[pwvr4]

Goin for 850rwhp + - Need a fuel system that can easily support that. Will dual walbros go that far or will I need dual stockers?

 

[MK4LIFE]

Walbros flow 255lph and i have 2 with my setup and havent run out of fuel yet. Actually my 1000cc injectors are tapped out, the pumps still have more.

The supra stock pumps are almost the same as the walbros, at least flow the same. Some people claim the walbros flow better at higher HP. who really know.

 

[pwvr4]

are u running any kind of voltage booster or just hotwired?

 

[MK4LIFE]

They are hooked straight to the battery through a relay. need the full 12V.

 

[silvino]

I've had people claim that both were the best. My concern with the stockers is that they suck WAY more juice from the alternator. It makes me wonder about what happens when the heater is on, lights and under load if the pumps are getting enough juice to flow enough. I'll be running some logs with my fuel pressure sensor hooked up soon.

Any other feedback on people's experience with the power consumption would be appreciated and probably help the guy's question .

 

[bigmike]

jsut for cheap insurance i'd run dual walbros vs dual stockers.

 

[Guest]

dual stockers is the best, especially if running two power aders

 

[Guest]

The problem is that when you use the battery the pumps are seeing alternator voltage. It is unregulated. The pumps can see over voltage or under voltage. Not real healthy for the pumps as they can see as much as 14v at times. Do we really need this much voltage at cruising? No!!

The stock ECU regulates the voltage across the pump terminals. With the walbros, you can use the stock 14awg wiring from the fuel ECU to the connector. I re-pinned the bracket assy with 12 awg although it probably wasn't needed. 14awg wire is rated for 28 amps alone in open air. When bundled with additional wires the rating drops some.


Here is a link for the difference in current draw between the walbro and denso

As you can see, the walbros draw almost half the current as the stockers.

The stock fuel ECU uses 9v at crusing and only at higher rpms does it give the pumps 12v. This preserves fuel pump life and reduces noise. I have no idea why people run the walbros off the battery and overkill the wire with 12awg or even 10 awg. Very silly to me. And yes, I know Lar with SP has an EE degree, and so do I

I have had the walbros running off the the stock fuel ECU for a year now with no issues at all. You can see that I have no tip issues or AFR issues at all. From viewing this thread and observing my FJO graphs you can see there are no problems. I have made back-to-back hard pulls and got out of the car and felt the connectors and wiring. Not even warm.

 

[Guest]

dual stockers is the best, especially if running two power aders

Wrong....we have had several members on the forum solve lean-out issues at high boost and HP by swapping the stockers for the walbros.

 

[pwvr4]

good point stoker. SO I guess walbro's outdue the stockers. I am gonna use the AEM EMS. Haven't read much on it but will it control fp voltage by what parameters u set it at? That be awesome if you can set rpm/boost parameters and set voltage outputs in correspondance to boost.

 

[Guest]

My stock pump died causing me to run lean on high boost. I now have two new walbros.

 

[TT_6SPD_95]

My stock pump died causing me to run lean on high boost. I now have two new walbros.

I don't really see how that says too much unless that was a brand new stock one that went out on you. Comparing a 40k mile+ stock supra pump to a brand new Walboro with 0 miles on it isn't really a good comparison as far as durability under high hp applications....unless you have run very high hp for 40k+miles on your walboros...then I guess it would be a pretty good comparison.

Take Care

 

[chevyeater-on-sf]

Various fuel pumps tested against the mk4 and mk3 Supra stock pump (mk3 is the "stock pump")* :

It is easy to see the Walbro is clearly the highest flowing unless you run close to 100 psi fuel pressure.

Doesn't the mk4 use the same type of fuel pump resistor setup as the mk3 (sorry I'm a mk3 guy)? A fixed resistor that the fuel pump power is routed thru under cruise? If it is a fixed resistor it isn't going to deliver the same voltage to the Walbro as it would to the stocker. Also, most manufacturers besides Toyota run their fuel pumps at unregulated B+ I'd think Walbro designed thier pump for "most" cars and not Toyotas specifically. It may not pump well at low voltage at all. :scratch:

*Credit for the chart and more info can be found on www.supras.nl

 

[pwvr4]

hrm, you make yet another good point.... Only way to tell is to have someone flow bench one at 9 v. I'd imagine that walbro's would be fine at 13v constant but who I am I to say.

