Where's my n20 mph?
Thread Starter
Joined: Nov 2003
Posts: 834
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From: St. Louis, MO
Where's my n20 mph? I'll try to give as much info as possible.
Mods: All boltons, Tsp tv2/5.3 h/c pkg, Edge 3400 stall, 3.73s, Racetronix pump & Lucas 42 lb injectors. Full weight car at around 3650 lbs.
Before my passes, I've installed a new n20 line, filter, no.4 line from the noid to the nozzle cleaned the filter in the noid with a air compressor.
Track temp was around 55-60 degrees, 40% humidity give or take. Window switch pills set at 3200 on, 6400 off.
Wed, I got in four passes, two n/a and two n20. My h/c car ran a new best of 11.86 @ 114, 1.64 60' on motor which is still low. Now, on the spray, it ran a best 11.07 @ 119, 1.53 60', 1/8 6.98 @ 96.50. So close to those damn 10s.. This was on a nx 150 shot. Though, I dropped 8 tenths, it only picked up 5 mph from my n/a mph. The psi was at 1000 and the bottle was about 1/2-3/4 full. I know the faster you are on motor, the more it takes the car to pick up on n20, but not this bad. I was running that mph on a 100 shot with a stock cam, stock ported heads and tci 3800+! Something's not right, so what could be the problem?
Mods: All boltons, Tsp tv2/5.3 h/c pkg, Edge 3400 stall, 3.73s, Racetronix pump & Lucas 42 lb injectors. Full weight car at around 3650 lbs.
Before my passes, I've installed a new n20 line, filter, no.4 line from the noid to the nozzle cleaned the filter in the noid with a air compressor.
Track temp was around 55-60 degrees, 40% humidity give or take. Window switch pills set at 3200 on, 6400 off.
Wed, I got in four passes, two n/a and two n20. My h/c car ran a new best of 11.86 @ 114, 1.64 60' on motor which is still low. Now, on the spray, it ran a best 11.07 @ 119, 1.53 60', 1/8 6.98 @ 96.50. So close to those damn 10s.. This was on a nx 150 shot. Though, I dropped 8 tenths, it only picked up 5 mph from my n/a mph. The psi was at 1000 and the bottle was about 1/2-3/4 full. I know the faster you are on motor, the more it takes the car to pick up on n20, but not this bad. I was running that mph on a 100 shot with a stock cam, stock ported heads and tci 3800+! Something's not right, so what could be the problem?
Last edited by shortdog; Oct 13, 2007 at 05:10 PM.
What was your pressure after the run? Sounds like pressure falling off up top to me if you had about a half bottle. Go back with a full bottle and try it again to eliminate that variable.
Thread Starter
Joined: Nov 2003
Posts: 834
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From: St. Louis, MO
The pressure was around 950 psi after my first pass. I forgot to mention, I put in 175 jets for the second pass and lost 1 mph (118 mph)! 
I got my bottle refilled yesterday and it was only 1/2 empty.
Plugs are gapped at .032-.033.
Could it be blowing out spark? Though, the tranny shifted good, could still be unnoticeably slipping causing my mph loss? It had a heavy duty rebuild w/shift kit 1 1/2 yrs ago.
I got my bottle refilled yesterday and it was only 1/2 empty.
Plugs are gapped at .032-.033.
Could it be blowing out spark? Though, the tranny shifted good, could still be unnoticeably slipping causing my mph loss? It had a heavy duty rebuild w/shift kit 1 1/2 yrs ago.
Thread Starter
Joined: Nov 2003
Posts: 834
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From: St. Louis, MO
The pressure never went below 900 psi after neither of my passes. I never had this problem, even with the pressure dropping a little.
SilverZ98, could it be the converter? I thought my smaller, tighter converter would've help for the bottle. Coincidentally, the tci 3800+ I swapped out seemed to like the bottle. On just a 100 shot, it ran a 11.40 @ 118 with that converter.
SilverZ98, could it be the converter? I thought my smaller, tighter converter would've help for the bottle. Coincidentally, the tci 3800+ I swapped out seemed to like the bottle. On just a 100 shot, it ran a 11.40 @ 118 with that converter.
Launching!
