View Full Version : Fuel pump question

07-13-2012, 08:57 PM
I am switching to a front bumper mounted 3 gallon fuel cell for the car. I am putting a inline 255lph Walbro external pump with a Aeromotive regulator in with the cell. I currently have red top 32# injectors. I am under the impression that I can now just raise and lower the fuel pressure and won't need to swap out injectors? Was wondering if that is correct. If so, what pressure will I need to set the regulator at? Thank you.

07-14-2012, 03:04 PM

07-16-2012, 05:48 AM
A little help please!!!

Lonnies Performance
07-16-2012, 07:42 PM
You can alter the pressure to change flow, but it is not linear.

Flow increases with the square root of the ratio.
For example changing 43 to 58psi = sqrt(58/43) which equals 1.16 times the flow.

You wll likely have excessive pressure before you get a big flow increase.

07-17-2012, 02:19 AM
Okay, I am switching from a 236/240 .598/.608 cam to a solid roller 248/254 .673/.673. I was running red tops with the old cam. I also switched from ported LS1 heads to AFR 230 heads. This is all on a 347ci LS1. Do you think I will need new injectors? The Walbro pump I am installing with the new fuel cell has a max pressure of 60psi and the Aeromotive regulator has a pressure range of 3-65psi.

07-19-2012, 11:47 AM
With the 32# injectors, you are looking at around the mid-400's for power @ 43 psi.

At the stock system pressure (58 psi), you'd be able to get close to 500, maybe a little more.

Depending on the nitrous setup you have, you might want to consider being able to cover the power you'd make on the shot with injector flow.

07-20-2012, 12:49 AM
I am running a second pump and regulator out of that same fuel cell for the nitrous kits. I would think I will be making somewhere around 450 to 550 hp on the motor. That is my best guess. I am only worried about this covering the motor.

07-20-2012, 08:38 AM
Well, if you want to play around with some numbers, we have a few calculators on our site >

Couple of parameter suggestions for the injector size calculator:

BSFC - .45-.5 for NA and gasoline
IDC - 80-85%, you should be able to use the injector up to 90-93%, so choosing 80-85 will give you some headroom.

09-26-2012, 06:05 AM
What is the lowest IDC % that is recommended? I am currently building a 454 motor and it will be around 875 to 950 hp on the motor. That calls for around a 68 to 74# injector with a 80% IDC. I can get a deal on some Racetronix's 80# injectors tho. Will it be ok to use the larger injector at a lower IDC?

09-26-2012, 10:16 AM
The injectors should function just fine in most IDC ranges. Operating in the 50-60% IDC ranges shouldn't be an issue.

One of the key characteristics for a set of injectors besides overall flow, in how well they are matched and balanced. I'm not familiar with Racetronix's procedures, however, they are a long standing company and supporter of LS1Tech, so I'm sure it is within spec.

09-26-2012, 10:54 AM
Ok, now on a different note. As for a fuel pump for this new setup. I am looking at the Aeromotive A1000 pump that can do up to 1300 hp n/a. Is this pump to much? Also will it work in my current setup with a 500 hp n/a motor until I put the new motor in?

Here is the link to the pump I am looking at: