USA-PI Posted February 13, 2017 Report Share Posted February 13, 2017 (edited) Hello to all, does it matter where the PRV is mounting , I'm thinking it will better to mount it close the MU rather than close to the pump this is the prv that Malcolm Jones of Prestige sent me , if mounting close to the pump is the better idea, can it be mounted directly to the Lucas pump? Edited February 13, 2017 by USA-PI Quote Link to post Share on other sites
barkerwilliams Posted February 13, 2017 Report Share Posted February 13, 2017 The PRV should be operating and spilling excess pressure at all engine revs, even beyond maximum revs, otherwise the engine will run weak. At low revs the PRV will be spilling perhaps 99% of the pumps output. The longer and narrower the low pressure return fuel pipe, and any small radius bends then it is more restrictive to the return flow and the greater will be the load placed on the fuel pump and the less chance of maintaining the constant pressure which the metering unit needs to deliver accurate fuelling. Now pumps are in various locations on the PI from the boot, wheel well or outside under the wheel arch. The high pressure line from the pump to the PRV is not as critical as the low pressure tank return and the PRV is usually sited adjacent to the lower corner of the tank with perhaps only nine to twelve inches of pipe to the tank return fitting. The PI typically needs to keep a gallon or two of fuel in an emptying tank to act as a heat sink for the fuel pump and everything you can do to minimise the load on the fuel pump and hence the heat it generates is a bonus. Also the fewer fuel lines running the length of the car must be a safety bonus in the event of an accident, Alan Quote Link to post Share on other sites
snowric Posted February 13, 2017 Report Share Posted February 13, 2017 the PRV Malcolm sent you can be screwed straight into the t-piece whcih holds the standard PRV and then feeds on to the MU. As the PRV has three lines - from pump, into t-piece to MU, bleed back to tank, I think it is better to fit the t-piece and PRV in the boot next to the pump ie where TR6s put them. Then you get a shorter return from the PRV. Snowy Quote Link to post Share on other sites
USA-PI Posted February 14, 2017 Author Report Share Posted February 14, 2017 (edited) Guys Thank You, So can I screw the PRV directly into the Lucas pump?, or does it have to be a line between the PRV and pump, I have a separate swirl pot,(US tanks do not have a swirl pot), it's one gallon in size,( 3.78541 liters ), it will be filled from tank by a facet red top pump, swirl pot will feed CAV filter, return line from PRV will return to swirl pot, return from filter will also go to swirl, and return from MU will go to fuel tank, and overflow from swirl pot will return to fuel tank. Edited February 14, 2017 by USA-PI Quote Link to post Share on other sites
TriumphV8 Posted February 14, 2017 Report Share Posted February 14, 2017 The PI typically needs to keep a gallon or two of fuel in an emptying tank to act as a heat sink for the fuel pump and everything you can do to minimise the load on the fuel pump and hence the heat it generates is a bonus. As there is not the biggest fuel tank fitted it might be a good idea to fit a swirl pot and a fuel cooler like from VW Sharan or the BMW Diesel. Quote Link to post Share on other sites
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