Who knows about in car fuel systems?

[muz]

I need a quick bit of advice. The fuel system is being moved into the boot of the RST but retaining the original tank as the BTTC and UK spec Group A cars had but I need to know based on a 2.0 ZVH running greens, soon to be grey injectors though at circa 300 BHP. * Do I need two low pressure lift pumps or is just one ok? Are Facet the best ones to go for (I know they are noisey) or are the unbranded eBay ones just as good? I've been told they are exactly the same pumps just unbranded. The group A cars ran twin high pressure fuel pumps, will a single pump be ok? I'm surrently running a Bosch 979 Motorsport pump rated at 200lph @ 5 BAR. As for a swirlpot, I've been asked what size I want, 1, 1.5 or 2 litre? The set up I order was thinking was; Fuel Tank - Mk4 Escort Fuel filter - Lift pump - swirl pot - high pressure pump(s) - MK6 Escort fuel filter - Injector rail - return back to fuel tank.

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[Shonky]

Don't know about the fuel pump selection but to calculate the swirl pot size you need to know the injector cc/min at the base fuel pressure you're running, the amount of boost you run and the time you wish to protect yourself against surge, I've used this post on Scoobynet to calculate what I needed....

or stick a 2 litre in one and not worry about it again lol

[Cossie Sean]

Totaly overkill,
my little brothers mk3 with 300bhp Zetec turbo on 803`s EASILY runs with no need of greys, at all!

underbody tank with standard XR/RS fuel pump top feeding a boot mounted swirl pot, this in turn can graviry feed a 044 (gpA) Bosch pump, these can fuel easily 500bhp on many different applications (not shit ebay jobbie though)

then choose your feed lines to the fuel rail

-8 is normaly choice of use

fuel rail pressure is normally 4 to 5 BAR

[xr2wishy]

i run a zetec turbo and get injector duty to 86% on 630cc siemens.
i run a 979 fuel pump fed from a 1 litre swirl pot fed from a single red top facet interrupter lift pump. i haven't had any issues with fuelling at all.

[stuart collins]

return the rail to the swirl pot then swirl pot back to tank

[xr2wishy]

as above too, missed that bit in original thread, always return to swirl pot, otherwise you could easily end up emptying the swirl pot.

[stevieturbo]

Originally Posted by xr2wishy

as above too, missed that bit in original thread, always return to swirl pot, otherwise you could easily end up emptying the swirl pot.

And returning to the swirl pot results in hotter fuel.

There is no reason a properly designed setup cannot return all fuel to the main tank. Although the easy option is returning to the swirl tank.


Although surely if this car is a race car spec of any kind with a custom fuel tank there cant be a need for any external swirl tank ?
Isnt that part of the reason you'd design a custom fuel tank in the first place ?

[crazycage]

Originally Posted by Cossie Sean

Totaly overkill,
my little brothers mk3 with 300bhp Zetec turbo on 803`s EASILY runs with no need of greys, at all!

underbody tank with standard XR/RS fuel pump top feeding a boot mounted swirl pot, this in turn can graviry feed a 044 (gpA) Bosch pump, these can fuel easily 500bhp on many different applications (not shit ebay jobbie though)

then choose your feed lines to the fuel rail

-8 is normaly choice of use

fuel rail pressure is normally 4 to 5 BAR

greens wont do 300hp on a zvh.

[Cossie Sean]

Originally Posted by crazycage

greens wont do 300hp on a zvh.

i agree

***after reading origional post again, i thaught it was a zetec turbo

My bad

[JonnyBravo]

Originally Posted by stevieturbo

And returning to the swirl pot results in hotter fuel.

There is no reason a properly designed setup cannot return all fuel to the main tank. Although the easy option is returning to the swirl tank.


Although surely if this car is a race car spec of any kind with a custom fuel tank there cant be a need for any external swirl tank ?
Isnt that part of the reason you'd design a custom fuel tank in the first place ?

I commented on someones install recently, was a stock tank under the car and swirl pot in the back so in that case returning to the swirl pot and the top of the swirl pot returning to the tank is how I'd plumb it in but he was told that was not right, by quite a good source too.

Whats your opinion on that ? is overheating the fuel that much of an issue ?

[xr2wishy]

Originally Posted by stevieturbo

And returning to the swirl pot results in hotter fuel.

There is no reason a properly designed setup cannot return all fuel to the main tank. Although the easy option is returning to the swirl tank.


