Modded CP3 is on - Dyno and review:

[steved]

Hohn, I liked your calculations, made more sense to me.



Could it be that some pumps flow 150gph at a lower pressure like 5 psi?

Maybe at 40 psi they are only capable of flowing 50gph

Most pumps are rated at "X volume @ X psi"... so yes, the FASS might be rated at 150gph @ 0 psi... I don't actually think I have ever seen a true flow rating for their pumps other than 95gph or 150gph... this coming from someone that owns one too.



I also think you start to exceed the maximum flow of the stock lines, and even custom lines) at some point (a 5/16" line will only flow so much volume at a given pressure)... so it wouldn't matter if you have a pump capable of 300gpm @ 5psi if you are pumping through a line that can only sustain 30gph @ 5psi.



I believe the FASS95 uses 3/8" line while the FASS150 uses 1/2" line IIRC... so a 150 might supply the volume, but not at the pressure these new CP3s are wanting.



steved

 

[AK RAM]

JeffK brought up a good point after running over these with a rotating pump engineer at work. It would appear that pressure is more important than volume with the mods that are done. Chances are, the changes to the suction side of the pump are the reasons for the suggested 40psi feed pressure. The idea is that the built in lift pump (1st stage) had to be significantly modified to be able to increase the flow through the Cp3. More pressure after the first stage allows the Cp3 second stage (plungers) to move further up their flow curve, providing more fuel up top. The adverse effects of modifying the built in lift pump stage is that it can no longer feed itself with a really low supply pressure regardless of the flow GPH at the inlet. It is all push and no pull. Kind of like running a huge single turbo. Takes a lot of exhaust pressure to feed it well enough to make it do its job. The stock Cp3 could take care of itself as long as you had positive pressure to it. Just a theory, but just about any pump that can maintain 40psi to the inlet should work fine. I suspect the higher the pressure, to a point, the better this pump will do.



They did say the Stage 1 Cp3 flows 12% more fuel than the stock Cp3. 12% over stock is not a huge amount when you think about it. On my truck, if the FASS 95 can keep up with the stock Cp3 (maintains 13psi at the Cp3 inlet at WOT), then it should have no problems keeping up with the Stage 1 as far as volume goes. It is only going to eat another 12%. Tomeygun's FASS did maintain 6psi of pressure, indicating there was enough residual volume left to back up and keep 6psi in the line, so 95gph is more than you need. The FASS 95 motor is just not strong enough to keep that kind of volume pressurized to the pressure it needs. Pressure seems to be key to making the Stage 1 mods work for you. My $. 02

 

[Tomeygun]

Tomeygun's FASS did maintain 6psi of pressure, indicating there was enough residual volume left to back up and keep 6psi in the line, so 95gph is more than you need. The FASS 95 motor is just not strong enough to keep that kind of volume pressurized to the pressure it needs. Pressure seems to be key to making the Stage 1 mods work for you. My $. 02

Theres something I've been thinking about here. I have a HPFP 95 gph fuel pump, Not the full FASS. And the full FASS has a fuel return line, and that is one way it regulates PSI, by returning fuel to the tank.



BUT mine, the HPFP does not have a return line, all the fuel that goes through it goes all the way to the front and through the filter, etc,etc



My point is that maybe the FASS flows better the the HPFP unit due to it have the bypass system...



Any thoughts??

 

[CRiggan]

KEEP this thread going... I need the CP3 system mod also





Tomeygun would you go with the stage one or stage two if you had to do it over again?



Not sure if I should spend the extra $ to have the availabilty of fuel there

 

[Hohn]

Hohn, I liked your calculations, made more sense to me.

Could it be that some pumps flow 150gph at a lower pressure like 5 psi?
Maybe at 40 psi they are only capable of flowing 50gph

Bingo! You need to know where these pumps are on their delivery curves.


It's one thing to say that I need X amount of flow in GPH at Y amount of PSI.

It another entirely to choose a pump, because you're trying to guess at how much reserve capacity you need.


In the end, I'm CONVINCED that the solution for a case like Tomeygun's is a serious pump, like the Aeromotive USCG Marine pump-- capable of well over 600lb/hr (about 90GPH) @ 45psi and 13. 5V

#ad



It's important to match this to a good BYPASS REGULATOR-- Try their #13114 which adjusts from 40-70psi.

For lower psi, try a different regulator (I'd stick with aeromotive). A bypass regulator is the only way to keep PSI at the CP3 inlet constant, regardless of fuel demand.

