do this AFR look ok??

[skatermckimm]

wondering how others feel about the afr, ive been getting a ton of mixed feedback, so just trying to get some more opinions....safe, to rich??

its a stock 2003 gt motor with 150 shot wet kit on it. I'm happy with results, it got my bucket in the low 12s so I can't complain

 

[itSSlow98]

Even n/a it's a half point too lean. On the bottle your definetly getting a lean spike on the hit which could be the fuel solenoid hitting a tad after the nitrous solenoid. I'd say the a/f reading was wacky on spray because the hp follows the n/a curve perfectly and if it truly was that lean to rich the graph would be wavy. Must have had a bad reading on that pull.

 

[skatermckimm]

well he only did 1 nitrous pull, so you think the AFR reading on this sheet is not accurate?

 

[itSSlow98]

Yes, I believe that reading on the sheet is not accurate. Was it a tailpipe sniffer?

 

[skatermckimm]

no, it was an 02 plug he put into one of my 02 slots in the mid pipe

 

[itSSlow98]

My .02 is the curve would not be that flat if that a/f was doing what it shows on the graph.

 

[skatermckimm]

the afr tanked just like the torque curve did, I don't know enough much about this stuff just making observation,

 

[itSSlow98]

Torque and spray is all load dependent. If you sprayed at 2500rpm it would make even more tq

 

[skatermckimm]

oh ok, that makes sense. im going to have another shop check the tune to see how it looks on another dyno and check the afr

 

[itSSlow98]

Do yourself a favor and buy a wideband.

 

[Justin@VMP]

TQ always drops off at high rpm.

I'm not sure what you think the issue is. Nitrous a/f is a function of nitrous psi and jetting. In your case the bottle was at the bottom of the pressure range (barely warm enough) and probably dropped 75psi by the end of the pull (bottles cool as a function of discharging them). Nitrous is almost never prefect on the hit especially if using a lab grade wideband that shows everything and not a dampened tailpipe probe.

 

[VFORCEJOHN]

I have a 2004 4.6 running a very similar setup with a ZEX wet kit. making 241 motor and 341 NOS.

Mine dips rich, but not into the 10's.

Ideally I want to see 11.5 range it's about 10.9-11.5 range. I had to lean the fuel out, I run 900-1000 psi bottle pressure.

I also use the dyno o2 sensor and screw it into the exhaust.


perhaps all you need is a smaller NOS fuel pill? Less NOS fuel pressure?

OR make a NOS tune and suck some fuel out of the motor past 4500-6000 range.

I'm no major tuner like most of these guys, it's fixable no doubt. I have my own dynojet 248x just so I can mess with things when I want to.

John