dennisbernal91z

iTrader: (2)

I have a forged 386 with N20 ready rings and all in my street car. I am just getting into spraying. I tried a 100 shot on the highway and it seemed to work right. Now my question is, since I can buy any jet size I want, is it good to go with low or high fuel pressure and then get the right jets for that?

Like should I get smaller jets and up the pressure or bigger jets and lower pressure? I did data logging on 2 100 shots, very short with my LM-1. Everything seemed ok, but there are a few spikes that I need to deal with I think.

But in short can someone explain the fuel pressure theory? Thanks

PS- I would assume higher is better to have it atomize more efficiently with the N20, but you guys let me know.

Thanks again.,

dennisbernal91z

iTrader: (2)

bump, need to know soon. thanks.

xpndbl3

iTrader: (5)

thought you were carbed? You'd buy jets for a carb kit, then purchase a fuel pressure safety switch as well...it will turn off nitrous if pressure drops below 5psi. You're looking for WOT readings in the high 11s IIRC for a safe tune on spray, 11.6-11.8 or so.

dennisbernal91z

iTrader: (2)

Yes I am carbed. But I can buy jets for whatever I want. but the jet size changed when you change pressure.

You saying I should start low like 6 (I tried 6.5) and then tune pressure with the wideband?

I can see that. I will shoot for what you said. I was just lost on what order to tune things. I thought you had to buy jets first and then have a set amount of PSI and then.... I dunno... I am so new to this.

I have jets for a 100 and for a 200 shot. I will just toss in the 100 and do a pull and see how I am AFR wise. If I am rich, I will lower the pressure till I get to 11.7. Thanks xpndbl3.

Where would I be without your advice? haha.

a/fool

i have never done any wide band testing, only track time. so this might not be of any use to you.
i also have a carbed LM1, alot less built than yours, and have ran .082/.085 jets on cast pistions. with 30 degrees timing. i also have a seperate blue pump, 3/8 line and -6 with a regulator set at around 10 psi. i started out keeping the jets 10 numbers apart but that appeard to be to rich so i increaced the N20 jet to where it would burn the strap off the plug. then instead of going back, i increased the pressure until i arrived at around 10psi. the strap just starts to round off, now mostly all i do is play with timing, and pressure. depending on what the air is like.
i'm sure this seems gettho to some, but i work on A/Fuel dragsters also, and i play with jet sizes and pressures on that, i have a racepack computer also (not on the camaro) and that tells me everything i want to know. so my mind just kinda works that way now when i think of tuning with gas and N20.
it would be intresting if you reported back on what you found using a wide band while adjusting the pressure. i'm sure alot of people would be suprised.
i could go on for hours......

dennisbernal91z

iTrader: (2)

Understood. I will report back. I plan on maxing out at about a 250 shot since it is just a street car, but I will play with fuel pressure in the coming weeks. And I will post what the wide band graphs here labeled with what I did.

xpndbl3

iTrader: (5)

just remember to only change one thing at a time, don't swap jets and pressure at the same time, etc.

dennisbernal91z

iTrader: (2)

Of course. I will just keep doing pulls on the highway from 70 to 90 changing the fuel pressure 1 PSI and then upload the data to my PC. That way i have every pull on a different graph. I did 2 pulls before and was driving kinda nuts since I was nervous about using the N20 for the first time. Now I am comfortable with is and can really do some tunning.

I think I have a clear game plan as to what to do. Now I just need some free time and one last trip to the dyno to see what this is REALLY doing