Your highest fuel demand is up top where injectors have the shortest window to spray fuel. So 30 psi+ 43 psi = 73 psi, which is well under the 87 psi.

 

So, calculating the fuel pressure under load is around 79psi (5psi give or take for the fuel line losses). So, the pump sees around 85psi at WOT. The 267 pressure relief valve opens at 87psi so I think you are good for now. But if you decide to build the motor and give it more boost, 267 won't cut it.

Keep in mind that when we monitor the fuel pressure, the sensor is near the fuel rail (either before, or after). The fuel pump in order to send this pressure to the rail, it works at higher pressure. There was an article around the forum which calculated the losses from the pump to the rail. Obviously, the bigger lines help with those losses. I think around 10psi for oem hard lines and 5psi for larger lines? So the losses is another part of the equation and not only base fuel pressure and boost

 

Yea man exactly. I have this issue at the moment that I try to figure out. But because I have another issue with the batt voltage, first of all i have to resolve this and then swap to twin 274's and give it a try. But as I explained, 58psi + 25psi of boost + 5psi(estimate) equals to 88psi which is higher than the wally's 450 pressure relief valve. The problem however is not the wally, but the AEM which opens from 80psi. So, in WOT the fuel pump instead of sending fuel to the rail, it dampens fuel back to the tank.

I also plan to boost it to 33psi and i am certain that i will run to more fuel issues. So twin 274's which have a pressure relief valve at 112psi will hopefully resolve my issue

 

Twin 274 sounds good. The relief valve opening at 87psi on 267 is not good. I didn't check this, when I bought it. My afr was floating running 35psi to 28psi. Maybe the valve was opening/closing or the pump just wasn't able to flow more.

Read Mrfred's writing about 267 and 274 here in post #294:

https://www.evolutionm.net/forums/ev...-8-9-a-20.html

I was thinking the Aem pump as a primary but as mentioned, the relief valve opens at 80psi. At the moment, Deatchwerks 255 pump looks the most economical e85 specs pump for me as a primary. And if I do a double pumper, I will probably install another one. And the specs says, it has 100psi relief valve. And it doesn't run big Amps and flows 190L/80psi.

 

Was never truly answered is it okay to run a 255 as the main pump then have a 450 as the 2nd pump. Thinking maybe the 255 would help with drivability and the 450 would help get all the fuel needed up top.

What the power max on e for two 255?

Does it just make sense to use two 450, i just didn't want to try to drawl to much power out of the system.

Around 600HP

 

A single walbro 525 will make 600whp. Dont overcomplicate it.

 

I second what letsgetthisdone said. I went to a dual 255 setup and wish I would have just went with a single 525 for simplicity.

 

Well i ran out of pump on a 450, So what i was reading i would need to change out the lines to help with flow and move up to a 525. I didn't want to do a double pump but here we are

 

You should change the lines anyways. A single 525 with a 6an feed line and fuel pressure regulator set at 58-60psi base will support around 675whp with 1650 injectors.

 

Just don't run the 525 at full voltage around the clock, as it wastes the life of the pump and heats the fuel.

 

You kinda have to run it full voltage full time to run 60psi base to stretch the injectors out. I haven't had one fail running them like this for years.

If you want to run normal 43psi, hi/lo voltage is fine. But then the injectors run out.

 

Why would you run it at full tilt while not even under boost? It needs full voltage to make 60psi even when the injectors are just sipping at a stop light? That doesn't make sense to me. I'm not saying that it wouldn't work to run it full tilt and walbro pumps are great so maybe it lives a long life, but I still don't see why to heat the fuel and have it looping from rail to tank and back over and over for no reason (not even in boost or load).

 

It'll barely do it, You have to about max the regulator adjustment to get it to make 60psi on low voltage. Then when it crosses over to full voltage you get a fuel pressure spike and creates a dead spot in the tune where it'll hiccup/act weird.

If you're running ethanol, the fuel doesn't get hot.

 

Oh I understand, that makes more sense. That might be something I am seeing a bit now with my DW340il going from 9v to 14v at 100 load.

 

So with a 525 the issue becomes more running out of injector. So you have to bump up pressure to make more power?
I take it if you have a little more injector so a 2150 you would not need to bump up pressure as high?

I know you say a double pump isn’t need but I’m just doing math in my head to understand, so basically two 255 pumps would net you about the same amount of fuel as a 525?

from the original post I’m not sure if you can even run two different size pumps or if it would course any issues?

letsdothis- do you just run stock return lines on builds like this or do you end up using the stock line for the return?

I appreciate all your information and time?