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Swirl pot question
theprisioner - 13/7/12 at 06:08 PM

Sylva special tank
Sylva special tank


I have a swirel pot, but not enough head to gravity feed a Bosch type 044 pump.

All the recommendations are that the 044 must be gravity fed with a minimal head.

So I have been following the SBD advice about going down the external swirel pot route:

SBD recommends
SBD recommends


I have done some experiments with a solid state pump and I can easily solve the head problem.

Question: As I have a swirel pot can I just leave out the external one and put both pumps in series?

P.S. I don't want to go the in tank pump route.


paulf - 13/7/12 at 08:14 PM

I dont think it would be a good idea as the flow rate of the LP pump would most likely be less than the HP and restrict the flow and would therefore achieve nothing.
Why do you think the feed from the in tank swirl pot would not be enough? most people fit a swirl pot and then fit the HP pump level with the base of it so the only head is the depth of the swirl pot.
Paul


tomgregory2000 - 13/7/12 at 08:57 PM

quote:
Originally posted by paulf
so the only head is the depth of the swirl pot.
Paul


And all the fuel above that


theprisioner - 13/7/12 at 10:11 PM

My understanding is part of the HP pump in my case would be below floor level to gain head when the fuel is level with the top of the swirel?

Pump issue
Pump issue


britishtrident - 14/7/12 at 05:31 AM

You are adding too much complication -- keep things simple.

if the tank shape is as shown in the sketch you don't need anything other than the HP pump mounted with the pump inlet level (or below ) the bottom of the tank. You don't even need the baffle (what you call a swirl pot) in the bottom of the tank.


adithorp - 14/7/12 at 07:47 AM

quote:
Originally posted by britishtrident
You are adding too much complication -- keep things simple.

if the tank shape is as shown in the sketch you don't need anything other than the HP pump mounted with the pump inlet level (or below ) the bottom of the tank. You don't even need the baffle (what you call a swirl pot) in the bottom of the tank.


What he said... KISS!

HP pumps don't like to pull/suck and can cause cavitation in the fuel lines but with the pump level with the outlet from your tank you'll have no problem. Mine was level with the top of the tank for 1 1/2 years (5000miles) with no running problems. Then moved level with the outlet where it''s been fine for 2 1/2 years.


theprisioner - 14/7/12 at 08:29 AM

I do have a habit of over complicating designs, that is why I posted this discussion in the first place, so I am grateful for the responses. That is why I find this forum so valuable.

Part of my question was prompted by the leaflet in the Sytec box:


" FUEL PUMPS ARE LUBRICATED & COOLED BY THE FUEL - DO NOT ALLOW THE FUEL LEVEL TO RUN EXCESSIVELY LOW"

"INJECTION PUMPS MUST BE GRAVITY FED (OR BY A LIFT PUMP)"


I assumed (possibly wrongly) a solid state pump could be regarded as a lift pump?

Note no reference to a swirel pot in between?

Anyway thanks for the responses I am listening!


britishtrident - 14/7/12 at 01:22 PM

Tank -> hp pump - > hp filter -> regulator (with return) - > injectors = job done.

It is no different from a Bosch HP pump fitted in tank the fuel in the tank gives you a positive head of pressure at the hp pump inlet.


tomgregory2000 - 14/7/12 at 08:04 PM

quote:
Originally posted by britishtrident
Tank -> hp pump - > hp filter -> regulator (with return) - > injectors = job done.

It is no different from a Bosch HP pump fitted in tank the fuel in the tank gives you a positive head of pressure at the hp pump inlet.


The regulator comes after the injectors in a normal set up


owelly - 14/7/12 at 08:30 PM

It matters not where the regulator comes off as long as it holds the correct pressure in the fuel rail. I had mine mounted on the return at the tank for a few weeks during some under-bonnet tweaking and it was fine.