Hey Guys, my name is Darell and I've been lurking for a few weeks. I bought my S2000 here in New Mexico about a month ago and just finished installing a wet nitrous kit. After reading some threads I decided on a Zex 82021 wet setup. The car has an Invidia 70mm test pipe, Innovate MTX-L wideband 02, and a single exhaust exhaust. My TPS wire to give WOT to the Zex NMU is split by a relay and only activated between 5k and 8600rpms. I finished my kit last night and made a few runs on the car with the 55hp jets installed. I warmed the bottle up to 950psi, purged for 3-5 seconds and started rolling. Watching my AFR was difficult, even with a passenger who was filming and trying to do the same.

The initial engagement at 5000 rpms was VERY noticeable but tapered off and I didn't feel much of a difference after each shift. I'm wondering if my A/F ratio's are causing a problem and that a jet swap may be needed. I have 7405 plugs installed, checked them this morning and found nothing that made me worried. There were no specks or white dots on the electrode, it was a brown/muddy color. There were no soot deposits either, this was after maybe 4 passes. I did calibrate my 02 sensor as per the instructions when I first installed it so I would hope it is where it should be. I figure the butt dyno obviously isn't going to tell me much but the car does pull the same if not almost harder without the nitrous. Any help/advice would be greatly appreciated!

[media]https://www.youtube.com/watch?v=0PYerp8CgG4[/media]

Here's one of the better runs we could film. My brother in law was holding my HTC one and trying to keep it steady. I know its difficult to see the wideband, the MTX-L has software to pull the logs, gonna try to get 'em uploaded in a bit.

 

From what I see when you're on it you are a bit lean, 13.2 a/f is too lean IMO for nitrous, you want to be low 12s or lower for safety, change the fuel pill for something that will run you richer

 

I swapped out the #17 fuel jet for a #19 and it put the afr at 9.9-10.5 which seems too rich. I'm guessing the high altitude at which I live has an affect on the air density. After swapping jets out and testing the car I found that in my area and at my elevation a #40 nitrous pill and a #19 fuel pill give me the best results. The afr right at 5k drops to 11.2 and slowly goes up to 12.0 after Vtec and near the nitrous cut off at 8600. And the car pulls like a mofugga , which of course feels great. Gonna keep an eye on the plugs and hit the track this Friday night . Thanks for the help Justin

 

I was having trouble finding the right mixture of jets for my nitrous set up a couple years back. I had a 75 wet shot on a Zex kit with all the perks, purge kit, warmer, window switch, remote opener etc. I was having problems with my AFRs staying in the 11s, and what ended working the best for me was running a 65 shot fuel jet and an 80 shot nitrous jet.

 

Dont go over a 75 shot on the stock ecu. Keep the afr in lower to mid 11's. Do a 4th gear pull on a highway so you can watch the afr easier. Have fun.

 

Didn't think about the highway run since It's about a 25 minute drive to the nearest one but that makes alot of sense. Trying to shift, keep an eye on the gauge and make sure I can see what the AFR does between 5k-8.6k is such a pita. I have the logs but without an RPM along with the 02 reading they're nearly useless. I can see the shifts and what the AFR does just cannot pinpoint at each rpm what its doing.

I know either way is bad for the engine but until I can buy a few more jets would I be better off keeping the car at 9.9-11.0'ish or the 11.2-12.0'ish. I know it makes more power leaner but I'm more concerned with engine life than power. I just didn't know if in the grand scheme of things if the 9.9 the afr drops to upon activation was too rich or not.

 

9.9-11.0ish a/f ratio is fine, you want more fuel in the grand scheme of things, fuel is what "protects" things from going KABOOM

 

Awesome, thanks for the quick reply! I had to order a bottle blanket last night, hoping it helps the bottle heater keep the pressure up. I didn't believe the reviews of how terrible the Zex bottle heater was and man was that a bad choice. It was about 78 degrees here saturday and with the bottle heater on for like 30 minutes I couldn't get it over 800psi. Might have to just go with another brand, any recommendations?

 

I used the zex bottle heater and didn't have any problems. Soon as I got in the car to go anywhere I would turn it on and leave it go til I got to where I was going. It has an auto thermostat in it. Mine hovered at 900 psi typically after 15 mins.