Wanting to add a hobbs switch to my twin pump in tank setup, which one?
06-07-2016, 12:00 PM
#1
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Wanting to add a hobbs switch to my twin pump in tank setup, which one? I have to Walbaro's in my tank, I wanted to add a Hobbs switch. I found 2 at NAPA. One seems to be a high pressure and the other a low pressure hobbs switch. Which one should I get? Also, does anyone have any install write up's or diagrams for installing a hobbs for twins intank?
Low Pressure: https://www.napaonline.com/napa/en/p...575/BK_7011575
High Pressure: https://www.napaonline.com/napa/en/p...577/BK_7011577
Low Pressure: https://www.napaonline.com/napa/en/p...575/BK_7011575
High Pressure: https://www.napaonline.com/napa/en/p...577/BK_7011577
Last edited by MoNoXSizzlE; 06-07-2016 at 05:30 PM.
06-07-2016, 12:38 PM
#2
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It helps to know the EXACT pressure. The low pressure switches are usually 4 PSI and adjustable, so that's probably your best bet.
Just take the ground wire for the 2nd pump relay and put the hobbs switch right in the middle of it. Your 2nd pump relay won't get ground until you're running enough boost to close the switch.
I have dual 340s in my tank and just run them all of the time.
Just take the ground wire for the 2nd pump relay and put the hobbs switch right in the middle of it. Your 2nd pump relay won't get ground until you're running enough boost to close the switch.
I have dual 340s in my tank and just run them all of the time.
06-07-2016, 05:11 PM
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It helps to know the EXACT pressure. The low pressure switches are usually 4 PSI and adjustable, so that's probably your best bet.
Just take the ground wire for the 2nd pump relay and put the hobbs switch right in the middle of it. Your 2nd pump relay won't get ground until you're running enough boost to close the switch.
I have dual 340s in my tank and just run them all of the time.
Just take the ground wire for the 2nd pump relay and put the hobbs switch right in the middle of it. Your 2nd pump relay won't get ground until you're running enough boost to close the switch.
I have dual 340s in my tank and just run them all of the time.
06-15-2016, 11:03 AM
#4
I would get the low pressure one for sure. My thinking on it is always this: Whatever the psi engage the switch has (Let's call it 4psi), that is the exact moment that it turns on the pump, and the pump has to spin up and start producing the extra fuel flow. This process is fairly quick, but still obviously takes a little bit of time. So with that being said, you may not receive your full twin pump fuel flow until a few psi later. I would hate for this phenomena to happen at a higher psi, so that is why me personally, I always choose the lower psi switch. Just my $0.02.
06-15-2016, 05:54 PM
#5
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I would get the low pressure one for sure. My thinking on it is always this: Whatever the psi engage the switch has (Let's call it 4psi), that is the exact moment that it turns on the pump, and the pump has to spin up and start producing the extra fuel flow. This process is fairly quick, but still obviously takes a little bit of time. So with that being said, you may not receive your full twin pump fuel flow until a few psi later. I would hate for this phenomena to happen at a higher psi, so that is why me personally, I always choose the lower psi switch. Just my $0.02.
06-15-2016, 08:09 PM
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I run this switch, it says Hobbs right on it,cheapest real I've found. And there's a removable cap for adjustment
(even though it says not)
Edelbrock 72213, Edelbrock Fuel Pressure Safety Switch | Edelbrock
(even though it says not)
Edelbrock 72213, Edelbrock Fuel Pressure Safety Switch | Edelbrock
Last edited by LT1PWRD; 06-15-2016 at 08:17 PM.
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06-16-2016, 10:54 AM
#8
To the people saying to run both pumps on at all times. I admit, I used to do this as well. I was the same as you guys where I did NOT want an EXTRA point of failure wired into my car. But then I noticed that running two pumps on at all times put a lot of stress on my my regulator at idle and cruise regions. It was buzzing at a really high rate because it has sooo much flow to regulate. So I turned to the Hobbs switch idea.
06-16-2016, 11:51 AM
#9
I've been trying to figure if I want to do this myself as my truck will be street driven sometimes although not a Dailey driver. I know the twin 044 pumps are going to push a lot of flow and the regulator is going to be working overtime trying to keep up. And the fuel is going to heat up as I only have a 10 gallon cell.
I like the safety of not running it, but I also don't like what happens to other parts if you don't run it.
One question though about the FPR. I am going to run a boost referenced FPR. So if you set the base pressure with only 1 pump running and the FPR does what it does on a 1-1 ratio with boost reference, what is going to happen when the 2nd pump comes on? The pressure increases as well as flow of course, but does it effect the FPR from delivering the right fuel pressure/flow?
I did find this one with a real quick search. Its adjustable. I will also look for others.
http://www.atpturbo.com/mm5/merchant...&Store_Code=tp
This one is NO and NC. 1-25psi adjustable
http://www.coolingmist.com/pagedispl...mart_injection
I like the safety of not running it, but I also don't like what happens to other parts if you don't run it.
One question though about the FPR. I am going to run a boost referenced FPR. So if you set the base pressure with only 1 pump running and the FPR does what it does on a 1-1 ratio with boost reference, what is going to happen when the 2nd pump comes on? The pressure increases as well as flow of course, but does it effect the FPR from delivering the right fuel pressure/flow?
