How long will my nitrous tank last? Not long enough!

I spoke with the Cold Fusion Nitrous tech this morning and he told me that nitrous is consumed at 1lb of nitrous per 100BHP per 10 seconds. So I came up with a quick formula to estimate how long a tank will last depending on the tank size and HP generated. You must know if your system is rated at engine power or wheel power and use the engine power (BHP) figure. My algebra is a little rusty so let me know if there's a better way.

X = tank size in lbs
Y = BHP setting (engine HP)
Z = time in seconds of nitrous use

X(100hp/Y*10sec) = Z

Example:

I have a 10lb bottle and I am using the 150HP jet. My system is rated at WHP which equals 179 BHP. Let's plug my number into the formula.

X(100/Y*10) = Z

10(100/179*10) = Z

10(.558*10) = Z

10(5.58) = Z

55.8 = Z

So, my 10lb nitrous bottle, with 150HP jets (170BHP) should last 55.8 seconds. The best I can tell from datalogs this is about correct.

There is a good jet/HP calculator on the Cold Fusion website. They are very helpful and a fun bunch of guys to talk with.

http://www.coldfusionnitrous.com/calculator.aspx

nitrous works off pressure not pounds....you need to maintain proper system pressure for the A/F ratio to be correct. purchase a bottle heater as this will allow you to use the last bit of nitrous. Typically a nitrous refill for me is only 7 pounds, maybe 8 before I pull the bottle.

Good point. I forgot to address that. The formula of 1lb per 100hp = 10 seconds, assumes 900 psi bottle pressure.

As you stated, it's best to refill at 2-3lbs so I suppose you'd have to multiply the "time" by .8 to know the "useable" time available in your tank.

I thought it was interesting cause if I take 10lbs of nitrous to the track, I'll only have 5-6 1/8 mi runs. Looks like I'll need a spare bottle!

The 210 shot I'm running used up about 2 lbs per run last time out. Using a NOS Cheater plate system.

i was wondering about this since i plan to run nitrous. i hear 150shots last about 7 passes on a 11-12 second sprayed car if your fully pressurized using a 10lb bottle. Doesnt seem like alot to me and at 50 a bottle i can see this adding up

I plan to be in the 10's on bottle and spraying just off the line, probly a second or 1.5 seconds into the run so i should get a few passes in spraying for 9 seconds on a 150 shot and 10 lb bottle

Bah, hit it right off the line or it's just a waste of gas

bye bye 10 bolt then

Ran Friday night. Only 2 n2o runs, 150 shot then 200. Used about 2lbs of nitrous for about 16 seconds of spray.

NA run was 8.71 @ 81.17. 150 shot went 8.24 @ 92.35. 200 shot went 7.98 @ 93.38 (all 1/8 mile) So, I picked up 0.7 et and 12.21 mph! Bear in mind this is with a snail like 2.0 60ft. I planned to hold back til 3000 rpm in first but ended up spraying from 1300 rpm on according to the datalogs. I run T5 and it's a little tricky to launch with summer tires. But let me tell you, this thing got big in all gears. It was lifting the front of the car and I was running down other cars I thought had beat me.

I inspected my plugs and don't see signs of any problems. There are no new knocks or ticks. Datalogs shows the computer was pulling 4-6' of timing. I may pull a couple degrees out but suspect its octain/fuel related. BTW I ran a mix of about 4 gallons 93 pump gas and 6 gallons of 100 racing unleaded.

While the 200 shot is awesome, I may play it safe(r) with the 150 til I get more bottle time. After all, this is my daily driver with a stock bottom end, T5 and 9 bolt!

Hey that just means it's time to upgrade

indeed! i do plan on a 12 bolt whenever i get 2grand saved up..this motor build killed me still not done yet

I only get 6 lbs out of a 10 lb bottle before it starts surging. I also use a 15lb bottle and only get about 10-11 pounds out of it before it starts surging also. The rest of the bottle is just air from the shop that pumps it in when filling it.

I've never tried freezing the bottle in the freezer and then letting them fill it by opening the valve on the fill bottle and then letting the nitrous just flow into my bottle. Might get more nitrous than air, but I don't know for sure.

I hit mine on take off, 125 shot & 10 bolt. No probs yet.

Bottle pressure is important. I learned that this weekend. Bottle pressure in the back hatch sitting in the sun at the track was 1250 psi. Purge solenoid and nitrous solenoid wouldn't work, only got fuel. Sun went back behind the clouds later on in the day and bottle pressure was about 1150, both solenoids worked. I guess around 1200 psi is the key. The hot underhood temps sitting in the staging lanes got the solenoids even hotter. I should have brought a bag of ice or those re-freezable ice packs and cooled the bottle down between runs.