Is there a better Walbro pump?
08-12-2007, 08:43 PM
#1
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Is there a better Walbro pump?
I'm looking to finally do something with my fuel system, and I've been looking at the various Walbro-based kits.
Turns out that the 392 in most kits is way too big. It runs about 66GPH at a typical fp of 20psi.
Walbro makes a GSL-394 model which only flows 50gph at the same pressure, yet it's just as rugged and strong because it can handle pressures up to 130psi!
Keep in mind that a CTD at the 600hp level is burning 33gph. Add 25% for cooling fuel, and you're right around 41gph.
The idea is that pumping all kinds of fuel that you can't use is very inefficient. It aerates fuel. It HEATS fuel as well! Hot fuel won't cool your VP44 as well.
I'm sure there's nothing wrong, per se, with a 392, it's just that a 394 might be more applicable to those of us below sledpulling HP levels.
It's something to think about.
here's the chart:
Turns out that the 392 in most kits is way too big. It runs about 66GPH at a typical fp of 20psi.
Walbro makes a GSL-394 model which only flows 50gph at the same pressure, yet it's just as rugged and strong because it can handle pressures up to 130psi!
Keep in mind that a CTD at the 600hp level is burning 33gph. Add 25% for cooling fuel, and you're right around 41gph.
The idea is that pumping all kinds of fuel that you can't use is very inefficient. It aerates fuel. It HEATS fuel as well! Hot fuel won't cool your VP44 as well.
I'm sure there's nothing wrong, per se, with a 392, it's just that a 394 might be more applicable to those of us below sledpulling HP levels.
It's something to think about.
here's the chart:
08-13-2007, 12:19 PM
#2
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I thought the same when I built my fuel system and concluded, after experimenting, that none of the Walbro pumps have low enough fuel flow to remain within reasonable pressure without a return/bypass. This is why I decided it was inconsequential which GSL to get, and got the 392. The choice is further simplified by the fact that they all cost about the same.
Now what is very interesting to me, the in-tank Walbros can be had for quite a bit less, and the bypass regulator would be in the tank (read: no extra plumbing at all required on the frame rail), and the pump is cooled by all the fuel in the tank. I think in-tank Walbro is the pump of choice if one wanted to make a truly drop-in replacement for the stock LP.
The only problem with in-tank Walbro would be, if adding HP or simply wanting higher pressure, one needs to drop the tank to get access to FP regulator inside the tank. Oh well; how many people tweak their FP all that much, anyway? Most are just happy with 17/15 or 14/10 or something like that.
-P
Now what is very interesting to me, the in-tank Walbros can be had for quite a bit less, and the bypass regulator would be in the tank (read: no extra plumbing at all required on the frame rail), and the pump is cooled by all the fuel in the tank. I think in-tank Walbro is the pump of choice if one wanted to make a truly drop-in replacement for the stock LP.
The only problem with in-tank Walbro would be, if adding HP or simply wanting higher pressure, one needs to drop the tank to get access to FP regulator inside the tank. Oh well; how many people tweak their FP all that much, anyway? Most are just happy with 17/15 or 14/10 or something like that.
-P
08-13-2007, 02:48 PM
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Doesn't have to be, of course. But I was thinking about drop-in, zero outside mods... like, no understanding from the user required, kind of setup. In this case it would be simpler to have the pump and reg in one unit, and it would dump right back into the tank. Buy a single unit, install and forget. I think many people would like one of those things.
-P
-P
08-13-2007, 02:51 PM
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-P
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08-13-2007, 05:02 PM
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Not at all. The efficiency of the pump is completely unrelated.
What I'm saying is that pumping a lot more fuel than you need to-- with ANY pump-- is less efficient.
Think air compressors, for example. Most air tools run at 90psi max. So why do you need a compressor that goes to 175psi? You don't! The idea is just that the compressor won't run continuously. Far more efficient to have a 80gal tank at 120psi than a 30 gal tank at 180psi. But no one wants to give up the huge space for a massive air tank, so they crank up the pressure on a small compressor.
The most efficient way to compress air for a 90psi air tool is to continuously run a compressor at 90psi. But that doesn't give you any wiggle room and no one wants the compressor running continuously.
Taking it back to the fuel pumps, it's most efficient to pump what you need-- no more, no less. In the case of being over-pumped, this just shows up as hotter fuel temps.
..Just like an air compressor that runs at 175psi runs a lot hotter than a lower psi compressor. Compare a small Craftsman home-user compressor to a small IR home user compressor (garagemate) and you'll see the IR runs a lot lower PSI, but delivers just as much air. It runs cooler and will last a ton longer.
Sorry for the tangent, I hope it helped make the point.
JH
08-13-2007, 05:41 PM
#10
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But I was thinking about drop-in, zero outside mods... like, no understanding from the user required, kind of setup. In this case it would be simpler to have the pump and reg in one unit, and it would dump right back into the tank. Buy a single unit, install and forget. I think many people would like one of those things.
-P
-P
Tony
08-13-2007, 05:44 PM
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i think i am just going to get another walbro and run 2 of them
08-13-2007, 06:36 PM
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How are you noticeing your running out of fuel, by a gauge or the truck stuttering. I think all your doing is draining your rail because the cp3 cant handle the stack. The walbro should supply more fuel than you will be able to burn.
08-13-2007, 06:47 PM
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All of the things you mentioned HOHN have been my thoughts on the high output of the Walbros as well. All that pressure being regulated down must build up heat, aeration, or something. I like overkill (CON FE with ~400 HP) but I don't know if Walbros are smart overkill.
Still running my factory LP in its factory location so I have had a while to mull over all the pump options. I still don't have a lock on which is best. Time is ticking and I'm sure I'll emergently pick one at any time now...
Still running my factory LP in its factory location so I have had a while to mull over all the pump options. I still don't have a lock on which is best. Time is ticking and I'm sure I'll emergently pick one at any time now...
08-13-2007, 07:13 PM
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I agree with HOHN that running a high volume pump is not optimum. The Fass and Airdog claim that fuel pumps cause air to be entrained in the fuel and their pumps separate the air out of the fuel. I believe this is because the pump is running at full speed and whips the fuel into a froth.
Last week I received a cheap PWM motor driver kit. By using a pressure sender and this kit it is possible to run the pump at the speed needed to maintain the pressure you set but not whip the fuel up. There will be no need for a bypass regulator.
Here is a link to the manufacturer of the kit. http://www.vellemanusa.com/us/enu/pr...iew/?id=350605
If you do a search for the K8004 DC to PWM kit you will find them for less than $20.
In the next week I hope to post my experience with this kit driving an Aeromotive gerotor pump, similar to the Walbro pumps. It looks like this kit will power an electronic pressure sender and by using the pots on the PC board, makes the pressure adjustable. Just give me a few days.
Last week I received a cheap PWM motor driver kit. By using a pressure sender and this kit it is possible to run the pump at the speed needed to maintain the pressure you set but not whip the fuel up. There will be no need for a bypass regulator.
Here is a link to the manufacturer of the kit. http://www.vellemanusa.com/us/enu/pr...iew/?id=350605
If you do a search for the K8004 DC to PWM kit you will find them for less than $20.
In the next week I hope to post my experience with this kit driving an Aeromotive gerotor pump, similar to the Walbro pumps. It looks like this kit will power an electronic pressure sender and by using the pots on the PC board, makes the pressure adjustable. Just give me a few days.