EFI Fuel Line Size

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EFI Fuel Line Size

Postby vegastre » Sun Apr 27, 2014 12:33 am

I'm putting a 3800 Supercharged EFI V6 in my SJ, Installed a high pressure pump and now hooking up the fuel lines. The SJ came with 5/16 line and the 3800 is 3/8. My question is? Will using the 5/16 line be ok > Does 1/16 make a huge difference. My only guess would be a lean condition at high RPM?
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Re: EFI Fuel Line Size

Postby spencerforhire » Sun Apr 27, 2014 6:59 am

Due to the high pressure used, line size on a SFI system is not as critical as it is with a carburetor. I've seen late model 600-700hp street cars with stock 3/8" line. I'm pretty sure a 5/16" line would feed your 3800 ok. Wasn't the original application for your V6 a return system? It would have probably been 3/8" feed and 5/16" return. What are you planning for return? A lot of retro-fitted fuel injection systems use a new 3/8" feed and use the smaller original line for return.
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Re: EFI Fuel Line Size

Postby vegastre » Sun Apr 27, 2014 2:54 pm

A lot of retro-fitted fuel injection systems use a new 3/8" feed and use the smaller original line for return.


Yep,
That is what I had in mind originally but the SJ lines are already in place molded and bent to fit the body. This is not a high performance application and I'm not a street racer so I was thinking the 5/16 feed would do the job. Still a lean condition at sustained high RPM would not be good for the piston tops which is my only concern =)
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Re: EFI Fuel Line Size

Postby Monza Harry » Sun Apr 27, 2014 5:10 pm

Phil if you are worried, put a low pressure, high volume pump at the back (in the tank) and add a high pressure (application correct) pump in the front, that will boost the flow through the smaller line. But that still doesn't answer the fuel return line situation. Unless your 3800 is a non-return system you will need to add a line, so why not just add a big supply, and recycle existing for return/vent/emissions duty? It is my understanding that the return less systems are pretty new like 2010 (+/-) up. Is your "New" power plant "Really New"? Harry
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Re: EFI Fuel Line Size

Postby vegastre » Mon Apr 28, 2014 1:59 pm

Right harry,
The SJ has a return line but it was for the early evap canister to recirculate fumes back to the tank instead of venting to atmosphere. Ya, I may just use the stock lines because a 16th doesn't seem like a deal breaker to me =) Hmmm...
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Re: EFI Fuel Line Size

Postby TimMcCabe » Tue Apr 29, 2014 8:59 am

I used the original 5/16 as the return line and ran a new 3/8 line for the pressure side on my TPI.
if you need a return line anyway, you might as well run the bigger line for the feed.
I used steel, but 3/8 aluminum would be pretty easy to bend to shape with a coil tube bender.

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