Dodge SRT Forum banner

List of Regulators that Hold Pressure

17K views 87 replies 21 participants last post by  woltegsrt4 
#1 · (Edited)
I know that people are using quite a few different regulators out there. Was hoping to compile a list of regulators that are KNOWN to hold pressure at startup. ie, you turn the key, pressure comes up, and VERIFIED by gauge, the regulator holds the full 58psi for an extended amount of time after the pump cycles. There are tons of regulators out there that do not hold pressure, and either immediately drop, or drop within 2-10 seconds. I am not interested in those. What brand and model number regulator are you using that hold pressure. Also, please note how linear the response is to boost/vacuum at the reference port. Thanks to all who respond!



Based on some comments I received I will compile two lists, as people contribute, below.

Regulators that DO hold pressure:
1. SX Performance 15404
2.
3.
4.
5.


Regulators the DO NOT hold pressure:
1. Aeromotive Compact EFI 13105
2.
3.
4.
5.
 
See less See more
#2 ·
Have you found a regulator that would hold pressure?

I've not seen a "return" system with a one way in it ever - I have seen "pulse dampners" that hold enough in reserve to simulate "holding pressure" but it's really the Pulse dampner maintaining that pressure while it bleeds off.

What "is" the big deal about holding pressure? - by design our stock system held pressure as it was returnless and our FPR did not back purge.

In a regulated - RRFPR situation, I understand the pressure drop is apart of the physics of the deal...

I'm always game to learn something new - Drop it on me Nimero -


NachO
 
#4 ·
I always thought fuel pressure was partially maintained by the pump. Don't all fuel pumps have a built in check valve? Obviously if the reg is weak/bad, and allows pressure to leak below it's set psi, it won't matter if the pump is good or not... Correct me if I'm wrong.
 
#5 ·
Your on the answer -

Stock we have a "dead head" style regulator - it stops and starts the flow in a "pop off" style to give you the calibrated (maybe!) fuel pressure.

I'll use an example from century: (this is a good one anyhow, I did this to my lil brother, too funny)
Do you remember as a child, running around the house chasing a sibling or a friend? What happened when you chased them to a room and as they tried to close you out and they did not quite get the door closed? They are pushing, you are pushing, the door is only open a few inches, and then the person on the other side of the door lets go and moves out of the way. Remember stumbling across the floor trying to catch your balance and not destroy furniture or land on your face? A dead-head regulator is similarly doing the same thing, with the fuel being the object pushing, and the regulator holding the door and then periodically jumping out of the way.
That said, physics suggests that the pressure between the fuel pump in our cannister (Stock or S3 returnless system!!) and the FPR is ALWAYS higher than the pressure between the FPR and the fuel rail -

Stock RAIL pressure is....yeah 58psi

S3 rail pressure is...75PSI, on a walboro thats pushing the bypass valve limit (~79-85psi) - you pop that "one use" bypass and guess what? Get one the failboat boys and girls we're sailing into the failhurricane and going to die in a failtsunami. - yeah it fails.

How much higher is that "in cannister" pressure - I do not know, it's kind of hard to get a guage on there and have my head in the tank while WOT'n on the highway in 3rd and 4th to check that - sorry... :ben:

So here we go on the denoument -

Stock we have a bypass/check valve in our fuel pumps - SRT-4 specific genuine walboro pumps have them but the chek valve is more suspect than the bypass, Bosch 040's and 044's have a "check valve fitting on the outlet that will hold the desired fuel pressure after operation stops, a proper pulse dampner will maintain your "static" pressure (I run vac/boost source) so when I shut off with the restrictor installed the pulse dampner pushed my extra 10 psi to the reg, I shut of at 60psi and it rises about 9psi to 69.

The rub - that little check valve is a RESTRICTION! - bingo the only sources I have that use these things on a LARGE basis are located in Greece and Europe in general - the word is 15LPH at Peak flow restriction - lowering the 044 to 285 lph. for a daily/with benefits, that may be doable.

For a race car - or anyone needing that extra volume, deal with the little bit harder to start, or let the pump fully prime twice before you go.

It has, as far as I can see, no other effect on the operation of a NON deadhead regulated fuel system - as always, I'm open to having some discussion on this point.


NachO
 
#8 ·
This brings up a good point, after re-reading my last post I was not quite clear - The walboro can have the bypass removed, eliminating the issue - this is a modification thats done to the pump - old DSM trick really.

this will effectivly remove any safety built into the pump, it will basically overpump at will and attempt to pump itself through the pump outlet if not regulated properly. - keep that in mind.


Or - you can switch up to another type of fuel pump - I know at least one that works without issue - and keep it's standard check valve, you wouldnt feel the hit from 15 lph on that pump anyhow.


NachO
 
#11 ·
NachO... what about the old style return line setup chrysler used in the K-cars. those seemed to keep pretty good pressure in the rail and/or line after shutoff. (based on the # of times I got sprayed working on the wagon last year. stupid car.) wonder what they were doing that we're missing?
 
#12 ·
I had a K-car! - it sucked...

I havent loked at a K car in years, I'll look at my old FSM and see "mechanically" what holds pressure .


