N2O Activation Issues ???

[71 Nova]

I went to the drag strip last weekend (08/04/07) and attempted a nitrous pass, but the system seemed to only activate for the 1st few feet or so, then flattened out. Here's the data from my best NA run that nite, the failed N2O run and my best N2O run to date (for comparison):

_________Run #1 (NA)____Run #4 (N2O)___Best N2O Run to date (05/05/07)
60'________1.845___________1.734___________1.669
330'_______5.391___________5.092___________4.704
1/8________8.366___________8.040___________7.274
MPH_______82.12___________82.51___________95.02
1000'______10.995__________10.635__________9.511
¼_________13.149__________12.839__________11.410
MPH_______102.77__________102.24__________118.45

I weighed the bottle tonite and it weighed 20 lbs, with an empty weight of 14.5 lbs and a full weight of 24.5 lbs. I shook the bottle but didn't hear any liquid sloshing around in it. Should have I heard the liquid? I have put 1 partial pass and 4 full passes on the bottle so far (was full when I started), spraying a 150HP shot. It would seem to me that 5.5 lbs of N2O should be enough for a few more runs. I was getting convinced I had an empty bottle until I weighed it. Any thoughts or ideas?

Also, I'm wondering if the activation switch dropped out. I had a problem with the activation switch on my 1st ever N2O pass early this year (didn't activate at all). I tweeked the switch a bit and it worked after that. The switch provided with the N2O kit is kinda wimpy and I want to replace it with something stronger (I have a 750 DP Demon carb). I was looking at this one: http://jimmy-jams.tripod.com/activationswitch.htm. What kind of switches are you guys using or would recommend?

On the positive side, I swapped in a 3000 stall converter (was 2500) and went from 13.444 with a 1.975 60ft (65deg day, 2500 converter) to a 13.149 and a 1.845 60 ft (98 deg day, 3000 converter), backed up with a 13.210/1.861 and a 13.225/1.859, all thru the mufflers. So the trip wasn't all bad, 12's are just a tick or 2 away

[John_Heard]

By the looks of the mph incrementals it looks like the switch turned off. Carb switches suck, everyone seems to have to fight them often.

You won't hear liquid in the bottle when you shake it. Given the weights that you had it wasn't empty yet. At least your converter change worked out good!

[71 Nova]

Thanks, John. Yea I'm happy for the improvement for relatively small change in stall speed. I would have really liked something closer to 4000, but I had this converter on hand, so in it went.

One other thing I should have mentioned. It was a hot day (100 degF +), and the bottle was in the trunk of the car all day. When I cracked the bottle open for my nitrous run, the pressure went up to 1200 psi. No bottle heater required for this run, I thought. After the run, the pressure had dropped to 750 psi. Is it possible the bottle was initially too hot and I was sucking gas during the run? Maybe the bottle heat soaked too much during the day. Is this an issue with running N2O in the heat? Do you guys cool your bottles prior to going to the track? Or am I just full of hot air???

[John_Heard]

At 97 degrees (approx 1050psi) Nitrous is supposed to start turning into what they call a super-critical fluid, which means it's neither a liquid or gas - kinda a mixture of both. To keep your tuneups consistent, and stable, avoid pressures over that temp/psi. It also starts turning back to a gas as the temp drops around 75 degrees (approx 820 psi). So to keep things working as they should, try and keep the bottle at a stable temperature between 950 psi and 1050 psi. It can take hours for nitrous to heat soak up to a temperature through the entire contents of the bottle. It's easy to bring the pressure up quick with heat, but without soaking it at that temp the entire contents of the bottle are not at the same temp. I have a chart I made a few years ago that helps illustrate the point http://www.dragstuff.com/techarticles/b ... aters.html

On another note, don't rely on the gauges that are on the bottles, those are terribly inaccurate in some cases. It wouldn't hurt to compare all your bottle guages to a master high quality gauge.

[pro70z28]

Is there a problem with getting a bottle too hot on hot days? I'm not a nitrous guy, but just wondering if I should avoid standin' by a car with a bottle in the sun. I assume they have some sort of pressure relief valve to avoid a kaboom?

[John_Heard]

Most bottles "should" have a pressure relief pop off valve on them that is just a disc that blows off when pressure exceeds a certain amount.

Depending on the brand they can pop off somewhere around 1200 psi and up to protect the bottle itself from exploding from internal pressure.

The most likely time those things will go off is when someone forgets they have their heater on, or in the bottle heater tank too long - it's easy to forget they're in there and next thing you know they are cooking off. So as long as the pressure relief valve is functioning, should not be a problem.

Now, on another note I've been meaning to tell a story about our good buddy David Lemmond that moderates in our chassis forum. David don't like to talk about this much, but I want to post this pic to make a point about how dangerous those things can be.



