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turbolarry
08-02-2005, 12:28 PM
At what load point is the resistor turned off and the higher fuel voltage triggered? Is it RPM related too?
http://www.roadraceengineering.com/evo/tech/fuelpumpinfo.htm
I recently upgraded the IC and now getting some knock (pulled timing) only between 3500-5000 RPM's. After 5K it jumps back to rich and the timings fine. I'm wondering if this might have something to do with it.

Mike W
08-02-2005, 01:11 PM
It trips pretty much as soon as you get into the throttle at all. If it is actually load based it is as soon as you get to zero vacuum maybe. Otherwise it seems about 25% throttle. I hooked up an LED to the wire and tried to find exactly when it tripped once a long time ago. It was hard to distinguish which affected it more since they both happened about the same time.

Mike W

Smogrunner
05-28-2006, 09:40 PM
When I did the experiment with my 03 Evo, I had 10.6volts off throttle, and 13.4 volts under any load at all (like Mike said above). I'm hoping that the Denso 195130-1020 run at 14.x volts will outflow the Walbro. I wonder if there is any real drawback to just hardwiring you fuel pump to run with 14 volts all the time? I'm thinking that it won't last quite as long and that it will be a little louder at idle.

trinydex
05-30-2006, 02:50 PM
what causes the whine from the whinebro ?

Mr. Moose
07-01-2006, 10:29 PM
A Denso 1020 will outflow a Walbro 255 by 30+ liters/hour at 14 volts. You can see a comparison of the measured flow volumes at different voltages for various pumps, including the Denso 1020 and Walbro, at http://www.roadraceengineering.com/fuelpumpflowrates.htm.

07-01-2006, 11:01 PM
I looked at that same data, but then this data seems to somewhat contradict that: http://www.stealth316.com/2-fuelpumpguide.htm#j3. I'm not sure if this test was done with the exact same pumps that the RRE website refers to, but both pumps seem limited to mid the mid to upper 500s whp range.

Here is the chart from the link:
http://www.stealth316.com/images/flowtest-densowalbro.gif

In the end, I just ended up going with twin Walbro's, one in the tank, one external. I went so far as to order the Denso 1020 pump, but it was backordered and I decided to save money and go with the inline twins.

Mr. Moose
07-01-2006, 11:12 PM
What did you decide to use for the supply and return line size for the twin pump setup?

07-01-2006, 11:22 PM
What did you decide to use for the supply and return line size for the twin pump setup?


Actually, the car is at Tuning Technologies right now to getting this done. I'm using this aeromotive FPR (http://www.aeromotiveinc.com/pdetail.php?prod=10) with two -6 AN inlets and one -6 AN return with braided stainless steel lines. If you have any suggestions to offer, I'm open to listen and read...

Hmmm, the graph link was working when I first posted it...

tabio42
07-01-2006, 11:28 PM
Question-

Why would two inline pumps flow more than one?
I understand how two pumps in parallel will flow twice as much as one but I don't understand two in series.

Mr. Moose
07-01-2006, 11:38 PM
The AMS upgrade fuel lines/regulator kit uses -8AN SS lines, and I'd guess the same size inlets on the regulator and fuel rail, driven by two Walbro pumps, as you are considering.

I'm building a system with an intank Denso Supra TT pump (1020) and a Bosch 044 inline pump, both of which have a little higher flow volume capacity than the Walbros, and, in my opinion, a little more reliability. I'm thinking about using a regulator with -8 inlets, but -6 should be fine, based on any reasonable fuel demand calculations :)

Mr. Moose
07-01-2006, 11:43 PM
Why would two inline pumps flow more than one?* I understand how two pumps in parallel will flow twice as much as one but I don't understand two in series

The intank pump prepressurizes the fuel, allowing the second pump to "start" its work at a lower intake pressure compared to a system without the intank pump.

tabio42
07-01-2006, 11:49 PM
Kinda like two turbos in series I guess.

Mr. Moose
07-01-2006, 11:53 PM
That's probably a good analogy.

07-01-2006, 11:54 PM
The AMS upgrade fuel lines/regulator kit uses -8AN SS lines, and I'd guess the same size inlets on the regulator and fuel rail, driven by two Walbro pumps, as you are considering.

