modified FRx
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Senior User
Joined: Jul 2004
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From: Halstead, KS
modified FRx
A true regulated return setup redirects the fuel flow to the back of each head. From my understanding, this helps any air move uphill, and it also provides more fuel to the 6-8 cylinders.
I'm getting ready to install the FRx tomorrow. Is there any actual benefit to have the fuel rerouted to the back of the driver side head. I can easily do this with minimal cost if there truly is a benefit, if not, i'll slap it on like everyone else and go about my day.
I'm getting ready to install the FRx tomorrow. Is there any actual benefit to have the fuel rerouted to the back of the driver side head. I can easily do this with minimal cost if there truly is a benefit, if not, i'll slap it on like everyone else and go about my day.
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Joined: Jun 2015
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I installed the FRx and it was not hard to do. No performance gain that I could tell. The only thing I don't like is you are introducing more possible fuel leaks if it fails. The line on the drivers side is very close to the turbo, so I added some heat shielding. FYI, the biggest pain was lining up the billet housing, the return spring and the factory return line. Also while you are doing this mod, I would clean out your fuel bowl and remove the check valve in the filter stem (big restriction) Also, if you have not used the drain valve, don't. Just suck the fuel out with a turkey baster, works better anyway and less mess. Be sure to save the plugs in case the soft lines fail.
Hotshot
Joined: Jan 2011
Posts: 18,849
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From: Puget Sound
The important thing is to eliminate the deadhead issue - which the FRx does. If you supply air to the fuel, having the fuel feed to the back of the heads may help the air escape a little faster - but you still have air in fuel.
It's a bit of work to redo the fuel line to the rear of the driver side for those events where air gets in the fuel - but that added effort may be better used to prevent air intrusion in the first place. That's where a proper Hutch mod comes in. Hutch mod for prevention plus a standard FRx to eliminate deadhead is a nice combination to protect your injectors.
Under the heading of FWIW: I botched my Hutch mod and got a ton of air in there for a while. This damaged my #2 and #7, but #8 survived it just fine. So... my FRx couldn't protect the sticks that had "first dibs" on the incoming air - but it likely prevented the issue from spreading.
It's a bit of work to redo the fuel line to the rear of the driver side for those events where air gets in the fuel - but that added effort may be better used to prevent air intrusion in the first place. That's where a proper Hutch mod comes in. Hutch mod for prevention plus a standard FRx to eliminate deadhead is a nice combination to protect your injectors.
Under the heading of FWIW: I botched my Hutch mod and got a ton of air in there for a while. This damaged my #2 and #7, but #8 survived it just fine. So... my FRx couldn't protect the sticks that had "first dibs" on the incoming air - but it likely prevented the issue from spreading.
Hotshot
Joined: Jan 2011
Posts: 18,849
Likes: 179
From: Puget Sound
Opening the filter housing lid and removing the fuel filter to fit the turkey baster can make a big diesel mess in the valley - where you get to enjoy it in the cab for a while.
Fleet Mechanic
Joined: Nov 2005
Posts: 1,508
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From: North Carolina, Raleigh
Im with rich in this.. drain into pan on ground. done.
I installed additional fitting to rear driver head, protecting the fitting with 3000° ceremaic wool foil faced insulation.
I can tell you it did infact make the engine quieter at speed. so quiet my wife noticed and commented. replace all the fuel line replacing with SS braided race car fuel lines and AN-6 fittings. I was doing turbo rebuild and orings on pedestal as well so i had everything off the top.
Another good reason to redo fuel lines - Ford Truck Enthusiasts Forums
on thing to note,,, the back driver head fitting is not square. When you screw in a fitting it will not look right, it will look crossed threaded. its not. I used the gasoil? sealer in a tube and it works perfect not a leak at all.
interesting issue on back driver head port.. - Ford Truck Enthusiasts Forums
good luck, got every thing at summit racing.
I installed additional fitting to rear driver head, protecting the fitting with 3000° ceremaic wool foil faced insulation.
I can tell you it did infact make the engine quieter at speed. so quiet my wife noticed and commented. replace all the fuel line replacing with SS braided race car fuel lines and AN-6 fittings. I was doing turbo rebuild and orings on pedestal as well so i had everything off the top.
Another good reason to redo fuel lines - Ford Truck Enthusiasts Forums
on thing to note,,, the back driver head fitting is not square. When you screw in a fitting it will not look right, it will look crossed threaded. its not. I used the gasoil? sealer in a tube and it works perfect not a leak at all.
interesting issue on back driver head port.. - Ford Truck Enthusiasts Forums
good luck, got every thing at summit racing.
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Senior User
Joined: Jul 2004
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From: Halstead, KS
I've already replaced my factory steel lines with #4 braided line. After racing sprint cars and modifieds for the last 10 years I've collected quite a bit of these so routing one from the bowl to the back side of the LH head is not a big deal, just didn't know if there would be any actual benefits, since all the true regulated return systems are built this way. Plus I've got the turbo off right now to install the RR billet wheel and dorman up pipes, so getting to that fitting is pretty easy.
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Joined: Jun 2015
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Riffraff makes a another item that increases fuel flow, it goes in where the fuel enters the heads. Great time to add that little item, I have them but not installed yet. they replace the check valves.
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Senior User
Joined: Jul 2004
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From: Halstead, KS
When I replaced my factory lines with braided line I had to remove the check valve fittings and install #4an to 1/8" pipe fittings. Same as what RR sells.
I went ahead and just hooked it up like it is supposed to be. I've got probably 50-60 miles on it since install and honestly I cant tell any difference in motor noise. That doesn't bother me, knowing the air, if any, has a place to escape is what I was after.
Recap....this buckzooka go around, installed dorman up pipes, RR return and RR billet compressor wheel. ET of about 5hrs.
Next up, 4" exhaust probably in a couple weeks
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