Fuel pump sizing

Paul_G · Mar 16, 2022

Been chasing down many issues on the new to me 69 RR, 528 Hemi with with a Procharger.

This problem, the engine lays down after a few seconds of wot, like it drains the bowls and runs completely out of fuel. I experienced that, and do not not push it there again. Lean is bad. I have been looking at many things that can cause this. Electric fuel pump sizing may be a main factor.

No numbers are on the fuel pump thats on the car now. But it looks exactly like this one. https://www.summitracing.com/parts/crt-p5001

Spec; Designed to operate applications with system pressures between 9 and 22 psi, they are flow-rated at 50 gph at 20 psi.

Right on Summits site it gives a chart to help size a fuel pump.
https://help.summitracing.com/app/answers/detail/a_id/5245/~/what-size-fuel-pump-do-i-need?

I am going by 650HP, which is probably on the low side of a Pro Charged 528 Hemi. It says I need 67 gph for a carbed with power adder engine. The carter pump I have is only rated at 50GPH at 20psi. When the boost comes in, probably close to 20 psi. that pump cant even push fuel in to the bowls. Am I wrong?

HEMI-ITIS · Mar 16, 2022

Buy a larger pump than the chart says. You can never have too large of a fuel pump!
Aeromotive or ProStar.

bearman · Mar 16, 2022

You can always regulate pressure if it's to much. I with hemi never enough fuel.

pnora · Mar 16, 2022

Did you get a fuel pressure gauge on it that you can actually verify fuel pressures when it is acting up??? You need this so you are not guessing. You most likely are on to something but you need actual numbers.

33 IMP · Mar 16, 2022

For what it's worth..... I just bought my second 140gph trickflow, both for 500hp engines, and I had a 250 mallory gerotor on my 500hp Cortina, all n/a. Love the Mallory but they are outrageously priced since holley bought them and is trying to kill them.
For your application , I would use a holley hp150 gerotor. About half the price of the Mallory I would really use.
(And I despise in tank pumps! In a fuel cell in the trunk, maybe, but I literally threw away a car after the second pump failure. The cost of getting a shop to drop the tank and put in a new pump, again, was more than the car was worth, to me).
You are using a boost referenced regulator, and a return line, right?

RJRENTON · Mar 16, 2022

WHY GUESS on your requirements or take some other person's work. The following is what I offered as a possible solution. Every installation and requirements are different. Do your own calculations to be sure.
From the previous post....
IMO.....perhaps the question to ask is: what does my fuel delivery system require (carburetor or EFI) both in volume AND pressures OR a more quantifiable term of pounds per hour, at the maximum engine operating conditions. How the engine system produces its horsepower (thru displacement, stroker, compression ratio, cam etc) not with standing but total fuel consumption at the desired condition. This number should be calculatable factoring in the volumetric efficiency of the engine and its operating point plus a 10% - 15% safety factor. There is no hard line number or "one size fits all" solution but each individual application should be determined by the vehicle's owner or engine builder for the application at hand. Not guessing if Holley #xxxxx or Carter pump xxxxxx will perform to expectations but calculations will determine specific requirements. Just a few additional talking points to consider.....
BOB RENTON

Paul_G · Mar 16, 2022

pnora said:
Did you get a fuel pressure gauge on it that you can actually verify fuel pressures when it is acting up??? You need this so you are not guessing. You most likely are on to something but you need actual numbers.

The gauges have not arrived yet, soon. That will be the tell all. It will be a couple of weeks before the new Dakota Digital cluster is installed and the fuel pressure and boost gauges are installed.

pnora · Mar 16, 2022

Paul_G said:
The gauges have not arrived yet, soon. That will be the tell all. It will be a couple of weeks before the new Dakota Digital cluster is installed and the fuel pressure and boost gauges are installed.

As said in the other post you need to see what it is doing by actual numbers. If low you have a supply issue. If ok you could have a simple float drop set wrong or needle and seat problem. The gauge is your tool. Seeing you know nothing about the pump you could run a couple of tests in a measured container to get an idea of the pumps capabilities. As said above you need to know what the motor needs. So all the specs of the build need to be known as well as to what the power adder will increase the amount.

diesel_lv · Mar 16, 2022

"Assuming" 9-22 psi pump. That means max pressure it's rated at is 22 psi. Subtract 7 for carburetor needle/seat. You're left w 15 psi. That means the pump can theoretically overcome 15lbs of boost. But that's 1/2 the equation, you also will need "X" volume at that boost level to sustain the proper A/F ratio of around 10 5:1 w blowthru. There are quite a few fuel requirement calculators out there.

Paul_G · Mar 16, 2022

pnora said:
. So all the specs of the build need to be known as well as to what the power adder will increase the amount.

Now that is a problem. I bought the car from a dealer, he bought it from another dealer. I have no information at all about the build. A retired PD friend is trying to see if he might be able to get some history on the cars previous owners.

pnora · Mar 16, 2022

Paul_G said:
Now that is a problem. I bought the car from a dealer, he bought it from another dealer. I have no information at all about the build. A retired PD friend is trying to see if he might be able to get some history on the cars previous owners.

