I been testing some jets and so far my car can handle 58/31 (125 shot) if I put bigger shots but the car start to go slower and very rich (the car have no fuel pressure for bigger fuel jets and start to retard the ignition timming because have too much nitrous)... do you guys think that we need a fuel pump for the 150+ shots? if any of you is putting 150+shot please tell the jets size, dyno charts and mod to get it rigth...

Thanks!

 

Hi - just to clarify, so the car actually goes RICH because it can't sustain the fuel pressure for bigger jets? Instead wouldn't it actually go LEAN instead, if the fuel pressure drops?

 

when the car have not enougth fuel pressure the ECU read the lean condition and start to retard the ignition to prevent detonation... but the ignition have its limits too, so the car can go extremely lean and break... To know the limit of fuel pressure that the motor can handle w/o blowing is a good info also!

 

My car has run fantastic using 73/40 jets with the factory fuel pump. A/F on this combo (dyno verified) was just slightly lean, nothing to be concerned with. 51 psi is plenty of pressure for these shots, so long as you are getting fuel AFTER the fuel damper; pressure off the pump is erratic and can affect performance so it is best to tap in using the SPX adapter (mine never leaked once) or drill into the fuel rail itself.

My success was with a G35 but someone else has dynoed the Z using this same combo with great results.

 

My stock pump made 12.9 -13 A/F at 11 psi when it hit 7000 rpm's. Then it maxxed out, can't provide any more, this is with larger injectors too.

If you add a fuel pump you have to add a regulator then a vaccum line up to the front to tell it when to dump not dump because of returnless fuel system

 

I have the SPX adapter!... mine is a NOS system, I believe yours is Zex, rigth! the jets and the selenoids are different... your combo in NOS is good for 240 crank hp (about 200 RWHP) but you don't have that RWHP with that combo... rigth? and again you have a G35... is suppoust to be the same so who knows maybe I'm the only one with this issue!

hey 12segZ the S/C kits bring this thing that you mention about a regulator then a vaccum line up to the front to tell it when to dump not dump because of returnless fuel system?

 

My combo is a ZEX and is listed by ZEX for 200 CRANK hp. Ask anyone who has experience with NOS and they should tell you that NOS overstates their shot sizes. Also, if there was an issue with inadequate fuel pressure, then the car would run lean. I do not have that issue, nor did a friend with a Z using the same combo. He had some additional mods and ran low 12s with that combo without incident, so it may in fact be your car (or the NOS system) and only you have the issue.

 

Ok I check everything again (also doble check the Jets combo, maybe they are not drill rigth)... but the first jets that I install (52/28 100 RWHP) put what the NOS company said 100 rwhp.
I have 2 friends w G35 that have Zex and their jets never put what zex said on the wheels... one of then change to NOS and the car is putting the right RWHP now!

 

Exactly!

FWIW I also ran a 52/28 but I do not think that is optmimum, the Jets were NX on a ZEX Kit. I think it varies with mods too (intake exhaust etc.) The stock fuel pump flows like a ****!

Lots of variables.