5 Liter Eater

iTrader: (5)

Via my digital multimeter I am reading my bank 2 sensor 1 HO2 voltages. Off the hose they are ~900mV which seems good. On the bottle they are 1150-1200mV. I know that fine tuning is not possible with the stock O2's but 1200mV seems REALLY high. My bottle pressure is never optimal, it probably sits ~850 PSI on average as I don't have a bottle heater yet so this could be contributing to the apparent over rich situation. Could I have a nitrous delivery problem? I run the two NOS super power shot N2O noids in series (N2O flow) for redundancy. I also have a couple 90 degree elbows in the mix. Could these be cutting down on the N2O flow? I'm thinking about going up in N2O jets or down in fuel. Right now I'm 47/26.

Going to the track this weekend and would like to be running a little more optimal.

70Stang

iTrader: (2)

The jetting is dependant on bottle pressure. Get that bottle to around 1050 and you will lean it out a bit more...
The elbows should not effect it...

5 Liter Eater

iTrader: (5)

Well if I don't get a heater by Friday what are some options? Increase the N2O jet size, reduce the fuel jet size, strap a heating pad to the bottle?

PREDATOR-Z

Put your bottle in HOT water for less than 30sec while monitoring the pressure guage, quick safe and effective. Bottle will keep pressure for the run. Then repeat.
Just don't take your eyes off that guage. Once you reach 1100 remove and install Bottle. It happens really quickly.

5 Liter Eater

iTrader: (5)

Well I decided to up the N2O jet and leave the fuel alone so I ran it with a 55/26 combo. So basically by the NOS jet estimates this is a 125 shot N2O jet paired with a 100 shot fuel jet. Does this seem weird to anyone else? Bottle pressure started @ 950 and ended at 925 after three test pulls. The first run the O2 voltage seemed to have really come down. Around 975mV which is great in my book. It pulled harder than ever through the whole powerband. The next two runs though, the voltage went back up to ~1125mV and it did what it had done before, starts off strong, loses a step in the mid range and starts to pull hard again on the top end.

PREDATOR-Z

What is your AFR? I would Autotap on the run you'll get a much clearer picture.

5 Liter Eater

iTrader: (5)

Well, going off the chart on http://www.speedshop.org/store/scrip...p?idproduct=67 975 would be around 12.5:1 but 1100 is off the scale rich. I don't really agree with cutting off the N2O @ .99 like their switch does but whatever. The Helms says the O2's read from 10 mV to 1000 mV. I'm leary of leaving the 55 jet in with the 26 jet but I can't see the O2's lying to me that bad. I would imagine an autotap would say the same thing. An autotap would most likely tell the same thing although it would be much more granular and imformative.

PREDATOR-Z

You would be amazed how much an O2 sensor will "lie".
An Autotap would give a chart reading at every rpm.

5 Liter Eater

iTrader: (5)

If the O2 is lying, wouldn't it lie to AutoTap as well? In the mean time I'm bumping up the fuel jet for tonight's runs.

Chicago Z06

5 liter eater, you are definitly playing with fire. the factory 02's are there to keep AFR at Stoich 14.7:1. the 02's are NOT accurate when tuning.. they are not fast enough for tuning to be even remotly accurate. i learned hte hard way when trying to tune my LT4 Camaro in 96 with DFI... i washed the rings out becuase the 02's were so far off. by adding more n20 to take advantage of lower bottle pressure your askign for problems. it is easy to forget these changes when o nthe street to play with a 5.0 or something.. not to metnion when at the track and the bottle pressure creeps due to sun or whatever.. never tune the system for low bottle pressure. if anyhting yo uwant it how it is... fat at low pressure and 11.8-12.5 AFR at 11-1200 psi. this is just a word of advise from experience in many broken parts and spraying over the past 15 years... good luck and i hope all works out for you.

5 Liter Eater

iTrader: (5)

Thanks for the advice Chi. I'm definitely going to stop trying to compensate for the low bottle pressure with N2O jets. But do you think that I am running so fat that I stand a chance at washing my rings? Tonight I'm planning on running a 55/28 setup which is .001 small on the fuel side because I don't have a .029 jet. 55/29 os NOS's recommendation for a 125 shot so I wouldn't think I would be close to washing out my cylinders just because of low bottle pressure. Not that it was that low the other night when I only upped the nitrous jet. Bottle pressure started @ 950 and ended @ 925. I'm going to top off the bottle before going to the track so it should be back up to ~950-975.

So you're saying:

1. Don't stray that far from the recommended jets to make up for an apparent rich condition. Got that, good advice.

2. Don't run it as it is with the 1100-1200 mV readings I'm getting until I can get it on a dyno?

Thanks again.