Just installed a Nitrous Supply wet kit in my brother's 02 Z28 with bolt ons. We are using 61N 37F, what they consider a 150 shot. Not too much info on this kit. When we were doing some testing today I noticed it doesn't initially hit very hard. At 3k RPM (using a window switch) there is a slight burp and then cleans right up and seems to pull moderately hard. I just remember when I had my LT1 NOS 5176 kit it would hit real hard with 100 dry shot. I picked up 9 mph with that 100 shot, haven't been to the track yet with the 02 (car normally traps 117 on motor).

Any ideas why this might be. It just might be the nature of the wet kit with the single nozzle, but we were expecting more.

Doug D

 

The calculator I use says that a 32 fuel jet will get you 142 to the wheels. You may be too rich. Also, what was your bottle pressure?

 

Doug, you gotta see what that thing is running at a/f wise, but also, put the bottle pressure to 1150, motor purge a couple times and I bet that bitch will hit hard and it will have no initial burp, that initial burp makes it feel weak since it's not an instant hit!

 

Sounds like a purge issue. Your jetting is probably pretty close with the bottle pressure at 1000 to 1100, if you have it down any lower then 1000 then it's definately rich.

Personally the Nos plate I am using has supplied jetting for a 150 at 62 Nos 44 fuel, and I KNOW that is rich, a good bit rich. I put the bottle pressure at 1050 and it was still plenty rich. I didn't notice much of a delay at all with it, right off the brake it engaged, and pulled really good.

I was trapping 125 to 126 n/a, 100 hit got the car to 135, 150 got it to 139.2 but it spun (1.35 60 foot on the 100 shot, 1.40 on the 150)

 

Bottle pressure was at 1050.

Can't really tell what the A/F is. What is a motor purge? We used the normal purge right before the runs.

Should I lower the fuel jet to 32?

I do have a scan tool, I guess we can lower the fuel jet till it starts knocking?

Doug D

 

If you don't have ur own wideband, just get it on a dyno with one, but I suggest buying a wideband, it's always good to have on a spray car. To motor purge, before the run with the car in neutral, bring the rpm's up to 3000 and blip wot real quick, first one will usually have a hiccup, second one will usually be clean and means ur ready to go, sometimes it takes 3 to get it clean and ready to go. And bump that bottle pressure up to 1150!

 

I wouldn't just go strait to a 32 jet if you have a 37 in there now, I'd go one jet size at a time, jumping around like that is a good way to hurt stuff.

what are you running for compression/fuel/plugs/timing?

 

Thanks Devon, we'll try that.

We've never been in the motor, running Autolite 103's (1 step colder) gapped at .035. 93 octane on a Diablo tune.

Doug D

 

Take a look at your spark plugs...that'll tell you a lot. If it looks rich, back off on the fuel or up the nitrous. A .063 and a .032 sounds about right to be honest.

 

first step, ditch that tune and get a reputable tuner to get it done right. That will make a big difference, that diablo handheld thing is not gonna get you where I think you're trying to get to. The plugs you are running with stock compression are probaly o.k., I tell everyone to go a step colder then you think you should to start, worst that will happen is a couple fouled plugs, alot cheaper then a melted piston. Your octane is o.k, only because you are on stock compression.... I think with 10 to 1 you can run a 150 with pump gas pretty safely, start getting into 11 to 1 on stock pistons, and things get a little more risky.

 

It's not just a off the shelf Diablo tune, it was dyno tuned a few years back at Diablo. Although we have no wideband, the plugs have always looked spot on with that tune and the car runs 12.00's at 117 at a 3550 race weight with only bolton's. I know it's not a nitrous tune, but it's solid NA. I'll start reading the plugs and keep an eye on knock with my scanner.

I'm thinking it might be a bit rich with the 37 fuel jet with the feedback I'm getting. Thanks for all your help guys.

Doug D

 

mine seems a bit weak also on the initial hit. i think its kind of the nature of the game unless u r getting a good purge into the motor.

 

if your have a purge kit, would motor purging and purging with the solenoid be the same thing?

 

i am not saying you did this but i did when i was new to nitrous, if your pulling fuel from the stock rails which i assume you are. just curious but did you take the schrader valve out. I know from experience, i was basically running a dry 75 shot on a wet kit for like a week. I got lucky and we caught it, so we didn't have any problems

 

I had a purge and just took it off, cuz I still had to motor purge anyways, cuz if not, it still had a slight delay, would hiccup and then wake the **** up!

 

You have a kink in the nitrous line somewhere?

If you're doing a small blip-blip type purge, it could look big, but not really be flowing everything it should. Kind of like when you kink the water hose and squeeze the trigger. It comes out hard for a second, but dies off quickly once the pressure in the line downstream of the kink bleeds off.

 

I have my purge located right before the actual nitrous solenoid, and have had no problems with a hesitation. I let go of the transbrake and the car might move a foot before it hits if that....

If you have a purge, move it as close to the nitrous solenoid as you can... that should help.

 

before i got my purge i had a slight hesitation before itd hit and then itd go yunderway. Purge and now no hesitation, instant ***** to the wall.

 

i have my purge after the n20 noid. my theory was that it drew the n20 threw the first noid during the purge.

 

I am kind of wondering how having your purge after the N2O noid works?
I have mine right before the N2O noid, and it hits great.