I'm building a system with an intank Denso Supra TT pump (1020) and a Bosch 044 inline pump, both of which have a little higher flow volume capacity than the Walbros, and, in my opinion, a little more reliability. I'm thinking about using a regulator with -8 inlets, but -6 should be fine, based on any reasonable fuel demand calculations :)


Thank you very much for sharing your knowledge. We were able to get 540whp/492wtq out of the single Walbro before it started showing signs of being tapped out. I'm hoping to give my car enough fuel supply to push for ~600whp (or a little lower) for drag racing purposes. I have absolutely no desire to go any further than that. I've been having to focus my money on other more important *aspects of life lately, so I'm having to go slow and get the most bang for the buck.

Mr. Moose
07-02-2006, 12:07 AM
It's interesting that Evo tuners have been using single Walbros on the 4g63 at HP levels that the DSM 4g63 tuners would have already upgraded fuel systems at substantially lower HP levels. Perhaps the stock Evo system is higher flow capacity, but my personal observation is that lack of fuel is a very common cause of major engine damage (from running lean). Lean can be caused by lack of pump volume capacity overall (engine demand higher than pump can meet), or by lack of pump capacity at higher pressures needed to overcome the increased pressure in the manifold at high boost. I just figure that upgrading the fuel system is cheap insurance if you have a 500+HP motor you're trying to keep happy and healthy.

Do you have a fuel pressure gauge, optimally with a warning function? If you use Defi gauges, the controller has a function that compares boost with fuel pressure and warns if they don't rise together...

07-02-2006, 12:23 AM
The only fuel pressure gauge I have is under my hood, fine for dyno tuning and adjusting at idle, but otherwise useless. For all the mods on my car, I have a long ways to go in terms of gauges and logging. I'll get there soon enough I suppose. Mr. Moose, who are you? You seem offer pretty solid advice.

Mr. Moose
07-02-2006, 12:37 AM
I'm worked on DSM 4g63Ts for quite a while.* I've owned 20 DSMs in the last 5 years, including probably a dozen Galant VR4s.* Alot of the knowledge base translates over. :)

The Walbros and the Denso both are very sensitive to voltage (and voltage drop).* Make sure your wiring will withstand the loads from the dual pumps, so that you get the volume capacity at the pressure you're intending to have.* For example, if you're using 25 lbs of boost, the injectors have to overcome atmosphere +25 lbs of pressure to open, so you're looking at base pressure + 25 lbs of additional pressure just to stay even with the pressure differential inside the manifold.* Your pumps need to supply the volume your engine will demand, at that pressure, or you'll run lean.* The charts mentioned above give data about fuel pump capability at higher pressures and volumes, but the voltage driving the pump makes a big difference in the pump's capacity.* Good background reading for anyone who is thinking about having sufficient fuel capacity on a high HP motor.

07-02-2006, 09:09 AM
I'm worked on DSM 4g63Ts for quite a while.* I've owned 20 DSMs in the last 5 years, including probably a dozen Galant VR4s.* Alot of the knowledge base translates over. :)

The Walbros and the Denso both are very sensitive to voltage (and voltage drop).* Make sure your wiring will withstand the loads from the dual pumps, so that you get the volume capacity at the pressure you're intending to have.* For example, if you're using 25 lbs of boost, the injectors have to overcome atmosphere +25 lbs of pressure to open, so you're looking at base pressure + 25 lbs of additional pressure just to stay even with the pressure differential inside the manifold.* Your pumps need to supply the volume your engine will demand, at that pressure, or you'll run lean.* The charts mentioned above give data about fuel pump capability at higher pressures and volumes, but the voltage driving the pump makes a big difference in the pump's capacity.* Good background reading for anyone who is thinking about having sufficient fuel capacity on a high HP motor.


Yeah, I've thought of that. I'm wiring the external Walbro directly to the battery with a 10 gauge wire in the fashion Mike W. posted on his website (14Volts for sure). The only question I have is that I was planning on using a 30 amp fuse for this but on the side of the Walbro is say to use a 20 amp fuse. Which should I use?

tabio42
07-02-2006, 09:32 AM
Having a Fuel Pressure Gauge inside the car is a good idea as long as it is getting an electronic signal from a signal in the engine and not actually running fuel into your cabin eh?

Also, I notice on that chart that the Supra Denso uses almost twice the amount of amps as the walboro. Any downside to that?

And also also- does the stock fuel pressure regulator on the evo have a 1:1 rising ratio?