I am looking to see what fuel jet I should run with a 70 nitrous jet. The jetting supplied by nos is too rich. Any suggestions?

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1991 Firebird
350 L98 (was a 305 TBI)
T-5 transmission
Edelbrock TES and cat back
Accel manifold
NOS
subframes
jegster torque arm
MSD Digital 6
AFPR
Lakewood lcas
Hurst linelock
SLP cam (206 212 .480 .486)
relocated battery
cold air
Hypertech chip
centerforce clutch
poly bushings and mounts
AFR 190s
Harland sharp 1.5 rockers
a/f gauge
autopower rollbar

14.0 at 100 NA before heads


Juice and AFRs??......TBD

New g-tech time without juice 13.46 at 108.8

 

Sorry, I don't know why it came out three times.

 

Configuring jet sizes is dependant on pressures. Assuming 900 psig nitrous and 50 psig fuel, a 37 fuel jet teamed with a 70 nitrous jet will yield ~12.7 to 1 air/fuel ratio.

But let's say that your fuel pump(s) cannot sustain 50 psig with a 37 fuel jet. Let's say it drops to 44 psig. In that case, the fuel jet would have to be increased to a 39.

As you can see, calculating fuel jets is an iterative process.

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Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
Former Paxton (6-psig): 12.57 @ 111 mph.
Former Paxton (6-psig) & former 50-hp nitrous: 12.04 @ 114 mph.
Current ATI D1SC (Initially 10-psig): Projecting high 11's.
Future ATI D1SC (15-psig): Gotta catch them pesky 26-psig boosted TTA's!!

http://willie.camaro-firebird.org/

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.

 

What fuel pressure are you running, measured with the vacuum hose off the regulator?

What is the pressure of the nitrous?

You may just need a bottle heater to get the nitrous pressure up!?


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Tracy /AKA IROCKZ4me
'86 IROC-Z Camaro
"Cogito ergo zoom"

• 355 cid
• AFR heads
• Arizona Speed & Marine hydraulic roller cam w/ AFR hydra-rev kit
• modified SLP runners
• TRW forged pistons/ceramic coated
• fully balanced
• Edelbrock headers/ceramic coated
• SLP cat-back
• Paxton supercharger
• Nitrous Express nitrous oxide

EFI Performance Club on Yahoo

 

My bottle is oriented in the correct position and in the spare tire well. I am running about 51 psi at WOT. I have two fuel pumps and my nitrous pressure gauge usually says 850-900 psi. If not, I heat the bottle until it is there.

 

Willie, how did you calculate that?

 

I'll second that, how do you calculate that?

I've been trying to figure that out for a few days now for my crossfire car (it uses 13-15psi fuel pressure, so no one seams to know the right jets)


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Mark
’83 Crossfire TA


[This message has been edited by 83 Crossfire TA (edited June 06, 2001).]

 

I have an Excel spreadsheet with a built-in formula that calculates fuel jet size given nitrous pressure, fuel pressure and nitrous jet size. If you want a copy, e-mail me.

Willie