back in the nitrous game... few questions

[MISFITmalibu63]

its been about 5 years since i ran nitrous... but i just got my bottle re-certified and filled.

i converted over to a stand alone fuel system just to feed the fuel solenoid. im going to run 110 through it, since i can get it right at the gas station. i have my plate set for a 125 shot right now, but plan to step to the 150 jets down the road. what should i set the fuel pressure at with the solenoid open?

i remember that for timing, the rule of thumb is take out 2* for every 50 shot.

as for the spark plugs, do i need to run colder plugs? the guy at the local speed shop said with my combo, i shouldn't need to worry about it because its such a small shot. use fresh plugs?? im currently running autolite 3924's.

any info would help. im trying to pick some brains and do some reading before i spray it. hoping to head out in 1 week!

 

[Ed Cannon]

No plug change needed for 125. Best tips I can give is to check your flowing fuel pressure often. Maintain 900 to 1000 psi bottle pressure. Install a fuel pressure safety switch.

 

[MISFITmalibu63]

should i change the plugs for a 150 shot?

 

[454RAT]

keep the plugs, just watch the gap. I would tighten them up to .30

for fuel pressure it depends on what brand of nitrous you are running.

 

[Night Stalker]

Every brand is different is fuel flow psi due the spread of the jets..Heck i just seen a ZEX plate system and the fuel setting was 6 psi for a 100-300 hp shot,, its was all controlled by the jet spreading from the fuel and NOS and timing..

Plug wise,,when dynoing they only dropped 1 plug heat range.... :shock:

 

[monte ss496]

i see a ten second pass in your future mikey!

 

[RdCamaro79]

Yeah I agree with everyone else dont worry about going to a colder plug(unnecessary) on a small shot unless you run high compression 12:1 or higher which would probably mean race gas. But like everone else has said It depends what nitrous system you have they all reccomend running different fuel pressure on the nitrous side.
I also reccomend setting It with a flow thru gauge so you know your pressure under power but If you have no access to a flow gauge just set it a touch high (1 psi over reccomended) to be safe. ALWAYS REMEMBER LEAN IS MEAN! :twisted:

 

[bfurches]

Here is how I have always set fuel pressure on my nitrous installs...

-First thing I do is take solenoid off the plate and have the outlet line going into a small container.
-Next with the solenoid closed, I turn the pump on and set the regulator to 6.5psi
-After the baseline is set, I energize the coil of the solenoid to open it up and watch to see how much of a pressure drop I experience from my baseline of 6.5 (which realistically should be next to nothing but always check adjust accordingly until I am BACK at 6.5)

Start off with a very conservative jetting (i.e. NOS recommended). I have found that the NOS guidelines are usually 15% richer then they need to be....probably to keep the motors more then safe and avoid having less then genius customers grenade there motors...

It is VERY important...and I cant stress this enough....that you shut the vehicle down under LOAD to read the plugs...after EVERY pass until your tune-up is on. DO NOT idle back to the pits to read the plugs. Especially after a nitrous pass, the plugs can get some heat in them quick and give you a false reading.

Starting off by pulling two degrees for every 50 is more then adequate on such a small shot. I am sure you will find yourself putting a few degrees back in (especially if you are running a dedicated 110 cell)...but start safe and keep it conservative.