Hey Ive been thinking of nitrous for a while for my 97 (see sig). Im thinkin about spraying as high as a 150hp shot in the form of a dry system. What size injectors do you think would be required ???

 

I've been wondering the same thing for my application, but it shouldnt be too hard to figure out: Your Z sports an 83 MPH 1/8th mile time. It's probably 300 HP at the crank. You probably have what, 22 lb, maybe 24 lb. injectors? If you add another 150 HP with nitrous, your fueling demand should be approx. 450 HP. Eight 30 lb. injectors are capable of delivering 500 crank HP worth of fuel at 45 PSI. So, your injector size should be 30 lb or less. Maybe even 27 to 28 lb. Try scoring some used LS1 injectors.

 

Depends how your dry system works. The NOS 5176 for the LT1 increases the fuel pressure to as much as 85-90psi when you spray. That's enough to allow you to spray a 125-150 shot on a fairly stock engine, using stock size 24# injectors (although the stock RP injectors will not be happy with 85psi - you'll need to use a pintle style injector).

 

I did not know about the fuel pressure bump in the NOS system. I was thinking about the racetronix delphi/lucas 32lbs even before I get the NOS. Is lt4 heads and hotcam considered mostly stock ??? Just makin sure you saw my sig.

 

If your gonna run the LT1 NOS dry kit, you MUST get rid of your factory injectors cause you will risk locking them up when your spraying since the pressure gets doubled when you spray with that kit. The Ford SVO injectors are a nice affordable setup and you can find lots of them on ebay for pretty cheap. I was running fine with a set of 30lb SVO's with my 5176 dry kit at 150 and my heads and cam, but I was pushing them hp wise. I'm running 36'ers now but will probably be bumping them up to 42's soon. If I were you, i'd get a set of 36lb'ers, get your computer retuned for them also. This will leave you some room to grow also.

Ken R.

 

thats what I was thinkin ,I contacted racetronix and they recommended 32lbs over 36lbs tho , my goal for fwhp w/o nos is 400-425 hp which I may have already hit , im gonna get my car in tip top shape with my currend mods and then get the injectors and NOS

 

Im another fan of 30# SVO's I had them on my car for years with the 5177 kit with no problems. I also highly suggest a 255 intank pump. I have one I am about to put on ebay that works great. LMK if interested. I am going to post it sunday I think.

 

Sounds like you have an LS1 (NOS 5177 kit). Can't compare the LT1 and LS1 kits, since the LS1 kit does not raise the fuel pressure. The LT1 (NOS 5176) kit requires higher pressure, and comes with an inline booster pump.

As far as BigJustin's question, I wasn't suggesting your engine was "stockish", only telling you how the NOS dry kit worked, and trying to find out if that was the kit you have (or are getting). I agree, you will need larger injetors with your setup. Size them correctly for the NA flywheel HP, then play with the "fuel jet" on the NOS kit (which is really a "FPR vacuum compensation line" jet) to get the correct fuel pressure for the size of the shot you jet the nitrous for. You will need tuning to get it right.

On the other hand, if you are using a setup like I have... dry nitrous with the fuel controlled by a secondary program in a a MoTeC ECU... you would have had to size the injectors for NA + N2O. I run about 500 flywheelHP NA, and a 300-shot, and the injectors are 64# running at 58psi (= 78#/HR).

 

Yes, and get a 255 in tank pump too. Racetronix makes a nice LT1 setup and it's plug and play. I was using the factory with the NOS booster pump. But when I first hit the spray, I would have a lean spike, then the pump would catch up and i'd get a good A/F. Didn't like that so I put in the 255 and problem solved. I then had a flat A/F curve (wouldn't actually be a curve then I guess) even when I hit the spray. The factory pump will have a hard time keeping up in a lot of cases, even if you have the booster pump on too.

Ken R.

 

cool , i contacted racetronix as well they recommended 32lbs. Im not gonna go much further N/A on this car , maybe lil harder cam , hoping for 400-425 flywheel hp before I start setting up the N2O. Ill get my car dynoed first and see what I have now. If im at 400 Ill go ahead and go for N2O

 

One note: When installing the in-tank pump, make darned sure you have a good ground path. My factory ground path went through two spot-welds and up to a spade connector outside the sending unit assembly. Resistance of the wire from pump connector to exterior spade connector was 3.2 ohms. I had to silver-solder the pickup in three different places to get the resistance down to 0.1 ohms. If you dont have a good ground, your new pump cannot pump fuel due to the high voltage drop across the ground wire.