need some fogger tuning advice...

ok...i need some help from the big guns. i just switched to a fogger setup on my lt1-powered s-10 but i can't seem to get it to run. i'm using a seperate low pressure fuel system just for the nitrous. my current tune is 32 nitrous/28 fuel jet sizes, 7.5 pounds of fuel pressure, and timing 12 degrees retarded. i've used this tune on 3 other small block chevys and it worked perfect but my lt-1 doesn't seem to like it at all. i've tried making a few adjustments but all i get are backfires. so i defer to the experts... is anyone willing to tell me their tunes or point me in the right direction on a good tune. if you don't want to post here you can e-mail me at StevenPud@aol.com. thanx in advance to everyone for their help.

I can help you out, but I need to know what nozzles you are using, and how much hp are you trying to get? I ask that becuase if you are using NX nozzles, you have a little over 300hp tuneup, and it should be a little fat. If its an NOS tuneup, your off. Give me some more info, and I can try to help you out. If you would like to email me, its Scott@ZimmermanMotorsports.com, or hit me up on AIM at Zimsport.

its a NOS setup...regular fogger nozzles...i bought it used so they are the older style nozzles. this tune has given between a 300 and 350 shot on the other cars i've used it on.

Are the nozzles black? I am assuming they arent a soft plume nozzle. a 32 nitrous jet could possibly net you about 325hp, but very unlikely. This is from my own experiences. a 31N 26F NX tune gives about 304 to the rear wheels. If you are using the old black nozzles, you are at about the max they will flow. When you say backfire, is it backfiring through the intake, or the exhaust. Typically, a backfire through the exhaust means you are way fat. The only way to be sure is to read the plugs. They will tell all. Email me if you would like to get into some specifics, and I will help you any way I can.

they are the black nozzles...not soft plume. it is backfiring through the intake the instant i hit the switch. i did get one crappy pass on the nitrous when i hit it from a roll...it hesitated then ran bad. the plugs read perfect though...looked like i never even used the nitrous. i'll e-mail you with some more details.

What size fuel jet are you flowing with? Maybe try sqaring it up and going to a simple conventional style tune up. High presure setups can yeild nice power gains but sometimes can be a little picky. The old style black NOS foggers will flow allot. Annular nozzles are fine. What fuel are you running for fuel and how much total timing (after retard)? Did you phase the rotor for nitrious?

Vince

i'm running vp 121 octane fuel. i'm running a low pressure system...fuel was flowed at 7.5 psi with a #71 holley jet. the timing is around 24 degrees after retard. how do i phase the rotor on an opti-spark :confused: ??

I don't think you can phase an opti for spray. Sorry I am used to my distributor setup. I am going to make a suggestion. Just a tune up to try:

NGK #9 plug fresh istall just before pass- .35thou
975lbs bottle
32/ 32 pills
7.25lbs on a 73 jet
with C16
26 degrees of timing locked down inside the ecm...no retard box(only if this is possible) If not then set timing as close as you can to your NOS target timing so the rotor sweep isn't to far.

If you choose to try this tuneup I just want to say you might find it a little soft but it does work. This is not a race tune up..my guess is about a 275hp shot. By high presure I meant over 6psi of fuel presure.

Good luck

Vince

i'm used to high pressure being 45psi...like when i used to run off the fuel injection :D . i'll definitely try squaring the jets first and maybe take out a couple degrees more timing. thanx for everyone's help.

Originally posted by StevenPud
i'm running vp 121 octane fuel. i'm running a low pressure system...fuel was flowed at 7.5 psi with a #71 holley jet. the timing is around 24 degrees after retard. how do i phase the rotor on an opti-spark :confused: ??

Hey Dude,

You need to step back for one second and look at this whole tuneup your running. For startes if I new more about the motor I would be more comfortable telling you this is the direction to go. But for starters get a different fuel like something along the lines of Torqo NOS 116 then try a 32/32 jet pattern, your flow jet will be a .091 start at 6.00 psi and then start pulling fuel out to no less then 5.00psi Your timming should be Ok. This is a 300hp tuneup.

Remember if your using a solenoids smaller then a Pro Race or Pro shot solenoid this jet pattern will not work worth ****.

I think you're retarding a lot of timing for the octane you are running. I think that the LT1s generally can/should take more advance than regular SBCs.

You could try lowering the retard on the spray and see if that helps. Not enough advance could surely cause bogging.

From my experience, I am thinkin you have a classic way to much fuel press and not enuff timing FOR THE OCTANE FUEL you are running. 121 ?? where did ya get that?? are you running this in the tank also?? Fuel that burns this slow also burns really clean. It snot gonna look the same on the plugs as a 100-108 oct fuel.

I think every one is definitly on the right track, I would square your jetting and get back to the baseline NOS settings.

The TORCO 116 no2 fuel would be good insurance (expensive) or if your running it in the tank also I'd be ok with dropping it down to 114 as long as the fuel press is on the safe side 7psi+

Definitly make sure you have enuff fire power for the NO@ level your shootin at.. That will cause a big No2 burp blowin the spark out.

ANy how good luck and remember to creep up on the tune dont run it over with the crank LOL;)

call N.O.S!!!!!!!!!!!!!!!1

not that the tips here aren't good but i am just saying that because after blowing my motor once casue i tuned it like i was instructed by the builder that was it!

g'luck.

No one on this board has heard of VP Fuels?? 121 is their 'nitrous blend' fuel. I'm surprised that anyone would recommend using a lower octane fuel while on nitrous :confused: .
Anyway, the problem has been solved and it had nothing to do with jet sizes or timing. It turned out to be air in the fuel lines. on a large nitrous system, especially a fogger, the fuel has to be purged just like the nitrous to get all the air out of the lines. when i hit the spray, i wasn't immediately getting fuel and that was causing the backfire right off the line.
once that problem was solved all i had to do was close up the plug gaps a little and it runs mint. now hopefully i can catch one more good week at the track before it gets too cold!!

Originally posted by StevenPud
No one on this board has heard of VP Fuels?? 121 is their 'nitrous blend' fuel. It turned out to be air in the fuel lines. on a large nitrous system, especially a fogger, the fuel has to be purged just like the nitrous to get all the air out of the lines. when i hit the spray, i wasn't immediately getting fuel and that was causing the backfire right off the line.


I run VP 123 octane. I have never heard of C21 but I learn something new all the time. Where do you flow your fuel system? If your doing it right you will not have air in the system.

Vince

ok, maybe its 123...around here its advertised as 121...probably the same thing. i don't flow the nitrous every time i use it. if the truck sits for a few days, air builds up in the lines. after making about 20 phone calls over the weekend i was told this is a relatively common problem...i don't know what else to say...all i know is i followed the proceedure i was given for purging the fuel and then the nitrous and everything works fine now. go figure...

glad to hear it! i run C16 ....all i can say is VP fuels rock! made for nitrous, helps to prevent detonation. i flow my fuel prior to each run! unless i don't have time to, but that hasn't happened yet!

thanx again everyone for the help. taner... i just gotta say your car is sick! i read about your car on here all the time and have shown your videos to all my friends. i'm hoping to run those kinds of #'s with my truck...unfortunately, its a little late in the season and i may have to wait til next year....

thanks alot for the comments :) i can't wait till the spring!!!! woohoo!!!! it will be 10's on motor for fun!

So you decided to keep the s-10...cool. can't wait to see some slips.