke. As you said, the NO2 reduces the temperature of the inlet air hence making the air denser. On a 4 stroke this will work a treat because the air is being sucked straight into the combustion chamber via the inlet valve. However on the two stroke where the air/fuel is being charged via the crankcase, would this not mean that the system requires more air/fuel mixture to feed the crankcase volume and hence require more nitrous oxide to keep the said air at a cooler temperature?

Also, would the nitrous cooled air be detrimental to the lubrication effect of the oil on the big end of the 2 stroke engine? If the oil is more viscous, the friction on the bearings is going to be higher, causing more heat, reducing the effect of the nitrous and really leaving no major performance gains?

Thanks for the reply mate, hopefully you check this thread again to see what you think of my hypothesis.

Cheers

Matty

 

[Ruby]

I've just had a friend peak over my shoulder and point out that "rotaries run NOS and they're essentially 2 strokes".

They are similarly 2 strokes in their combustion process, but not in design. They do not draw their air/fuel mix into the crankcase. The mix enters and exits through inlet and exhaust ports like a 4 stroke (but without the valves). A bit off topic from 2 stroke engines, but I was sure someone would ask this Q sooner or later.

I guess the debate here with regards to 2 strokes and nitrous being required to be injected directly into the combustion chamber to be an effective means of boost to power, and not hamper the lubrication system of the 2 stroke engine. Yes, the cooling effect of the nitrous would not assist the oil to do its job.

 

[pegleg]

Cactus Jack,


Also, would the nitrous cooled air be detrimental to the lubrication effect of the oil on the big end of the 2 stroke engine? If the oil is more viscous, the friction on the bearings is going to be higher, causing more heat, reducing the effect of the nitrous and really leaving no major performance gains?


Cheers

Matty

Hi Matty,
with the constant heat generated by the engine, would the viscosity change with the injection of NO2 enough to be detrimental to the big end?
I would think because the NO2 would not be present all the time, that the oil would have time to return to it's original viscosity.
Remember, this is a question, not a explenation.

 

[mech_eng_matty]

Mmmmmmm, i did think that myself while i was writing the post. It is true, the constant heat generated would be enough to negate the more viscous oil i would assume, but without actually doing some calcs on it or even better, testing it, i can't say either way.

It is an interesting concept though, i would just think that it'd take a bit of a redesign of the motor to accept the charge of NO2 and have it make a substantial power benifit.

The cooling effect of the NO2 could also perhaps be created by putting a dry ice (liquid nitrogen) cooler on the intake side after the reed valve, this would attempt to cool the inlet material enough to create a larger temperature differential between the intake fluid and the combustion chamber creating more power. However it may just end up hydraulic-ing the fuel/air mix to a point where it just floods the engine (bit like starting on a cold day).

Why can't all the topics of conversation be like this??!! It is a good thread, with a decent conversation relating to a seirous matter. I think this is what miniriders is missing at the minute and is why guys like Flarry are cracking the ***** a bit.

Thanks to all you guys who are posting decent responses, its nice to have an intelectual conversation on here for a change!

 

[pegleg]

Mmmmmmm, i did think that myself while i was writing the post. It is true, the constant heat generated would be enough to negate the more viscous oil i would assume, but without actually doing some calcs on it or even better, testing it, i can't say either way.

!

I will ask my wife when she gets home in regards to this, she works as a industrial chemist for one of the largest lubricant manufactures in the country.
She will have all the calcs and specs on every oil available today.
A lot of her day is spent on analyzing used oils, looking for ways to improve them.

 

[Ruby]

It would be ideal just to plumb the nitrous injection into a tapped hole in the head (similar to and near the spark plug). However, the problem now is setting the system up to inject the nitrous at a timing consistent with good combustion.

It would, in my view, be more beneficial to power to inject it through the head on about 1/3 of the up-stroke (compression). Any earlier and it some would be lost through the exhaust camber. Also this amount of leaking nitrous into the expansion chamber may affect the role of the expansion chamber as the exhaust gases are now too cool for the extraction process. Any later on upstroke and there would be little time to 'squirt' the required amount, especially at higher rpms. There should be no injection on the down stroke for the obvious reasons of cooling the exhaust gas charge and affecting the extraction process, and also the waste of unused nitrous out the exhaust system. The exact timing of direct injection of nitrous would need to be tested and tuned, but through the head, and not through the camber, seems the better method to me.

Removing the injection of nitrous in the chamber altogether seems the ideal solution. Then there would be no need to fret about air/fuel/oil mix etc.

 

[mech_eng_matty]

It would be ideal just to plumb the nitrous injection into a tapped hole in the head (similar to and near the spark plug). However, the problem now is setting the system up to inject the nitrous at a timing consistent with good combustion.

It would, in my view, be more beneficial to power to inject it through the head on about 1/3 of the up-stroke (compression). Any earlier and it some would be lost through the exhaust camber. Also this amount of leaking nitrous into the expansion chamber may affect the role of the expansion chamber as the exhaust gases are now too cool for the extraction process. Any later on upstroke and there would be little time to 'squirt' the required amount, especially at higher rpms. There should be no injection on the down stroke for the obvious reasons of cooling the exhaust gas charge and affecting the extraction process, and also the waste of unused nitrous out the exhaust system. The exact timing of direct injection of nitrous would need to be tested and tuned, but through the head, and not through the camber, seems the better method to me.

Removing the injection of nitrous in the chamber altogether seems the ideal solution. Then there would be no need to fret about air/fuel/oil mix etc.

I agree Ruby, i think a direct shot straight into the cylinder would definately be the way to do it. I don't think it would be incredibly hard to do either.

