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SF.com Member #0000000023
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Discussion Starter #1
Maybe I'm not reading this right, if so, hopefully someone can enlighten me.....

I think it's pretty much PROVEN that our factory fuel pumps are good for at the very least, 450rwhp safely .....probably a good bit more at the limits, infact a few individuals that I know of are pushing almost 600rwhp at BPU + NOS on the STOCK pump...a little insane IMO, but just stating facts. In any case, let's take 450rwhp as a "safe" figure.

My question, why is it necessary to go with dual Walbro fuel pumps? looking at the fuel pump tests on www.mkiv.com....

http://www.mkiv.com/techarticles/fuel_pumps_test/pump_test.jpg

I think we can narrow this discussion to the 60-70psi fuel pressure range (40 psi fuel pressure + 20-30 psi would be the range I would expect to see 450rwhp out of the stock twins).

Our stock pumps flow....
[email protected] FP or 15psi boost
[email protected] FP or 20psi boost
[email protected] FP or 25psi boost
[email protected] FP or 30psi boost

The higher flow Walbro flows...
[email protected] FP or 15psi boost (almost 50% better)
[email protected] FP or 20psi boost (50% increase)
[email protected] FP or 25psi boost (DOUBLE the OEM pump)
[email protected] FP or 30psi boost (oh crap!... that's 2.5x the flow of the OEM pump)
[email protected] FP or 40psi boost

This would indicate that a single Walbro pump is good for at least 700rwhp before even approaching it limits.

Any thoughts?

-Mike
 
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attn all the SMART PEOPLE :)

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attn Larry, Billy Barr, Dusty etc etc etc etc
 

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Well.... I think its a safety factor...

I had a fuse blow for the pump a while back(primary pump) which caused both pumps to turn off since the second pump is triggered off the first. To get home, not knowing what really happened, I just wired the second pump to run by itself(12V direct) while the primary was off....

I was easily able to run 1.5BAR with absolutely no indication of fuel pressure loss. I didn't turn the boost up for more testing, but I'm sure it could go a bit higher. I believe I could easily just run one pump at hight boost, but I have yet to test this.....

Interesting to note, on another web page, they showed that the Walbro pump wasn't as good as the stock Supra pump when tested by RC injectors. On a test bench, this could very well be true. But looking at some of the other info, I noticed that the Walbro pulls a LOT less current(I think less than half) than the factory pump. With such high current, you can't help but get some significant voltage loss to the factory pump, which may explain the differences between the tests. I know a Bosch 30AMP relay tends to MELT when running two factory pumps at 12v.
 

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SF.com Member #0000000023
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Discussion Starter #5 (Edited)
"Well.... I think its a safety factor..."

My main problem with the dual pump setup *IS* safety factor. My concern about the dual pump setup is if one of the pumps, the wiring or hoses to it fail for some reason. You would never know the difference until you went from 20-25psi and blew your motor. It simply does not make any sense to me to add a point of failure which would certainly result in a blown motor as well as the additional complexity. I would much rather pay for a single higher flowing fuel pump.

I actually just saw the article which you just referenced. Interesting. Anybody seen any flow tests for a 300zx twin turbo fuel pump? -I've heard those things easily outflow our pumps, but with the other limitations of that platform, it's hard to get a straight answer about the limits of such a huge pump.


-Mike


cr133r said:
Well.... I think its a safety factor...

I had a fuse blow for the pump a while back(primary pump) which caused both pumps to turn off since the second pump is triggered off the first. To get home, not knowing what really happened, I just wired the second pump to run by itself(12V direct) while the primary was off....

I was easily able to run 1.5BAR with absolutely no indication of fuel pressure loss. I didn't turn the boost up for more testing, but I'm sure it could go a bit higher. I believe I could easily just run one pump at hight boost, but I have yet to test this.....

Interesting to note, on another web page, they showed that the Walbro pump wasn't as good as the stock Supra pump when tested by RC injectors. On a test bench, this could very well be true. But looking at some of the other info, I noticed that the Walbro pulls a LOT less current(I think less than half) than the factory pump. With such high current, you can't help but get some significant voltage loss to the factory pump, which may explain the differences between the tests. I know a Bosch 30AMP relay tends to MELT when running two factory pumps at 12v.
 
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is there a way to wire the second pump so that it fails it causes the first one to fail or stop as well?

know what i mean?

that would be perfect.

:)
 
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