Fuel pressure: OEM FPR vs OEM FPR + 4:1/6:1/8:1 FMU ratio
#41
Originally Posted by IceY2K1
Stephen,
So, what would be a better assumption?
The fuel pressure rises from 43psi-to-XXpsi, but the bhp stays constant at whatever 43psi supported?
If so, that would mean my "fmu kick-in" point would be lower to whenever the ratio, 1/2(SFP)+(psi*fmu), exceeds 43psi, correct?
I DO NOT want to mislead anybody, so please help me fix my chart to be more accurate.
Thanks.
So, what would be a better assumption?
The fuel pressure rises from 43psi-to-XXpsi, but the bhp stays constant at whatever 43psi supported?
If so, that would mean my "fmu kick-in" point would be lower to whenever the ratio, 1/2(SFP)+(psi*fmu), exceeds 43psi, correct?
I DO NOT want to mislead anybody, so please help me fix my chart to be more accurate.
Thanks.
#43
Originally Posted by subs1000w
whats the MAX BHP the walbro 255 can handle with stock 1:1 FPR
can anyone tell me this
can anyone tell me this
At 10 psi, fuel pressure is 53 psi, the fuel pump can deliver about 54 gal/hr, and power capacity is about 630 hp.
#45
*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.
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.
#46
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
#47
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.
The fmu is a reliable, but crude way to provide proper fuel for your injectors.
#48
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.
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.
#49
Originally Posted by 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.
NO.. emanage can run 150% larger injectors than a stock programmed ecu, WITHOUT an FMU.
You can use an FMU WITHOUT emanage as well.
#50
Originally Posted by slimer
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.
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.
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
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