Seperate Swirl Pot

[boxhead]

Originally Posted by C0braed

The only thing I would suggest is to not return your fuel to the surge tank but return it back to the tank. The reasons for this is that you are retuning hot unused fuel back to the surge tank and then sending it back to the engine for consumption or recirculating. If you think that your lift pump is not capable of maintaining a full surge tank either your tank is to small or your lift pump is to small. The advertised flow ratings for most pumps is in US gallons (3.75 litres) per hour at what ever restriction required to achieve a rated pressure, when you remove the restriction and the pump is in free flow the volume is greatly increased, Make sure that the surge tank has the same size return as supply.

I agree with you there, I initialy only set it up that way wanting to be able to get every last drop of fuel from the tank, and I have similar issues as Gregg is describing in hi speed cornering and accelerating when the tank is below about 1/4 full, I was thinking that by returning the fuel to the swirl pot then atleast it is not getting sloshed around in the tank and missing the intank pick up.
I figured I was not chassing every single last bit of HP so the small loss due to warm fuel did not bother me.

All feed and return lines to and from surge tank are the same size, being 8mm ID

[C0braed]

Originally Posted by boxhead

I agree with you there, I initialy only set it up that way wanting to be able to get every last drop of fuel from the tank, and I have similar issues as Gregg is describing in hi speed cornering and accelerating when the tank is below about 1/4 full, I was thinking that by returning the fuel to the swirl pot then atleast it is not getting sloshed around in the tank and missing the intank pick up.
I figured I was not chassing every single last bit of HP so the small loss due to warm fuel did not bother me.

All feed and return lines to and from surge tank are the same size, being 8mm ID

The thing with returning fuel to the surge tank is that under full throttle or anything apart from idle is that less fuel is returned to the tank so in effect you will get little gain from it, at idle the engine is using less fuel and the return volume is at its highest and the lift pump should not be having any troubl supply the tank. The problem I have found with most surge tanks I have seen is that they usually have a -6 or -8 supply into them from the lift pump and the same size -6 or -8 as the return to the tank and then the have a -6 or -8 return into the surge tank for the returned fuel, so in effect you have double the supply into the tank but only half the area for returning to the tank. This in effect especially at idle will create pressurization of the surge tank and will apply pressure to the back of the regulator which can cause a richer than normal idle.

[Aussie Mike]

I reckon a bit of pressure in the surge tank is a good thing. I would even reccomend putting a restrictor in the return line to create a few PSI of possitive pressure in the surge tank.

The way I've got mine set up I have a #6 line from the in tank lift pump. This is a low pressure in tank pump from a VL commodore. I have a #6 return from the swirl pot but I've piece of brass in the line with a hole drilled in it to provide a bit of restriction. The feed from the swirl pot is a #8 line and it goes into the fuel filter and from the filter to the Bosch 044. There's a 1/2" line from the bosh 044 to the back of the left fuel rail and a crossover to the other rail. On the back of the right fuel rail there is a line to the regulator. The regulator bleeds off pressure to a #6 line back to the swirl pot.

There's also a check valve on the output of the 044 that stops fuel draining back trhu the pump when the car is sitting. It starts first turn of the key.

Here's a pic of the swirl pot looking from under the car (The pic is the wrong way round so it's a bit confusing)



The fuel lines running up the tunnel and you can see the reg on the firewall. the 3rd line is for the purge on the carbon canister.



Here's the fuel pump mounted on the underside of the boot floor. Not a position I would reccomend as the boot cavity makes the sound resonate even worse. You can see the check valve on the output.



Cheers