In the process of throwing a lil juice onto the ol motor and wanted to know how everybody is leaving the beams. I was going to wire it up on a WOT and window switch and have it completely seperate from my trans brake/2 step button (1 button) however I came across a schematic on here that had the t brake/2 step button interupting the nitrous circuit so it would NOT allow it to spray while on the brake.

I would think spraying while on the brake/2 step would yeald better results than hitting it after you've gotten off the brake ...

so i'm new to this and would like peoples input, what's everybody doing, what's been working and what hasn't been and ofcourse...why

thanks in advance fellas

 

I have mine setup to interupt the nitrous while on the transbrake. Spraying while on the brake would cause some huge cylinder pressure and torque. That would be rough on all the motor/transmision parts. I would not run the nitrous while sitting on the brake.

As it's wired now, the nitrous comes on the instant I let off the trans brake button and flashes the converter. I haven't used it at the track because I have trouble hooking on the foot brake launches.

Mine is set up with a relay from the power wire of the trans brake to the N20 relay. I've just ordered a FJO nitrous controller and it has a built in trigger that I will use when it is installed.

 

Racing is always hard on parts, the increase in cylinder pressure/power is what i'm getting at. Damn near the point of doing it that way no?

 

no way in hell I would spray it while on the Tbrake. Wiring it inline with the Tbrake will have you leaving on the spray...no need to have it squirting while you're waiting on the jerky next to you. On the tranny brake is one the tranny brake. You'll be at the RPM you want...why be on the juice too if you're not moving?

 

i donno...figured having it under a constant load would make the car leave harder and make chassis tuning easier because u know it'll hit the tires as soon as it moves forward not a fraction of a second out...like i said, new with this

so far sounds like it's not the way to do it tho

 

You could always wire it through an rpm switch. On the transbrake at 4000 rpm and the window switch is set for 4500. As soon as the transbrake releases, the rpms climb. At 4500 the NOS kicks in and if for any reason at WOT, the rpms drop below 4500, the NOS turns off.

Others have wired it through a timer. As soon as the transbrake releases, the timer starts. At the preset time, the NOS kicks in. Set it for something like .3 seconds which will allow the car to start moving before the NOS hits.

 

I know how to wire it to come in later, i want to know for what other reason than longevity should i not be spraying before i even move.

If i will see virtually no difference in ET/60ft what ever then i'll rig it up so while on the t brake it wont spray and as soon as i let go it does. Simple enough

just trying to get some info on what works and what doesnt

 

I don't believe there would be any noticeable change in performance between spraying while on the brake and spraying the instant you let off. The difference in time between spray and no spray is the time it takes the relay to activate and the solenoids to open. We're talking hundreths or thousanths of a second.

As soon as you let go of the button and power goes through the relays and the solenoids your spraying and flashing the converter.

 

Depends on your setup. In the Camaro, when I had the automatic, car I would launch at 4,000rpm (converter stall) and had the nitrous set up with a WOT switch and a 2-step MSD box. I had a 4,100 and a 6,500 chip in the MSD. At the line, even though I was at WOT the Nitrous would be off because of the rpm. So, as soon as the the car left, the nitrous would hit and never turn off because the engine speed was always above stall after leaving (and, or course, with the extra torque of the nitrous). At the big end, my rev limiter was set at 6,600rpm because I wanted the nitrous off before redline (hence the 6,500rpm upper limit chip). It sent through the traps with the nitrous on at 6,400.

My race car is setup the same but works differently because I use a throttle controller. My foot is on the floor, but the throttle is not wide open. Typically, I set the controller to launch at ~3,000rpm. Immediately after releasing the transbrake, the throttle opens and the nitrous turns on when the low chip rpm is reached. I choose a chip according to track conditions. Usually about 4,900rpm (just a litlle below stall). That gives it a chance to start rolling before the nitrous comes on. I do NOT purge because I want it to hit a little soft.

Rich

 

thanks fellas, very informative

 

this is how I would do it....it will engage the nitrous as soon as you release the trans brake.

 

yup thanks, seen the schematic but using a mallory 685 box. So exact same way but violet wire (window switch) goes to the one end of the fpss and the yellow wire (timing retard) ties into the hot noid wire. I'm too lazy to draw it out

 

I run a WOT switch only. Instead of leaving off the foot brake. I go about 80% throttle while on the T-brake. I release T-brake to cut the light and go wide open instanly OR, if the track sucks....I stay 80% until 10-20 ft out, then go wide open. I really need my foot in it to activate the switch.

The last 5 times out I've sprayed 200hp right against the T-brake and WOW does it wake up. My lazy, coughing, 3000 stall turns into a 4200rpm beast. Release the t-brake and it jonh force blows the tires away. Still haven't hooked it yet, maybe this year!!

1.48 60' footbrake
2.9 second 60' fighting the converter.

 

Consider that you are using a 2-step that cuts ignition sparks to maintain the set RPM. If you were already spraying while on the 2-step & brake, I would be concerned that you could get into problems with spikes in the cylinder pressure when a cylinder isn't fired. No telling what the air, fuel, nitrous ration is for the next cylinder firing.

Later ... Larry S.