Well to put things to rest we've taken the initiative and built our own fuel pump test rig and conducted a series of tests. If anyone has any pumps to test let me know and we'll have Chewbacca run it on the test rig.

Here are some pictures of the rig

http://amsteam.net//files/5/IMG_8788.jpg

http://amsteam.net//files/5/test01.jpg

http://amsteam.net//files/5/test02.jpg

http://amsteam.net//files/5/test03.jpg

We're basically using a variable voltage power supply to run 12V and 14V to different fuel pump configurations. The pumps feed into a fuel pressure regulator and we measure the bleed-off at that pressure. We fill a graduated & calibrated container and track how much time it takes to fill, then with a simple calculation you get flow in liters per hour (LPH).

For starters the base fuel pressure in a stock fuel system is around 42psi, then it goes from there. For every 1psi of boost you add 1psi of fuel pressure. So at 20psi you're running 62psi of fuel pressure. At 28psi boost, 70psi fuel pressure. 40psi of boost, 82psi fuel pressure, and so on.

We learned a few interesting things, especially with the EVO VIII & IX pumps. The EVO VIII pump has a pressure relief valve that opens up at around 65-68psi and the flow output drops dramatically after that, eventually going to zero flow around 75-80psi. The IX pump flows a little more than the VIII pump at lower pressures but doesn't dump the flow at higher pressures. That's the reason you can make decent power at higher boost levels with the IX pump.

We also found that if feed one pump into another (series), the flow only drops slightly through the pressure range. The first pump is feeding the second pump and the second pump doesn't have to work as hard.

The best choice was the twin Walbro 255lph HP external pumps in parallel, meaning both pumps feeding the regulator.

The twin Walbro 255lph HP in-tank pumps in parallel was interesting. If you notice the flow starts dropping off at higher pressures and actually starts to get close to the performance of just one 255lph HP external pump over 90psi. The in-tank 255lph HP Walbro pumps have a pressure relief valve that starts to dump flow at roughly 85psi and the output flow drops.

http://i21.photobucket.com/albums/b276/freeDonkeyride1/fuelpumpgraph2.jpg



Next up are the OEM Subaru fuel pumps, we'll post results as soon as we have them!

Thank you

Rich K
Marketing Director
AutoMotoSports Inc. (AMS)
Tel:847-709-0530
www.amsperformance.com
Rich@amsperformance.com
AIM: RICHatAMS

Thanks Chewy!!

Nice testing! I'll give you $1 if you email Buscher Racing and see if they will send you one of their set-ups. David Buscher is NOT skeerd, and I'd bet he'd want to be included in your testing with his set-up.

wow.... with a great test rig like that ....

how about testing the -044 Bosch motorsport pump and -979 porsche pump.... and the MKiV Toyota Supra stock pump....

Awesome and conclusive results!!!

ME LIKE!!!!!

Thanks guys!

Nice testing! I'll give you $1 if you email Buscher Racing and see if they will send you one of their set-ups. David Buscher is NOT skeerd, and I'd bet he'd want to be included in your testing with his set-up.

intrested in his pump test as well

:subscribe:

:banana:

We have a digital flow meter on the way which will make testing 100 time quicker. I'll be able to test every 5psi of pressure and at different voltages.

Awesome info - great work! Looking forward to the stock Subaru pump results.

intrested in his pump test as well

Nice testing! I'll give you $1 if you email Buscher Racing and see if they will send you one of their set-ups. David Buscher is NOT skeerd, and I'd bet he'd want to be included in your testing with his set-up.



Any comments on this AMS? I'd like to see this as well.

Very nice, can't wait to see the results. Keep up the great work guys!

any updates?

awesome data! subscribed

It would be VERY interesting if you test the BOSCH 044 motorsports and modified Walbro Buschur fuel pump

I think those 2 pumps would of great interest to many people because of their reasonable price for the performance they claim to offer. (Bosch $210, modified Walbro $275?)

http://esm.logic.net/gallery/d/3305-2/bosch-044-2.jpg

we actually have a bosch 044 here as well as a slew of subaru stock pumps. Martin has been at Autobahn and tuning the past few days to get ready for the GTlive event in utah coming up. Once we get past that Im sure we will jump back into the fuel pump test.

Eric

^^^
Awesome!
Looking forward to test results......
Kinda reminds me of college-days lab classes.... test, collect data, use Excel (I remember using Lotus 1-2-3) to generate a nice chart :lol:

AMS: you're providing alot of people a great service by providing actual data we can use to make fuel-delivery decisions

Thank you!

Thank you, You can expect alot more like this to come from us. We LOOOVE to test :)

Eric

bump for some results, come on we are dying!

well we have a bunch of subaru pumps here, Bosch 044 and a weldon. Finding time with the race events we have been attending and the upcomming track day has proven to be a bit of a task in itself.

update on the test. Here is some more data and I split it up to make it easier to read hopefully. I ran some Bosch 044 pumps which work really well (external pumps). I ran an STi pump but lost the data and will have to re-run it.

http://amsteam.net/files/8/fuelpumpgraph-1.JPG

http://amsteam.net/files/8/fuelpumpgraph-2.JPG

http://amsteam.net/files/8/fuelpumpgraph-3.JPG

From what I remember the STi pump was very similar to the EVO IX pump but we'll know in a few days. Also the Bosch 044 flows a bunch, especially at higher pressures.