These are the shoes David was standing in about 14 years ago when a mother bottle blew up on him, he was standing a few feet away heating the bottle up with a torch on a very low setting. Almost immediately the mother bottle blew up knocking him out of his shoes and into the side of his Nova. The blast wave was so big that it rippled the body of the Nova, lifted the top off the cinder block building and knocked a buddy that was standing with him across the room. The explosion was heard for miles around and they found parts of the bottle 100's of feet away. David got banged up pretty good and was in the hospital for a while after this accident and so was his buddy. This is the short version of the story, and maybe if David feels like it he'll expand on it, but if he doesn't respect that too.

Note: Your first thought might be that using a torch wasn't the best idea, but keep in mind that when he was doing this he wasn't putting heat directly on the bottle, just directing the heat at it quite a ways away. Heating with a torch years ago was VERY common, not that it was a good idea it's just how it was done. Regardless David will be the first one to say to never use a torch because you never know when you're going to get ahold of a weak bottle that can't take uneven heat applied to it.

The deal is never over temp a bottle or overpressure it, IF the burst disc doesn't blow then you have a bomb on your hands that packs one hell of a punch.

[Rich_1028]

I remember hot rod tellling of this very story years ago.

[ytnova]

Just another quick note on heating of bottles. I was warming one in a water box and removed it a 1100 psi according to the gauge, as soon as I picked up the bottle, which probably aggitated the liquid and also increased the pressure, the bust disc ruptured and froze part of my hand. Try going to the er room in florida with frost bite, they were clueless. Moral of the story, the gauges suck, and always pick the bottle up by the knob and keep your fingers/hand and everything else you have away from the burst disc area. I got lucky and only had some skin frozen.

[pro70z28]

That sounds like David had somebody lookin' out for him that day.
I've also wondered about that 1200 PSI bottle sitting in the passenger side of the car inches away from the driver. Maybe I worry too much but in an accident or an over pressure situation that seems dangerous to me. I see allot of set-ups like that so it must not present a problem or it wouldn't be allowed.

[Craig W.]

Do you guys cool your bottles prior to going to the track? Or am I just full of hot air???

Bottle temperature management is something that you have to do all day long. Whether it be too hot or too cool. You need to establish a pressure that you're going to have the system at when you launch. This is the only way to have a repeatable and reliable tune-up.

My tune-up likes 900 psi. So I launch on every run at 900 psi. I manage the bottle with a Nitrousaurus-X. www.gotsqueeze.com

Its the latest and greatest when it comes to bottle heaters/coolers. I have one mounted in the car and one in the trailer. So I can have one bottle in the trailer ready to put in the car at all times and I can control the temp and pressure of the bottle in the car. Its a big help when in the staging lanes on a really hot or really cool day.

You set the temperature you want and it'll heat or cool the bottle until it gets there. Then it kicks off until the bottle temp rises or falls 1 degree. Takes all the work and worry out of it since it automatically manages things.

Combine one with a remote bottle opener and you've got a street racer's dream. But I didn't say that

[71 Nova]

Thanks guys. A lot to think about here. We all want to keep racing a long time.

Checked out the linkage tonite, and the N2O switch was properly positioned and picked up when I manually actuated the throttle by hand. But what I did tonite find was, when I activated the N2O switch by pushing on the gas pedal, I found that it was just barely picking up. So if I didn't have the throttle mashed to the floor or released it slightly under acceleration, it might have only temporarily picked up. With the heat at the strip (100 deg vs. 65 deg tonite), it was probably even more marginal. Guess I messed up the adjustment when I was changing the converter and didn't check it afterward. Some testing is in order this weekend. Also, I noticed that the arm on the microswitch is kinda sloppy and could possibly slip off the throttle linkage, so I am going to replace it. Any suggestions for a switch to fit a Speed Demon DP 750?

[David Lemmond]

I don't mind talking about it at all. I'll try to tell the story tomorrow, I just got in from the shop and about to raid the fridge. lol

[79 Camaro]

I have a question... I have the NX 10lbs bottles and I put NX NHRA Safety fittings on all of them. My bottle is mounted in the passenger floorboard and will have a blowdown tube that goes on the safety fitting and throught the floor. They say 3000psi on them. Does this keep me safe?? Some of you said that one blew the cap off at 1100psi.. Did you have a safety fittiing and blow down tube. And if mine say 3000psi, does that mean that they wont blow the cap until that psi? My desired psi will be 950psi, I plan to do some testing this weekend for the first time on the nitrous. Any other comments welcome.

Here are the safety fittings.
http://www.shopatron.com/product/part_n ... 1709/300.0


Adam

[ytnova]

I was actually removing the bottle from a hot box, and my best guess was the gauge stuck and I had the blow off valve between my fingers because of the way I picked it up. This was on a old bottle with the old design blow off, which I think was rated somewhere around 2000. I updated it to the new design which accepts a blow down tube.

[John_Heard]

Moose had one blow off last year at MoKan, it was an edelbrock bottle. I can't remember the temp it was at but don't remember it being real high. 3000 sure sounds high Adam