**IMO ANY SERIOUS FUEL SYSTEM WITHOUT A BYPASS REGULATOR IS FLAWED**

It's the only way to keep FP rock-solid.

JMO

 

[CATCRACKER]

superduty did say that other pumps would work fine but suggessted the wlabro b/c of price quality and past experience. . the walbro is capable of 100psi for along time. . off course he said that anymore than 60 psi it would crack the cover on the oem filter housing. also he said a dirty fuel filter could cause problems also. . this has been discussed for atleast 6months on the DTR I bet there is 40pages of info. . check it out



now to clarify: i dont have this pump on yet but there is not doubt what i am going to run when i do... walbro 392 a couple of tapped bajos from genos some fuel line a wiring harness and a regulator. Heck i will even buy two walbro just incase this one goes out and in10 min and i will have a new one on there... go do that with the fass

 

[Tomeygun]

In the end, I'm CONVINCED that the solution for a case like Tomeygun's is a serious pump, like the Aeromotive USCG Marine pump-- capable of well over 600lb/hr (about 90GPH) @ 45psi and 13. 5V



For lower psi, try a different regulator (I'd stick with aeromotive). A bypass regulator is the only way to keep PSI at the CP3 inlet constant, regardless of fuel demand.



**IMO ANY SERIOUS FUEL SYSTEM WITHOUT A BYPASS REGULATOR IS FLAWED**

It's the only way to keep FP rock-solid.



JMO

I could add a bypass regulator to any fuel pump right? I wonder what the 150HPFP does when un-internally regulated? And then use a bypass from aeromotive?



uhh-ohh, cogs are turning...

 

[Stefan Kondolay]

This thread is really getting good now.



These fuel systems are starting to get very similar to the set-up that all of us are running in our race cars. When you look at the fuel systems that we run in fuel injected type cars, they are running dual by-pass set-ups and when I was talking with John @ Floor-it I personally feel that this will become mandatory for the guys with the modified CP3's. Systems like the RASP already have this set-up in place, you run a certain volume at idle (obviously lower) and at higher RPM/heavier throttle the volume goes way up. Another thing to keep in mind that the harder/more pressure that you run through the electric pump the faster they burn out.



Remember pressure isn't volume.

 

[CRiggan]

Stefen,



Who would make a fuel pump setup that would raise and lower fuel pressure depending upon RPM ? Could the FASS 150 with filters be able to run at 15psi at low rpm and up to 45 psi at higher RPM ?



Or maybe I could come up with a switch that mounts on the accelerator pedal that would activate the pump to increase fuel pressure at W. O. T.



How much fuel volume and fuel pressure does the stage 1 CP3 Need at w. o. t

to operate to its full potential?



How much fuel volume and fuel pressure does the stage 1 cp3 need at idle to mid throttle to stay alive and work well?

 

[Tomeygun]

Stefen,



How much fuel volume and fuel pressure does the stage 1 CP3 Need at w. o. t

to operate to its full potential?



How much fuel volume and fuel pressure does the stage 1 cp3 need at idle to mid throttle to stay alive and work well?

Stage one was tested at 10psi at the inlet and it made the 12%(or whatever Diesel power quoted) more fuel, BUT it never even thought of dropping I bet...



I think this means 10psi is sufficient, BUT with a $400,000 test stand, I bet the GPH were way up there, with most likely a by-pass utilized.



BTW - at 16psi, I made power, once the RPMS got to 2500, the cp3 was depanding enough to pull down under 10psi, and what do you know... Power fell off accordly!

 

[Jeff_K]

Stage one was tested at 10psi at the inlet and it made the 12%(or whatever Diesel power quoted) more fuel, BUT it never even thought of dropping I bet...



I think this means 10psi is sufficient, BUT with a $400,000 test stand, I bet the GPH were way up there, with most likely a by-pass utilized... .

Then the question should be asked of people doing the cp3 flow testing (Industrial Injection??)... . What are the max flowrates of the stock/modded cp3's?

 

[GWoody]

The pump does control volume and this spring is part of the pump. Pressure is determined by the amount of restriction that the fuel encounters. If you are flowing 5 gph at 10 psi and you raise the psi to 20 you will not double the volume but it will increase. Maybe some of the mathmeticians around here have a formula that will show this.

