Had my 05 V tuned for a 100 shot last week and am running a HSW Sudden Impact Single Nozzle wet kit. Had the .052 nitrous jet as recommended and had the .028 fuel in as recommended. Long story short to get the A/F right we wound having having to step up to a .033 fuel jet and the tune came out spot on. Now I have a Nano system that I am getting retuned for next week and Nano recommended stepping the fuel jet up to a .036. Seems like im having to jet the fuel side higher then normal. Any input?

Car has mods in sig, basically stock, stock pump and fuel system.

 

The reason you will need to jet the fuel up with NANO is because the nitrous is liquid. With a heater, it turns the nitrous into more of a vapor form. This is how it builds pressure in your bottle. So with two of the same pressures with NANO vs. a heater, the NANO will flow more through your same nitrous jet because it is in liquid form at the same pressure.

 

I don't have a NANO, but I had the same problem with the recommended jetting in my HSW plate kit. Using the .052/.028 jets that they recommend I was running extremely lean. I ended up using a .034 fuel jet and it was slightly rish, but on the safe side. I'm thinking that a .033 will be perfect like you used.

I sent HSW a technical inquiry about needing to run such a bigger fuel jet than recommended and they responded:

"It's normal to have to change jets to get the desired A/F ratio. When doing so
make sure the bottle pressure is consistent (950 PSI) and make sure the bottle
is toped off after each run. The A/F will go richer and rich after each run as
the volume of nitrous being lowered. You can purchase individual jets, here is a
link:"

 

Oh i totally understand the Nano jetting i wasnt questioning that at all. It was just the fact that without it i was already running a higher jet size then what HSW rec.

 

I was definitely suprised that I had to go so much richer on the fuel side. I had already been running the kit and was just checking plugs and they always looked good, but then I got it on the dyno and it was way lean. Made me nervous about my spraying it previously and I haven't hit it since I got it off the dyno.

 

Be carefull rich is not safe!!

 

Guys,

Its perfectly normal. This is why it says its recommended jetting. Each car might require different jets to optimize a/f which is why we recommend getting it on a dyno/or use wideband to verify. So don't be alarmed if you're having to switch jets around to dial in your a/f. Just keep in mind that you should always a)ensure that the sensor you're using is good and b)there aren't any exhaust leaks etc. as this would easily skew any results.


Nick

 

With the .034 fuel jet and the 100 shot the air fuel was around 12.2 until about 5200 rpm and then it goes to about 11.2. Everyone I've talked to says that low 11's is very safe, but that I could run with it in the low 12's. I'll probably try to get jetting so that whatever shot I run, the air fuel stays about where it is now.

On that 100 shot I picked up well over 100 hp down low, and the gain slowly drops to about 85 hp up top. Once I buy a bunch more jets I want to get it back on the dyno and figure out what jetting I need to gain a true 75, 100, 125, and 150 horsepower at the wheels.

 

Keep in mind that nitrous is not rpm dependent and you will generally see larger gains at lower RPM's versus upper.

Nick

 

It made more power at 12.2 than 11.2 because thats where the motor is happy. A happy motor is a safe motor.
Richer is not safer.

 

if I put a .034 jet in my car it would be dead rich on the .052 jet let alone .062 jet, we run a .062 and a .032 right now and the plug is rich, afr is low 12's. I guess every car is different, I still find it interesting though. That is a huge fuel jet for a .052 nitrous jet at stock fuel pressure.

 

My car was the exact same way. Made good power down low with the bigger fuel jet but when rpms increase I lost power.

 

Exactly.

Basically to make approx 100rwhp (itsslow98 made like 80rwhp on a 52n 33f) he's gonna need a 52n,36f and a nano? something doesnt seem right to me.

First - you need to address the issue with dropping bottle pressure (i guess the nano will help with that obviously) but that significant drop 950 to low 800's on a dyno pass on a "100" shot isn't going to help getting jetting correct

2nd - you said the nitrous hit lean and then richened up....seems odd with such a huge fuel jet IMO.

Got a scan of dyno sheet w/ AFR?

 

I figured as much. That just means that when I get the kit dialed in for the top end gains I want then I'll be making more down low too.

Should I try to get it into the low 12's across the board? I was originally going to try that, but I figure if I get it to run leaner at the top of the pull, via jetting, then I'll be leaner at the bottom too and I was told that you want it below 12.4. I don't want it to start out in the low 13's and then drop into the low 12's. The current setup seems safer to me, but maybe I'm wrong.

 

With the recommended .028 jet it went lean. with the .031 jet hit hit rich and leaned out too much. With the .033 it hit just at 12.75 and ended up top at about 12. I dont have a scanner to scan the dyno sheet.

 

what is your fuel pressure doing? and what was the bottle pressure at?

 

no fuel pressure gauge.....run started at 950 and ended at 830. hence why i ordered a nano system.

 

Was the bottle getting low? My pressure stays pretty consistent throughout a run, even after a few passes.

 

id say it had 2-3 dyno runs on it after being filled. then it started to drop significantly. No leaks in the system.

 

No way it should drop that much on a 3 second dyno run.
How are you heating it? Are you sure your not over filling the bottle? that will make pressure drop real fast.

put 9lbs in a 10lb bottle, heat with hot water.