I have a 2003 350z with a Vortech SC, 2.87 Pulley making 12 lbs of boost, and 440cc Deatschworks injectors, stock in tank pump. The Vortech inline pump is a Pro-Flow 500 (40GPH@90PSI). The FMU is a 6/1.

I've always had to tune in more fuel in the upper boost and could never seam to get it richer than 11.7 AFR like I was running out of injector, and yes injector DC maxed out. This did not make any sense to me.

Always thought that was odd.

So, I installed a fuel pressure gauge, and under WOT fuel pressure climbs to about 82-84psi and then in the upper boost above 10psi and 6200rpm the pressure drops off (instantly) to about 70-72psi.

I then installed a 8/1 in the FMU. (just to see what would happen) Same thing happened but pressure climbed to 95, dropped to about 80psi in boost above 10psi.

What is going on here?
Is the vortech in line pump bad?
Is it possible the stock in tank pump is just not able to keep up?
Do I need to install a Walbro GSS-432 IN TANK PUMP?

Thank You,
Tim

 

In short, without a fuel return system the more boost you make the less fuel pressure you will have while making boost.

 

So what is the LONG version. Are you says nothing is wrong with my fuel system?
Per Vortech they say "The system should hold pressure, not drop off"
The Performance Factory has done many cars with 500whp and no fuel return.

 

The factory setup is unable to increase fuel pressure as demand increases - so, more boost = more demand != increase in pressure. It'll drop off as the IDC's increase due to the higher fuel requirement under boost.

In the very least, you should get a Walbro 255 in the tank.

 

obviously those injectors r too small, you even said so.

your IDC should only be around 80%. whoever told you that you could run a 2.87 off 440cc and a stock pump should be fired.

 

FWIW, I'm installing my vortech kit tomorrow with 600CC, walbro 255 for the 2.87 pulley. I"m also running a UTEC.

So, to answer your question in bold:

No, the stock pump cannot keep up, you need to upgrade to a 255. You should also STRONGLY consider going with bigger injectors, as str8dum1 said, 440's just aren't going to cut it.

 

Good Advise Car vs Driver, But take a look at the link, one of DW's customer cars. 459rwhp. Yes it's a Turbo, but I think I'm making a max of 435rwhp. 440cc's are just cutting it to close.


http://www.deatschwerks.com/catalog/...mers.php?id=01



Oh, and by the way, YOUR FIRED! can I fire myself?

 

Two things ...

1. I guarantee you he's using something like a UTEC and a walbro and a fuel return system. None if which you have.

2. He's also not battling with parasitic horespower loss due to spinning the super charger, which can be as much as 30-50HP. So, you're probably making the same power if you back that out of the equation.

Just trying to help out. I still stand by my statement: a 2.87 pulley without quality EM, a walbro and bigger injectors ... you're just asking for trouble.

Of course, you don't have to take my word for it. When you blow up your motor, you can learn the hard way. Just do some searching on here and you'll see what I mean.

 

Car vs Driver, I AGREE WITH YOU.

Just wanted you to look at the link.

The fired part was directed at me.

I'm greatful for your Help. Thank you...............

I have 30,000 miles on This Setup, maybe I've just be Lucky......

 

lol ... no problem man, good luck!