Nutz: yes - the "PUMP" is the pressure switch - if it has a check/bypass installed it "should" hold your pressure for some time after shut off.



NachO
 
#15 ·
most (if not all) our fuel pumps are not positive displcement pumps (centrifugal), so once the check valve aspect to them is removed you are likely to not hold any pressure once the pump is off.

off the top of my head the only way I can think to easily check would be to cap your fuel return line, switch the gauge from the supply side to the rail side of the regulator (if it already is not), jump the fuel pump and watch the gauge. Since the pump is not positive displacement it shouldn't be an issue dead heading the pump (pretty sure most pumps including the walbro have a built in bypass anyway). Your likely going to also find out the delta fuel pressure to your fuel pump...

Where are you going with this anyway Nemiro? Just curious.
 
#19 · (Edited)
Sorry, been away from this a while. OK, the reason I am even looking into this is two-fold. For purposes of discussion, I am uninterested in what people's opinions of pumps are, or how it compares to a stock, returnless system. I am focusing ONLY on return type systems. Yes, we know the limitations of the Walbro 255. Pick a pump, any pump. Sota did bring up an interesting subject on the old turbo car Bosch pump, but again, this has to do with the regulator.

I am using Aeromotive's compact EFI regulator. It looks pretty, but it sucks. Very inconsistent, and will not hold pressure at key cycle. This latter problem results in slow starting, especially if the tank is low, and the pump picks up some air. This lack of sealing also indicates that the regulator has its own measure of parasitic flow loss. What I mean by that, is that if the regulator has zero ability to hold every last bit of fuel flow, the limit of the pump or the rest of the fuel system will be found artificially early.

So, let's say that you are using almost all the fuel that the pump can support (say, 85%). If the regulator is not allowing a full amount to hit the rail, you may be operating at a 15-20% bypass "overhead" that you would not have, had the regulator been able to effectively seal, and allow a 0% bypass, if the desired pressure was not reached. If you have a 400lph pump, and you lose 20% to the regulator, guess what? You now have (effectively) a 320lph pump.

Taking apart the Aeromotive Compact EFI regulator showed it all. Pretty piece, POOR design that has no hope of ever sealing. We did some basic machining to mine, and it helped slow how fast pressure would drop (I have the Autometer servo type fuel pressure gauge inside the car), but it still cannot seal, due to the lack of an actual needle and seat (with appropriate sealing material) in the design. Sota is right. The simple Bosch type regulators used in older turbo Dodges, many Fords (including ALL 2.3 turbos), Volvos and others, just to name a few, does indeed seal, and it will hold pressure for minutes, and in some cases hours.

I do realize that a proper check valve is required at the pump, but that is only one piece in this equation. The regulator is allowing bypass under ALL conditions. That is my issue here.
 
#22 ·
I see - Your finding the same issues with the aeromotive equipment that other friends of mine have found -

I use a Magnafuel Regulator - and have not had an issue with it leaking off quickly after shutoff - I have no issues with a consistant "prime and hold" pressure associated with most oem fuel system operations - I'm certinly not using anything stock in my fuel system either -

Of note - when I removed the "check valve" (poor name for how it really functions) and the ability to hold the line pressure is gone.

In my case at least - it is all related to that 044 fitting.


NachO
 
#20 · (Edited)
What are your design parameters?:
Must it be a rising rate?
Must it have an inlet, outlet and return or will just one inlet suffice?

Have you contacted Aeromtive? They have quite a few different bypass regs. I always thought their 'compact' version was the El cheapo of the bunch.
Any pictures of the problem area and fix?


Maybe I should design and model an SRT rail that uses the old TI/TII 55psi bosch reg. I'll do it for some 750cc.
 
#21 ·
okay I see what you are saying and I'll go with it. The pressure is regulated by dumping pressure >58 psi from the rail side back to the canister vice dumping pressure <58psi to the rail side.

That drawing is really hard to follow. I'm trying to think of a reason they would go with a reverse style regulation like that.
 
#23 ·
I know on the Red Sled the Aeromotive ended up being the weak link. After hitting a fuel brick wall with a Magnafuel 850 pump, all -10 lines, 1600cc injectors and a custom sumped tank It was removed and replaced with a magnafuel and the issue went away completly. But that was more related to the delta pressure the aeromotive could handle. If I remember correctly it was 75psi on the Aeromoive and 90psi on the Magnafuel. That was per inside tech suport and not advertised Specs though. I'll verify the numbers if I remember.


magnafuel >>> aeromitive
 
#24 ·
Any links to the preferred Magnafuel regulators?

It should be noted that many people use incorrect terms when referring to FPRs. A boost/vacuum regulator is assumed to be a 1:1 ratio, and is what we generally want. A rising rate (RRFPR) has a rising rate of gain, so it is generally 2:1, 3:1, 4:1, etc. These are often used on supercharged vehicles that do not want to deal with retuning the ECU. They are often called FMUs, or Fuel Management Units. Some people call them 'pinch off' regulators. I personally have had these (and despised them) on Ford Mustangs and other vehicles.

