Returnless Fuel Pump Options
10-02-2014, 11:37 PM
#44
formerly turbo4.8 (2014-06-25)
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This last part confused me. Yes it's old, but Idc. So your saying to stay return less and toss a 450 in with 80lb injectors and should be good for around 700-800hrsp?
10-03-2014, 07:55 AM
#45
With 80lb injectors and a walbro 450 assuming max of 20psi of boost:
Returnless, base pressure set to 58psi -Injectors flow 315 l/hr and pump is 380 l/hr so you are injector limited and 315 l/hr is about 720rwhp.
Return, base pressure at 58 - Injectors flow 385 l/hr and pump flows 328 l/hr so you are pump limited and 328 l/hr is about 750rwhp.
For comparison, with a return setup with dual walbro 400s - Injectors are 385 l/hr but pumps are 571 l/hr so you are injector limited and 385 l/hr is about 883 rwhp.
Same setup with returnless and you are still injector limited, just like with a single 450. So with a reutnless setup it is not useful to have huge pumps because you will mostly always be injector limited.
I used this spreadsheet I made to figure this all out: https://www.performancetrucks.net/fo...p-flow-510434/
Returnless, base pressure set to 58psi -Injectors flow 315 l/hr and pump is 380 l/hr so you are injector limited and 315 l/hr is about 720rwhp.
Return, base pressure at 58 - Injectors flow 385 l/hr and pump flows 328 l/hr so you are pump limited and 328 l/hr is about 750rwhp.
For comparison, with a return setup with dual walbro 400s - Injectors are 385 l/hr but pumps are 571 l/hr so you are injector limited and 385 l/hr is about 883 rwhp.
Same setup with returnless and you are still injector limited, just like with a single 450. So with a reutnless setup it is not useful to have huge pumps because you will mostly always be injector limited.
I used this spreadsheet I made to figure this all out: https://www.performancetrucks.net/fo...p-flow-510434/
