Dear Friendly1_uk
03-26-2007, 08:56 AM
#1
Boost Czar
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Dear Friendly1_uk
You pm me:
im sorry pal, but not an ounce of that is true. look on the walbro site.
you also appear to advocate the use of the 190 hp when its struggling to meet delivery so much that it can no longer meet demand and the rail pressure drops below that set by the cars own fuel pressure regulator. that leans out number 4, a major cause of engine loss. fitting an equal pressure manifold (duel feed rail) will help, but is in no way an acceptable way of using a pump beyond its capability. its meant to have some reserve.
the 255 is fine. the problem is the cars own fuel pressure regulator cant return enough to the tank. it needs upgrading, not badly working around.
my response to you is:
No, i'm right. When do i say, "use a pump beyond it's capability?"
The stock pump is perfectly suitable to flow enough fuel to support 305 BHP at 50psi.
it flows around 35 gal/hr. at 50psi.
So we have two choices of Walbro; the 190 lb/hr or the 255 lb/hr.
The 255 HP can only flow enough fuel to about 100-110psi.
The 190 HP can flow the same to about 110-130psi.
At idle (35psi):
The 255 HP can support around 600 BHP at IDLE
The 190 HP can support around 400 BHP at idle
at 50psi (OEM FPR):
The 255 HP can support about 565 BHP
The 190 HP can support about 420 BHP
at 100psi (using FMU):
The 255 HP can support about 260 BHP
The 190 HP can support about.....260 BHP, weird!
Now, no sorry, the OEM FPR can return plenty of fuel, but at 35psi while idling, it shouldn't be trying to regulate flow for 600 Brake Horsepower, which is exactly why everyone who runs a 255 model complains. It overloads the FPR with too much fuel and raises your fuel pressure from 35psi to about 40-45psi. The 190 does not.
So in your eyes, choosing a pump that gives no problems and supports plenty of fuel is the bandaid solution as opposed to running a 255 pump and replacing the OEM FPR to allow it to idle properly? I guess I'm not crazy.
The 255 HP gives you absolutely no benefit when run at 100psi over the 190 HP, since they support about the exact same BHP.
The 190HP is cheaper.
The 190HP is the correct choice when using an FMU, 190 standard when using EMS.
The End.
Originally Posted by friendly1_uk
Regardless, there are still a few options in fuel pumps. The ideal pump is the Walbro 190 lb/h HP fuel pump. HP stands for high pressure. It is important you get a HP unit if you plan on raising the fuel pressure levels past 90psi. The HP models can supply fuel up to 130psi. The standard 190 lb/h fuel pump is maxed at 90psi and the standard 255 lb/h pump is maxed at 80psi. The 190 HP unit will not only supply four 700cc injectors with enough flow to maintain 40-50psi in the fuel rail (enough for 400hp), but out flows the 255 HP model after 100psi.
you also appear to advocate the use of the 190 hp when its struggling to meet delivery so much that it can no longer meet demand and the rail pressure drops below that set by the cars own fuel pressure regulator. that leans out number 4, a major cause of engine loss. fitting an equal pressure manifold (duel feed rail) will help, but is in no way an acceptable way of using a pump beyond its capability. its meant to have some reserve.
the 255 is fine. the problem is the cars own fuel pressure regulator cant return enough to the tank. it needs upgrading, not badly working around.
my response to you is:
No, i'm right. When do i say, "use a pump beyond it's capability?"
The stock pump is perfectly suitable to flow enough fuel to support 305 BHP at 50psi.
it flows around 35 gal/hr. at 50psi.
35 gal/hr. converts to 210 lbs/hr (35 x 6) (gal/hr x 6 = lbs/hr)
210 lbs/hr x 80% DC / .55 BSFC = 305BHP
at 90psi however, the pump can only flow 5 gal/hr. or 43BHP.210 lbs/hr x 80% DC / .55 BSFC = 305BHP
5 x 6 = 35 x .8 / .55 = 43
Since I'm pretty sure you want to be able to flow enough fuel to support a little more than 43 BHP while boosting, the ideal solution is using a HP model fuel pump, one that can support higher fuel pressures while using an FMU.So we have two choices of Walbro; the 190 lb/hr or the 255 lb/hr.
The 255 HP can only flow enough fuel to about 100-110psi.
