The V8 Owners Forum -

Ian Anderson wrote:Chodjinn

Sorry no the comment was not pointed at you but to some others who thought it better to run the fuel rail return to the tank.

It is better, but also requires a better fuel system in general. Which will be more expensive.

It isnt re-designing anything, it is the best way to do it. Of course the cheaper option of returning to the swirl tank is very functional too.

Even my car, that doesnt run a swirl tank, does heat the fuel quite a bit, and thats only of the main 75 litre tank !!! If you have big pumps, shifting a lot of fuel at high pressure, the fuel will get heated up quite a bit. Im sure If I was feeding and returning to a very small tank, it would get roasting in no time at all.

So its a case of building a fuel system to meet your requirements.

Ref the fuel filter itself i used a vauxhall one, its a cansiter type one with straight fittings which a standard fuel hose can slide over and be secured by a jubilee clip or similar. Makes life really simple! The part number is 25164435 and its about £18 i think retail although mine was free as i work in a vauxhall garage he ha he ha!

Ref the fuel return put it into the tank if poss not a swirl pot as overheating the fuel has happened to a couple of peopl ei know one of whom is Will Holman from PPC mag with the v8 capri. In traffic the fuel overheated and the thing wouldn't run. I think maybe the fuel was trying to evaporate or something like that.

ok cheers for the info.

What about fuel line sizes? And filter/pump connection sizes?

Do they all have to be the same internal diameter, and has any one got a comparison for AN fittings to NPT or equivalent?

The Inlet connection on the BOSCH 910 pump is quite large, gues about 10-12mm. It has a screw connection on the other end but it looks wierd!

Should my filters be the same size (12mm)?

Also, what about connecting to the fuel rail, as that looks quite small (6mm?)? And the return from the fuel rail looks tiny.

Sorry for all the questions but google just gets me confused. I just wanna sort my fueling out, this is doing my nut in!

chodjinn wrote:ok cheers for the info.

What about fuel line sizes? And filter/pump connection sizes?

Do they all have to be the same internal diameter, and has any one got a comparison for AN fittings to NPT or equivalent?

The Inlet connection on the BOSCH 910 pump is quite large, gues about 10-12mm. It has a screw connection on the other end but it looks wierd!

Should my filters be the same size (12mm)?

Also, what about connecting to the fuel rail, as that looks quite small (6mm?)? And the return from the fuel rail looks tiny.

Sorry for all the questions but google just gets me confused. I just wanna sort my fueling out, this is doing my nut in!

AN and NPT are totally different. Do you even need to use any such fittings anyway ?

What fittings do you intend to use ?? The outlet on most Bosch pumps is just a simple M12x1.5

The inlet on the smaller ones is 12mm, the bigger ones are about 15/16mm.

Just make sure, whatever flexible hosing you use, is intended for efi high pressure use, because a lot of hose isnt.

an 8mm OD hardline tube, steel, copper, whatever, will be more than sufficient for pretty much any Rover V8 engine.
Ive ran Subarus to over 500bhp on a single 8mm line. they normally use a simialr 8mm return.

I don't know about that pump that you have mine at least i can tell you about. Its from a calibre and simple push on fittings, that being slide the hose over it and clamp away. The feed to the pump is typically large so that the pump can get enough fuel but the output of the pump is 3/8 or 8mm (i can't remember which) which again is a simple push on and clamp it jobbie. This then feeds up to the aformentioned filter which then goes to the fuel rail which again has a push on fitting which you clamp up by way of jubilee clip or similar. the output of the fuel rail is the same fitting which goes to the fuel regulator which is the restriction which the pump pushes fuel up against and creates pressure. The output of the regulator then feeds back to the tank. I'm lucky in that i could just fit a 2.8 capri injection tank which instantly sorted the swirl pot problem but my fuel route setup is basic and functional but one i was advised to do as it works. You could copy the pump, filter, fuel rail and regualtor set up which will work which leaves just a swirl pot to sort out. I'd go along with fitting a sump to your tank and add what ever inputs and outputs you needs, seems the simplest and you shouldn't get any over heating issues.

Been there and got the confused T shirt!

Probably best to say there never seems to be a direct answer.

I ended up using 8mm inside diameter fuel hose (high pressure) all around and all connectoins are with jubilee clips. I was told this should be good for up to 300 hp and my engine is less than that so should work ok

Reasoning at that stage was cost as eachaero fitting was about £20 and I'd need about 20 of them! Also did not go for braided hose for the same reason.

No not the Bling factor I wanted but that can come when the bank balance recovers.