This thread kicks ass. Thanks again AMS!

^^^
what he said!
Very useful test for a very important component of the fuel system!
No wonder why the Brits & Aussies like the 044 so much. (I got one myself)

An important variable to consider is that we must think about is how well these pumps work at around 13.3 volts which is where our cars seem to run. Will the modified Walbro run the same or will it require more power. I like how the 044 is stable across the pressure range, that it is unmodified as the factory intended, and that it is German (usually most stuff is overengineered). It should be enough. I am working with Davon on an intake kit. We will post the installation tips and results. It has been done before and we will improve upon that. Engineerx, Davon, and I have been working on this stuff for a month.

Approx 210 for the pump
Fittings 35
filter 65
The last pump you will ever need for most of us.

Stay tuned

The tests were done at 14V and the voltage was held constant with the power supply and amp draws were recorded. Checking my data shows that the modified walbro didn't really draw more amps than a stock one. I'm not sure what is done to the walbro, all I can tell from the outside is that the pressure relieve cup/spring is pushed in compared to a stock one.

The tests were done at 14V and the voltage was held constant with the power supply and amp draws were recorded. Checking my data shows that the modified walbro didn't really draw more amps than a stock one. I'm not sure what is done to the walbro, all I can tell from the outside is that the pressure relieve cup/spring is pushed in compared to a stock one.


Yes that is all that is done to them but hell it works and i wont complain. now if i could just get some solid directions on how to do it myself.

Yes that is all that is done to them but hell it works and i wont complain. now if i could just get some solid directions on how to do it myself.

We took a stock Walbro and pushed that cup down and there was an increase in flow at higher pressures but the 'Modifed Walbro' still outperformed it at every pressure level. They are supposedly modified internally but when I see the amp draws the same as the stock walbro it doesn't make sense.

I'l put up the data for the stock walbro with the relief cup pushed in and you'll see the difference.

We took a stock Walbro and pushed that cup down and there was an increase in flow at higher pressures but the 'Modifed Walbro' still outperformed it at every pressure level. They are supposedly modified internally but when I see the amp draws the same as the stock walbro it doesn't make sense.

I'l put up the data for the stock walbro with the relief cup pushed in and you'll see the difference.

If you are talking about the Buschur modified walbro, then all that's done to it is the pressure relief valve is modified. Dave says it himself in this thread, post # 227.

http://forums.nasioc.com/forums/showthread.php?t=1090766

We took a stock Walbro and pushed that cup down and there was an increase in flow at higher pressures but the 'Modifed Walbro' still outperformed it at every pressure level. They are supposedly modified internally but when I see the amp draws the same as the stock walbro it doesn't make sense.

I'l put up the data for the stock walbro with the relief cup pushed in and you'll see the difference.

gotta stay up with the drama i mean entertainment. lol read the above thread its very informative yet entertaining at the same time.

Good lord! I'm staying out of that one for sure, I read it for a bit and my head hurt. Anyway, I'm not trying to discredit anyone or prove anything, just doing some testing on different pumps so the info is out here for everyone to feed from.
The modified pump we recieved was donated from someone who got it from a different vendor.

i didnt notice this mentioned but did you use water or gas to do this test? using water will significantly skew the results

i didnt notice this mentioned but did you use water or gas to do this test? using water will significantly skew the results

I think I read in another thread somewhere that the were using a special type of gas that is for testing.

Any updates to this? Did AMS ever test stock subaru pumps?

Great info ... Thanks

Bump this thread because AMS did a good service to Nasioc by testing pumps!

Good call. Awesome testing!

I'm quite impressed with the modified Walbro. I have a dual pump setup: In-tank parallel. Main one is a modded Walbro, 2nd one is std Walbro that comes on line at 15psi.

The niggling concern I have is that even with an Aeromotive FPR, the fuel pressure steps up a notch when the 2nd pump comes on-line. I'd prefer that the pressure to the injectors stay the same and that they just keep getting fed all the fuel they need.

This can be worked with via tuning, but it feels icky. Will the Boost Switch always kick the 2nd pump in at the same boost pressure? Can the ECU map be set up to handle this perfectly? Etc.

I'm toying with using just the Modded Walbro and Boost-A-Pump to provide more voltage on boost. But heck, the FPR may not handle that perfectly either.

why don't you just wire both your pumps to run all the time then... that way, no need to tune around the jump when the second one comes in...

Well... Even more pump noise, plus, if one fails, the motor automatically goes lean. If one fails in my current setup, 50/50 chance it's the primary and the engine just quits. Maybe even better than 50% since the secondary gets a lot less use.

With a voltage boosted single pump, 100% chance the motor just quits vs. going lean.

I'll probably just stick with my current setup for now though.

Oh dear.. pumps don't magically work or not work when they die.. They tend to fade out.. as in not being able to keep up with the fuel demands over time. In other words, over a period of time, you find your AFR's getting leaner and leaner..They get tired...

In any case, you will run lean when a pump is on its way out. But that's where AFR gauge and a fuel pressure gauge come in handy.

Bah, does anyone know the lph of the Subaru pumps? I have been told they actually flow more than the EVO 8 and 9.