mrfred

iTrader: (50)

I had high expectations that a Walbro 400 would provide sufficient fuel for 500 whp on E85, but I was finding that even when using a -6 AN fuel supply line to minimize pressure drop between the pump and the rail and using a custom fuel pump rewire, fuel pressure across the injectors was falling off somewhat at high fuel flow rates. Seeing this happen, I decided to upgrade the the higher flow Walbro 416 pump. I also decided to try to figure out why the Walbro 400 wasn't up to the job. Two things I was considering to help figure it out were logging voltage at the fuel pump and logging fuel pressure right at the pump outlet.

Logging voltage was fairly straightforward and no permanent mods to the fuel system were required. I logged voltage using the new EvoScan DLPIO8 cable that can accept 0-5V analog inputs. I built a voltage divider using 10K-ohm and 5.6K-ohm resistors, and attached it across the wires at the fuel pump plug outside the fuel pump housing. I logged voltage across the 5.6K-ohm resistor and converted that voltage to actual pump voltage.

Logging fuel pressure at the actual pump outlet would have required me to drill and tap a 1/8" NPT fitting through the top of my pump carrier to measure the pressure between the actual pump outlet and the pump carrier filter, but I didn't really feel like taking a chance on creating a leaking pump housing, so I passed on this. Maybe I'll do it in the future.

So here are the comparison logs for a Walbro 400 and Walbro 416. Looking first at the Walbro 400, the two items of greatest interest are the pump voltage holding a steady 13.2 volts and the pressure across the injectors falling off to 40 psi after 5500 rpm. In comparison, the Walbro 416 runs at a slightly lower voltage of about 12.9 volts, but it cleanly holds the target 44 psi across the injectors all the way out to max air and fuel flow indicating that its providing sufficient flow.

Now that I have pump voltage, I decided to calculate pump flow and compare to the engine fuel requirements. From previous logs, I know that pressure at the outlet of the pump carrier is about 72 psi at peak power, and I'm estimating another 5-8 psi pressure drop across the factory filter which gives about 77-80 psi at the pump outlet itself. Looking at the third chart below, a Walbro 400 at 13.5 V can flow about 4950-4750 cc/min. 13.2 V is a bit lower, so I'll say it can flow about 4800 cc/min at my peak fuel requirements. The Walbro 416 13.5 V and 77-80 psi is 5600-5400 cc/min, but the pump is running at 12.9 V for my setup. Interpolating between 12V and 13.5V in the Walbro 416 flow chart (can be found online), I get roughly 5000 cc/min at 12.9 V which isn't much better than the Walbro 400. Engine fuel flow requirements are pretty easy to figure out because my FIC1100s are going static right at peak power, so that's 4400 cc/min. That's about 10% less flow than what either pump can supply, so either should have gotten the job done, but it was only the Walbro 416 that did.

EDIT: For those people running this pump on the stock fuel pump wiring and stock fpr, I recommend raising the fuel pump low/full voltage transition up to 130-150 load between 0-3500 rpm and then taper down to 90-100 load by 5000 rpm. If this isn't done, the fpr will get massively overrun when running 50-150 load range.

Bottomline for the W416 is that based on my testing, it is a clear step up over any of the previous single pump options and is the first single pump setup I've run that can fully support 500 whp.


Walbro 400 pump performance



Walbro 416 pump performance at 45 psi base pressure



Pump flow rates at 13.5 V or 14 V, Note: Walbro 460 = Walbro 416



EDIT (January 1, 2013)

I finally got around to installing an AEM FPR and doing some testing at higher base pressures. My interest in high base pressures is that my FIC1100s are going static at about 500 whp, but I want to try to reach 550 whp on these injectors. Higher base pressure can push more fuel through the injectors, increasing the HP range that they can support. I decided to post my results here because running a higher base pressure is one way to explore the flow limit of the Walbro 416. The chart immediately above shows that as pump pressure increases, pump flow capacity goes down. I can find the flow vs pressure curve by increasing base pressure until pressure across the injectors begins to drift below the base pressure at high fuel flow. Hope that makes sense.

