WannaBeGearHead

How can you adjust your fuel pump(s) to push out 65psi? Also, how do you know if a pump or pumps can handle pushing out that kind of PSI?

And what about the fuel hat? Can that handle dual pumps or increased PSI at the pumps?

cliffyk

With the electronic returnless fuel system you don't adjust the pump, you adjust the tune--it's the Returnless Fuel Rail Pressure Drop scalar IIRC.

You ferret out the fuel pump's specfications--however pressure is only one part of what's important. Related to engine output rate of flow is the arguably more important part.

By itself, put forth without a specific flow rate also being stated, pressure is meaningless--you could have 5000psi, and 0.1gph flow if the lines were sufficiently restrictive, and have enough fuel to produce a whopping 1.03fwHP.

The exact pressure value is only relevant so that the pressure drop across the injectors can be determined, and thus their flow capacity, so that the PCM and can calculate how long to keep the injector open to squirt the required amount of fuel.

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Fluid dynamics is not something that can can be "picked up" through a few posts on a forum, and not something that be particularly well discussed unless both players have mastered the fundamental concepts and physical laws involved. Get some books from the library, or find an engineering course at a local junior college/tech school.
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65psi is nothing, When I was running 18psi boost on my '90 Miata I was pushing 135+psi to the injectors with a Walbro high pressure 255lph pump, and did in fact blow a fuel hose out once. Goodyear makes a 185psi rated fuel hose.

The "fuel hat" just a piece of metal, pressed steel crimped and electro-welded like the stock unit, or CNC machined from billet like many of the after market units. It would take a lot more pressure than you could get from a fuel pump to cause it harm.

I have seen dual pumps setup using the stock "hat", generally they are jury-rigged and not a pretty sight.

Hangwire

Awesome info so far in this thread, as with all threads cliffy the king is involved with.

How did Gook get in your belly?

cliffyk

Mother nature put it in there--have you ever seen what that stuff looks like?

Hangwire

Its hideous!!

WannaBeGearHead

Wow there is a lot of info in here that I am having a hard time wrapping my mind around. Cliff I appreciate the help.

The one thing I still have to search around and re-read what you wrote is how to determine what kind of fuel setup would be the best setup for the different routes I could go in the future (i.e. turbo, s/c, N/A). Like if I was just going to build a N/A car I need to figure out how to find out which pump would be best for my setup or if I was going to build a turbo'd car what fuel setup would be best.

Like you said this isn't something I would figure out in a few posts on here. Unfortunately, I won't be attending any tech classes. I just want to get a good understanding of how everything works (which I do now) and how to determine which fuel parts are the best for me.

Thanks again and I'm sure I will find a few more questions for you later

GTRACER88

The best pump for your application is power level. It doesn't matter if it is turbocharged, supercharged, or all raw power, it depends on the fuel demanded by the power your putting to the ground. More power = bigger fuel pump and injectors. The reason why this is true is because of the duty cycle of your pump. If your car needs a lot of fuel, a small pump will only be able to pump at 100% duty cycle and still not be enough for the power or demand of fuel needed. There also is no best type of system. Both have pro's and cons. Many people prefer return set up because it is the cheapest and very efficient way of getting fuel. The con is that its pretty noisy. Return-less is more expensive but will be quieter.

cliffyk

I agree, the "best" system, in any endeavor, is the one that works--and in the case of fueling an engine the one that works will be that which delivers sufficient amount of fuel to make maximum power.

Configuration (return or returnless) is irrelevant, properly selected components, properly configured will do what is needed--manufacturer's moved to the returnless system because it provides more precise control over rail pressure, which makes the engine run cleaner and better EPA requirements. However if maximum power is your goal it's not needed (it's not bad either, just not needed).

It should be obvious that nothing can operate at greater than 100% duty cycle--not even the Federal government's spending, though those in charge don't seem to get that--it doesn't matter if the pump(s) is(are) small, medium or gigantic, all they've got is all they've got. And again, pressure is only part of the story; you need pressure @ "x"gph flow to have a meaningful specification.

WannaBeGearHead

I looked around at the different pumps people offer and sometimes, actually most of the time, don't give you the pressure @ "x" gph. They give you maybe the hp limits and or the max pressure the pump can handle. I guess it's just a matter of trying to find the actually specs of the pump.

cliffyk

I know. When those are all that are given the HP capacity is the more meaningful of the two, and you can assume that it will support the more common rail pressures.

Here is some very complete information re: Walbro's pumps.