Synapsis

I've had this problem since I put in the system.

The nitrous will pull like a **** in first and second, but once I get to third it'll either surge a little or just bog and stay at the same RPM. After I shut off the nitrous, my O2 sensor will read pig fat for around 10-20 seconds afterwards. When I first put on the bottle, I was getting knock retard in the computer so I pulled the timing back 6 degrees. I'm still getting high knock retard, only in third gear, around the same time the car falls flat. My tables are set to 15.1 degrees of advance. 6 degrees base (stock setting.)

System is totally new, I just finished the first bottle tonight (it bogged in second and sat there.) I have a purge system and use it before the run. Window switch kicks it in between 3000 and 5000 rpm. 100 wet shot on a L98 with Stealth Ram, 24# SVOs, tuned chip and full exhaust. The fuel pump is a 255 lph Holley, installed today (which increased my fuel pressure by 4 PSI over previous setting, I adjusted it back down to 42 PSI vac disconnected.) The fuel pressure safety is set to 33 psi. Ignition is MSD 6AL with MSD blaster coil and MSD pro billet dist. Plugs are accel header plugs, temperature approx equivalent to Delco R43T (according to the box).

I'm guessing I'm spraying too much fuel for the short runner intake, or my plugs need to be one step colder. I'm going to try Delco R44TS's (one step colder than stock, stock length plug) this weekend. I'm thinking of also putting in a smaller fuel jet, or a larger nitrous jet.

What do the experienced nitrous users think?

Synapsis

The 15.1 degrees advance setting is in the 3000 - 5000 rpm area, 85+ kPa, by the way. PE spark tables are zeroed.


Not being able to edit posts leads to postwhoring.

B4Ctom1

If I had to guess I would say one of thre things is happening.

1. your fuel pressure is too high

2. your bottle is too empty

3. your bottle pressure is too low

Synapsis

My fuel pressure is 2 PSI *below* stock to compensate for the SVO injectors. It did it when the bottle was full in 90F degree weather as well. I'm getting a nitrous gauge today so I'll be able to confirm the pressure soon. Maybe the bottle pressure is still too low, even in the desert wasteland I live in.

Synapsis

I just compared 3 different nitrous kits jet recommendations for 100 and 150 shot.


100 shot:

Nitrous works: 55 N / 31 F
Nitrous Express: 52 N / 31 F
NOS: 55 N / 42 F

150 shot:

Nitrous works: 62 N / 34 F
Nitrous Express: 62 N / 35 F
NOS: 70 N / 53 F

Now while the jets are different companies (I guess), the orifices are still .0xx" I think my problem is that I'm filling the damn thing with fuel. I already have really fat PE mode because of the SVO injectors at near GM pressures. In lower gears, the plenum itself would be totally dry. I think the fuel is starting to build up in the plenum during the run and by the time I get to third, I got a decent about sitting in the back. I'm going to try a ~34 fuel jet and see how it works out.

Synapsis

Just to keep people updated....

Bottle pressure turned out to be 900 psi. ChrisFormula showed me a jet sheet (for carbs) and all the jets have the fuel side bigger so we swapped em. It was a little faster than stock, but pretty dull over the whole run, nothing compared with having the bigger jet on the nitrous side. Of course after that run the bottle pressure dropped to 500 psi as it emptied.

I have a 55 nitrous and a 34 fuel jet in it right now. When I fill the bottle I'll see how it turns out.


Oh, and I love my new remote bottle opener.

razor

Make sure you do NOT run the Delco R44TS plugs as they are one step HOTTER. I run 10.4:1 compression on iron heads and a 150 shot on Delco R42TS plugs if it helps. If you want to you can run one plug colder yet.

Synapsis

Yeah, I noticed that after buying the plugs, but before installing them. I'm running R42TS plugs now.

Oh, and the bog was because NOS recommends a fuel jet that's way too big for a stealth ram. I swapped to a 34 fuel jet and it ran pretty good.