Maximum lift pump pressure?

[Lonnie]

What are the guidelines for lift pump pressure?

If I understand things correctly, you can have idle issues if the pressure is set too high..... but does increasing the pressure still help with rail pressure at full throttle?

Obviously negative pressure at the inlet will restrict CP3 output, but is there a significant rail pressure difference by going from 5 to 10 or even 20psi?

Thanks for any info that you can provide.
Lonnie

 

[Mike]

What are the guidelines for lift pump pressure?

If I understand things correctly, you can have idle issues if the pressure is set too high..... but does increasing the pressure still help with rail pressure at full throttle?

Obviously negative pressure at the inlet will restrict CP3 output, but is there a significant rail pressure difference by going from 5 to 10 or even 20psi?

Thanks for any info that you can provide.
Lonnie

0 to 5 yes, 5 to 10 a little, but over 12 I have not seen much of a difference with a single cp3 for sure. Hope this helps.

 

[sweetdiesel]

Ever see the Mitusa


I think if you could maintain 8-9 psi all the time that would be great
I would look more for the GPM than pressure

 

[Killerbee]

I would look more for the GPM than pressure

TRUTH.

it must maintain a decent pressure at the expected flow rate. if you get somethiong that works great, 15 psi at 5 gpm, but it drops to 1 psi at 10 gpm where it is needed, you have wasted time and money. Just an example.

 

[Lonnie]

As for GPM, the objective would be to design it for sufficient capacity to hold desired pressure at peak power levels.

I ask because I'm trying to layout my pump system. I routinely build fuel systems feeding 600 to 1000+rwhp cars while holding over 70psi fuel pressure for fuel injected performance cars, so this should not be a problem.

Since I'm doing a conversion, I'm starting with a custom tank, pumps, & lines to the engine & back. Therefore, I'm not trying to adapt existing parts to my vehicle as it will be totally custom.

What I mainly need is the peak idle pressure desired & also the maximum presure (that will not damage the fuel controller or CP3) or the point of diminishing returns which relate to rail pressure increases.

For example, Lets say 15# ruins idle quality (not factual, but hypothetically), then we would use slighlty less, say 10# at idle/low RPM for drivability & increase pressure to a significantly higher number (say 50#) at full throttle. Will 50# help the rail pressure more than 20#? Will it damage something? Has anyone explored these limits?

I'm trying to think outside the box here.

Lonnie

 

[Mike]

As for GPM, the objective would be to design it for sufficient capacity to hold desired pressure at peak power levels.

I ask because I'm trying to layout my pump system. I routinely build fuel systems feeding 600 to 1000+rwhp cars while holding over 70psi fuel pressure for fuel injected performance cars, so this should not be a problem.

Since I'm doing a conversion, I'm starting with a custom tank, pumps, & lines to the engine & back. Therefore, I'm not trying to adapt existing parts to my vehicle as it will be totally custom.

What I mainly need is the peak idle pressure desired & also the maximum presure (that will not damage the fuel controller or CP3) or the point of diminishing returns which relate to rail pressure increases.

For example, Lets say 15# ruins idle quality (not factual, but hypothetically), then we would use slighlty less, say 10# at idle/low RPM for drivability & increase pressure to a significantly higher number (say 50#) at full throttle. Will 50# help the rail pressure more than 20#? Will it damage something? Has anyone explored these limits?

I'm trying to think outside the box here.

Lonnie

Really for what I know, 50# could cause some problems with the transfer pump on the back of the cp3. I think 10psi consistently would be best at all rpm levels and power levels.

 

[The Neens]

For example, Lets say 15# ruins idle quality (not factual, but hypothetically), then we would use slighlty less, say 10# at idle/low RPM for drivability & increase pressure to a significantly higher number (say 50#) at full throttle. Will 50# help the rail pressure more than 20#? Will it damage something? Has anyone explored these limits?

Just as an FYI, an unregulated Holly Black pump made my Dad's '02 LB7 idle horribly...

I like your idea though...

 

[Lonnie]

Aren't the black pumps rated for 14#?

 

[The Neens]

Aren't the black pumps rated for 14#?

Yes it is...

http://www.holley.com/12-815-1.asp

 

[LBZ]

Remember the heat factor though. The more pressure you run, the more heat you are going to put in the fuel system. Unused fuel does return to the tank.

 

[sweetdiesel]

mitusa runs at 100 PSI IIRC
I like your ideas to lonnie but i dont think you need that much untill you get into big fueling AKA Duel CP3s,but i still like your idea

Im doing the same right now as you with the custom tank and lines,but im so busy right now i havnt had much research into this

 

[sweetdiesel]

you might try getting in touch with Opie,perhaps he could answer your questions better......I think you could get in touch with him on the DP or maybe even talk to MIKE L

 

[Mike]

mitusa runs at 100 PSI IIRC
I like your ideas to lonnie but i dont think you need that much untill you get into big fueling AKA Duel CP3s,but i still like your idea

Im doing the same right now as you with the custom tank and lines,but im so busy right now i havnt had much research into this

you might try getting in touch with Opie,perhaps he could answer your questions better......I think you could get in touch with him on the DP or maybe even talk to MIKE L

OT

I see how you get a post count increase, Two posts within 2 minutes in the same thread and no one between you. :rofl:

JK, :joker:

I got an extra one by saying this.

Back on topic.

 

[Lonnie]

Mike L. has talked with me probably more than he wants to lately. His efforts have been immensely helpful, so hopefully he will chime in as I do not want to bother him anymore than I have to.

Although, I would like to know the max safe/beneficial pressure to design for...

 

[JoshH]

Pressure hurts idle quality if the pressure is going into the FICM. The MITUSA plumbs the pump in after the FICM so it doesn't matter what pressure it runs because the FICM is still seeing stock (vacuum) pressure. The LBZs don't even have an FICM so I don't think they would have any problems with rail pressure.

 

[Stingpuller]

Lbz

I run my lift pump at 18# at idle on my LBZ. Works great.

 

[sweetdiesel]

Pressure hurts idle quality if the pressure is going into the FICM. The MITUSA plumbs the pump in after the FICM so it doesn't matter what pressure it runs because the FICM is still seeing stock (vacuum) pressure. The LBZs don't even have an FICM so I don't think they would have any problems with rail pressure.

Thanks Josh
so you think it would be benificial to have a pump after the FICM,Not necesarly a MITUSA but any pump?

 

[SmokeShow]

where is the FICM? Pics would be great.

Getting ready to tear into mine and every bit of knowledge before hand would be great.

 

[BIG DIPPER]

There is nothing in a FICM that will have any effect on pressure. It is nothing more than an empty chamber that is bolted to the electronics. If you take the torx (IIRC) screws out and take it apart, you will see for yourself. Take the banjo bolts out and drill the opening as close to the thread size as possible. Open up te banjo bolts by elongating the hole. That's about all you can do......

The only reason to go around an FICM is if you are going to run high pressure as in 50-100 like they set the Mitusa up to under WOT.

FWIW, my 02 ran 10-12 for a few years with no issues.