Draco1340
Registered
I think we can all agree that its time to start a new thread.lease:
With all the recent discussion centered on methods of getting N2O into the motor, I wanted to compare and discuss various methods of accurately and simplistically controlling the flow of nitrous via controllable and steady bottle pressure. I have tried all of the following methods, and I don’t care for any of them! They all suck. Advice please??
The propane torch method – Yup, have to admit that in a pinch with only 5 minutes between rounds, I’ve succumb to the “fast-stupid†method. Take your plumbers tourch and heat that bottle up, checking with your on board gauge, and purge down to 1kpsi right before your run. Some tracks point a blind eye to this. Some will kick your ass off the track. Dangerous and stupid, but also cheapest, fastest and lightest.
Heater blanket and pressure relay method- This is the most standard method were a pressure switch switches the blanket on and off between 850 and 1050 psi. On a 50 shot, this can swing you’re A/F ratio +/- 0.5. If you add a purge valve and an accurate gauge, you can always purge down to the 850 psi and tune for that, but you have added about 4 pounds of crap to your ride. Also, expect to have to replace and charge your battery continually. These systems draw big current. They can also turn on during a run, pulling available current away from the coils.
The bottle in the truck method – This is the ultimate “keep it simple methodâ€. If you have 4 bottles, you can just keep them in the truck at a moderate 75F and swap them between rounds. Unfortunately all of us frequently experience the 1 hour oil down right after we roll up to pre-stage. Bottle pressure drops down to 750 psi, and all of a sudden you’re A/F ratio has dropped 1.5. I have personally logged runs as low as 10:1 after having tuned for nominally 12:1 under this scenario.
Land Speed considerations - So far all of these systems work OK for the drag strip (although never reliably enough for me) but none of them work well for land speed were you might be on the spray for 20 seconds or more. I log bottle pressure with my data logger, and was amazed at how bottle pressure drops as a function of time. With a 2# bottle starting at 1100 psi, I initially purge down to 1Kpsi. On solenoid activation with a 50 shot, the bottle immediately drops to 750 psi. The pressure eventually drops to about 700 psi in the first 4 seconds. By 15 seconds, the bottle is down to 400 psi. The phase change “super chills†the bottle, and the pressure drops like a stone. Even if you tune for super lean in the beginning, you can see you’re A/F drop over 2.5 points. To combat this you can see Tiger racing caries 3 x 2# bottles. I also remember seeing a ZX12 with a 5# bottle looking a bit like Wiley Coyote. Bigger volume creates less drop, but its still a crap shoot on a 30 second pass like Maxton.
The Nitrogen Gas “push†method – A buddy of mine and I played with this method for a while. We created a bottom feed nitrous bottle with a second inlet into the top. We attached a regulated supply of nitrogen gas to the surface of the nitrous and pushed the N2O out with this regulated supply. The system was complicated, and took at least 45 minutes between runs. It comprised of a carbon paint ball canister charged to 4kpsi with nitrogen, and a specially engineered adjustable regulator. The system could completely drain a full bottle with no drop in pressure. It also added at least 10 pounds to the rig, and was arguably a bloody time bomb in a crash. One tech inspector just rolled his eyes and walked away...
The N2O regulator method – I was initially skeptical of this method, but I started using this method at the end of last year as an experiment with a 30 shot. I have the nitrous regulator set at 750 psi, and I just let the bottle pressure be what it wants as long as its moderately warm to the touch. Low tech, simple, cheap and light. Quick purge in the water box, and that’s it. I don’t have enough experience to know if this is limited to very small shots.
Pictures forthcoming. My daughter lost my USB cable this weekend, but I want other ideas and solutions to this problem.
With all the recent discussion centered on methods of getting N2O into the motor, I wanted to compare and discuss various methods of accurately and simplistically controlling the flow of nitrous via controllable and steady bottle pressure. I have tried all of the following methods, and I don’t care for any of them! They all suck. Advice please??
The propane torch method – Yup, have to admit that in a pinch with only 5 minutes between rounds, I’ve succumb to the “fast-stupid†method. Take your plumbers tourch and heat that bottle up, checking with your on board gauge, and purge down to 1kpsi right before your run. Some tracks point a blind eye to this. Some will kick your ass off the track. Dangerous and stupid, but also cheapest, fastest and lightest.
Heater blanket and pressure relay method- This is the most standard method were a pressure switch switches the blanket on and off between 850 and 1050 psi. On a 50 shot, this can swing you’re A/F ratio +/- 0.5. If you add a purge valve and an accurate gauge, you can always purge down to the 850 psi and tune for that, but you have added about 4 pounds of crap to your ride. Also, expect to have to replace and charge your battery continually. These systems draw big current. They can also turn on during a run, pulling available current away from the coils.
The bottle in the truck method – This is the ultimate “keep it simple methodâ€. If you have 4 bottles, you can just keep them in the truck at a moderate 75F and swap them between rounds. Unfortunately all of us frequently experience the 1 hour oil down right after we roll up to pre-stage. Bottle pressure drops down to 750 psi, and all of a sudden you’re A/F ratio has dropped 1.5. I have personally logged runs as low as 10:1 after having tuned for nominally 12:1 under this scenario.
Land Speed considerations - So far all of these systems work OK for the drag strip (although never reliably enough for me) but none of them work well for land speed were you might be on the spray for 20 seconds or more. I log bottle pressure with my data logger, and was amazed at how bottle pressure drops as a function of time. With a 2# bottle starting at 1100 psi, I initially purge down to 1Kpsi. On solenoid activation with a 50 shot, the bottle immediately drops to 750 psi. The pressure eventually drops to about 700 psi in the first 4 seconds. By 15 seconds, the bottle is down to 400 psi. The phase change “super chills†the bottle, and the pressure drops like a stone. Even if you tune for super lean in the beginning, you can see you’re A/F drop over 2.5 points. To combat this you can see Tiger racing caries 3 x 2# bottles. I also remember seeing a ZX12 with a 5# bottle looking a bit like Wiley Coyote. Bigger volume creates less drop, but its still a crap shoot on a 30 second pass like Maxton.
The Nitrogen Gas “push†method – A buddy of mine and I played with this method for a while. We created a bottom feed nitrous bottle with a second inlet into the top. We attached a regulated supply of nitrogen gas to the surface of the nitrous and pushed the N2O out with this regulated supply. The system was complicated, and took at least 45 minutes between runs. It comprised of a carbon paint ball canister charged to 4kpsi with nitrogen, and a specially engineered adjustable regulator. The system could completely drain a full bottle with no drop in pressure. It also added at least 10 pounds to the rig, and was arguably a bloody time bomb in a crash. One tech inspector just rolled his eyes and walked away...
The N2O regulator method – I was initially skeptical of this method, but I started using this method at the end of last year as an experiment with a 30 shot. I have the nitrous regulator set at 750 psi, and I just let the bottle pressure be what it wants as long as its moderately warm to the touch. Low tech, simple, cheap and light. Quick purge in the water box, and that’s it. I don’t have enough experience to know if this is limited to very small shots.
Pictures forthcoming. My daughter lost my USB cable this weekend, but I want other ideas and solutions to this problem.