Just got back from the Dyno and the Viper was to lean on N2O

[Devin 97 Blue GTS]

Just got back from the Dyno and the Viper was to lean on N2O. The fuel pressure stayed @ 54 and N2O pressure was @ 1000. Just ordered the MSD Boost a Pump to give the factory fuel pump more voltage to increase the volume. Any ideas on the lean problem

Numbers on the Dyno ( NX 150 )
537 HP @ 13.3 A/F 5000 RPM
1997 GTS

Mods on the car

VEC 1 ( set to zero on the high and plus 4 on the low)
Headers
No Cats
3” pipes all the way
355 gears

 

[2MANYTOYS]

Drive upstate and let Macedo fine tune it.

 

[Snakester]

Ouch! That's dangerous. What size NX jets are you using?

I used 46/24 and came out totally rich instantly ******* the A/F at 10 (lowest reading) and got 508RWHP/585RWTQ with my VEC1 settings (+10/low,-10/high).

I just ordered some extra jets to dyno tune it for a normal 10.5-11.5 range). Remember that you want it a bit rich (12 or below) because the ram-air will lean the mixture a bit at speed.

As long as you have normal fuel pressure and N2O pressure then you should dyno tune the nitrous setup with different jets.

-Dean.

 

[1TONY1]

Recommended bottle pressure for NOS systems is 900-950. Try 850 - 900 or smaller on the N02 pill. What kind of kit ? Bigger fuel jet may or may not help without the boost a pump.

 

[Devin 97 Blue GTS]

Thanks for the replies

The system is a NX 150 shot wet systems with a MSD window switch set at 3000 on 5800 off, a 41 pill on the Nos and 22 on the fuel. (According to jet card). (I just orded couple of jets) jet# 46,44,42,24,26,28)

 

[bwhitmore]

I would go with the larger fuel jets or smaller nitrous jets to start. Then maybe investigate the fuel pump if there is still a problem.

Actually 1000 psi for a nitrous bottle is nothing new, just a little more potent is all.

Out in California, probably not unlike Florida, we don't use bottle heaters, just good old natural sunshine seems to do the trick just fine... sometimes too good.

 

[WESTCOAST JASON]

I would strongly suggest that you speak with the tech department at NX. By changing the jets without consulting them you are breaking the most sacred rule in nitrous tuning. Let their experience help you. There are specific flow rates on the solenoid sizes along with line sizes that need to be accounted for in regards to jet changing. They aided us in setting up a 300 shot customer to a 450 shot and it is more than just jet sizing, thats for sure.

.02

 

[Russ M]

Before you go playing with the jetting you should find out the problem with your car.

We dynoed a Viper a few months ago with basicly your identical setup and the mixtures were always way too rich. Your car being lean probably means you have a problem with fuel delivery.

Check your:
Fuel filter-probably the best bet
Fuel Pump-doubtful but possible
Nitrous solinoid-doubtful if its NX
Nitrous fuel filter if you have one-Very possible
O2 sensors-highly unlikely that they have the abbility to lean out your car like this.

Also where are you getting your A/F readings from? Please tell me its not from the tail pipe, if it is then forget about your readings and go to a dyno shop with a real lambda meter.

 

[Russ M]

Almost forgot,

The numbers you are quoting are also virtualy identical to the car we dynoed and its A/F was 11.0:1, so make sure your readings are accurate.

 

[BigCarrot]

Before you go playing with the jetting you should find out the problem with your car.

We dynoed a Viper a few months ago with basicly your identical setup and the mixtures were always way too rich. Your car being lean probably means you have a problem with fuel delivery.

Check your:
Fuel filter-probably the best bet
Fuel Pump-doubtful but possible
Nitrous solinoid-doubtful if its NX
Nitrous fuel filter if you have one-Very possible
O2 sensors-highly unlikely that they have the abbility to lean out your car like this.

Also where are you getting your A/F readings from? Please tell me its not from the tail pipe, if it is then forget about your readings and go to a dyno shop with a real lambda meter.

Where in the world do you find one of those? Every shop I've been to uses the tailpipe method.

 

[Devin 97 Blue GTS]

The A/F reading are from the tail pipe.( I looked at the dyno sheet closely and it starts the A/F @ 14 then down to like 12.5 to 12.9 @ 5000 RPM )

 

[BigCarrot]

Mine is really wierd! It starts at 14 or so, spikes to 16 or 17 for about 100 rpms, and then drops all the way to 10. I think it may be partially due to the tailpipe 02 readings.

 

[Russ M]

Any self respecting tuner or dyno shop opperator will have an O2 lambda meeter like a Motec/Horriba/Autronics/AEM etc...

They will always charge you for installing it because it is time consuming and wears on the expensive O2 sensor, but well worth the cost.


Devin,

Ignore the A/F ratio you got from the tailpipe is about as accurate as smelling your spark plugs.

Find a dyno that has the A/F meter and go there. I think Titan motorsports is in Miami as well go there they have exactly what you need. Ask for Nero and tell him Russ sent you, and you can always go to DLM I am sure he has one as well.

 

[Devin 97 Blue GTS]

Russ,
Thanks for the info, I will be installing the Boost a Pump and new fuel filter before going to the place you recommended. thanks again.

 

[Qualitywires.com]

Will that boost a pump burn out the pump prematurely?

 

[1TONY1]

Devin...Do you have cats in the exhaust ? If so that will really skew the a/f results. Spend $50 or less and let a muffler shop or the dyno shop put you an 02 **** up front. I just did one tonight on a car I am s/cing and it took at least 10 minutes.

 

[Devin 97 Blue GTS]

No Cats and the dyno shop used the tail to get the results
The MSD Boost units adjust the voltage as needed. So I was told. (I even got wiring instruction for a viper)