I did find this one with a real quick search. Its adjustable. I will also look for others.
http://www.atpturbo.com/mm5/merchant...&Store_Code=tp
This one is NO and NC. 1-25psi adjustable
http://www.coolingmist.com/pagedispl...mart_injection
Last edited by Taxman20; 06-16-2016 at 12:00 PM.
06-16-2016, 12:06 PM
#10
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To the people saying to run both pumps on at all times. I admit, I used to do this as well. I was the same as you guys where I did NOT want an EXTRA point of failure wired into my car. But then I noticed that running two pumps on at all times put a lot of stress on my my regulator at idle and cruise regions. It was buzzing at a really high rate because it has sooo much flow to regulate. So I turned to the Hobbs switch idea.
06-16-2016, 04:23 PM
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To the people saying to run both pumps on at all times. I admit, I used to do this as well. I was the same as you guys where I did NOT want an EXTRA point of failure wired into my car. But then I noticed that running two pumps on at all times put a lot of stress on my my regulator at idle and cruise regions. It was buzzing at a really high rate because it has sooo much flow to regulate. So I turned to the Hobbs switch idea.
06-16-2016, 05:43 PM
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I've been trying to figure if I want to do this myself as my truck will be street driven sometimes although not a Dailey driver. I know the twin 044 pumps are going to push a lot of flow and the regulator is going to be working overtime trying to keep up. And the fuel is going to heat up as I only have a 10 gallon cell.
I like the safety of not running it, but I also don't like what happens to other parts if you don't run it.
One question though about the FPR. I am going to run a boost referenced FPR. So if you set the base pressure with only 1 pump running and the FPR does what it does on a 1-1 ratio with boost reference, what is going to happen when the 2nd pump comes on? The pressure increases as well as flow of course, but does it effect the FPR from delivering the right fuel pressure/flow?
I did find this one with a real quick search. Its adjustable. I will also look for others.
http://www.atpturbo.com/mm5/merchant...&Store_Code=tp
This one is NO and NC. 1-25psi adjustable
http://www.coolingmist.com/pagedispl...mart_injection
I like the safety of not running it, but I also don't like what happens to other parts if you don't run it.
One question though about the FPR. I am going to run a boost referenced FPR. So if you set the base pressure with only 1 pump running and the FPR does what it does on a 1-1 ratio with boost reference, what is going to happen when the 2nd pump comes on? The pressure increases as well as flow of course, but does it effect the FPR from delivering the right fuel pressure/flow?
I did find this one with a real quick search. Its adjustable. I will also look for others.
http://www.atpturbo.com/mm5/merchant...&Store_Code=tp
This one is NO and NC. 1-25psi adjustable
http://www.coolingmist.com/pagedispl...mart_injection
06-16-2016, 08:08 PM
#14
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I'm running -6 return with fuel lab reg, no buzzing here as that would bother the **** outta me..but I'm also running Hobbs switch to kick on second pump. also, if your worried about wearing the primary pump out before the other, you can just switch your relay connector after a while and run the opposite pump as your primary pump at any time...takes 30 seconds to switch with car on lift
Last edited by boostedxs; 06-16-2016 at 08:24 PM.
06-16-2016, 08:55 PM
#16
HOBBS is a brand of pressure switch. . A true HOBBS brand pressure switch is VERY reliable. I've run many of them for years and years, never had an issue. The pump/relay is more likely to fail than a true HOBBS brand switch IMO.
With both pumps on all the time you can still have failures without a fail safe in place... What happens if one pump fails during a pass and the other keeps going? Or if one pump slowly starts losing pressure?
With something like an MS3 you don't really need to worry about a switch/relay failure. There are many safeties you can put in place to protect you in the unlikely event of a failure.
Running both pumps is pointless IMO. heats up fuel and wastes energy. No reason to do it if you're running something with fail safes IMO. I'd run a tiny quiet pump for cruising and something huge for a secondary. (or dual pumps for a secondary) Best of both worlds that way.
With both pumps on all the time you can still have failures without a fail safe in place... What happens if one pump fails during a pass and the other keeps going? Or if one pump slowly starts losing pressure?
With something like an MS3 you don't really need to worry about a switch/relay failure. There are many safeties you can put in place to protect you in the unlikely event of a failure.
Running both pumps is pointless IMO. heats up fuel and wastes energy. No reason to do it if you're running something with fail safes IMO. I'd run a tiny quiet pump for cruising and something huge for a secondary. (or dual pumps for a secondary) Best of both worlds that way.
06-17-2016, 10:26 AM
#17
Running both pumps is pointless IMO. heats up fuel and wastes energy. No reason to do it if you're running something with fail safes IMO. I'd run a tiny quiet pump for cruising and something huge for a secondary. (or dual pumps for a secondary) Best of both worlds that way.
06-19-2016, 12:59 PM
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I just ordered a 2psi Stewart Warner 5000 series switch. I also have an adjustable one if I choose to go that route.
I am running two external Bosch 420liter/hr bumps with -10AN feed, and -8 return. Each pump has its own filter and use a dual -10 sumped modified factory tank setup then -8s from each pump with check valves to a Y block that exits as -10 to fuel rails. Hoping to hit 900+rwhp.
I am running two external Bosch 420liter/hr bumps with -10AN feed, and -8 return. Each pump has its own filter and use a dual -10 sumped modified factory tank setup then -8s from each pump with check valves to a Y block that exits as -10 to fuel rails. Hoping to hit 900+rwhp.