You can run some tests on the pump you have to see how much it will pump. Use that for a baseline. Get the gauge so you can monitor it and go from there. You should follow through on the whole system from the tank to the pump. What do you have for the rest of the system?

Geoff 2 · Mar 18, 2022

650 hp requires about 55 gph. Power adder means just that....more power. You will need some idea of how much extra power is added. Once that is known, fuel requirement can be calculated. Choose a pump that delivers that amount at the carb with a 30-50% reserve.
Do not just choose a huge pump. It will just wear out quicker.

Paul_G · Mar 22, 2022

Installed both the fuel pressure gauge and the boost gauge. The fuel pressure regulator is a newer looking Aeromotive. No id on it but looks exactly like this one.
Pressure Range (psi): 3-15 psi
https://www.summitracing.com/parts/aei-13204

Took the car around the block. Normal neighborhood driving the boost gauge barely comes off 0, fuel pressure is at 6 psi. When getting just a little more aggressive with the throttle, as boost comes up fuel pressure comes up with it. I saw 8 to 10 psi of boost for short bursts. Car ran fine. I layed in to it one time to build boost and watch the gauges. As boost climbed over 15psi, fuel pressure went up with it then the engine fell flat like I hit an off switch, got off the gas immediately. I heard the PSSSSHT of blow off valve open. Fuel pressure dropped down to 6 psi and engine was idling. Hard to watch the gauges closely while driving.

That fuel pressure regulator is rated 3 to 15 psi. Can I assume 15psi is max output of the regulator even with boost?

We already know the fuel pump can only put out 22 psi.

RJRENTON said:
WHY GUESS on your requirements or take some other person's work. The following is what I offered as a possible solution. Every installation and requirements are different. Do your own calculations to be sure.
From the previous post....
IMO.....perhaps the question to ask is: what does my fuel delivery system require (carburetor or EFI) both in volume AND pressures OR a more quantifiable term of pounds per hour, at the maximum engine operating conditions. How the engine system produces its horsepower (thru displacement, stroker, compression ratio, cam etc) not with standing but total fuel consumption at the desired condition. This number should be calculatable factoring in the volumetric efficiency of the engine and its operating point plus a 10% - 15% safety factor. There is no hard line number or "one size fits all" solution but each individual application should be determined by the vehicle's owner or engine builder for the application at hand. Not guessing if Holley #xxxxx or Carter pump xxxxxx will perform to expectations but calculations will determine specific requirements. Just a few additional talking points to consider.....
BOB RENTON

So what to do if you dont know the engine build? All you have is whats in front of you between the frame rails?

diesel_lv · Mar 22, 2022

I see it says 1:1 boost/vacuum ratio. I would personally assume it maxes at 15 psi as carburetors don't run over 7-8psi. But I'd call Aeromotive to confirm. If you set idle at 6psi and are going to run "X" boost, it needs to be able to regulate 6 + X psi. Fuel pump needs to be capable of 6 +X psi also. You will need to know what your turbo wastegate is set at to know it's max boost psi.

Paul_G · Mar 23, 2022

I found a spec sheet for the F1 Pro Charger. It is capable of Max boost of 38 psi. I would assume that is dependent on pulley sizing. That being the case, the fuel system needs to make at least 45 psi max fuel pressure to keep pushing fuel against the boost pressure. Right or wrong?

Paul_G · Mar 23, 2022

diesel_lv said:
I see it says 1:1 boost/vacuum ratio. I would personally assume it maxes at 15 psi as carburetors don't run over 7-8psi. But I'd call Aeromotive to confirm. If you set idle at 6psi and are going to run "X" boost, it needs to be able to regulate 6 + X psi. Fuel pump needs to be capable of 6 +X psi also. You will need to know what your turbo wastegate is set at to know it's max boost psi.

No waste gate, it is a belt driven Procharger

RemCharger · Mar 23, 2022

The 528 hemi crate motors usually put out close to 650 hp N/A.
I would think if everything was spec'd right , it would be 850 +. If you can pick up the fuel pump with one hand it might be too small lol

Paul_G · Mar 23, 2022

RemCharger said:
The 528 hemi crate motors usually put out close to 650 hp N/A.
I would think if everything was spec'd right , it would be 850 +. If you can pick up the fuel pump with one hand it might be too small lol

Yep! Just got off the phone with Procharger. As I was explaining the build and the symptom he stopped me short and said the fuel system on the car right now is not going to work with the build. He suggested I call Aeromotive and have them spec a system. Which I am going to do right now.

RemCharger · Mar 23, 2022

Paul_G said:
Yep! Just got off the phone with Procharger. As I was explaining the build and the symptom he stopped me short and said the fuel system on the car right now is not going to work with the build. He suggested I call Aeromotive and have them spec a system. Which I am going to do right now.

exactly

diesel_lv · Mar 23, 2022

Theoretically an engine doubles it's hp for every 14lbs of boost. You would be looking at a little over 2.5 times the n/a hp. You are going to need a way to limit the boost. If it does not have a way to bleed boost (waste gate) then underdrive pulley. From your questions, I am assuming very little experience/knowledge of boosted engines. Do you have a timing curve for boost etc.....

Fuel pump sizing

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