I'm about 2 weeks away from putting in my custom turbo kit. I have stock injectors and will be running a fmu. How much boost can this handle with stock fuel pump?(I might end up changing the fuel pump)(I also have an intercooler )I was thinking of starting with 4psi and work my way up. What boost does the f-max and ns kit run with stock injectors? Do those kits upgrade the fuel pump? thanks

without injector and fuel pump upgrade i would not recomend going past 4psi. I belive nsport and fmax run 7psi, but i could be wrong.

Stock pump won't respond very well to increase fuel pressure at the rail, wouldn't push it past 4 PSI if I were you. But then you wouldn't need the FMU would ya.

true

well how does that work?

you are playing with fire man, upgrade the fuel system first! bigger pump and injectors, adjustable regulator and both a fuel pressure and air/fuel gauge. Would you bungee jump with a thin cord?:eek:

Hmm....none of those "reputable" kits use upgraded injectors--just upgraded fuel pump and FMU...and they run 7 psi. That's what I'm using---at 7 psi, the injectors won't be at 100% duty cycle, it should be fine w/stock injectors. If i'm leaning out I'll just get new injectors..

ITs not the psi thats at question, but how much power you want to make.

I ran 6.5 psi for a year with a 8:1 FMU and stock fuel pump. If the pump is working fine, then you can probably get away with it. I wouldn't try to push it much more without a pump capable of high flow at high pressures. I had a bad wastegate that caused some occasional 8-9 psi boost spikes and I'd hear some detonation when it did...

Quote »I ran 6.5 psi for a year with a 8:1 FMU and stock fuel pump. If the pump is working fine, then you can probably get away with it. [/quote]wow... I'm surprised that the fuel pump was capable of both pushing out enough fuel to generate 95psi... let alone last a year at that configuration. I'm guessing though, that fuel pumps well vary in ability due to wear and tear... my stock fuel pump was already leaning out the car in stock form.... while others have been successful running 10psi of boost on the stock pump.

Quote »ITs not the psi thats at question, but how much power you want to make.[/quote]No, the question is very much psi related, as his fuel system is/ will be controlled directly by manifold pressure. The limit of fuel the pump can flow, and the limit of the injectors' ability to atomize fuel will determine the psi limit. Power in this case is irrelevant.

MarkEmark wrote:Hmm....none of those "reputable" kits use upgraded injectors--just upgraded fuel pump and FMU...and they run 7 psi.

FMax used to only offer their kit with at least 370's and a JWT ECU... that's changed though.....

Quote »That's what I'm using---at 7 psi, the injectors won't be at 100% duty cycle, it should be fine w/stock injectors. If i'm leaning out I'll just get new injectors.. [/quote] That's right... at 7psi they'll be at around 126.85% duty cycle (ideally, with a 10:1 FMU). That's been said to be the limit of fuel pressure before the injectors will fail to atomize fuel properly.

BTW Mark: if you need help during the turbo install (noticed ur sig said June though) let me know. e-mail = [email protected] I'll prolly be up around Storrs (UConn) for the most part, but I spend some weekends in New Haven. (noticed your CT loc)

I chose a more dangerous route with the hacked MAF with 370cc injectors... although it theoretically is controlled "as safe as stock".