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What hp and et is this pump good till? Its two Walbro 340 pumps side by side? Whats another alternative? I want to buy something big so I dont have to keep upgrading any suggestions?
 

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The main pump is a 340 and the second one is a 307. Guy's are easily running low 10's, I imagine it should take you into the high 9's with no problems.
 

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Why would one use a 340 and a 307 together? 307 has a lower bypass spring and uses more current?

It's really not as simple as saying this pump is good to here and two are good to here...:) of course, we do it all the time :D

You can calculate the flow of the pump at a given voltage and pressure and figure how many hp it will support. That is easy. Unfortunately, that is at the pump with no g force or line size taken into account so what you calculate is not necessarily what you get at the fuel rail.

And given that the line size stays constant, putting two pumps together may not give you as much additional delivery as you might expect. In order to optimize this, you need to replumb the system from the tank to the rail.

Now, I don't like double pumpers...seems like an old gimmicked technology that has been obsoleted by modern high capacity pumps. Seems to me that if one is going to spend the money on a drive train that will run into the nines, then one ought to spend enuf money on the fuel delivery system to protect it instead of relying on bandaids in the fuel tank.

I would prefer a sumped tank and an external pump with a controller to turn it down when I wanted to. I am in the minority on this, but, it has never bothered me to be in the minority on such. :D

Most cars seem to need more fuel than a single 340 once they get to the high tens from what I have seen. Depends a lot, obviously, on the combo and the tune.
 

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If you run injection.. that adds to the fuel delivery.

My car has a single 307 and no fueling issues. Ran 132.9 at BG couple weeks ago. I datalog my runs with my FAST and look for patterns of fuel correction top of third gear. If I dont see any.. life is good.

At some point one needs to address how much HP the engine will eventually make.. then make/develop a fuel system to support it. Point is you need data to make decisions. Without data... assumptions will cost you a ton of money and grief.

HTH
 

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Steve Wood said:
Why would one use a 340 and a 307 together? 307 has a lower bypass spring and uses more current?
Yes you are correct Steve! I was thinking of one thing and writing something else. I had a long discussion with Red last year about his double pumper. I was half a sleep when I wrote that. :eek:
 
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