OK, back on subject, I am looking for a boost/vacuum referenced regulator (1:1), and I need only a feed from the rail, and an outlet to the tank. I am using -6 return lines, as this is all I need for my application. The current regulator also has a 1/8" NPT gauge port, which I am utilizing, and do like about this regulator. That's where my love affair with this thing ends.

I will post up some pics some time, but the premise of this regulator is that a spring presses on a metal lined rubber diaphragm, and under that diaphragm is a metal ball (5/16") that seats into a simple hole drilled into the regulator body. all of the sealing has to happen on the edge of this approx. 1/4" hole. Of course, this is not a lot of sealing area. What is worse is that my regulator was worn (stainless ball riding on aluminum), and guaranteeing that a seal would never be made. As soon as the pump finishes priming, the needle immediately falls. We remachined this lousy seat with a ball end mill, and that helped. Now the needle drops within 2-3 seconds, instead of less than half a second.

But again, this illustrates the fuel flow 'overhead', that in effect, makes your pump flow "less" than it actually does when at the limit. If your regulator is set to 58psi, but the pump is running out of huff to keep up with injector demand, as well as regulator loss, then you will see pressure bleed off more quickly than the math on your system is indicating it should. The regulator should be functioning in an "on-off" (bang bang) configuration, not an "on-less" arrangement.
 
#26 ·
#28 ·
How do you run yours? Do you block off one port with an AN plug?
 
#30 ·
Do you recall what type of plug you needed to use for that regulator?
 
#34 ·
Headed to the shop tonight - I'll get the info for you.

You can add that magna fuel to the list of DO NOT's - none of the Aeromotive or Magnafuel regulators on cars at the shop currently hold pressure. The magna's kind of do, but I'd not call it holding. it drops off pretty quick.

:intrestin do you have any pictures of this new setup?
Will have here soon, the car is just now comming together, Surge tank, 2 044's feeding a boomba rail with a -6 return, for now - I'm thinking a -8 maybe needed on the return to get the pressure in line.

You can expect a full update write up, with pics on my new set-up. I've got a couple of days worth of cam testing to do and the final numbers will be posted after that.

I already have plans to devide the car into the different SRTforums sections and post each system detail in the proper section - kind of an open source race car. Nothing in the bag on this one, I'll share it all.


NachO
 
#33 ·
Started the list in the first post. Please post up here your experiences, and I will add (or take away from) the list.
 
#35 ·
Awesome! Thank you very much for sharing!
 
#37 · (Edited)
#39 ·
some information from an aeromotive tech pertinent to the thread topic:

You can disassemble the regulator and inspect the seat the poppet sets down on. A couple things to consider:



1.) Technically, the only time the diaphragm ball ever touches the poppet seat is when the fuel pump is off, i.e. when the pump runs there’s always flow on the bypass, separating the two. If the poppet seat is beat up (anodizing worn off) that indicates the system is/has been cavitating (vapor bubbles in the system). As vapor bubbles pass between the ball on the diaphragm and the poppet seat the pressure of the spring/poppet collapse them. This causes the poppet to drop and strike the seat. Heavy cavitation will beat the seat out of the regulator body.



2.) Aeromotive regulators are not engineered to seal when the pump is off, like the OEM regulator. EPA mandates the stock regulator hold fuel pressure for 30 minutes after shut down. The mechanism used to achieve a seal when the pump is off compromises its ability to control flow and pressure when the engine is running. We believe our customers prefer the regulator to deliver best performance when the engine is on as apposed to when the engine is off. Pressure drop when the pump turns off is therefore common and does not necessarily indicate a problem with the regulator.



Don’t hesitate to take the regulator apart. You can purchase a replacement diaphragm assembly, but if the poppet seat in the regulator base is beat out you’ll need to replace the regulator. Aeromotive components come with a one year warranty to be free from defects in workmanship and material.



You need to find out what’s going on in the system and, if after replacing the pump its still cavitating. This can be a real problem, not only is it hard on the regulator, it’s can starve the engine for fuel under load. Let us know if you have further questions.







Brett Clow
Aeromotive, Inc.
7805 Barton St.
Lenexa, KS 66214
913-647-7300 Ext. 109
 
#40 ·
I hear what he is saying, but I'm sorry, the Aeromotive regulator is cheaply made. If it gets beat up and effectively ruined due to air in the system, then it is not only cheaply made, it is poorly designed. All the pretty anodization in the world will not fix that. I disagree with the assessment that the ONLY purpose of sealing completely is to satisfy OE requirements. If I set the regulator to 100 psi, but my pump only makes 50, then I full well expect that not a drop of fuel is going down the return, and I have that full 50 psi at the rail.

I am not a mechanical engineer, but I can look at the design and see that the addition of a simple viton (or other material) needle or seat in that regulator would make it a very precise regulator (with repeatable results), and also one that accomplishes what I am asking for. Most of us are modifying our cars for OEM type driveability, with LOTS of power added. No one wants to take a hit in the fun factor of the car if they do not have to. Hard to start every time, due to not holding pressure, as it should, means more wear and tear on the starter, engine, etc, not to mention just a pain. Loss of ANY flow at the top end is a reduction in fuel system capacity, no matter how you look at it.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top