Joined: Dec 2003
Posts: 208
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From: claymont delaware
my guess is that you need a tune for the nitrous you should of picked up a good 10-12 mph with a 150hp shot
on my 02 vette stock motor,trans, exhaust and 273 rear i ran 122mph with only a 100hp shot first time out in mid summer........cooler air i should hit a bit more
on my 02 vette stock motor,trans, exhaust and 273 rear i ran 122mph with only a 100hp shot first time out in mid summer........cooler air i should hit a bit more
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Verdad Gallardo Thread Starter
Joined: Nov 2003
Posts: 834
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From: St. Louis, MO
I used 62n 33f as recommended by nx, but check this out: The tuner hooked it up to a wideband several weeks back and we made some wot passes. The A/f is around 12.6 n/a, but was very rich on the bottle. The a/f was in the low 10s on a 175 shot, so we leaned it out by putting in a .033 150 shot jet and that put it at around 11.3-11.5 wot. BUT, it was hot outside and my bottle psi was very high, around 1150. Nx mentioned that the nitrous noid could possibly not open if the pressure is too high, causing the system to run rich. I was "probably" getting an inaccurate reading due to that, but i'm not sure though. I thought it would be too lean with the pressure that high.
We also tested the noid when cleaning the filter. It "seemed" to work fine. I haven't checked the tranny fluid, so that will be next.
The bottle is full and will give it another shot next week. I wanna go with a smaller fuel jet, but don't wanna risk it since I don't have a wideband.
how do the plugs look after the spray passes. a LOT of people don't believe in the old method of just simply looking at the plugs, but it can definetly tell you something.
you said you fucked with the jetting, well maybe throw the jets the manufacturer reccomended in there and see what happens. widebands can be off, and you could be REALLY lean right now.
you said you fucked with the jetting, well maybe throw the jets the manufacturer reccomended in there and see what happens. widebands can be off, and you could be REALLY lean right now.
Thread Starter
Joined: Nov 2003
Posts: 834
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From: St. Louis, MO
I actually pulled about four plugs right after my pass. They were a grayish color with no detonation spots on the white porcelin.
I used the recommended jetting for a 150 shot (62n 33f) and gained what's stated in my first post.
All I can do now is get the bottle psi on point, reduce the timing, tweak with the jets and hope for the best..
I used the recommended jetting for a 150 shot (62n 33f) and gained what's stated in my first post.
All I can do now is get the bottle psi on point, reduce the timing, tweak with the jets and hope for the best..
Get your airfuel at 11.8. If you were in the low 11s and then the bottle pressure droped off a bit up top the airfuel probley ended in the high 10s. causing the car to nose down alittle..
The bottle pressure you ended with is fine.
Another thing could be the convertor if it is not the nitrous.
Dave
The bottle pressure you ended with is fine.
Another thing could be the convertor if it is not the nitrous.
Dave
Thread Starter
Joined: Nov 2003
Posts: 834
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From: St. Louis, MO
Well, I just got back from the track with the tci 3800+ installed. I got in one motor pass: 11.78 @ 114.55, 1.60' which is a little better, but my et & mph still should've improved. Now, for the two n20 passes going for 10s on the last day of the season. Nx 150 shot using a 31f jet (leaned it a bit) and 4* timing pulled to 22.5-23*.. Ready?? 11.33 @ 118.23, 1.54 60' 1/8 7.17 @ 94.30. I went down to a 100 shot to see if it'll run any better: 11.46 @ 117.71, 1.61 60' (spun) 1/8 7.29 @ 94.01. I should've been easily trapping 125+ My car is officially a TURD!!! 
Don't feel bad. Haven't sprayed yet, but, the kit is on waiting for a tune. NA, I gained .5 on my 60' and .8 on E/T and lost nearly 2 mph ... didn't make sense to me either. Track conditions were nearly identical on two seperate nights. Good luck ... still scratching my head.
Thread Starter
Joined: Nov 2003
Posts: 834
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From: St. Louis, MO
The season is over now, but I still need to find out why i'm not making any power on nitrous. If anyone have more ideas of what it could be, chime in. I'm down like 6-10 mph.
There's a bottleneck somewhere. You look to be down on power through the 1/8th so I would rule bottle pressure out. You're about 4 mph short on the 1/8th. What kind of exhaust do you run?