external pump hobbs vs constant
Thread Starter
Burning Brakes
Joined: Sep 2016
Posts: 979
Likes: 102
external pump hobbs vs constant
Im building a fuel system for my z06. I like the idea of using a factory style pump along with a 2nd external. I read a few guys who ran their 2nd pump constant vs using a hobbs switch. Ive never ran a hobbs switch but I like the thought of a external constantly on vs the hobbs switch. Constant power would also be more clean of an install.
Just looking to the pros and cons before I start buying everything.
Just looking to the pros and cons before I start buying everything.
Drifting
Joined: Dec 2003
Posts: 1,755
Likes: 88
From: Pearland Texas
Turpid Porpoise is correct. All I have seen do that have had the external pumps burn up over time depending on the pump, but most wouldn't make it 6 months. Staged fuel systems work great and don't add any unwanted heat. The fuel regulator should keep the fuel pressure from swinging much if at all when they come on. GL!
Burning Brakes
Joined: Nov 2010
Posts: 1,112
Likes: 62
From: Chicago IL
I have an external Magnafuel 4303 wired to run continuously. Personally I would rather not rely on another component to turn on the fuel pump. To me that's just one more component that could malfunction and not turn my pump on when I need it. I run E85 so I'm not worried about my fuel getting overly warm. I ran a Bosch fuel pump externally for about four seasons and I am on my second season with the magna fuel pump. My car is not a daily driver, more like a weekend warrior.
Last edited by junk c5; Apr 11, 2017 at 02:05 PM.
Thread Starter
Burning Brakes
Joined: Sep 2016
Posts: 979
Likes: 102
I have an external Magnafuel 4303 wired to run continuously. Personally I would rather not rely on another component to turn on the fuel pump. To me that's just one more component that could malfunction and not turn my pump on when I need it. I run E85 so I'm not worried about my fuel getting overly warm. I ran a Bosch fuel pump externally for about four seasons and I am on my second season with the magna fuel pump. My car is not a daily driver, more like a weekend warrior.
Thats how I feel. My car is a daily driver in the summer when its nice out. I will also be on e85. Hoping to run flex fuel on the c5 as well.
Drifting
Joined: Dec 2003
Posts: 1,755
Likes: 88
From: Pearland Texas
I have an external Magnafuel 4303 wired to run continuously. Personally I would rather not rely on another component to turn on the fuel pump. To me that's just one more component that could malfunction and not turn my pump on when I need it. I run E85 so I'm not worried about my fuel getting overly warm. I ran a Bosch fuel pump externally for about four seasons and I am on my second season with the magna fuel pump. My car is not a daily driver, more like a weekend warrior.
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Drifting
Joined: Dec 2003
Posts: 1,755
Likes: 88
From: Pearland Texas
Not that I can see. I think you could use a WOT switch or window switch how ever you want, what ever you wanted to trigger it with as long as you can verify your not going lean or dropping FP during a pull etc...
Burning Brakes
Joined: Nov 2010
Posts: 1,112
Likes: 62
From: Chicago IL
I've been doing some reading about adding a Hobbs switch to get away from the constant race car sound and what I've seen sounds concerning. From what it sounds like, with just one pump going and the fuel pressure at 43 lbs guys have had problems with the fuel transfer system at that low of fuel pressure. Does anyone have any input on that topic ?
Le Mans Master
Joined: Dec 2007
Posts: 8,375
Likes: 97
From: Somewhere in the Mid 9's TX
Turpid Porpoise is correct. All I have seen do that have had the external pumps burn up over time depending on the pump, but most wouldn't make it 6 months. Staged fuel systems work great and don't add any unwanted heat. The fuel regulator should keep the fuel pressure from swinging much if at all when they come on. GL!
Race Director
Joined: Dec 1999
Posts: 10,230
Likes: 885
From: Alexandria, Virginia, USA VA
what ecm are you using for e85?
I'm going to try a Haltech S2000 with flex fuel sensor and the computer will control the external pump and has penty of failsafes if either of the pump fails.
I've also heard of backfitting a factory e85 computer and repining and reprogramming to work with the c5 stuff.
broke right now, but $ are coming
I'm going to try a Haltech S2000 with flex fuel sensor and the computer will control the external pump and has penty of failsafes if either of the pump fails.
