Dual Fuel Pump Setups!?

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Apr 18, 2010, 08:24 AM

#31

fre

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Quote:

Originally Posted by icantdrive75

The larger return line is a product of running both pumps full time, not the progressive system. As for part throttle/low boost, your standard 255lph pump handles cars with 30+lbs of boost. You don't have to trigger the pump anywhere near low boost settings. If you have it set to come on at 5psi then it'll be clicking on and off as you tackle traffic, but set it for 15 and it only comes on when you need it.

I have mine set to come on at 5psi through a relay hooked up to my AEM and you would be surprised how far you need to dip into the throttle to hit 5psi on a larger turbo (35r). I have tried switching on at 15psi on E85 and my car will run lean. I just set it at 5psi and it seems to work ok. I could probably compromise at 7-8psi, but haven't bothered trying yet. This is on an inline setup though, so maybe a parallel setup would work okay at a higher psi. The second inline pump being off might restrict the flow of the first one more so, causing the lean condition earlier.

BTW, I am on stock lines all the way to my second inline pump which is mounted on my firewall. I then use -6 line from the pump to the fuel rail and from the rail to the regulator. Right now on 1150cc injectors I am maxing out at around 530-550whp on E85. Once I build my engine I will try out 1450cc injectors and see what that gets me.

Last edited by fre; Apr 18, 2010 at 08:29 AM.

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Apr 18, 2010, 08:25 AM

#32

sparky

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Yeah, I understand that both the progressively phased double pumper, ala BlackOps, and the Hobbes controlled, or staged double pumpers such as the Buschur Racing unit don't need larger fuel return lines. Both setups are similar in this regard.

Years ago, I ran an Applied Technologies& Research(ATR) staged double pumper on my Turbo Regal. It was a nice piece with a beautiful billet Y housing. At any rate it was equipped with two Walbro 340's(or 342's?). The secondary pump was boost activated via a Hobbes switch.

Those were the more primitive days of ECU tuning. What I am getting at is that to set the activation point for the secondary pump we would set the Hobbes switch to come on at somewhere between 16-17 PSI of boost. Which was pretty much at WOT usually.

Even with the secondary pump coming on at WOT and 17# you could tell when the secondary pump would kick on if your car had a fuel pressure gauge as the needle would jump up about 2 PSI although it would immediately drop back down to the previous pressure.

So with the Hobbes switch activated secondary pump there is a split instant in which the fuel pressure regulator gets kind of an overload and has to compensate. By contrast, with this newer progressively activated secondary pump technology you would avoid these sort of pressure spikes altogether and the transition from primary pump on to both pumps being on would be much more linear than with the Hobbes activated system.