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Are nitrous purge systems a real performance thing? I only ever see them on Fast and Furious type cars, not that some of those cars aren’t fast, but they always seem to be more flash and show? This video seems to back up the more show than go?

 

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It’s to flush the lines of any gas and ensure that the line is charged with liquid so the engine gets the right amount of nitrous and does not potentially bog down at the hit.
 

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A bad example for others
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Getting fresh nitrous to the solenoid and making sure the bottle pressure is correct are but a couple of reasons to purge. We purge through the engine during the burnout with a bang button.
 

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The Liquor Makes Me Think
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Yeah you don’t want that stale nitrous in the motor. You need that fresh sheet.


Sent from my iPhone using Tapatalk
 

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Making sure the pressure is consistent is key to running the number in the fast classes like T/S.
Go up a little warm, purge down to exact pressure every pass, and filling the line is secondary in my book.


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When it's nice and cool outside, purging doesn't make much of a difference... but when it's HOT, it makes a huge difference. In 90+ degree heat, my car would run 6.4's with a good purge, and 6.7's without. The hotter the outside temperature, the more important it is to give the system a good purge. Seriously... I was just giving my car a little baby purge, and it ran like crap. After a full, healthy purge... along with banging it through the engine in neutral a couple times until it got nice and crisp... it dropped 3 tenths!

The above is for 'normal' street cars shooting limited amounts of nitrous. The SERIOUS guys go to the line with too much bottle pressure on purpose, then purge it down to exactly where they want it... which is why it looks like they are wasting so much.
 

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A lot of guys around here purged it through the motor. Myself included in that. I use past tense because I've been out of that for a while. I don't know anyone still actively running it. Turbos and underhood superchargers have taken over.
 

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Would some mind explaining the “bang button” terminology to me.
You activate the nitrous system and band purge the system during WOT like during the burn out or while snorting the engine a few times before staging to clear the line and or lower the bottle pressure to the desired PSI.

 

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That is exactly what I meant by "purging through the motor". I've never heard it called the bang button. Maybe it's a regional thing.
 

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WTF is nitrous?


Last time I used that stuff I was sitting in a dentist chair. Much better use for it IMO. I spent more fuckin money running nitrous than I have forced induction. Going in to have a bottle refilled and I’d have 2 guys helping carry all the crap I bought out of the store.
 

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I would "purge" my ZEX system through the motor on the return road after the all motor shakedown pass to see if Edgewater was hooking that night. Slow 15.1-2 Honda pass and the twin cammed swapped CRX's would cone over looking for a race. They'd ask for $100 and I'd counter with a $1 beer or $1 hot dog, depending on their age.

Because the ZEX was a dry kit, I could nail the launch and then about 5 feet out just as the tiny 20x8x14 MT's were hooking up, the 85 shot came in, keeping the same amount of tire slip. I was at the limit for the time of keeping my slicks properly hooked at the launch. With better suspension 15+ years later, I could have taken the purged big hit right at the launch.
 

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You activate the nitrous system and band purge the system during WOT like during the burn out or while snorting the engine a few times before staging to clear the line and or lower the bottle pressure to the desired PSI.

https://www.youtube.com/watch?v=VMOmKLeL_30
Well if you heat the bottle with a torch you might have to lower the bottle pressure by purging. I ran at 900-950 psi in the Honda, could get 8 full runs before pressure would drop.
 

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Well if you heat the bottle with a torch you might have to lower the bottle pressure by purging. I ran at 900-950 psi in the Honda, could get 8 full runs before pressure would drop.
Things get a lot more complicated on the big nitrous cars. Even with two bottles there is enough pressure drop during a pass that they need to start with a fresh fill every run. Then the only way to be consistent, especially when trying to tune for traction is to have the exact same bottle pressure every run which requires filling the bottles above your desired pressure and purging down to that exact target pressure, which is why you see the fast nitrous cars purging a what seems like a shitload of nitrous off before they get into the beams.
 

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Things get a lot more complicated on the big nitrous cars. Even with two bottles there is enough pressure drop during a pass that they need to start with a fresh fill every run. Then the only way to be consistent, especially when trying to tune for traction is to have the exact same bottle pressure every run which requires filling the bottles above your desired pressure and purging down to that exact target pressure, which is why you see the fast nitrous cars purging a what seems like a shitload of nitrous off before they get into the beams.
They generally run two bottles and swap in a single fresh bottle every run to balance out the pressure. A lot gets vented in the name consistency.
 

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Well if you heat the bottle with a torch you might have to lower the bottle pressure by purging. I ran at 900-950 psi in the Honda, could get 8 full runs before pressure would drop.
You must be in a super hot area. I’d need the bottle warmer 3/4 of the time just waiting in the staging lanes because the pressure would get to low before the pass.

I purged externally all for bottle pressure consistency.
 

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I run the bottle at 23.7#, usually around 90* has it 950ish when I roll through the water box. Flip the 1/4 turn after the burn-out which drops it to 925ish, purge to 900 and it's ready to go; not a crazy amount bled off like so many seem to do for show. Usually shut the 1/4 turn off while I'm slowing down and purge the line off after. Not a good idea to leave pressure standing against the solenoids in the pits, staging, etc before starting the motor. Bottle gets changed after every pass, the next two in-line are in the bath in the trailer ready to go.

Have used a bang-button in the past; just brought the motor up to around 3500r's in neutral after the burn-out and bumped it 2-3 times. - Didn't make any repeatable difference in performance so we just went back to using a simple purge noid.
 

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You must be in a super hot area. I’d need the bottle warmer 3/4 of the time just waiting in the staging lanes because the pressure would get to low before the pass.

I purged externally all for bottle pressure consistency.
Same here. Even out in the hot sand dunes, I typically have to run the heater to get/keep temps where I want, then purge for consistency.
 
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