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Hey everyone. I have a 1992 Formula 350 with the NOS05151 kit. It is set for 150 hp. I am going to be having an engine built and the longevity of the stock one in now is not of great importance to me. I want to jet the system for some more power. I have been looking at some sites but cannot find a solid answer. The jet sizes now are 70 N2O and 53 fuel. Does anyone have the right size jets to step up to say 175 or 180 hp? The closest answer I have found is 73 N20 and 82 fuel. For some reason it does not sound right. Anyone have any ideas? Thanks for the help.
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After some extensive searching I seem to have found an answer. It would seem that a 175 hp jet for a wet efi system is .073. The fuel jet is where it gets confusing. I have found two sites that say .041 and a .042. In the 5151 kit the 150 hp jets are .070 nitrous and .053 fuel. I have read that NOS jets their fuel side a little rich. I have also read that jetting a little rich is way better than jetting lean. What I think I am going to do is go ahead and install the .073 nitrous jet and leave the .053 fuel jet in that came with the kit. I'll make a few runs and see how it goes. If all is well I will then pull a couple plugs and see what they look like. Anybody have any comments?
Maybe I can help.
I have been tuning my NOS kit for about a month.
Is your fuel system stock?
Is your motor stock?
I am running a 70 nitrous jet and a 32 fuel jet. I started out at a 53 fuel jet and now am at a 32.
The reason I am at such a low jet compaired to the stock one is due to my fuel system. I have a in tank 255 pump and -08 feed to my rails.
Second I have a dyno jet wide band controler in my car.
It all started when I started spraying. I would watch my a/f gauge peg 10 so fast plus it would back fire like crazy after letting off. So I jetted down and down till I got to a 38 fuel jet. I then went to the dyno. These numbers are on a mustang dyno.
Fuel pressure was 48psi
First Run (NA)
276HP 386TQ
Air Fuel was about 12.9
Second Run (Spray 70 Nitrous jet and 38 Fuel jet)
321HP 462TQ
Air fuel was about 9.5
Third Run (Spray 70 Nitrous jet and 34 Fuel jet)
361HP 516TQ
Air fuel was about 10.0
I gained 40 WHP and 50FTLBS with one fuel jet change. I then stepped down to a 32 fuel and now my a/f right on at 11.5.
So I guess the best thing to do is put it on a dyno and tune from there. Also reading plugs is highly recomended. Plugs can tell you if your rich and or detonating. One of my buddies was using a spark plug magnifier and found he was detonating really bad. He ended up taking 8 degrees of timing out of his motor. Now he is a little more extreem but its good to check no matter how much your spraying.
Wow sorry for the rant. I hope that all makes sense.
I definitely appreciate the help. My fuel system is completely stock. I have ran the car to a best of 12.41. It runs great so I am willing to push it just a little bit more. I figure going up to the .073 N20 and leaving the .053 fuel will be ok.
I have this very same kit on my car mine went 12.3@109 on the 150 pill you could actually drop the fuel jet down to a 42-45 and still be very safe.Mine was a 32 lol no joke but i also had many passes with a wide band to confirm my airfuel.Then when I put the hsr on my car it went 11.8@113. Also what plugs you running i had good luck with ar133 autolite plugs super cold I also didn't take out any timing and I sprayed my car thru the shifts, with nitrous coming on as soon as it went wot with a 2800 stall.
Most jetting runs rich. I dont have a plate but my nozzle is rated at .062/.035 for the 150 shot but i'm now gonna try a .028 fuel jet to get that air fuel down
Thats what i suggest as well. Wideband makes tuning sooo much better and safer than just plug reading. Couldnt run a car without it, no matter if its fuel injected or not
I've scorched so many TR6 plugs from my setup going lean, trust me you'de really have to try to kill one of these engines. I switched over from the old $32 tuning to the $6e and didn't know about the full throttle upper limit crap so my car would fall on its face in 3rd gear, it makes sense, the thing was trying to pull fuel out back down to 14.7 afr. Don't be scared to go a little leaner, just be sure and check your plugs or the temp of your headers after every run and go down gradually. BTW your small NOS solenoids won't flow much over a .073 jet but the plate has the cheater plate bars in it and will go all the way to a 250 shot. NOS themselves told me that the .070 jet and a .041 fuel jet should take the power level up to around 175 and yes you can do this on a stock fuel pump they just don't recommend it for liability reasons. Get a Walboro 255 lph pump, throw some colder plugs in it, pull a few degrees of timing and lean down a bit. You should be able to get some decent gains by just dropping the fuel jetting.
I had good success going up to 200WHP (73N/39F) with my stock bottom end L98. Ran 100+ race fuel, 30' total advance and NGK UR5 plugs. Running the TTA fuel pump at 48 PSI set pressure (runs 42 w/N2O) and hit the nitrous from 1300+. Best of 7.98 @ 94- 1/8 mi.
i'm using that same kit on a built carbureted 355....was using the 125 pills for the '06 and '07 season then stepped up to the 150 pills which NOS says is 73n/82f. I started out with that keeping an eye on my WB innovate meter of course and the whole pass my a/f was bouncing slightly between 9:8-10:2 RICH!! took the fuel side down to 78, still rich, down to 74 a little better but it wasn't until I went down to 63f before the a/f were around 11:6-11:7 @WOT and I made sure to leave that little bit of wiggle room in there for when it cools down considerable at the track in the fall, it doesn't lean out pass 12:1 or so. You just have dink around with the jetting carefully to reach the sweet spot because nitrous manufacturers usually jet their kits excessively rich for liability reasons against users doing dumb things.
I hear ya on the rich factory settings. I don't yet have a WB so I'm still a bit on the consirvative side. My fuel jet sizes are so much smaller cause I'm running high pressure with the EFI.
RICH!! took the fuel side down to 78, still rich, down to 74 a little better but it wasn't until I went down to 63f before the a/f were around 11:6-11:7 @WOT and I made sure to leave that little bit of wiggle room in there for when it cools down considerable at the track in the fall, it doesn't lean out pass 12:1 or so. You just have dink around with the jetting carefully to reach the sweet spot because nitrous manufacturers usually jet their kits excessively rich for liability reasons against users doing dumb things. 
