Btmhwb

just as the title says, I have a c5Z, Texas speed torquer V2 cam, long tubes. i recently put a 100 shot on the car also, pulling fuel from the rail. Nitrous outlet plate kit, using 52 nitrous and 23 fuel like the chart says. i always thought they were supposed to be jetted rich, or at least close. I just installed an Innovate wideband and took the car out to see what it would read on spray. i thought for sure it would at least be in the 11s, but it seems to be in the 14s!!! I shut it down until i can figure it out. i calibrated the wideband just like it said to and it reads about 14.8 at idle so i think the gauge is accurate. Thank god i had some octanium booster and 93 in the tank. i am now wondering if i should believe the gauge or not. could it be that i am running out of fuel? I thought C5Z fuel pumps were good to about 550 rwhp, and my car should only be making like 520 on the 100 hp pills. i know the fuel pressure isnt dropping below 35 psig or the fpss would have shut it off. should i just get a few bigger jets to bring AF into the mid 11 range? Also curious if anyone else has or had a similar setup and if they ran out of fuel. I planned on putting a boost a pump on it before going to the 150 anyways.

silver408z

If you are still on the stock pump, it might be a little weak from time. Not that is bad just that it might not be good for 550 anymore. Also these cars are older and the power supply to the pump might be lower than when it was new. The only way to truly know the answers to some of your questions is to verify it against known working parts. Verify your gauge is calibrated correctly against a gauge that is proven. With the mods are you are talking about I would be looking into power to the pump and upgrade the pump.

Btmhwb

thanks for the reply silver 408. I will definitely need to check out at least a BAP. Its crazy because i have seen some on here claim to be stock pump and run over 550 with no issue, and others say 475 and they ran out of pump. maybe that is how variable they are? or low mileage vs high mileage? mine has 62K

mykream

Do you have a racetronix pump rewire on the car? Change the filter and see if that helps, but essentially if the filter was bad then fuel pressure would be a little lower most likely. I would do a fuel pressure check while running to make sure. At least that would tell you if the pump is not up to pace. I would bank more on the pump not getting enough juice.

What is WOT AFR off the bottle? And how is the timing being pulled? Just always have the 4ish degrees out? Or are you using an LNC box?

mykream

Also, I am assuming you are running stock injectors? Would like to know the complete setup of the car if you could.. Stock manifold/tb?

Btmhwb

Yes stock injectors. Setup is just blackwing intake, stock TB, stock intake manifold, torquer v2 cam and supporting upgrades, xs power long tubes, catless x pipe, and 100 wet plate kit. Im actually not pulling any timing, I was reading that you dont on a 100 so I just add octane booster on top of 93 for some insurance.

I just hooked up a cheap fuel pressure tester and started the car, showed 58 psi at idle. I really can't do anymore because I dont have hp tuners or anything. I may look into that hardwire mod as I have not done anything there yet.

StatmanRN

I think you are asking for trouble on several fronts TBH. Yes others have got away with it but you wont be happy if you don't...
First, Id be concerned about fuel distribution on a wet kit which could exacerbate a lean condition.
The fuel pressure issue could be a real problem. A boost a pump will help [run one myself] but the wiring should be upgraded as well. Also, pumps are realtivly cheap to upgrade
Also, I would think pulling at least a couple degrees of timing would provide a little more safety margin.
Nitrous can be unforgiving- know a lot of guys who got to greedy or pushed their luck too far.
It will cost you far less to upgrade than repair.
My $.02...

mykream

I agree on all points here. The fuel pump and wiring upgrade are definitely a must I believe.
Regarding the timing, when it comes to nitrous, it is much easier to add the timing back in than take more out. All it takes is about 2 seconds and you just huffed a cylinder (or more).
While I agree that a 100 shot isn't that large, it would be the start of timing pull for me. Hell, I would pull 2 on a 75 to be safe knowing I can always add it back if everything looks safe and the plugs look good still.

You are playing Russian roulette with a 6 shooter and 4 of the chambers are full.

BLOWNBLUEZ06@RKT Performance

More and more, I'm seeing a lot of C5's losing voltage at the pump due to fuse/relay connections burning up from the current load. I highly recommend bypassing the existing path, tapping the alternator for your power source and only using the stock wiring to trigger a relay. Also, I recommend making and running a 10ga ground strap from the pump hat to the frame. I don't understand why GM thought to ground the pump to the hat but then not the hat to the frame. I had a car that showed 30% lean at WOT after max'ing out his injectors and after doing this operation, it was 25% rich.

BTW, Racetronix makes a nice kit if you prefer not to make one yourself.

Bret

mykream

I agree with Bret, the racetronix kit is simple and takes little time to install.

Btmhwb

Guys, thank you so much. I will go ahead and get the racetronix hotwire kit and upgrade everything so I dont blow this thing up. I saw a used lnc2000 on here the other day also, sounds like I'll be finding one of those too. Shoukd I go ahead and get a new pump also? If so does racetronix have one?

thanks again for the good advice!!

mykream

Racetronix sells a complete new 255 intake pump assembly..Basically the factory one.. Or, if you can have the car down for a bit, you can send Bret your pump assembly and he can fit a larger pump to it. I'll be sending him my assembly over the winter to fit a 450 to it.

dankhts

I use the LNC2000 on mine, set up to pull 4* on a 100 shot, I played with my jets a bit to get the AFR in range - mine was rich..... the chart they give you is a basic guide, closer on stock engines than on modded engines... lots of good advice above though! Get your fuel system in shape to ease your mind then easy to play with your jetting...

Btmhwb

Dankhts, did you upgrade your fuel as well?

Btmhwb

hey guys i rented a fuel pressure gauge from auto zone and taped it to my windshield. I took the car out and it seemed to lose like 8 psig or so (maybe more, hard to tell) in the higher rpm range. would this be enough to cause the car to go lean like I am seeing on the wideband? I am thinking so, just wanting to make sure that is not normal to lose fuel pressure up top. It is supposed to be about 57-58 psig through the whole rpm range correct?

mykream

Correct.. That would cause you to go lean.

As we all suggested, definitely upgrade the wiring first. Check the pressure again and see if it is still dropping. If so (which I doubt it will) then replace the pump as well.

Btmhwb

Thanks a bunch for the help! I'm going to order the wiring upgrade today and try that first!

mykream

Any updates???

Btmhwb

unfortunately the racetronix wiring upgrade didn't do as much as i would have hoped. It did seem to help a very small amount. The car without nitrous ran below 13 AFR (seemed to run about 12.9 or so) but i did spray it again (I know im crazy) and it went lean so i got out of it. I even changed the fuel jet to a 28 (proper jet for a 150 shot) and the afr was still in the 12s on spray. I am going to add a boost a pump to see if that fixes it. i would have thought with a 100 shot nitrous jet and a 150 shot fuel jet it would have gone straight to 10 AFR but no........time for a BAP. at least it will go in easy with the racetronix harness. i would check the fuel filter but I have a 2004 so you have to drop the tank to get to it and they claim it should never have to be changed.