If the NOS shot was controlled by a solenoid valve or something, you could wire up another set of contacts onto the flywheel, similar to those for your ingnition coil. When the flywheel magnets go past the new set of contacts, the valve could open for a set period of time to inject the nitrous into the cylinder.

If i had the time and the money, its something i'd have a look at myself, but being short of both at the minute...it might just have to remain as a pipe dream!!

 

[Ruby]

I agree. Tapping into the head is far easier than farting about with oils and mixes, or remaking a new expansion chamber.

Wouldn't be too hard to use an old analog MicroTech D4S or Haltech F9 ECU to control the nitrous. The ECU could easily get its signal from the -ve of the coil. That will eliminate the need for more hardware (contacts etc). Then within the software tune the injector to fire a number of degrees/timing from TDC. And alter the duration for a short burst. Try to keep the burst as short as possible, maybe even use a larger cc/min injector if more nitrous is required but keeping duration short.

That reminds me ... me and a mate are going to fit nitrous to his postie bike CT110. Only its not a 110 anymore. It has a 150cc race engine! LOL

Hmm, all this talking now makes me want to fit nitrous to my 1600. LOL

 

[mech_eng_matty]

Once the nitrous is in the chamber, would there be a problem with
a) the density of the gas being smaller hence the chamber not being filled as much as usual
b) lack of fuel in the system causing a lean out and detonation

I know when turboing or supercharging (which is similar principle to running NO2) you have to increase fuel to stop the lean out from happening, do you think that running a shot of nitrous would cause the same problem?

I would definately NEVER run a Haltech system of any sort!! Tried to use a Haltech E11 on our FSAE car and had so so so many problems!! Replaced it with a Motec M4 and it was essentially just plug and play. I'm real shy about Haltech stuff now, even if it is just their sensors coz we had trouble with a Haltech O2 sensor as well!!

A mate of mine is building a Hotty 1600 at the minute, i can't give u a list of mods coz its been a while since i've spoken to him but i know he's putting a WRX turbo on it, had some head work done, he's running a Haltech E6X, designed his own intake, should be a pretty sweet little machine when he's done.

 

[Hillz]

what a good read ^^

 

[mech_eng_matty]

I spoke to a few guys i work with at lunchtime about the whole 2 stroke nitrous thing, and we kind of determined that there was no real reason that it couldn't be done.

One of them just sent me through an email with the following link;

Motorcycle Accessories Nitrous Oxide Injection Snowmobiles Jet Ski's

Apparantly they make a NOS system for 2 stroke Motorcycles and ATV's as well as Snowmobiles and Watercraft...obviously it can be done...i just wonder with how much work!!

 

[Hillz]

my boss here has NOS on his A80 2-stroke (vintage road bike)

 

[pegleg]

Find how he went about doing it for us Hillz, I would like to see some input in this thread from someone who has tried, and successfully done this!

 

[mech_eng_matty]

I'm with the pirate ^^^^^^

I'd be keen to find out how it was done.

 

[Ruby]

^^^ I'm with stupid ^^^

I know that on paper it should require alot of thinking to make it work. But we know in reality people build projects that just amaze us.



Matty, I've never had a problem with the F9. I've had it fitted to my turboed CBR drag bike and it worked like a charm, and the unit is now in my 1600. BTW, this should get a guy like you drooling:

I've got a CA18DET in the 1600 running a top mount VG30BB turbo on mandrel bends! Massive 320mm vented rotors and 4 pot Hilux calipers up front on adjustable 240K struts with 55mm spring kit. Adjustable lower control arms and adjustable radius rods. Supported by a 25mm heavy duty sway bar. R33 Skyline 5 speed box (rebuilt) with 3 inch balanced tailshaft into a H190 LSD rear axle off a series 3 Bluebird (the stronger diff and 29 spline axles) and custom rear disc brake conversion. On the rails are 550cc rotary injectors. Massive bar and plate intercooler. 58mm throttle body conversion. Plus more I can't recall right now. LOL

 

[pegleg]

Hey again,
Just in reference to the viscosity problem we were talking about earlier, I asked the missus and she said that depending on the quality and grade of oil used.
all good oils contain viscosity modifiers to prevent the change in the viscosity.

 

[mech_eng_matty]

Pegleg,

I'm a bit confused as to how an oil can contain a viscosity modifier. I understand the principle behind it, but wouldn't this change the viscosity rating to a single number instead of a 10W40 or 15W50 where as i understand it the first number is the cold viscosity and the second number is the hot viscosity...or is it the other way around, i can never remember!!!

Anyway, wouldn't this mean that the rating would end up being 40W or 50W or something singular?? I don't believe i've ever seen that.

 

[pegleg]

Pegleg,

I'm a bit confused as to how an oil can contain a viscosity modifier. I understand the principle behind it, but wouldn't this change the viscosity rating to a single number instead of a 10W40 or 15W50 where as i understand it the first number is the cold viscosity and the second number is the hot viscosity...or is it the other way around, i can never remember!!!

Anyway, wouldn't this mean that the rating would end up being 40W or 50W or something singular?? I don't believe i've ever seen that.

Matty,
the answer to this will have to wait until tomorrow night, as the better half has gone to bed.

 

[mech_eng_matty]

There is only one thing i can say to that Pegleg...

You should go and join her!!!!!

Mind you, i would say this, my missus lives in melbourne, an hour and a half away from me, i only get to see her on the weekends

No worries mate, look forward to hearing your response

Cheers

 

[pegleg]

where do I have been for the last 2 hours? lol