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  1. #11
    Join Date
    Jul 2012
    Location
    NW England
    Posts
    472
    Quote Originally Posted by richard8166 View Post
    Thanks for all the advice!
    I think I'll go for a swirl pot and lift pump. I guess if a facet red top lift pump is good enough for Jim and his supercharger, then it will be plenty for me! If I could mount the pump below the fuel tank it would be fine, but it's just not really possible on my GD.

    So, my plan will be tank to lift pump (facet has built in pre filter), then into swirl pot. Swirl pot bottom outlet to a pre filter, then EFI pump, then post filter, then the regulator. Regulated feed to engine bay. Regulator return back to swirl pot top inlet, and swirl pot top return to tank. It won't take up much room in the boot, so should all be fine with a bit of planning.

    I guess I was also a bit surprised the the regulator location, I kind of expected it in the engine bay, but the boot location makes the return line very short and convenient. I think it just regulates to a pre set absolute pressure. The regulator has a port for connecting to an air pressure feed, so I guess it would be simple to run a vacuum pipe back into the boot should I choose to do so. I'm not sure I quite understand; I thought the injectors were happy to see an absolute pressure at the fuel rail, and the car has been running fine like this since built. I did read about using the air pressure feed on these regulators if using forced induction, so that the fuel pressure is increased to compensate for the boost pressure working against them. I guess in a normally aspirated setup, the vacuum could serve to drop the fuel pressure at idle and cruise conditions, so would take load off the injectors?

    I'll check all the fittings and connectors I have, then I was thinking of asking someone like Merlin Motorsport to recommend a setup. For example, looking at the fuel filters I'm not sure of the best choice for pre and post EFI pump filter. I'm tempted to replace the Bosch 044 like for like, but GD recommend the Walbro pump as being fine, and it is nearly half the price!

    I'd love to see pictures of your setups!

    Thanks, Richard
    Seems some systems us an absolute pressure supply and others use a supply referenced to plenum pressure. As long as you don’t mix the two there will be no problem and as you say the latter system has simpler plumbing.
    The lift pump doesn’t need to be too special, as long as it has capacity to provide the net flow rate requirement and the swirl pot has volume to provide for peak requirements as long as they’ll be in effect (not likely to be very long) all should be good. This is why I feed the return pipe into the pot, means that once fuel is in the high pressure system it remains there until used.
    My swirl pot is only about 1.5L and the lift pump a cheap Red top copy (currently being changed for in tank type) but never given an issue.

  2. #12
    Join Date
    Aug 2004
    Location
    Christchurch, NZ
    Age
    59
    Posts
    2,371
    I'm guessing linking fuel pressure to inlet pressure is an economy thing - removing the enrichment that the apparent increase in fuel pressure would cause. Probably done entirely in the electronics in newer systems.
    Cheers

    Myles D-W

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