The 190 HP can flow the same to about 110-130psi.
At idle (35psi):
The 255 HP can support around 600 BHP at IDLE
The 190 HP can support around 400 BHP at idle
at 50psi (OEM FPR):
The 255 HP can support about 565 BHP
The 190 HP can support about 420 BHP
at 100psi (using FMU):
The 255 HP can support about 260 BHP
The 190 HP can support about.....260 BHP, weird!
Now, no sorry, the OEM FPR can return plenty of fuel, but at 35psi while idling, it shouldn't be trying to regulate flow for 600 Brake Horsepower, which is exactly why everyone who runs a 255 model complains. It overloads the FPR with too much fuel and raises your fuel pressure from 35psi to about 40-45psi. The 190 does not.
So in your eyes, choosing a pump that gives no problems and supports plenty of fuel is the bandaid solution as opposed to running a 255 pump and replacing the OEM FPR to allow it to idle properly? I guess I'm not crazy.
The 255 HP gives you absolutely no benefit when run at 100psi over the 190 HP, since they support about the exact same BHP.
The 190HP is cheaper.
The 190HP is the correct choice when using an FMU, 190 standard when using EMS.
The End.
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03-26-2007, 10:48 AM
#4
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The charts show that the 190lp hp is the way to go with an NA running an FMU and requiring over 100 psi fuel pressure. If I had an NB at static 60 psi I would get the 255.
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03-26-2007, 11:27 AM
#5
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it's still the difference between supporting 400BHP and 525BHP, both of which I doubt many will make. 400BHp is what, about 330RWHP.
Plus the FPR is still most likely get overflowed and run at 40-45psi at idle and 65-70psi at 0~hg.
not to mention all the complaints of idling issues with the 255.
If you dont need more than 70-80psi, then just go with the 190lph standard, you can support the exact same, without the capability of running past 90psi.
Plus the FPR is still most likely get overflowed and run at 40-45psi at idle and 65-70psi at 0~hg.
not to mention all the complaints of idling issues with the 255.
If you dont need more than 70-80psi, then just go with the 190lph standard, you can support the exact same, without the capability of running past 90psi.
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03-26-2007, 12:52 PM
#6
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BTW, Friendly1_uk, I'm not trying to be a dick posting here, but I guess there needs to be another full discussion on the matter here, and i want input from you and others as well on the topic. But my stance is clear.
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03-26-2007, 02:57 PM
#8
Brain, I knew you were full of **** all along. That FAQ you made that the whole community uses as a mini-Bible is all for crap, isn't it? You just made all that **** up and we fell for it. I'm ashamed!OK, back to reality: Didn't we decide that the argument for starving the #4 cylinder with a stock fuel rail to be somewhat of an unknown? Yah, huge boost and a massive pump/lines will overwhelm the fuel rail at some point, but wasn't the consensus that cooling problems (hence the need for coolant reroute) was way more of a contributor than #4 feed problems.
And we also decided that unless you're talking about the aforementioned large levels of boost, that the DIY dual feed mod was just as effective as the FM or Shiv's or ****o's. Am I remembering correctly?
In any case, Brain, these are for you:
And this is for that guy:
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03-26-2007, 03:06 PM
#9
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FM told me that with a dual feed fuel rail, I needed to reduce Master Fuel a couple points. So the DFR definitely gets more fuel to the injectors. Wether or not it's more or less even, I have no clue, but it's certainly more total.
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03-26-2007, 03:31 PM
#10
Also, it's known a DFR is a good mod or purchase, but I'm not sure it's ever been proven for-sure, without-a-doubt, no-room-for-argument that at XXpsi, you will starve the #4 cyl, cause knock, and fry a piston because of it... or whether it's a cooling issue, or combination. In either case, going with a DFR and coolant reroute makes it a non-issue at any boost level or fuel pressure.
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03-26-2007, 03:37 PM
#11
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HAHA
I wasn't referring to their passion purple rail. I was referring to a DIY rail.
Seems that their testing showed that there was more overall fuel getting into the motor with a DFR. But there is no evidence that it is more evenly distributed to the cylinders.
I wasn't referring to their passion purple rail. I was referring to a DIY rail.
Seems that their testing showed that there was more overall fuel getting into the motor with a DFR. But there is no evidence that it is more evenly distributed to the cylinders.
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