bigger fuel pump than 044?

[newt]

Yeah, that's a lot of pressure to ask of a single pump at that power level. A single 044 is typically fine for a 5-600bhp car with properly sized injectors, we've done dozens of them with a single 044. Much above that and you want to start looking at dual pumps. Even if you're on a 413 pump.

Make sure the entire fuel system is up to the flow levels you'll need though, you want to run a -8an sized feed line typically for that kind of power, be sure to use fittings with adequately sized orifices on the filter (if you're retaining the stock filter), ample relayed power to the pump, etc, etc.

[JSHADZI]

Our experience with the 044 pump (based on tuning dozens and dozens of cars with it), is that it will support well over 600whp on the average Audi buildup with boost levels approaching 3.75BAR absolute. In most cases, this necessitates a fuel line upgrade to at least -6AN or 9.5-10mm above the 500 whp range. The 413 pump is basically an 044 pump built to a higher tolerance, once source says that 413 pumps are the highest flowing "X%" of the 044 pumps that are manufactured. They are rated for flow at higher pressures than the standard 044, but based on what I've posted above, unless you are pushing 750+HP, there is no reason to run anything but an 044.

In my 80tq, static fuel pressure is set to 5.5BAR, with boost pressures exceeding 4BAR absolute, my dual 044 setup has NO trouble keeping up with this. The 1250cc RC Engineering injectors have no trouble either.

Many make the mistake of blaming the pump when in fact its the stock 8mm line that is the restriction. Beyond this, a dual fuel pump setup will allow fueling for well over 1k HP with good reliability.

HTH,

[S2central.net]

Good points well made there lads on use of dual pumps for big big power and the need for large bore fuel pipes on such beasts.

[repo]

http://www.hrpworld.com/client_images/ecommerce/client_39/products/636_1.jpg

If we rely on that chart, we see flow of 4 liters per minute at 5 bar. At 8 bar it looks like slightly less than 3,5 liters.

So at 8 bar You can max out the pump with 680-700cc injector. Meaning You can thoretically have 680ish Bhp with single 044. And that is pushing injectors and the pump to 100% duty.

But in real world, there is pressure loss in fuel line, so I agree with Javad, make big enough line, and You can live with single 044, but I would say to 650 hp absolute tops, and even then there is absolutely no room for error.

That is why I recommend using twin 044 or some other options, when getting closer to 600hp.

[S2central.net]

American belt, Finnish braces... I like it.

[A80Avant]

Very nice! at least we clarified some things on account of fuel pumps!

[JSHADZI]

But in real world, there is pressure loss in fuel line, so I agree with Javad, make big enough line, and You can live with single 044, but I would say to 650 hp absolute tops, and even then there is absolutely no room for error.

That is why I recommend using twin 044 or some other options, when getting closer to 600hp.

I definitely agree, twin pumps is always better, and you can use 2 much smaller, less expensive pumps like from a early CIS car or similar. In later applicaions like the B5 and B6, fitting dual pumps is more work, so sometimes a single 044 is held onto as long as possible for that reason.

Here is a dual 044 setup we did in a customer B5 A4 drag car recently, this car maxxed out one 044 pump with -6 hose at 630whp, now with dual pumps it has no issue obviously.

Dual pump setup here: http://videos.streetfire.net/video/d...mps_643749.htm

You can see the 630whp run here: http://www.034motorsport.com/gallery...0whp2.mov.html

[Jamo]

Interesting. MRC user the single 10 bar 044 pump in their installs it's what's in MRC600 AFAIK which is 649 bhp

[a4kquattro]

The pressure differential across the injectors is static, there shouldn't be any 'strange behavior' under boost that isn't there at any other running condition, for the injectors. As far as the injector is physically concerned the fuel pressure stays static.

I understand that the pressure differential across the injector remain constant, but that doesn't change the fact that most fuel pumps fall off in flow (044 included) at very high fuel pressure. Also, when dealing with enormous fuel injectors its often easier to get a smooth idle by lowering the base fuel pressure (effectively slightly increasing the required injection pulsewidth at idle).

[newt]

I understand that the pressure differential across the injector remain constant, but that doesn't change the fact that most fuel pumps fall off in flow (044 included) at very high fuel pressure. Also, when dealing with enormous fuel injectors its often easier to get a smooth idle by lowering the base fuel pressure (effectively slightly increasing the required injection pulsewidth at idle).

Fine, that's all basic, common knowledge. Where's the 'weird behavior' you talked about earlier?? That's what I was trying to clear up.

[newt]

Interesting. MRC user the single 10 bar 044 pump in their installs it's what's in MRC600 AFAIK which is 649 bhp

It's definitely possible, and been done many times. But it's at the ragged edge of what the pump is rated for. We had a customer with a 2.7t and single 044 putting down 650+whp. Still not somethin we'd recommend! In the grand scheme of things a second fuel pump that could save your motor is really, really cheap insurance.

[S2central.net]

So a related question... At what power level does one find the factory fuel pipe dimensions start becoming restrictive ?

I've never dabbled with these 'AN' fittings before - are they only suitable with braided / aeroquip style hoses or can they work with solid pipes as well ?

My fuel lines look horrible and need changes this year - along with 044 upgrade, new filter and I should really fit a fuel pressure guage as well. Just wondering if I can incorporate some of these high spec fittings with some good quality 8mm copper tubing.

For info I'm going to record the fuel flow delivered on the existing original setup just to see how much that has degraded in ~15yrs and 140k miles then see what the new stuff improves that too - I have a notion my fuel filter is a major limiting factor - just never bothered to change it before.

[EspenW]

So a related question... At what power level does one find the factory fuel pipe dimensions start becoming restrictive ?

I'm sure that Repo or the 034 boys have some flow numbers, but in my experience, it it fairly high. With 400+ whp on E85 (3.6bar base fuel pressure) I expected the factory piping to keep me from reaching target AFR, but it didn't. In fact, at higher fuel pressure, AFR dropped into the low to mid 10's (too rich), so the factory piping would support even more whp.
Single 044 pump with 14.6v at the pump.

[button]

So when I go to 650hp, the 044 fuelpump will be enough?

[newt]

I might be, thats the thing. All depends on boost levels, fuel pressure, fuel type, particular pump flow. It's at the edge of what a single 044 is typically run at. Chances are you'll be ok, but the question is: Do you want to chance it?