Heres my setup. 95 Z28 LT1 with the 5176 dry kit, 30lb svo's and the booster fuel pump. I started with the 67/59 jetting. I was on the dyno today and made a few N02 runs. My A/F was running at 17 and trended down through the run but only down to about 13.7. I changed the fuel jet from the 59 down to a 52 which should have richened it up a bit. Instead, it got even leaner starting at about 18 at the start of the run and trending down to about 14 at the end. I'm spraying at 1000psi, have about 4 deg of timing removed and my tune is set up for the 30lb svo's. Was lucky though because there was no detonation. Think if it was a hot day, I would have been doomed. It was about 50 deg today. My factory in tank pump has 85k miles on it and my thinking is that maybe the stocker isn't keeping up with fuel demand when the No2 kicks in and up's the fuel pressure. What do you guys think? I'm thinking about going with a 255 in tank unit. Runs fine NA and I can dial in the A/F where ever I want when it's off the bottle. Just don't think it's getting what it needs at the higher fuel pressure. I didn't get to look at the FP guage on my 2 runs. We were too busy watching the A/F and listening for detonation. But if I remember right on my last trip there, it never got over 80psi with the No2. By the way, my bottle was completly full when I made these 2 runs. Any help would be greatly appreciated. Thanks in advance.

Ken R. 95Z

 

Im not familiar with dry kits but on my lt1 wet kit I was running lean with the 175 pills,Fuel pressure would dip down to 35 psi and would backfire. Granatelli pump 255 lph fixed my problem,You say fuel pressure was at 80 psi is that whats required for the dry kit?

 

NEVER try and run a dry kit with a stock fuel pump...

Make sure to watch the FP gauge, this is the KEY indicator for a dry shot.

For my fuel system I had both the Walbro 340 (high pressure high flow) in tank and the Bosch (NOS) inline fuel pump.

I suggest you do the same.
Mike

 

n20ta2, I originally said my FP wouldn't get above 80 psi, but it should with the dry kits. When the nitrous kicks in, it doubles your fuel pressure and thats where the extra fuel comes from for the nitrous. mtxpert, where did you get your pump and how much? So you don't think a single 255 pump would be enough or should I keep the booster pump in along with it? My guess is that on a bone stock motor with the 150 dry kit, I would have been ok on the A/F and got enough fuel, but I have the 150 kit with another 100hp in bolt ons and I guess theres just not enough fuel with the stock in tank and the booster. Would that be a correct assumption? The 2 dyno runs I made yesterday yielded abotu 405hp/485tq up here at 5200ft altitude. The uncorrected numbers were somewhere around 485hp/570tq and that was all at the rears. Thanks for the input guys.

Ken R. 95Z

 

if you arent going over 150 the 255 should do it for you I talked to a dry kit guy with a similar combo as yours and he is running great with the 255lph

 

This is definiately no fun!
Have you checked your fuel pressure at the shrader valve, vacuum off?
If you have adequate fuel pressure/flow, and all the connections and fittings after the 'Tee' are free of leaks, you shouldn't have problems with this kit!

 

I dynoed last week with the NOS 5176 (67N/59F) and the car ran a bit lean climbing to 13.0:1. The car has LT4 hotcam kit, 30# injectors, inline NOS pump, and I ran straight 100-octane and 6 degrees retard to be safe. Peak horsepower was pretty good at around 110 rwhp, but torque was way low at only 100 rwtq. Next week I'm going to dyno again with the 42 fuel vacuum pressure tee and hopefully that'll dump some more fuel and get my torque up where it belongs. But I would guess if you're running that lean as you are, there are some fuel delivery issues.

 

Hungry, my fuel pressure is fine along with my A/F when checked at the fuel rail. Vac line off it is 42.5 and on its about 39. Of course the line has to be on with the dry kit or your screwed. I didn't get a chance to look at it last dyno day cause our eyes were glued to the A/F readings on the dyno screen, but last time I was out, it only got into the 70's as far as psi I mean. I put a smaller fuel jet in it and it actually went leaner. Weird, but i'm thinking that it's just not keeping up with demand. Figure i'm running around 480hp/570tq at the flywheel, so don't think a stocker in the tank with 80K miles and a NOS booster inline is gonna keep up. Gonna get one of the Racetronix 255 setups for the LT1 and probably keep the inline in there also. We'll see at the next dyno day.
Joe, I would think you should see more then 100 ft/tq from the 67/59 setup. Granted I have heads also, but I tacked on 200ft/tq with the 67/59 jetting and about 130hp. Did you have good bottle pressure also and was it full? Just curious. Anyway, thanks for the input.

Ken R. 95Z

 

Yeah, I was very surprised at the low torque numbers. The speed shop wouldn't let me get "hands on" while they dyno tuned the car, but they said bottle pressure was good and I gave them a full bottle. Unfortunately when I dynoed, the nitrous expert, especially with the NOS 5176, was not there that day so all I can guess is that they weren't doing something correctly. When I go back to re-dyno, the nitrous guy will definitely be there and I'm confident we'll get good numbers out of the car. I'm still running the stock in-tank pump, but hopefully I'll be okay running just a cam.

Make sure you post back once you get the new in-tank pump installed and the car re-dynoed. Good luck.

Joe

 

Sure. I'll post my results of the new pump. Just ordered the Racetronix 340 today. Should see it by friday. I also have a Moser 12 bolt to install too, so it may be a busy weekend. May not get back to the dyno for a few weeks to see fuel pump results. So you don't have the booster pump that came with the 5176 kit? Mine had a booster pump with it and I would imagine you shouldn't have any problem with the stocker and an inline since your not majorly modified N/A.

Ken R 95Z

 

I am running the inline pump that came with the kit, so hopefully I'll be fine with just that and the stock in-tank. But hopefully the 42 vacuum tee will dump just a little more fuel for me.

Joe