Fuel Pumps

4.2 V8 40v biturbo - 450 bhp
4.2 V8 40v biturbo - 480 bhp (plus)
Classik
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Re: Fuel Pumps

Post by Classik » Tue Jun 18, 2019 10:06 am

MattV8 wrote:
Tue Jun 18, 2019 9:25 am
I've actually got all the bits in a box (pump, manifold gaskets etc) to replace mine - but I can still hear it whirring after a run so have left well alone. I just bought all the bits "in case"
I also kinda came to the view that making sure to run the engine lightly loaded for the last mile or 2, let it idle down a bit, and regular oil changes are the keys to longevity.
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Re: Fuel Pumps

Post by Shoppinit » Tue Jun 18, 2019 10:09 am

Yeah, the last 2 or 3 miles in mine are at feather footed throttle. Even then I often have to leave it idling in the garage for a while until the oil temps drop back down to 90.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
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Re: Fuel Pumps

Post by Shoppinit » Tue Jun 18, 2019 10:11 am

Don’t know about the injectors I’m afraid. If you’re not getting lean conditions on WOT then maybe it’s not necessary. I don’t know what injectors bam is using on the mental manual. Presumably uprated ones to give 750+ bhp.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Fuel Pumps

Post by Classik » Tue Jun 18, 2019 10:22 am

Shoppinit wrote:
Tue Jun 18, 2019 10:11 am
Don’t know about the injectors I’m afraid. If you’re not getting lean conditions on WOT then maybe it’s not necessary. I don’t know what injectors bam is using on the mental manual. Presumably uprated ones to give 750+ bhp.
Actually I do get lean conditions from time to time using e85 (not SP98). Maybe I should ask him in PM, thanks for the suggestion! ;)
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

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Re: Fuel Pumps

Post by Mɐʇʇ » Tue Jun 18, 2019 12:35 pm

Only relevant if you know what duty cycle the injectors were running at at the time, otherwise it's just as likely a fuel pressure or mapping issue.
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Re: Fuel Pumps

Post by Shoppinit » Tue Jun 18, 2019 12:41 pm

I assumed he was mapped for E85.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Fuel Pumps

Post by Mɐʇʇ » Tue Jun 18, 2019 12:50 pm

Yeah, fair assumption.

But I caught myself out mapping an engine the other day - Lambda reported lean, so I increased fuel. Engine ran worse & still lean. So I increased fuel more, again.
Anyway, long story short, ended up rich enough that it was misfiring, meaning that lambda was reading excess oxygen, causing it to request to run even more rich and the whole system went unstable until it just demanded 8x midgets tipping large buckets of fuel straight in to the TBs.

So don't always trust what the Lambda is saying and make sure "everything else" is running just fine first.
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Re: Fuel Pumps

Post by Classik » Tue Jun 18, 2019 1:06 pm

Actually I have a small device which allows me to switch between 3 different maps: stock, optimized e98, and optimized e85; except for the stock one, those maps have been specifically tuned for my car and it takes like 5-10 min to upload a new map to the CPU, very convenient. Admittedly the e85 may have to be altered due to these (rare) lean conditions, but I guess the car would benefit anyway from a fuel system upgrade (fuel pumps + bigger injectors). FWIW injectors duty cycle have been measured at 85% on e85 at full load, and the car has registered 517HP on a dyno.
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

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Re: Fuel Pumps

Post by Mɐʇʇ » Tue Jun 18, 2019 1:11 pm

Sounds like size-wise, they're pretty well matched for what you need then?
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Re: Fuel Pumps

Post by Shoppinit » Tue Jun 18, 2019 1:16 pm

85% duty cycle is pretty high. I'd be worried that they won't be running linearly at that kind of load. Could explain your lean conditions at WOT.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Fuel Pumps

Post by Classik » Tue Jun 18, 2019 1:49 pm

MattV8 wrote:
Tue Jun 18, 2019 1:11 pm
Sounds like size-wise, they're pretty well matched for what you need then?
Well yes and no, as I have no margin for progress, and as Shopp just mentionned, 85% is already quite high, no?
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

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Re: Fuel Pumps

Post by Mɐʇʇ » Tue Jun 18, 2019 1:57 pm

That's interesting and I'll have to read up on it more. I've always understood that 85% was the sweet spot, so I'll need to research it some more.
But yeah, not much upside if you increase hp more, although imagine you could squeek a bit more on the fuel pressure if you really needed to?

Luckily this is just a hobby and I'm not a pro!
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Shoppinit
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Re: Fuel Pumps

Post by Shoppinit » Tue Jun 18, 2019 2:01 pm

And we're back to the original topic. :) After only 16 pages.

I wonder how much more pressure the OE pumps can provide sufficient flow for. Probably you wouldn't need much of a pressure increase because it sounds like your injectors are almost coping, or are coping and the issue is elsewhere.

I also wonder how the linearity of injectors changes with age / wear.

Can of bloody worms, innit.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

Classik
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Re: Fuel Pumps

Post by Classik » Tue Jun 18, 2019 3:06 pm

Hahaha, yes that's exactly what I was thinking also: 16 pages to come back to the original topic, but well worth the journey! ;)

I also believe the injectors are currently the weakest link in the chain so well worth investigating, and yes ageing doesn't help. Same apply to fuel pumps by the way. On the latter I've received some great feedback from local RS6 owners here and I intend to install an in-tank Walbro F274 (https://walbrofuelpumps.com/walbro-450l ... otive.html) and an in-line AEM 400lph (https://www.aemelectronics.com/products ... -fuel-pump).
Last edited by Classik on Tue Jun 18, 2019 3:24 pm, edited 1 time in total.
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

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Shoppinit
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Re: Fuel Pumps

Post by Shoppinit » Tue Jun 18, 2019 3:18 pm

Cool. l'll be curious to see how you get on, especially with installing the pump in the tank. Take some photos please. :thumbs:
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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