Although surely if this car is a race car spec of any kind with a custom fuel tank there cant be a need for any external swirl tank ?
Isnt that part of the reason you'd design a custom fuel tank in the first place ?

the heat in the fuel isn't a major problem and many external swirl pots are piped this way, you can get fuel coolers though, even my diesel has one for the return pipe.
the reason for the return to pot is the fuel not needed from the rail isn't dumped into the tank just to be pumped up again (which also heats the fuel in the tank like all other systems).
an engine rarely requires max fuel all the time, so you can spec the lift pump below the max needed, but better to go higher really.
consider a facet red top interrupter flows 37GPH, so 166LPH, 600cc injectors x4 flow 144LPH. so a facet will flow enough at max flow for four 600cc injectors just fine.

[Cossie Sean]

cc/min depends what pressure is held at the rail though

[stevieturbo]

Originally Posted by JonnyBravo

I commented on someones install recently, was a stock tank under the car and swirl pot in the back so in that case returning to the swirl pot and the top of the swirl pot returning to the tank is how I'd plumb it in but he was told that was not right, by quite a good source too.

Whats your opinion on that ? is overheating the fuel that much of an issue ?

Depends on the setup. By returning to the swirl tank, you're effectively creating a heating loop with a very small volume of liquid.
So if the rails/engine bay is a very hot environment, then it is possible for fuel to get very hot. As to how much of a problem this might be I dont know, or how hot it would actually get. But it could get pretty hot.
But the simple reason people plumb it this way, is so they can get away with a much smaller lift pump.

If you use an adequate lift pump, then there is no reason at all to need to return any fuel back to the swirl tank. This also ensures no hot fuel at all is ever re-circulated into the small swirl tank.

It's just a simple design matter.

As far as temps go, Ive only ever monitored my own but I just run a large fuel tank, no swirl. But I have seen as high as about 38degC on a warm day with the engine running. ( do have a cooler on the return line, although it's very badly placed. But probably does help a little.
So I'm sure with a small swirl tank temps could easily get pretty hot.

Although if you do return to the swirl tank and also use a decent lift pump, it may have sufficient volume of flow to dilute the hot fuel from the engine enough that heat in the swirl tank doesnt become an issue

return to swirl tank = lift pump only has to flow enough fuel that the engine is actually consuming.

return to main tank = lift pump has to outflow the main engine pump at all times

It's very simple really.

[AquariousRS]

Originally Posted by JonnyBravo

I commented on someones install recently, was a stock tank under the car and swirl pot in the back so in that case returning to the swirl pot and the top of the swirl pot returning to the tank is how I'd plumb it in but he was told that was not right, by quite a good source too.

Whats your opinion on that ? is overheating the fuel that much of an issue ?

Was that Dales?

Regarding a swirl pot I always believed the very top fitting was return to the tank and the next one down was a feed from tank or return from rail, but Dale has plumbed his slightly diferently.

[JonnyBravo]

Originally Posted by AquariousRS

Was that Dales?

Regarding a swirl pot I always believed the very top fitting was return to the tank and the next one down was a feed from tank or return from rail, but Dale has plumbed his slightly diferently.

Yes it was Dales car, was a odd one really as I've never known anyone to do it differently! I think his return from the engine was going in the top or it's the feed from the lift pump, a bit odd but he is only going off what he has been told to do.

[stevieturbo]

The very top fitting on the top of the swirl tank is always the return to the main tank. If it's plumbed any other way it's wrong.

[muz]

Originally Posted by stevieturbo

Although surely if this car is a race car spec of any kind with a custom fuel tank there cant be a need for any external swirl tank ?
Isnt that part of the reason you'd design a custom fuel tank in the first place ?

My car isn't race spec, yet, I'm using the standard ERST fuel tank, as all the UK spec BTTC, rally and Group A cars did with an external swirl pot. The European cars ran an ATL 80l bag tank, but after speaking to a German chap who builds them he does away with these ATL tanks and fits standard items like the UK cars, but I digress.

