I went to the track last night to get in some nitrous runs. The track was really cold (yeah even in Phoenix) and my runs weren't what I wanted, but the thing I was wondering about was about nitrous. I was running a .52 jet (like a 110 shot I guess?) and I noticed my air/fuel guage drop from rich to lean and then stay lean for a while. Because it was saying it was lean, I had to turn off the nitrous. Has anyone autotapped with a 100 dry shot? Some help as to how lean it was could really help me out. It was just as though the injectors could not keep up with the nitrous flow. Would a MAFT help with this, or is it a case of injectors just not having the capacity to flow enough fuel? Does anyone know how much these injectors flow? Any ideas are helpful.
P.S. I don't know if this helps answer any questions, but outside temp at the track was 44 degrees F. Also when I went back to a .42 jet it ran fine (rich the whole way). It's a 1999 5.3L stock internals - cam and what not) just intake and exhaust was all I was running that night.

 

Have you tried injectors from the 6.0? That should dump enough fuel for you to richen it up.

 

Check your fuel pressure and bump it about 4-5 PSI for stable nitrous use. I have run up to a single .061 orafice jet with good o2 readings (autotap.)

Richard

 

You know, I don't know what to think about the dry shot now. Bad things happen to my old engine with 100 shot. I won't be putting on the new one. Mine was a 4.8. Some guys have run as much as 135 shot on stock fuel systems just fine. I guess it is truck specific for variances. I have heard that a MAFT will help that problem.

Oxidizr, How do adjust the fuel pressure. Is that a dumb question ? <img src="images/icons/confused.gif" border="0">

 

Hey thanks for the feedback. Maxmumboom, the injectors are stock, but i was thinking bigger ones may help. Joseph, yeah my setup is a dry shot shooting before the MAF. Thanks for the fuel filter tip. It sounds like that is something to check. Its been changed before but prob. wouldnt hurt to put a new one on after like the 10,000 miles or so. Oxidizer I'm with fast 4.8 on that one, how do you bump up fuel pressure? Are you running a dry .061? what hp is that? Oh yeah, I went to your website too. That direct-port is sweet!! Thanks for your help guys. <img src="gr_images/icons/wink.gif" border="0">

 

Unlike the LS1/LS6 motor we do not have a static pressure fuel system. We have a more traditional GM fuel-pressure bypass system. This means the pump is running all the time and the regulator allows fuel to pass above a preset pressure. This pressure is adjusted like any after market Adjustable Fuel Pressure Regulator. The driver's side fuel rail/inlet has a cylindrical devise on the return side of the rail with a #10 security torx bit. You simply have to turn this screw to achieve desired pressure (clockwise=higher pressure/counter-clockwise=lower pressure.) In order to adjust the pressure you will need a fuel pressure gauge to read pressure from the schrader valve and a #10 security torx bit. Be sure to remove vacuum from the regulator to read WOT pressure before adjusting.

I have found 3-5 PSI lower = 5 rwhp on stock tune-no mods. To maintain stable nitrous operation 5-6 PSI higher for 125 (RWHP+.) I have seen much variation from factory on the settings of these regulators. I believe their is some coorolation between the color (lt.blue, yellow, pink) strip painted on the regulator and the factory preset pressure.

Richard

 

.061 = 130 RWHP

on my current set-up.

Richard

 

with a wet system i wont have to worry about any of that right? which is better anyway, wet or dry?

 

I would look at fuel pressure, and replace your fuel filter if not done already. Also you were spraying in front of the MAF sensor right?

 

I have a wet system (my direct-port) awaiting final insallation. I have a dedicated fuel system and the digital progressive controller to manage this system. With the wet system you stand less of a chance of taxing the fuel delivery system and do not tax the injector duty cycle. However, the truck manifold is a long runner design and really has no business flowing high volumes of fuel. I'm not saying it shouldn't or can't be done but slight mistuning can lead to a bad back fire...especially with the ignition related controls of Torque Management.

Richard