Semi-Returnless Fuel Setup

[MBS206]

9 hours ago, Dose Pipe Sutututu said:

Mark at MRC Performance & Dyno in NSW does this quite often, then uses both return/feed OEM lines as dual feed lines to the fuel rail.

The only drawback from this is the length of the vacuum hose from plenum to regulator at the back of the car, also increases the chances of that line failing from debris, unless you go tits out and make it all a hard line.

 

 

@Murray_Calavera I run a 40 micron filter, followed by a 10 micron filter, seems to be the norm? I just copied whatever most of the big shops do LOL.

Another sex spec option, something I may do in future if I still haven't gotten rid of the shit box is to run this:

http://injectordynamics.com/id-f750-fuel-filter/

has a gauge to show you the health of your filter too, no guessing around pulling things out to try clean/resolve.

Was doing some extra reading from ID on this filter (looking for info that I didn't find), and they do state, that the gauge is only really useful for normal return setups, and not returnless.

 

Only way the gauge is useful on returnless setup, is while you're at peak power.

[GTSBoy]

14 hours ago, MBS206 said:

and they do state, that the gauge is only really useful for normal return setups, and not returnless.

 

Only way the gauge is useful on returnless setup, is while you're at peak power.

To be fair, if it's mounted under the car, as it would be with most returnless setups, it's not as if it will get looked at very often. But it is a very valid point that you couldn't trust the differential pressure reading at all unless all the fuel was being pushed through it.

But even so - the actual dP through the filter will depend on the size of the fuel pump. If you have a small pump, a clean filter will read a (much**) lower dP than the same clean filter would with a much bigger pump. So the gauge should never be used as an absolute measure anyway. You would need to note the reading on a fresh clean filter and clean/replace when the dP goes up from that reading noticeably. I'm guessing that their instructions would say as much because the spec on the filter clearly shows different pressure drops across it at different flow rates, so they're right across the issue.

**This because dP will increase with the square of flow.