What's up with my N2O graph?
What's up with my N2O graph? Have any of you Nitrous gurus seen this type of graph before. We did several pulls and the N20 hp was very inconsistant. We varied anywhere form 540 hp to this 585 pull. Bottle pressure was right around 1000psi for each pull. Setup is a N20 Outlet plate kit with 150 hp N20 jet and what would probably be a 125 fuel jet, but it is still really rich as you can see. Also running a standalone fuel system maintaining 55 psi during the entire run. Trans is a th400 with a yank 3600 converter. When looking at the same same graph using wheel speed the graph was very linear so I know that it shouldnt be anything slipping in the trans. Could this be a bad ground? I really don't know. Plus I am thinking I might have to put in the 100 fuel jet just to lean it out further. I can't believe how rich the recomended jets make the car. Overall, still very happy with the kit, but I would like to get things a bit more consistant, smoothed out, and maybe a bit leaner. If you couldnt figure it out the 440hp run was NA.
EDIT: Sorry about the really tiny graph I cant seem to get it to show up any larger. But you can still make out how jumpy the graph is on the N20 and the A/F bottoming out lower than the dyno can register.
EDIT: Sorry about the really tiny graph I cant seem to get it to show up any larger. But you can still make out how jumpy the graph is on the N20 and the A/F bottoming out lower than the dyno can register.
Last edited by fastGBcamaro; May 7, 2010 at 09:39 AM.
We started with the recommended jet size for a 150 shot, then dropped the fuel pressure from 55 to 45psi, still RICH. Then dropped the fuel jet 2 sizes and put the pressure at 55psi again, Still RICH. SO we dropped fuel pressure on the smaller jet and it was still so rich that it wasnt registering on the wideband. At that point it was midnight and I needed to get home. We plan on dialing it in further, but I figured I would ask on here to see if anyone has seen anything like this before. I hope its just the rich condition causing this, but somthing tells me its not.
8 Second Club
Joined: Aug 2007
Posts: 160
Likes: 0
From: Statham,Ga
I have seen this happen when the nitrous was too hot and/or too much pressure.
(read supercritical phase)
I know you said the pressure was "around" 1000 psig but nitrous can go supercritical at 1050 psig.
It is not uncommon for the cheap bottle gauges to be off 50 to 75 psig.
(read supercritical phase)
I know you said the pressure was "around" 1000 psig but nitrous can go supercritical at 1050 psig.
It is not uncommon for the cheap bottle gauges to be off 50 to 75 psig.
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Looks just like mine when I broke a spring..... Have any of you Nitrous gurus seen this type of graph before. We did several pulls and the N20 hp was very inconsistant. We varied anywhere form 540 hp to this 585 pull. Bottle pressure was right around 1000psi for each pull. Setup is a N20 Outlet plate kit with 150 hp N20 jet and what would probably be a 125 fuel jet, but it is still really rich as you can see. Also running a standalone fuel system maintaining 55 psi during the entire run. Trans is a th400 with a yank 3600 converter. When looking at the same same graph using wheel speed the graph was very linear so I know that it shouldnt be anything slipping in the trans. Could this be a bad ground? I really don't know. Plus I am thinking I might have to put in the 100 fuel jet just to lean it out further. I can't believe how rich the recomended jets make the car. Overall, still very happy with the kit, but I would like to get things a bit more consistant, smoothed out, and maybe a bit leaner. If you couldnt figure it out the 440hp run was NA.
EDIT: Sorry about the really tiny graph I cant seem to get it to show up any larger. But you can still make out how jumpy the graph is on the N20 and the A/F bottoming out lower than the dyno can register.
EDIT: Sorry about the really tiny graph I cant seem to get it to show up any larger. But you can still make out how jumpy the graph is on the N20 and the A/F bottoming out lower than the dyno can register.
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TECH Enthusiast
Joined: Jul 2002
Posts: 660
Likes: 0
From: Dallas, TX
MAN you are very smart. You know one of the guys SAID it might be the valve spring. The other guy that worked there. WOW, that is what he said he thought it could be, the other guy said the torque converter. I DO have dual springs.
I am going to have them take a look! THANKS SO MUCH!
I am going to have them take a look! THANKS SO MUCH!
No Problem...one last thing Glad I could offer some suggestions that you think are worthwhile to look into. That's what's great about LS1Tech!. The Tuner also told me that a spring does not always have to break to go bad. In my case I was lucky and the broken spring was obvious. Kind of surprised the stock AFR Double Springs would break as I limit my revs to less than 6600 RPMs. He also said if there were no broken springs he would have tested each one on a spring guage to ensure each spring still provided the proper pressure. Good Luck!
Teching In
Joined: May 2010
Posts: 4
Likes: 0
I had the same thing on my first dyno run. It was my fuel pressure safety switch. It was set to just below my current fuel pressure. Every time the nitrous hit it dropped the fuel pressure and caused the surge. Not 100% sure if this is your problem but try it with out the fpss on the dyno since the afr is so closely controlled.
