Fuel System Questions

[Aussie Mike]

Hi All,

I'm getting my fuel system together at the moment and have been thinking of a few different ways to get things going.

I've got a VN Commodore tank with in tank pump but I'm doubtful as to whether the VN pump will keep up with the LS1's requirements.

lately I've been thinking about removing the in tank pump and having a straight pickup and using an external low pressure pump like a Holley red or Carter gold. This would then feed a 1 or 2 litre swirl pot up in the engine bay. From the Swirl pot I'd use a Bosch motorsport pump and regulator to feed from the swirl pot to the motor.

I was thinking of using an external low pressure pump as I've heard that high pressure pumps can fail when running under a light load just feeding a swirl pot.

I also thought that putting the swirl pot up in the engine bay keeps my high pressure fuel lines to a minimum and I've got plenty of room on the firewall for the swirl pot, pump and regulator.

What do you think? A silly idea? Any sugestions?

[Adrian S]

You mean you have to feed LS1's fuel? I thought they were powered by 'The Force' ! The dark side ain't that dark afterall.

What you're suggesting is very close to what I have except my swirl pot (1 ltr) is next to the fuel tank. Not so far for the small lifter pump to push the fuel. I'm running a Pierburg low pressure lifter pump and a Bosch high-pressure pump (good to 600Hp so VPW tell me).

The only thing that makes me nervous with your suggestion is having the swirl pot in the engine bay. I guess the fuel in it's being recycled often enough not to risk it getting too hot but after you switch the engine off - who knows? Perhaps I'm just paranoid. All I'm saying is just be careful. Noise could be another factor. The pumps are annoyingly noisy things and having the drone alot closer to you might be a nuisance.

Cheers,
Adrian.

[BevanWright]

I have a simlar issue. My car is Hillborn Injected which has its own pump driven by belt at the front of the engine, and sucks from the tank directly. I get surge around sweeping corners, or uphill when racing if the tank gets much below half full.

I was thinking about installing a tank as you describe, and letting the Hillborn pump suck from the surge tank, but... What do I use to provide enough fuel to supply the surge tank at as rapid a rate as the Hillborn pump takes it out? The Hillborn system takes a lot of extra fuel and returns to the tank, so potentially is pumping very fast (and up to the requirements of 600 - 700HP).

What is the answer? two pumps into a rear surge tank with an overflow back to the main tank? .

I have had a suggestion of feeding the return line back to the surge tank, but that must return warm fuel, and potentially under full throttle for prolonged periods wont return enough to keep the surge tank full?

Anyone had any experience in Hillborn systems?

[Cobra.au]

Hi Mike,
If you can locate a fuel tank or pump / sender from the early VN V8 they were set up with a low pressure internal pump and external high pressure pump from holden I went this way using a swirl pot and Bosch mototsport pump and have had no preoblems yet.
In the next month I am fitting my supercharger and intercooler so I let you know how well this setup supplies fuel as I may have to upgrade to keep fuel delivery up to scratch.

Cobra.au

[Aussie Mike]

Yes the heat into the swirl pot is one of my concerns. I guess I could go with my earlier plan of fitting the swirl pot and pumps in the rear wheel arch.

I like the idea of low pressure lines and fittings running along the chassis and high pressure lines being a really short run from the pump/regulator to the injector rails. Minimal loss of pressure/flow that way.

Bevan,

You could use an electric pump to feed the swirl pot and have a return line from the pot to the tank. Have the Hillborn pump take fuel from the swirl pot and return it to the swirl pot and you'll never run out of fuel.

The electic pump will be bringing cool fuel from the tank all the time and it has the whole run up the car in the fuel line to cool it too. That should keep the fuel tems in the swirl pot down regardless of the fuel coming back from the Hillborn pump. Engine bay heat would probably heat the fuel in the swirl pot more than returned fuel.

Cheers

[Aussie Mike]

I had a bit of a brain storm this afternoon!

Boxhead gave me a fuel pump assembly for a late model LS1 Commodore. It won't fit in the VN tank but I could build a swirl pot that it would fit into. I could feed this with a lift pump or the VN pump and have the pot installed in the rear wheel arch. The LS1 Commodore pump will supply my motor no trouble and I can utilise it's integrated regulator and run a single line up to the motor.

Cheers

[boxhead]

Sounds like a good idea to me Mike, are you going to fit a carbon canister at the rear aswell?

[Adrian S]

Sounds like the go. The less lines the better but you will need either a vacuum line going back to a charcoal canister or a vent/breather line going forward.

In case anyone's interested, here is a picture of my fuel system setup. There is a regulator(not shown) on the end of the fuel rail.

Cheers,
Adrian.

[trularin]

Nice picture.

I think you forgot the bleed line for the regulator to "off-load" back to the tank or "swirl pot".

[Aussie Mike]

I had a bit of a measure up and a ponder in the shed tonight and I think it'll work a treat. The high pressure fuel pump assembly will fit nicely inside a 4" diameter tube by about 10" long so it'll make a nice swirl pot. There's plenty of room on the rear inner guard to mount it, the low pressure lift pump and 2 filters.

There will be a single high pressure line from the running from the pump/swirlpot to the engine bay since the regulator will be in the swirl pot. There will also be a vacume line to the motor for the carbon canister. I'll mount the carbon canster on the other side inner guard next to the filler neck. Should make for a clean un cluttered engine bay.

Cheers

Mike

[BevanWright]

I am not too sure about the idea of having a fuel pot sitting in your wheel arch tho. What happens if you get a tyre burst, or a rock flung up? JUst doesnt seem to be the safest spot.

[Adrian S]

Originally posted by trularin


Nice picture.

I think you forgot the bleed line for the regulator to "off-load" back to the tank or "swirl pot".

Look again, it's the one labelled 'Return'.

[Cobra.au]

The only problem with running one high pressure fuel line to your motor is that the fuel will not be recirculating back to the tank so you will get a bitt of heat soak which will affect performance

just a thought
COBRA.AU

[AC514]

Mike
Sounds like a lot of work to me
you should have put a FORD motor in that beast
like it was supposed to have at birth.

Cheers
GINO.

[Aussie Mike]

Originally posted by AC514


Mike
Sounds like a lot of work to me
you should have put a FORD motor in that beast
like it was supposed to have at birth.

Cheers
GINO.

Yeah, I thought about that but then I decided I wanted the car to go really fast instead.

Cheers

[Aussie Mike]

I'll put the swirl pot will be behind a 2mm thick aluminium panel in the wheel arch so it should be fairly safe from debris.

Heat soak into the fuel line might be an issue but this is how the factory run their system. The standard fuel rails on the LS1 don't have a return any way and I can't imagine getting much heat into the length of fuel line running under the car. I might run an extra line in and cap it incase I upgrade in the future.

Keep the feedback coming guys this is great stuff.

Cheers

[BevanWright]

I had some feedback from an old hot rodder that a return line pumping back into the swirl tank could cause fuel frothing as it was in a small container rather than the main fuel tank (where the froth gets a chance to settle). I am not sure how frothy fuel can get, but I guess it could cause a problem.