 

[Guest]

I am just going of our experience, that is why we have the stock pump with fuel system. This is a debate that can go either way I guess. Because every tuner and person has there own idea.

 

[KenHenderson]

Various fuel pumps tested against the mk4 and mk3 Supra stock pump (mk3 is the "stock pump")* :

It is easy to see the Walbro is clearly the highest flowing unless you run close to 100 psi fuel pressure.

Doesn't the mk4 use the same type of fuel pump resistor setup as the mk3 (sorry I'm a mk3 guy)? A fixed resistor that the fuel pump power is routed thru under cruise? If it is a fixed resistor it isn't going to deliver the same voltage to the Walbro as it would to the stocker. Also, most manufacturers besides Toyota run their fuel pumps at unregulated B+ I'd think Walbro designed thier pump for "most" cars and not Toyotas specifically. It may not pump well at low voltage at all. :scratch:

*Credit for the chart and more info can be found on www.supras.nl

Its not ready for prime time yet, but one of our members on [email protected], whose also an EE and worked with Russ Collins of RC Engineering, tested the stockers against Walbros and found exactly the opposite. According to the tests, the stockers outflowed the Walbros and it wasn't that close.

Its been proven, IMO, that you'll be fine anyway you go. There have been far too many big-power Supras with the stockers that haven't leaned out for me to believe that those who had lean problems were the norm and not an aberration (s).

Ken.

 

[Lagtime]

Its not ready for prime time yet, but one of our members on [email protected], whose also an EE and worked with Russ Collins of RC Engineering, tested the stockers against Walbros and found exactly the opposite. According to the tests, the stockers outflowed the Walbros and it wasn't that close.

Its been proven, IMO, that you'll be fine anyway you go. There have been far too many big-power Supras with the stockers that haven't leaned out for me to believe that those who had lean problems were the norm and not an aberration (s).

Ken.

Ken,

Jeff Lucius on the 3si site found the same, the stock Denso pumps outflow anything he tested them against.

The only caveat is they are very sensitive to voltage. But they rock at and above 14 volts.

I've posted this info on here more than once, but it gets overlooked.

Check out the link all ye doubters: http://www.stealth316.com/2-fuelpumpguide.htm

Edit: Ken, are you refering to John Cribb? if so, the site I linked above uses the data John obtained with RC.

 

[chevyeater-on-sf]

Yeah, from that link Lagtime put up it looks like the stock mk4 pump really responds to voltage. The chart I put up is all at 12v. Seems like more reason to try to minimize voltage drop on the way back to the pump.

 

[Lagtime]

Yeah, from that link Lagtime put up it looks like the stock mk4 pump really responds to voltage. The chart I put up is all at 12v. Seems like more reason to try to minimize voltage drop on the way back to the pump.

Yup. 6 or 8 gauge wire from the battery back to the pumps, controlled by a relay.

 

[Guest]

Andi B and Peter Blach have both solved lean-out issues at high rpm and boost by swapping twin stockers for twin walbros while leaving everything else unchanged. Search the threads. Those are just two of quite a few examples.

14awg wire can support one pump and you're saying you need 6 to 8awg for two stockers? Doesn't make any sense unless you're running 50+psi boost CONSTANTLY with a 1 to 1 rise FPR. I disagree entirely. WAY over engineered and they're not taking advantage of the stock fuel ECU streetability/drivability. For a FULL BLOWN race car...perhaps...for a 650rwhp street car...hell no.

This isn't rocket science. A given set of pumps will pull so much current under a given max load. You take the extreme case and design the wire gauge around it. With the stockers, yes, you need thicker gauge wire (not 6awg...*maybe* 10awg MAX), with walbros, no.

The walbros are a win-win situation. They support very high boost applications utilizing ~half the current. Their size is also an advantage.

And it's already been discussed why you don't want to run off battery if you don't have to ...unregulated!