Does anyone know what the ratio is on the FMU for the 01' Stillen Kit? If I downsize my pulley to add 2-3 psi, do I need to upgrade it, and if so, which one is best? Also, would it be a good idea to upgrade my fuel injectors, if so, what size is best?

 

Stock 5th gen kits come with 8:1 FMUs. If you are going to say 9psi, then 8:1 will be good.

If you want to go more or want to be safer, then get injectors.

BTW, I have a set of brand new RCengineering 440cc injectors for the 5th gen for sale.

Dixit

 

What if I wanted to go with 10psi, would I need to upgrade the FMU then or would I be fine?

 

At 10psi the 8:1 is still enough. But you are pushing near 97-100psi on the injectors which is dangerous grounds.

Dixit

 

i have a ? about that though

with an aftermarket fpr, fmu and hp fuel pump, how do you get 100 psi on the injectors?

that is with stock idle and wot fp

 

So what size injectors would be best if I wanted to go with 10psi on 8:1 FMU?

 

Cause if you got the SC you got an inline aux pump or you probably did the Walbro 255lph Fuel Pump in the tank. With that you can push close to 90-110psi FP. 100+ FP on the GSS342 Walbro High pressure pumps.

Aftermarket FPR basically helps you adjust the idle fp back to normal after having a high pressure pump installed. The fmu is just that. Boost relative fuel pressure management unit. It raises the fuel pressure X amount for each psi of boost you raise. That "X" amount is based on which disc size you have in or which ratio you have dialed in (if you got an adjustable one like a Cartech).

Dixit

 

If you go larger injectors you wont be using the 8:1 fmu disc size anymore. That is only used with the stock injectors. But like I said, you are pushing 95-100psi fuel pressure levels and technically the pump at that level is no longer flowing 255lph. So that means the most Crank HP you can put out is somewhere around 350hp if I remember correctly from the fuel pump flow charts.

If you go larger injectors, the next size up on the 5th gens is the 440cc. These are either the RCengineering or the PE injectors. RC run about 650 new for the set, PE runs in the range of 850-1000 for the set. If you go with 440cc, you probably can run 1:1 at 10psi, I cant be sure about that, need to look at the charts again, but maybe 2:1 or 3:1 may be necessary. But definetely dont need 8:1. Because you dont need to bump up the FP that high anymore with larger injectors which is flowing more fuel at a lower pressure.

Dixit

 

yeah, ive seen your cartech.

havent reinstalled the aem fpr since i had the leaks, im waiting for my thread sealant to fully dry.

I got the gss342 from pimp juice and its installed.

im just fuzzy on how the fmu actually works.

oh yeah, and what does that screw (bleeder valve?) thats on top of the fmu (vortech)

 

How do I figure out what FMU disc size I will need with the 440cc injectors at 10psi? Would I be better off with only 9psi and not upgrading the fuel or injectors?

 

What part of the boost related fuel pressure increase didnt make sense? As I said, for EACH pound of boost you raise you can raise the Fuel pressure X amount of psi. This can change depending on the disc size or the ratio you choose on the cartech.

As for the top screw, do you have a SFMU from vortech? Because the standard FMU from vortech doesnt have any adjustments except the disc size which physically needs to be changed.

Dixit

 

I have the regular Vortech FMU. Can I even put the SFMU on my car?

 

Nice plug Dixit... verrryy subtle.....

did the injectors not work with the e-manage?

 

i think dixit went bigger.

i know that it adds xx to each lb of boost, but since its after the fpr, i dont exactly know what the physical principle behind it is.

does it put more pressure in the fuel tank?

 

Im just helping others here if they want them. No plug. Also the injectors as I stated are new. Never eaten fuel. Didnt try it with the emanage because never got around to installing them. Going with larger ones for the new engine project. 600+cc.


Slimer, its physics. What you are basically doing is putting pressure on the return line which basically causes a backup, so the pump is going to force pressure into the line because of that. But as you increase pressure you wont flow as much fuel unless you get a larger pump with that flow. But a standard 255lph flow pump cannot flow 255lph at higher pressures.

Dixit

 

isnt the gss 342 hp?

 

You lost me. Thats the GSS342 HP is the Model# of the Fuel pump that walbro makes that most people on the board drop in as intank fuel pump upgrade.

Dixit

 

sorry.

i got the gss 342 and put it in last week

i was just confirming that it was the high pressure model.

thats all

thanks for all your help dixit
steve

 

Steve, GSS342 is the model. They come in standard and HP. So if you asked for just a GSS342, you might not have gotten the HP flow one. This is the tricky part. Some have done this and put it into the tank to find out they got the wrong one.

Dixit

 

ill ask pimp juice, he's that 3.5L 5th gen with the turbo.