Stephen Max

iTrader: (59)

Just use the hp number calculated for the fuel pressure differential. For example, suppose you are developing 10 psi boost with a 6:1 fmu, so you are getting 77 psi in the fuel feed line. The power producing capacity would then be calculated based on 77-10 = 67 psi in that case.

subs1000w

whats the MAX BHP the walbro 255 can handle with stock 1:1 FPR

can anyone tell me this

Stephen Max

iTrader: (59)

It depends on the boost pressure, but suppose your pumping out 20 psi. Then fuel pressure is going to be 63 psi. The Walbro 255 lph can deliver about 50 gallons of fuel per hour at 63 psi (see the chart on the first page of this thread). 50 gal/hr X 7 lb/gal / .6 lb/hr-hp = 583 hp.

At 10 psi, fuel pressure is 53 psi, the fuel pump can deliver about 54 gal/hr, and power capacity is about 630 hp.

subs1000w

well thats one thing you dont have to worry about maxing out unless your running insanely high FP thanks

IceY2K1

iTrader: (3)

*bump*

Just IGNORE the "OEM FPR" max bhp values ABOVE 0-psi, since Stephen Max pointed out "Flow cc/min" would remain 370cc/550cc for 1psi, 2psi, 3psi, etc..

The OEM FPR was just keeping constant pressure across the injector for the SAME amount of fuel to pass through the injector as manifold pressure increased, therefore the Max BHP would remain the same as at 0-psi.

Mximus

Ok, i still dont have this question solved so ill ask it. Do you still need a fmu if you are using an emanage to regulate a/f and timing and all that. Sometimes i hear that you do, and other times not. Also, when using say.....555's and a 255 fuel pump or something like that, would you need the fmu and the emanage, or just one or the other. Im really confused on this whole thing, cause i keep seeing turbo setups with them, without them, and all mixed together and its confusing. Any help would be great. Thanks

slimer

iTrader: (13)

if you had the 555's you would need to use the fmu to bump up the fp until you tuned with the emanage if i understood alex in another post.

The fmu is a reliable, but crude way to provide proper fuel for your injectors.

slimer

iTrader: (13)

Since some of us might be using a 3:1 and higher boost pressure soon, I thought that I would update the info on the original post.

Boost--OEM--------FMU------
PSI---- FPR--3:1--4:1---6:1---8:1
0--------43--43---43----43----43
1--------44--44---44----44----44
2--------45--45---45----45----45
3--------46--46---46----46----46
4--------47--47---47----47----49
5--------48--48---48----48----57
6--------49--49---49----53----65
7--------50--50---50----59----73
8--------51--51---51----65----81
9--------52--52---53----71----89
10-------53--53---57----77----97
11-------54--54---61----83----105
12-------55--55---65----89----113
13-------56--56---69----95----121
14-------57--59---73----101---129
15-------58--62---77----107---137


1/2(static fuel pressure at idle) + (Boost PSI x FMU ratio)

Bold still is the onset of fuel pressure in regards to the fmu.
Red is dangerously close to 100% duty cycle.

Remember kids, fuel pressure is fuel pressure, no matter how large or small your injectors are.

Bags

iTrader: (3)

NO.. emanage can run 150% larger injectors than a stock programmed ecu, WITHOUT an FMU.





You can use an FMU WITHOUT emanage as well.

Bags

iTrader: (3)

Nice info

and if your pushing 115+ psi through stock 4th gen injectors, your asking for huge problems

And if you look at the stickes, you'll see as fuel pressure goes UP, your fuel pump's ability to flow more fuel, goes DOWN