All I had time to do this evening was increase base pressure to 56 psi, increase injector scaling by 10% (to compensate for increased base pressure), and grab a datalog. As shown in the datalog below, the Walbro 416 was easily able to sustain 56 psi pressure across the injectors at high fuel flow rate, so this wasn't high enough pressure to reach the Walbro 416 (boundary) flow curve. Note that rail pressure was 84 psi peak fuel flow. Based on my previous measurements of pressure drop from pump to rail, I estimate pressure at the pump was close to 90 psi. Fuel flow was likely around 4500 cc/min, so that's some pretty good flow for 90 psi at the pump.

Perhaps tomorrow I will try 65 psi base pressure.

If anyone is curious about the ~58-59 psi across the injectors in the mid-rpm range, I suspect that its due to the fuel return system being overrun which causes the fpr to regulate to a higher pressure. One other tidbit worth mentioning is that the high base pressure does not get along well with the factory dual voltage power supply to the pump. The pump has a tendency to stall as manifold pressure crosses 0 psi when in low voltage mode.


Walbro 416 pump performance at 56 psi base pressure

sil80evo

Wow thats kind of interesting. I have an aeromotive which arent that great either.

zabes

i thought that the 400 wasn't designed for use with e85 and that the 416 is basically an e85 compatible 400. would believe that would explain the difference seen. good test showing the difference though

evoredy

iTrader: (7)

The hype is over. I bought a 400 (262), then found out it was e85 incompatible, then bought a 400 e85 (267) and then found out I'm still running out of fuel.

You have to modify it or boost the voltage (basically both for me) and spend as much as a double pumper.

Thanks for the info.

gt30revolXmr

iTrader: (11)

How much boost and hp are you at?

mrfred

iTrader: (50)

For your setup that has a 3582 with E85, the reality is that the entire fuel system needs to be upgraded. No matter what fuel pump is selected, a -6 AN fuel line and new power line to the pump(s) should should be part of the fuel system mods. At this point, I am convinced that the 267 is a clear step up from any of the previous single pump options. Whether it can keep up with a double pumper is something I'll likely never be able to effectively test with my <550 whp Evo, but the flow rate data from Walbro indicate that if it can be fed 13.5 V or more, it can actually flow as much as a double pumper.

mrfred

iTrader: (50)

https://www.evolutionm.net/forums/ec...-you-want.html

RJSP

Dumb questions: Is the 267 (W416 E85) pump also compatible with 93 pump gas?

Ted B

iTrader: (6)

Yes, it is compatible with both gasoline and ethanol.

mrfred, the decrease in voltage observed with the '267' pump leads me to question the capacity of the power/ground wiring. With my direct power and ground system, I see 14.2V with two 255s. That being said, the capacity of either pump tested will increase with greater voltage.

mrfred

iTrader: (50)

I keep wondering whether my power supply isn't up to the job, but its not much different than a regular full-power rewire. Its essentially the STM rewire kit with two relays instead of one. Power is attached to the battery terminal, and ground attaches to a bolt that holds one of the seatbelts in place. I plan to log voltage a several points along the rewire.

Do you have power attached at the battery or at the alternator as I've heard that some people do?

Ted B

iTrader: (6)

My wiring consists of heavy gauge (4awg) power and ground, with the power routed directly to the trunk-mounted battery. It maintains >14V under load with dual 255s, and therefore should do so with a single '267'.

mrfred

iTrader: (50)

The STM kit is fine-strand 10 gauge, so while its not 4 gauge, it's still plenty good. Do you recall where you attached your ground?

Ted B

iTrader: (6)

Actually, I believe my wiring is 8awg, not 4 (car not with me at the moment). My ground is anchored to a body bolt, near the pump assembly.

Boosted Tuning

iTrader: (12)

Good stuff like always MRFRED.

way2qik

iTrader: (5)

Mr. Fred, nice job on the test.

I've got two of these 416lph pumps now hanging on my double pumper with -8 feed to twin rails and two sets of ID2000s hoping to make close to 1000hp on a Mustang dyno this spring on E85. You think these pumps will get it done?