What should my fuel pressure be?
Does the NSX have an adjustable regulator? (Where?)
Does the NSX have an adjustable regulator? (Where?)
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Fuel Pressure Max/Min
- Thread starter RacerX-21
- Start date
The factory specification on regulated pressure is 36-44 psi (1991). Without regulation (control vacuum hose disconnected), it is 46-53 psi. I could find no provision for adjusting the regulator. The pressure will increase if you crimp the return hose, but this is hardly regulated.
Regards,
Bill
Regards,
Bill
the pressure is not adjustable. There is an AEM adjustable pressure regulator that bolts right in for around 185 bucks. (Bolted at the end of the fuel rail on the right rear of the engine bay.
NSXEE please write to me at [email protected] I have direct port on my car and have a couple of quetions to ask you.
Originally posted by NSXEE:
What should my fuel pressure be?
Does the NSX have an adjustable regulator? (Where?)
how much shot are you using in your direct port?
150ish Im going to tune it on the Dyno (its safest)I want to ultimately make 450hp. With slicks and adjustable suspension, I’m hoping to get into the high 11’s.
My 150 fogger netted me on a basically stock '91 (Intake/exhaust) an 11.66 @ 120.5 MPH.
I don't know what you are going to tune. There is nothing to tune on a NOS system...
Don't let the shops fool you. Ask them what the hell they are going to tune....
Don't let the shops fool you. Ask them what the hell they are going to tune....
Can't argue there. They could (If they had the wide band O2 and a dyno) switch out FUEL pills to better match the standard nitrous pills acording to whatever the cars fuel pressure is, (Say that five times real fast : P) but I've NEVER heard of anyone going that far. Nitrous kits come with a chart, depending on your fuel pressure, which tells you what your fuel pill should be according to their calculations. those charts have always done well!
Finally made it to the dyno-
Recap: 1993 NSX
40,000 Miles
No mods (Stock tires, air filter, exhaust… nothing)
Dyno results from May (Based on memory)
243 RWHP (Corrected-279 at the crank)
190 Ft-lbs of Torque (218 at crank)
Crank numbers are based on a 15% adjustment over RWHP; this has been the consistent loss from my past experience.
Yesterdays run
93 degrees and raining (Not optimal conditions)
300 ft above sea level
Added NOS Fogger system with fabricated fuel and Nos rail.
Used late model intake manifold with EGR system removed (Less heat in the manifold, and no exhaust gases in the air/fuel mixture.) Late manifold did require mod’s to function.
Dyno results (4th gear – closest to 1:1)
Base line run (No NOS)
245.2 HP 282 at crank
191.5 TQ 219 at crank
(I made a pull using 3rd gear, not much variation)
I removed my fuel pressure gauge, to link pressure to the dyno, and I welded a fitting to the exhaust for the O2 sensor. (The stock O2 location was a pain for repeated runs.)
Fuel pressure is
40 at idle
50 at full throttle
48 at max drop
O2 readings were high by my standards
Averaged in the high 13’s
And peaked at 14
First Nitrous pull (#22 jets on the NOS and #16 on the fuel side)
Purged the system an started between 3000 & 3500 RPM (Felt safer)
Didn’t feel any different, and sure enough it made the same power?
Initially I started thinking the worst; I knew the NOS was working, because of the purge into the engine.
I thought that maybe the computer was adjusting to its new intruder.
I checked the fuel pressure- it was the same? After my initial panic I relaxed and thought… even if it did adjust, I may not see 100+ hp, but even in lame mode I should see 50+.
I had someone watch the throttle switch while I pushed the accelerator peddle.
Problem solved, the cable is progressive, and would pull the cam past the switch actuator.
Next run (That’s more like it)
332 Hp 382 at the crank 100 HP increase
315 TQ 362 at the crank 143 TQ increase
No drop in fuel pressure
And the O2 sensor was off the chart at 10.5 (Way too rich)
NOS is known for jetting safe.
I was really happy with the torque rate of increase. And at such a low RPM.
My original goal is 450HP/TQ at the crank
My next Nos jet size is 28’s, so I will order 24’s and 26’s.
My predictions for next pull
24’s will give me another 25+ RWHP 29+ at the crank
And 30+ TQ 35+ at the crank
26’s should get me near the 450 mark with an extremely close TQ/HP figure
I also estimate a very safe 12.5 O2 reading.
