popping noise with nitrous
 

I'm taking my 93 Cobra to the track tomorrow, and I had a 75hp jet in my dry nitrous kit. I put in a 125 today and went to try it and it started popping around 5200-5500. Before it would go to 6800 and I tried without the bottle afterwards, and it will still go that high on motor. I'm pretty sure it is going through exhaust, and it's short pops. I am running 10 degrees base timing, an A9P computer, and have a new walbro 255lph pump. I am new to the nitrous game, and any help would be appreciated. Thanks.

Re: popping noise with nitrous
 

That would be detonation.

Retard the timing about 3or 4 degrees. You can run stock timing with a small shot but 100 shot and up you need to retard it for sure.

I believe the rule of thumb is 2 degrees for every 50 shot of nitrous.

I highly reccomend you pull all of your plugs and make sure you didnt melt the electrode off any of them.

Its also important to run a .035 or so plug gap with the larger shots of nitrous with a colder plug. I am sure you know this but just making sure.

Re: popping noise with nitrous
 

BTW: What engine are you running and whats done to it that makes you shift at 6800rpm?

Re: popping noise with nitrous
 

Thanks for the info, I will see what happens. It is still pretty close to stock, but has a decent size cam in it, don't know what exactly. Was told it was an X303, but no way that would clear the valves, especially with the stock 1.7 rockers. I don't shift that high though, more around 6000. Still getting used to the car. Thanks.

Re: popping noise with nitrous
 

It would rev to 6800 without a chip or extender?

Re: popping noise with nitrous
 

custom chip? ...The factory un-accurate tach might rev that high, but the motor probaly wont :D

Re: popping noise with nitrous
 

It used to go to 5900-6000, and the cobra computer is supposed to have a 6000 rpm limiter, so that's what I thought was going on, and it was pretty annoying hitting that quickly with 4.10 gears. I had an A9P and decided to try that, because I have yet to find an lx or gt with an actual limiter, but it already had an A9L in it. I went ahead and swapped it anyways, drove it, and same thing. Turns out I needed better valve springs. I have had the car on a Dynapack chassis dyno, which bolts directly to the axles so there is no slippage, and the tach is not far off. No chip, no extender, just good valve springs and a bigger cam. Ran today with a 75 jet and got a 13.19 on drag radials. Still need to get used to the car and the bottle. Thanks for your replies. :)

Re: popping noise with nitrous
 

I dont know why but my car doesnt have a limiter. :confused:

Re: popping noise with nitrous
 

Hell guys, my shift light is set at 8,600 and it LIKES it! I'll bet ya a donut that Mr. Chambers is shifting even higher than that. Not a big deal if all is right.

Now on to the point. Popping on Nitrous is NEVER a good thing. Even if the car is "behaving" well. Like mentioned before, I'd knock some timing out of her, and maybe even throw in a set of cooler plugs to boot. Autolite 24's should be on the mark. Unless your heads dictate the "extended reach" plugs, then I'm not sure what number you'll need. We can figure it out though. ;)