Nitrox nitrous issues

[samari]

I am running a nitrox stinger 130 kit on a 2.4 200. Last year it worked great but I'm having issues with it this year. I didn't have a pressure gauge last year and ran it with one tank until I ran out at a race so I installed another tank with a Y fitting and a pressure gauge. I'm thinking I am running at too low of pressure now at 700-900 but I can't see what has changed from last year. I am using a bottle heater but it just won't keep up because we basically hot lap during our drag races.

What it's doing is hitting soft then I actually loose rpm after about 5 seconds. Methanol pressure is set at 6.5 psi flowing.

I appreciate any input.

[STV_Keith]

As with any nitrous kit, trying to maintain bottle pressure is key. As you spray, the bottle cools and pressure drops. Because this does NOT happen on the fuel side, the motor will get more and more rich. If your kit is tuned to be used and safe at 1000psi, and your bottle is low and down to 700psi, it will be rich and not making the power it will at 1000psi. Nitrous Express makes a nice bottle heater that auto-cycles based on bottle pressure. I've been away from N2O for a while, so I'm sure there are even more new gadgets out there now.

[Chaz]

Chet,
Some basic parameters are a empty nitrous bottle ( 10 pounder) weigh's 15 lbs.empty and 25 when its full. Buy a cheap fish scale and weigh your bottle.
We dont use a gauge any more as a primary , instead we use a infared temp gun. I base my tune-ups off of a 1050 psi base pressure which is 91* F . Your 700 - 900 numbers would fall between 70* and 85* as a point of reference. Some believe that nitrous phase changes into a gas at anything lower that 760 psi and over 1069 .. I dont know what either would do to performance because I stay away from running in those parameters. I do know that at the moment of activation my data logger shows a 100 psi drop and loses another 75 psi durring the course of a 6 second run at 300 hp . The gauge will quickly climb back to pressure based on temp the moment the solenoid closes.
We will get into some tune up numbers in a moment but if you run your system jetted at .065 for a duration of 10 seconds you are consuming .14 lbs/sec or 1.4 lbs durring the run. If it were me, I would run one bottle while a crew man preped the other bottle for the next pass. And I would never run a bottle that is aproaching only half full which in your case would be three runs max. Myself, I replace one every run.
Many people think that overly rich is safe. I have found that the excess fuel will wash the oil off the walls and cause the rings to build heat thru friction rather than disapate the heat to the walls and onto the cooling system. And since N2O doesnt burn, the excess fuel will only kindle the fire. Either case the onset of detonation is enevitable.
Since you mentioned 130 hp as your base .. and I will assume that we are talking alky as an enrichment fuel .. its easy :
1 lb of fuel an hr = 1 hp . A .070 orifice at 6.5 psi = 130 lbs/hr
With alky a N/F ratio of 3 to 1 is pig rich , 5 to 1 is gettin on the edge .. so a N/F ratio of 4 to 1 is a pretty good place to be .
On the nitrous side @ 900 psi :
.058 = 400 lbs/hr
.065 = 498 "
.070 = 577 "
.075 = 622 "

So if it were me I would run a .065 in the winter 498/130= 3.83 N/F ratio .
And in the summer I would bump the Nitrous jet up to a .070 577/130= 4.43

If you are stuck running at 700 psi then ( would not recomend it) then :

.058 = 349
.065 = 438
.070 = 509
.075 = 584

Keep in mind that every engine is different , depending on quinch area , overall compression, timing and plug requirments will vary ... air / fuel ratio will alway be a constant ... Take baby steps and dont get greedy by pilling it to heavy while trying to tug the motor down and you'll be fine.

Charlie ... II

[Jay Smith]

Have you contacted the folks at Nitrox about your issue? My guess is that they could help. When I was sponsored by Chuck at Nitrox years back with 3 stages of NOS with Meth. injection on a 2.4 carbed motor ( 75 HP lean burn, 125 HP 1st stage and 100 HP second stage = 300 HP total ) I had a very complicated system Chuck was very helpful as well as knowledgeable about Nitrous in general as well as his systems...They are super people and have GREAT service after the sale reputation.. Bet they could help with any issues your having related to NOS on their system .. 1 318 965 0201

my .02
Jay

[Chaz]

Jay,
While it is wise to go back to the manufacture , I have found that when it comes to power adders , they will sell you a bat , ball and a glove .. what they wont do is show you how to hit it out of the park ... Perhaps Nitrox is a bit different.

Curious, with a base power level of roughly 300 hp on gas and an additional 300 added with alky, what kind of timing numbers did you wind up with using two dissimilar fuels .
And what was the total orifice area combined of the three kits ...
Thanks in advance
Charlie... II

[clayc]

Samari, I've ran a several semi's worth of NO2 on street and drag cars over the years.. All NO2 systems require delivery lines and solenoids.. Chaz is correct with the info in his post and I'd also follow Jay's recommendations. Several years ago I had an engine that would launch with no issue then suddenly or progressively loose NO2 power. The solution was simple but over looked. Some of the Solenoids have a fitting on the -IN- side of the NO2 solenoid that the NO2 line attaches from the bottle. In more cases than not, that fitting has a screen in it to catch particles off the threads and other contaminants that enter the line when changing bottles. If that screen catches any contaminants, it can obstruct your NO2 flow, which mimics a loss of bottle pressure. Also check your solenoids, make sure they haven't gotten lose and are loosing their electrical input / connection,,, seen a many engine scattered because of this.....