As you said though, I wanted to return the fuel to the tank to prevent over heating that's why I wanted to know if I needed twin lift pumps to keep the pot full. I think for peice of mind, I'll run a pair of Facet red tops and see how I get on. Not sure why I'm bothered about how noisy they are when I have a straight cut box and a stripped interior

[xr2wishy]

top feed from swirl pot is always to tank, this is to stop pressure build up and rid of any air in the system.
with a sufficient lift pump i would agree that there would be a decent flow back to tank, so i see no issue with retuning from fuel rail to swirl pot. i did run a test after idling for abot half an hour and temps did rise a little to be fair, just over 30 degrees. with the inlet being warm and fuel rail itself getting hot due to heat soak i didn't think there would be much of an effect doing it differently.
more to the point you'd have to make sure your lift pump is bigger than the injection pump, as in flows more.
more importantly if there is fuel surge in the tank for a few seconds, then the lift pump won't be filling the swirl pot, but the injection pump will be draining it quickly.
best thing is to try it different ways and see how it works best for your requirements.

[xr2wishy]

p.s. facets aren't that noisy lol!
you can live with them especially on a track car.
i have both my pumps in the boot, but it's not stripped out though.

[stevieturbo]

Originally Posted by muz

My car isn't race spec, yet, I'm using the standard ERST fuel tank, as all the UK spec BTTC, rally and Group A cars did with an external swirl pot. The European cars ran an ATL 80l bag tank, but after speaking to a German chap who builds them he does away with these ATL tanks and fits standard items like the UK cars, but I digress.

As you said though, I wanted to return the fuel to the tank to prevent over heating that's why I wanted to know if I needed twin lift pumps to keep the pot full. I think for peice of mind, I'll run a pair of Facet red tops and see how I get on. Not sure why I'm bothered about how noisy they are when I have a straight cut box and a stripped interior

So you have an RS Turbo tank, with presumably an RS Turbo efi pump already there which will flow plenty. Why buy a different pump as a lift pump when you already have one ?

Will a Facet flow more than the Bosch pump ?

What is the main engine pump you intend to use ?

[xr2wishy]

ERST pump flows about 130LPH IIRC

[stevieturbo]

At efi pressure or open load ? Not that great really.

[robertdt99]

i run a zetec turbo and get injector duty to 86% on 630cc siemens.

[AquariousRS]

Originally Posted by JonnyBravo

Yes it was Dales car, was a odd one really as I've never known anyone to do it differently! I think his return from the engine was going in the top or it's the feed from the lift pump, a bit odd but he is only going off what he has been told to do.

I questioned it aswell. He had the very top being fed from the lift pump and one of the ones lower down on the side as a drain. This means there is always going to be air in the top which will allow the fuel to slosh about in the pot.
I also thought having the fuel going on on the side is supposed to help de-air the fuel??

[stevieturbo]

Originally Posted by AquariousRS

I questioned it aswell. He had the very top being fed from the lift pump and one of the ones lower down on the side as a drain. This means there is always going to be air in the top which will allow the fuel to slosh about in the pot.
I also thought having the fuel going on on the side is supposed to help de-air the fuel??

What you describe is 100% correct. If he has it plumbed with a feed into the very top of the tank it is totally wrong.

[AquariousRS]

There you go, a pic of Dales setup. Can clearly see the feed from the tank goes to a filter to the very top of the swirlpot.

[xr2wishy]

is that not possibly a filter on the return and no filter on the feed from the in tank pump?
odd setup if it isn't though.

[clarke5700]

i run a redtop lift pump lifting from my tank into my 1 leater swirl pot and my 044 feeds from the pot and feeds a set of 650cc injectors and its been fine on my 415hp zetec turbo

[JonnyBravo]

The reason I have plumbed it this way is to ensure the tank doesn't pressurise by allowing all of the excess fuel to return to the main tank correctly since the swirl pot is above the main tank, in fact all of the pipes should be at tangent to the main swirl pot tank, this would help reduce airated fuel by the incoming fuel "swirling" around the top of the tank and then the "neat" fuel filling the swirl pot up to the over flow, this results in an unpressurised reserve of fuel to supply the main fuel pump. Some bag tanks have an internal swirl pot with upto 8 small lift pumps feeding the swirl pot, the over flow being a slot in the top of swirl pot which also contains the main pump and filter. This desigin is used by all top touring car, tin top, single seater race teams, a proven system, Fit and forget.....

That's the reasons I got for the fuel install being done that way.

[stevieturbo]

Originally Posted by AquariousRS

There you go, a pic of Dales setup. Can clearly see the feed from the tank goes to a filter to the very top of the swirlpot.

What an incredibly weird and wrong way to plumb the entire system.

[muz]

Cheers, guys, I think I have all the info I need.