Next goal
Suspension and slicks
High 11-second ¼ mile. (Remember… no other mods, still gets 25+ MPG and reliable, quiet running)
I can post the HP and TQ; RPM curves if anybody needs this info
I hope this answers the individuals who don’t know that tuning Nitrous is required.
Recap: 1993 NSX
40,000 Miles
No mods (Stock tires, air filter, exhaust… nothing)
Dyno results from May (Based on memory)
243 RWHP (Corrected-279 at the crank)
190 Ft-lbs of Torque (218 at crank)
Crank numbers are based on a 15% adjustment over RWHP; this has been the consistent loss from my past experience.
Yesterdays run
93 degrees and raining (Not optimal conditions)
300 ft above sea level
Added NOS Fogger system with fabricated fuel and Nos rail.
Used late model intake manifold with EGR system removed (Less heat in the manifold, and no exhaust gases in the air/fuel mixture.) Late manifold did require mod’s to function.
Dyno results (4th gear – closest to 1:1)
Base line run (No NOS)
245.2 HP 282 at crank
191.5 TQ 219 at crank
(I made a pull using 3rd gear, not much variation)
I removed my fuel pressure gauge, to link pressure to the dyno, and I welded a fitting to the exhaust for the O2 sensor. (The stock O2 location was a pain for repeated runs.)
Fuel pressure is
40 at idle
50 at full throttle
48 at max drop
O2 readings were high by my standards
Averaged in the high 13’s
And peaked at 14
First Nitrous pull (#22 jets on the NOS and #16 on the fuel side)
Purged the system an started between 3000 & 3500 RPM (Felt safer)
Didn’t feel any different, and sure enough it made the same power?
Initially I started thinking the worst; I knew the NOS was working, because of the purge into the engine.
I thought that maybe the computer was adjusting to its new intruder.
I checked the fuel pressure- it was the same? After my initial panic I relaxed and thought… even if it did adjust, I may not see 100+ hp, but even in lame mode I should see 50+.
I had someone watch the throttle switch while I pushed the accelerator peddle.
Problem solved, the cable is progressive, and would pull the cam past the switch actuator.
Next run (That’s more like it)
332 Hp 382 at the crank 100 HP increase
315 TQ 362 at the crank 143 TQ increase
No drop in fuel pressure
And the O2 sensor was off the chart at 10.5 (Way too rich)
NOS is known for jetting safe.
I was really happy with the torque rate of increase. And at such a low RPM.
My original goal is 450HP/TQ at the crank
My next Nos jet size is 28’s, so I will order 24’s and 26’s.
My predictions for next pull
24’s will give me another 25+ RWHP 29+ at the crank
And 30+ TQ 35+ at the crank
26’s should get me near the 450 mark with an extremely close TQ/HP figure
I also estimate a very safe 12.5 O2 reading.
Next goal
Suspension and slicks
High 11-second ¼ mile. (Remember… no other mods, still gets 25+ MPG and reliable, quiet running)
I can post the HP and TQ; RPM curves if anybody needs this info
I hope this answers the individuals who don’t know that tuning Nitrous is required.
"Rob I had the same problem with the car running way too rich I tried all types of jetting the best jetting is a a 26 nos and 14 fuel believe it or not. I also took out my EGR and put a block off plate but this has thrown the check engine light on which i think is pulling timming or doing something. Im gonna put it back on. My car made 396rwhp"
Disconnecting my EGR did not put my engine light on... did you do anything else?
When I unplugged the fast idle solenoid on the rear side of the Intake manifold near the throttle body, I had the same affect your describing. I ultimately bypassed it, but kept it plugged in.
Thanks for the jet info, I'm still going to experiment from 24 to 28's with 14 & 16's.
Did you have an O2 sensor reading?
Oh I forgot to let everybody know... The TCS cant be on for Dyno runs or NOS runs.
Disconnecting my EGR did not put my engine light on... did you do anything else?
When I unplugged the fast idle solenoid on the rear side of the Intake manifold near the throttle body, I had the same affect your describing. I ultimately bypassed it, but kept it plugged in.
Thanks for the jet info, I'm still going to experiment from 24 to 28's with 14 & 16's.
Did you have an O2 sensor reading?
Oh I forgot to let everybody know... The TCS cant be on for Dyno runs or NOS runs.