I've also heard of backfitting a factory e85 computer and repining and reprogramming to work with the c5 stuff.
broke right now, but $ are coming
Drifting
Joined: Sep 2009
Posts: 1,330
Likes: 61
From: Nantucket MA
The initial setup on my car was a internal LPE 255 and an external Bosch 044 that ran all the time. That setup literally lasted one day on Drag Week 2014. V2 on the car was an internal 255/340 combo with the 255 as the primary and the 340 coming on via Hobbs at 2psi. That combo ran great with no real issues. I'd do the Drag Week drives on one tank with no fuel stops and still have 1/8th tank left each day. I will say that that after the whole week the primary pump was none too happy with that low fuel level but it still toughed it out.
This winter I pulled both pumps and replaced them with two new Aeromotive 340's. Not expecting any fueling issues if the future. Also, we've swapped cam's and picked up a sizable amount of power. I'd expect 8.9X on 93 pump with the new setup.
- Travis
This winter I pulled both pumps and replaced them with two new Aeromotive 340's. Not expecting any fueling issues if the future. Also, we've swapped cam's and picked up a sizable amount of power. I'd expect 8.9X on 93 pump with the new setup.
- Travis
Drifting
Joined: Dec 2003
Posts: 1,755
Likes: 88
From: Pearland Texas
I've been doing some reading about adding a Hobbs switch to get away from the constant race car sound and what I've seen sounds concerning. From what it sounds like, with just one pump going and the fuel pressure at 43 lbs guys have had problems with the fuel transfer system at that low of fuel pressure. Does anyone have any input on that topic ?
Burning Brakes
Joined: Nov 2010
Posts: 1,112
Likes: 62
From: Chicago IL
Well you have to change the regulator in the passenger side tank to allow it to transfer at lower pressures. But if you've done that I don't know of a lot of issues with anyone locally. The Fuel system in general on vette's isn't user friendly, but it does work when all is together correctly. I run my current C6 at 40lbs base pressure. Not exactly the same but the function pretty much is. On other C5's setup's I never ran less than 45lbs but never had issues with the transfer. GL don't know if my info offers any help or answers for you, but it is all I have for you lol! GL!
Drifting
Joined: Dec 2003
Posts: 1,755
Likes: 88
From: Pearland Texas
http://www.lingenfelter.com/product/...l#.WPVpbJh1rcs
Team Owner
Joined: Sep 2001
Posts: 23,283
Likes: 906
From: Lake Elsinore, CA
Lingenfelter site says this is for the 2003-1/2 and up with the C6 fuel setup. Any application to the C5 platform prior to that?
"The Lingenfelter fuel pressure regulator block off is precision CNC machined from aluminum and then anodized red for added durability.
Designed for Corvette applications:
2005-2007 C6 Corvette LS2 engine
2006-2007 C6 Z06 Corvette LS7 engine
2003 1/2-2004 C5 Corvette LS1 or LS6
Note: General Motors switched the C5 Corvette fuel systems over to the C6 Corvette fuel system design halfway through the 2003 model year. Corvettes with the last 6 digits of the VIN being 114930 or higher were produced November 25, 2002 and later and have the new C6 style fuel system.
This regulator block off should be used in conjunction with the Lingenfelter driver side fuel tank block off fitting."
"The Lingenfelter fuel pressure regulator block off is precision CNC machined from aluminum and then anodized red for added durability.
Designed for Corvette applications:
2005-2007 C6 Corvette LS2 engine
2006-2007 C6 Z06 Corvette LS7 engine
2003 1/2-2004 C5 Corvette LS1 or LS6
Note: General Motors switched the C5 Corvette fuel systems over to the C6 Corvette fuel system design halfway through the 2003 model year. Corvettes with the last 6 digits of the VIN being 114930 or higher were produced November 25, 2002 and later and have the new C6 style fuel system.
This regulator block off should be used in conjunction with the Lingenfelter driver side fuel tank block off fitting."
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Joined: Oct 2004
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From: Providing the most proven supercharger kits for your C5/6/7 609-752-0321
If you are worried about a hobbs switch failing then set it up like an airplane and use two. Check them once a year just like an aircraft's annual inspection.
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