This would increase pressure, but the pump determines volume. And I think you will find they are running out of volume.



steved

 

[AEzzo]

The pump does control volume and this spring is part of the pump. Pressure is determined by the amount of restriction that the fuel encounters. If you are flowing 5 gph at 10 psi and you raise the psi to 20 you will not double the volume but it will increase. Maybe some of the mathmeticians around here have a formula that will show this.

Look at the flow chart on the previous page. It is the same as all others I have seen. As pressure increases volume decreases.

 

[AEzzo]

In the end, I'm CONVINCED that the solution for a case like Tomeygun's is a serious pump, like the Aeromotive USCG Marine pump-- capable of well over 600lb/hr (about 90GPH) @ 45psi and 13. 5V

I also looked at this pump. The only problem was it was a little pricey. Rated for 2000 hours continuous use.





Now the thing to find out is what's more important the pressure or high volume. I opted for the 15 PSI aeromotive regulator but if pressure is necessary I could always get the higher PSI regulator.

 

[BSwope]

This is just a question here but what kinda pumps did Wade and John use when testing the cp3's to rate the different stages? This may have been noted already though, just curious thats all!

 

[Tomeygun]

It's important to match this to a good BYPASS REGULATOR-- Try their #13114 which adjusts from 40-70psi.



JMO

http://www.aeromotiveinc.com/pdetail.php?prod=11



how awesome is that ?!?!



If I understand this right, the fuel pressure will rise as boost rises from the base pressure and at a ratio of 1:1



Idle - 15 psi, at full tilt, 50psi means 50psi of fuel pressure?



hahaha, thats crazy! -- Anyway, I know that deadhead (not using bypass) on my old 10sec 1/4 challenger was a no-no, why should this be any different?



So me thinks I better call DPP back and get a full FASS OR get one of these fancy-shmancy bypass regulators and make it work with my truck

 

[Tomeygun]

This is just a question here but what kinda pumps did Wade and John use when testing the cp3's to rate the different stages? This may have been noted already though, just curious thats all!

It was a $400,000 injection pump test stand. I do not know what pump was feeding the CP3's when on the stand... But it must have been a big bad boy

 

[Jeff_K]

The pump does control volume and this spring is part of the pump. Pressure is determined by the amount of restriction that the fuel encounters. If you are flowing 5 gph at 10 psi and you raise the psi to 20 you will not double the volume but it will increase. Maybe some of the mathmeticians around here have a formula that will show this.

The "mathematical formula" that you are hoping to find is the pump flow curve. It is different for every pump, and a good example of one is in Hohn's post above. The problem is that FASS/Air Dog do no provide pump flow curves for their systems, so no-one knows what those pumps will flow and a given pressure. Supposedly the FASS 150gph pump will flow 150gph, but at what pressure? Probably 0psi (free flow). As the discharge pressure is increased the flow tapers off (it does not increase). If the lift pump flow was sufficient to supply the cp3 at max demand, then the pressure would never drop, but since the higher pressure actually reduces the flowrate of the lift pump (from the pump curve), as the cp3 demands more fuel the pressure drops and the flow increases to meet the demand. As long as the lift pump can supply enough fuel without drawing the pressure down too far, most people are happy.



Stephan brings up a great point. We need to look at other high performance engine fuel systems to figure out the best way to get the fuel into the mighty cummins. The more I research the "Walbro" type system, the more I think it is going to be a great solution. A high pressure EFI pump that is designed to maintain 80psi contantly, paired with a properly sized bypass regulator should be able to supply more than enough fuel for our modded engines.

 

[Floor It]

AK RAM is on the right track, while volume is important it's the pressure that is more important due to the passage design's of the pump. Increasing psi on a stock CP3 will only gain a very small amount, but when you combine with our stage 1 it DOES make a difference. The 95gph pump will work fine with more psi. The only reason we recomend the 150gph pump is because we all know that a little bit of upgrade is never enough, so if you want to upgrade to say a Stage 2 or 3 you WILL need more GPH!! So why not buy one pump one time. Stages 4 & 5 might be better off with the DTT R. A. S. P system, because it will be able to have instant PSI as RPM goes up with the volume too. I am not sure yet, I am very busy and I do have a stage 4 pump right here just waiting to go on Oo. and see!



John

 

[AEzzo]

If I understand this right, the fuel pressure will rise as boost rises from the base pressure and at a ratio of 1:1



Idle - 15 psi, at full tilt, 50psi means 50psi of fuel pressure?

I don't think so, It runs from 30 to 70 psi. I don't think it will run a pressure lower than 30. But with boost will run as high as 70.