[samari]

Wow great info guys.

I run this boat in 2 classes back to back so I don't have time to get into the pits at all, that's why I added the second tank. I checked the filter and it was clean. I do also use a bottle heater on one bottle but it looks like I need to add another to keep the pressure higher. I will also check the solenoid to bee sure it's operating correctly.

Thanks for the great advice.

[Dave Strong]

Had a buddy with a Nitrous system on a sled keeping the bottle warm was a real problem in the snow and winter air temps. His system fogged the air box and the bottle was mounted beside the pipe stinger to keep the temp up, but unless he had run it hard before fogging it would hit real good sometimes and poor others. We used a handgrip warmer to heat the bottle and it fixed him up. If you were to go that way you may need to put a resistor on the power feed as it would get real hot in summer conditions vs winter.

Dave

[Jay Smith]

Chaz,
Back then I used 27* or ( .170" ) on a locked in timing system (Drag racing only ) It was on that timing all the time even at idle. Worked GREAT !

I found NO issues when the 2 main stages ( 125 HP and later in the pass 100 HP ) with the Meth. mixing fuels HIT with the NOS !

Timers as well as the fuel curves were set up by Goodman ( IMO the best in the business when it comes to 2 cycle outboard NOS systems, he was building successful WINNING NOS systems when most that "think" they know 2 cycle NOS were in pre school ! ) , he had it set so all I did was stab the throttle and "hang on"......

BTW: The first lean burn stage was 75 HP BAR system with NOS only used no mixing fuel , used the residue of fuel that is normally related to all 2 cycles with a fuel dirty front case half the next 125 HP stage was a FOGGER system with Meth. mixing fuel, then another BAR system at 100 HP or a total of 300 HP on a 2.4 in the 80's ( quite the cutting edge guy I'd say )

Chuck has been indeed ill for a while and I wish him the best and a speedy recovery......

Jay

[johnnyracer]

Great info on all parties here . " Hot Lapping" is a bottle pressure killer . System pressure is what makes the whole kit work properly. Low pressure = crappy hit. super rich condition. The drag car guys dont get affected as much by this issue because they usually get time to change bottles or build system pressure again before they have to run again. Our style of racing with 6-10 boats in the mix and no time to build pressure between runs equals a beat ass from someone that had a little more time to heat it up. Have to agree with Jay on the methanol deal. Nitrous loves it.

[fyremanbil]

IF your setup is the same as last year, but it doesn't run the same, I'd look for something not working correctly. Have you checked the nitrous solenoid plunger for swelling? Have you flowed fuel thru the entire system, all the way thru the nozzles and checked flow?

[Jay Smith]

The rock filters on the gas side are BAD about clogging up using the non medical grade NOS also...

Just a thought!

Jay

[Way2slow on H2O]

Nitrous has come a long way since it's introduction in the outboard world, and I have probably ran the most extreme complex systems available (and damn expensive), but if you see what I'm running now it's so simple and basic, no timers, no computers, just a nitrous pressure regulator and a bottle blanket controlled by temp (and really don't need the blanket here in Texas). I've got the N02 pressure set at 950 (87/88*) and a 6 second pass it's all there, no loss, constant pressure, and a true blistering 430 ponies of "Big Block Spanking" power!!!

Chuck at Nitrox got us started back in the 80's and we went as far as he could take us with his systems. Chuck was unable to continue his development of the foggers due to an illness so we were on our own. After years of development (destroying motors) with foggers we got it nailed, and it works.

One thing 4-stroke guys don't comprehend about 2-strokes are the holes in the sleeves, and an over abundance of liquid (fuel, alky, or liquid nitrous) will force (hydraulic) the rings into the exhaust port and break..... causing catastrophic failure.

There are parameters (as mentioned) for nitrous pressure to remain a liquid, under or over will become a gas, and a gas tune is way off from a liquid tune. (Charlie, it's a noticible loss of power when it goes to a gas, plus it's "pig" rich)

One thing that may help is the use of a controller that'll match the fuel to the nitrous pressure for the entire pass. We all know the bottle pressure drops as we go down the coarse, but the fuel (enrichment) pressure remains a constant, so this little gadget keeps both evenly matched. I don't use it, we "rope" racers make 1 pass and it's back to the pits so I can refill or change bottles.

Another helpful insight was to change solenoids annually, or rebuild the old ones (I've lost several motors due to solenoids getting contaminated).

Most of the nitrous guys I know don't run methanol as an enrichment, instead they prefer to use fuel....again, simplicity, one fuel cell, one pump, and a good "tune".....