single vs two line fuel system
Thread Starter
TECH Regular
Joined: Jan 2004
Posts: 426
Likes: 4
From: Austin, TX
single vs two line fuel system I am installing a 99 camaro LS1 in a tube-framed C1 Corvette and need some input on the relative merits of the single line versus the two line fuel systems that were used on earlier engines. A couple of vendors recomend swapping back to the supply and return system on my engine for "ease of installation", but I fail to see any time or effort savings by doing so. Is there any good reason to not use the single line fuel system on this car? I am new to the LS1 engine and obviously do not understand all the subtle nuances of these engines, but it seems simpler to install the pump and regulator in the tank and be done with it. Is there some inherent advantage to having the regulator at the engine and if so, why did GM change to the single line setup.
Regards, John McGraw
Regards, John McGraw
Joined: Nov 2001
Posts: 1,707
Likes: 33
From: Anderson, Indiana
GM switched to the single line fuel system to cut down on evap emissions that form when running all of the fuel up to the engine, warming it up, and then sending most of it back to the fuel tank.
With the single line system the fuel goes about 2 feet and then gets returned to the tank, without the heating effect of circulating around the hot engine.
From a pure performance standpoint the full length return line is better. You are sending lots more fuel than necessary right to the injectors, they use what they need and the rest is sent back. This setup is better at purging any air bubbles in the line and keeping the fuel going into the engine a little cooler.
If you can easily mount the factory fuel pump assembly/return line on your vehicle by all means go that way. On some swaps it's difficult to use, so going with an aftermarket fuel pressure regulator (or Vette filter/regulator) to "create" the return line becomes necessary.
Do whatever is easiest; you'll probably never notice a performance difference with either method.
With the single line system the fuel goes about 2 feet and then gets returned to the tank, without the heating effect of circulating around the hot engine.
From a pure performance standpoint the full length return line is better. You are sending lots more fuel than necessary right to the injectors, they use what they need and the rest is sent back. This setup is better at purging any air bubbles in the line and keeping the fuel going into the engine a little cooler.
If you can easily mount the factory fuel pump assembly/return line on your vehicle by all means go that way. On some swaps it's difficult to use, so going with an aftermarket fuel pressure regulator (or Vette filter/regulator) to "create" the return line becomes necessary.
Do whatever is easiest; you'll probably never notice a performance difference with either method.
__________________
91 Z28 LS2 408CI, LS9 Supercharger, LPE GT7 cam, Yank3000, 3450 raceweight.
Latest numbers: 9.71 ET, 141.42 MPH, 1.40 60' , 610 RWHP Mustang Dyno
www.speartech.com
91 Z28 LS2 408CI, LS9 Supercharger, LPE GT7 cam, Yank3000, 3450 raceweight.
Latest numbers: 9.71 ET, 141.42 MPH, 1.40 60' , 610 RWHP Mustang Dyno
www.speartech.com
Thread Starter
TECH Regular
Joined: Jan 2004
Posts: 426
Likes: 4
From: Austin, TX
Thanks John,
I pretty much figured that this was the case, but just wanted to verify. My car will be a cruiser, not a full gonzo street machine and I doubt that it will make a difference. It will sure make a cleaner installation in both the engine compartment and under the car!
Regards, John McGraw
I pretty much figured that this was the case, but just wanted to verify. My car will be a cruiser, not a full gonzo street machine and I doubt that it will make a difference. It will sure make a cleaner installation in both the engine compartment and under the car!
Regards, John McGraw