See the other post re heating fuel - possibly worth fitting a cooler on the retun line.

Ian

yeah I don't want fancy fittings or braided lines - too expensive!

Just spoke to a couple of MG specialists who reckon I can keep the original fuel tank but replace the fuel sender unit with a late spec one, which has an outlet actually built into the sender. I can then use the original outlet for the return line. Bonus is a new sender is about £12.

Alternatively a brand new RV8 fuel tank is about 300 and includes an internal swirl pot. Bit pricey tho.

That just leaves me to buy an external swirl pot, which will have to be made as I'll need a short/squat one to fit. Final system will be based on the 2nd schematic from the first page, with the exception of the fuel rail return and swirl pot return which will be T'd together to the tank.

Hope that's right!

Final question is do I really have to buy a new lift pump, or will I get away using the Facet?

cheers for the muchos help people

What flow rate are your 2 pumps
Facit is 45gal per hour
If he high pressure pump flows more than that the Facit is not beefy enough and the swirl pot will empty.

Hence the need to return to swirl pot

A tall swil pot is better - a bit more head of pressure feeding into the High Pressure pump but what fits is good!

Have you thought about movig the location of the swirl pot to the boot area instead of the bonnet?

Always more than one way to skin a cat!

Ian

http://search.ebay.co.uk/_W0QQsassZcater7manQQhtZ-1

This guy sells cheap ally swirl pots and collector tanks. He will also make things to order for a little bit more too.

I hadn't planned on fitting any of the fuel system under the bonnet really.

In an MGB there us a plate behind the seats that lifts up and there are two battery trays under the car (2x 6 volt old skool style). The whole thing has been ripped out as the battery is being moved to the tank (12v was in the engine bay).

I would put the fuel swirl pot in the boot, but the car needs to remain road legal and I dont think Mr MOT will like any high pressure fuel system in the cabin . . . ?

Swirl pot would have to be short and squat to fit under the body (and clear the diff/driveshaft)

. . . alternatives?

The swirl pot would not be at a pressure (very small perhaps) as it would be a loop from the tank through Facit to Swirl and back to tank. Only rise in pressure would be if the return line was smaller than the feed line.

Where did they put the spare wheel in the MGB? Could the swirl be located there and a steel firewall affair fitted over? Presume you have to run hard plumbed extinguishers and an extra nozzle here would kill any flames.

What would they do with a GT40? You step over the fuel tank mounted in the side sill and then sit down lower than the fuel tank with a single piece of aluminium or fiberglass (depends on kit) the fuel fillers are in front of the tank and have been known to blow out on frontal impact with fuel surge, The Filler to tank pipe is behind the instrument panel. Start to think on these things and you'd never drive one!

Ian

The bosch 044's have an M18 inlet, The outlet is indeed m12. I found a filter with a M12x1.5 female fitting, so plumbing it into the bosch just involved a m12 f-f adapter (i dont have the non return valve fitted)



I would be concerned about fuel getting hot - my fuel tank would get warm when it had about 5 gallons or so left.

Finalisation post! :

Item number: 110059321860

^ This stuff should be ok for most of the fuel lines?

As far as I can see I have two options then:

1. Fit fuel swirl pot, with return line to swirl pot, and return from swirl pot to tank. Use facet pump (this should work as the engine ran with the facet before) and HP pump/filter arrangement. Ok but not good r.e. vapourisation. (Schematic 1)

2. Fit fuel swirl pot (with 1 less fitting). Return from fuel rail and return from swirl pot T'd together, then to tank. Buy a better low pressure pump like a Holley etc. with better flow, with same HP arrangement as above. Better for keeping fuel cool. (Schematic 2)

For BOTH systems: Use Low pressure lines from Tank > LP Filter > LP Pump > Swirl Pot. Large feed from swirl pot to HP pump (10-12mm). High pressure 3/8" line fromt HP pump > HP filter > Fuel rail > Return to tank or swirl pot.

correct me if I'm wrong anywhere? Financially the first one is better, functionally the second one is better, but will require a custom swirl pot as most have 4 fittings.

thanks

By jove I think he's got it (Apologies to my Fair Lady)

Worth checking the inlet and outlet on the Holley pump if you are gong that route and just need to do the connections once. (I seem to remember the holly having BIG connectors)

I think I would still go return to swirl but it's your choice.

Ian

personally, all the systems I've seen have a return to swirl pot from the fuel rail, but I'm paranoid about fuel vapourisation now!

Mind you, for the sake of arguments I could do it that way first (and save money), then if I have vapour probs spend some cash on a new pump etc.

thanks guys!