I am still fighting my nitrous system. For the past couple of months since trying to go past a 150 shot I have had nothing but bad luck with tuning it. Every time I try and tune it, the engine pegs the A/F meter and no matter what I do you can't seem to lean it out. Here's what I am running:
346 Built bottom
12.2:1 CR H & C
TNT 250 shot F1 with bigger jets
Racetronix fuel pump - BAP - Return rails

Anytime you hit the nitrous the A/F maxes out @ 10.0:1 and its definitely rich.
Phil

 

Are you trying to pass more N2O through the solenoids than they can handle? I thought the F1 kits were limited to a smaller shot (150 and smaller) because of smaller noids. Don't F2 kits have the larger solenoids and can flow more N2O? Could be that you haven't approached the limit on your fuel noids, but maybe you have on the nitrous noids, thus keeping you stuck in pig rich land. Just a thought.

 

You may be on the money seeing everything over a 150 shot runs pig rich.
Phil

 

Sounds about right with the smaller noids, but i thought the f1 kits are good till about 250? and the only diffrence between the f-1 and f-2 was the jets? Did you try putting in a smaller fuel jet and see if that helped?

 

try jeting down the fuel till you aren't so rich. If you don't make the power your suppose to then the noid is too small

 

I emailed TNT about it....Last night I ran 250 nitrous with 250 fuel and 200 fuel and both times it was PIG Rich.
Phil

 

Something is restricting your nitrous flow, that's pretty obvious. Finding the choke point should solve your problems. Could be trash or something restricting your nitrous line or solenoid too.

 

Sometimes when ends are crimped on you'll get a little flapper, and this can be trouble. Seen manytimes at work. It does kind of sound like restriction on the n2o side if it works upto 150 fine. If you have an extra main supply line, try hooking it up? Is this all a single stage?
Robert

 

Yeah, single stage. I contacted TNT to see if there is any difference in F1 and F2 nitrous solenoids. When I pulled 10% fuel out of the computer and went to the 200 fuel jet it picked up almost .2 @ the 330' mark. It went a PB of 4.19 @ 330'
Phil

 

We are running a f1 kit at a 250 shot. We had to jet down the injectors on the pe table 6% and I believe 4 step down on the fuel jet. We were going pig rich on the dyno. On the track the a/f went from 12.3-11.6 gradually through out the run as nitrous pressure dropped. MPH was quicker by 3 mph @ the 1/8 mile mark over a 200 shot, but car ran out of gear and had to let off earlly. Will be testing again today. Check your lines for big bends or crap in the line. Disconnect at the solinoid and purge the line with the bottle to blow out any crap. We are running dual intank pumps were the second one is turned on with the nitrous activation switch. Pressure is around 63 psi.

 

So instead of 31s your running 27s and -6% fuel on the PE table?????
Phil

 

I had a similar problem with my dry NOS earlier in the year. My restriction was the line coming from the noid into my intake. I decided to run a bigger AN line and it fixed the problem. I now run two noids and my afr is good.

 

I would warn against under-jetting / PE reduction until you absolutely rule out the possibility of contaminated nitrous side: Siphon tube, each connection, valve, line obstruction, filter etc...or else IF there is one and it dislodges your fucked!

Good luck,
Charlie

 

We have a 28 jet and -6% pe over the motor tune. The motor tune however was on one pump, and the nitrous is on 2 pumps with more line pressure. We checked the lines and there was no blockage there. Pressure was at 1050 nitrous 63 fuel. There was a big difference between the dyno and the track a/f. I was using a lm1 wideband on both dyno and track. We tuned on the dyno going lower on the fuel jets in increments. Each time we lowered the fuel jet to lean it out we picked up power. I was using monitoring stock o2's, dynojet wideband o2, and lm1 wideband on all runs to confirm correct a/f ratio. There is 3an line to the nozzles. It could be a restriction, but we did get a 250 rwhp increase after some tweaking.

 

When you bump your fuel pressure up from 58 to 63, that is the same as putting bigger injectors in. That is how the lt1 cars do it, spike the fuel pressure with an extra pump to fake the injectors into being bigger. It's like Ford 30lb SVOs at 45 psi, is 36lb'ers at our 58psi. I have the math somewhere, now are these to rich conditions still related, maybe.
Robert

 

I know what it does when increasing the line pressure which is why I gave out that info. I want to give a true picture of everything that is going on. I could see having to lean out the pe table a bit to compensate for the higher fuel pressure, but the nitrous jetting shouldn't need to be tweaked unless it is a kit restriction. Lets say the fuel flows fine with the bigger jets but the lines out of the solinoid may be a restriction for the nitrous. Hard to say for sure. Just make small fuel jet changes and log the information to see whether knock is introduced and how a/f changes. We are running 113 octane if that is relevant.

 

I agree wholeheartedly!

 

PE isn't the way to compansate for higher fuel pressure. You would need to rescale your injector table to do it correctly. The rest of what you say I agree with.

Robert

 

I understand that, but this is a trailer only car that only sees wot. The car is going speed density tune soon. The base fuel is corrected by the computer. The extra pump is only turned on with the n2o activation switch right before the run so the base fuel would be out of whack if I tried to lean it out on the ifr.

 

I'm assuming you have pulled spark plugs to verify the rich condition?