Raising FP on stock regulator & Accufab junk

[Jerryl]

I just measured the springs. The average spring deflection using a 10lb force is :
233 = 0.030”
Accufab = 0.075”

Would be interesting to see if the 237 has a heavier spring, or the same spring with increased compression.

 

[Jerryl]

That might be why when the pressure rises the fluctuations get larger. The Accufab website does not give the pressure specs that the regulator is good for. Maybe they just spec'd it for 15psi and not more? For retail price of $159 on their website you would think the regulator would be high quality and stable at higher pressures-NOT.

The goal is to establish a few “DIY” mods people can make to stabilize the pulsation with the Accufab. To test and document this, we will need to ensure first and foremost that the seat is close to leak free. (A small percentage is expected and acceptable.) On this sample, the biggest challenge will be in micro polishing the seat while maintaining perpendicularity and more importantly, flatness. The seat is recessed and pressed in so not sure yet how to do this.

 

[Jerryl]

For those still following
Received the new Kirban FPR for comparison. Here are the pictures. (Need to upload from my phone )

 

[Jerryl]

For those still following
Received the new Kirban FPR for comparison. Here are the pictures.

 

[Jerryl]

And finally, the corrected comparison table.

 

[RmvBfrFlght]

Hey, I'm still following: area = Pi * R * R. (Pi * radius squared).

One thing I did note is how the fuel entry to the chamber is formed between the different regulators. The Kirban regulator uses a larger oval opening, which will reduce the pressure the entering fuel places on the diaphragm.

RemoveBeforeFlight

 

[Jerryl]

Hey, I'm still following: area = Pi * R * R. (Pi * radius squared).

One thing I did note is how the fuel entry to the chamber is formed between the different regulators. The Kirban regulator uses a larger oval opening, which will reduce the pressure the entering fuel places on the diaphragm.

RemoveBeforeFlight

Wow, can’t believe how bad I screwed that up (More like WTF ) and not even sure how that happened, but thanks for pointing that out.
The table has been corrected, and narrowed for better mobile viewing.

Your observation on the hole entering the chamber is correct. There are subtle differences between the FPR's with massive performance ramifications.

Some may rightfully argue that the Kirban and 237 FPR's have proven to be adequate at performance levels waaaaaay beyond my desire and skill level. The $1M question is; Is this really a concern or is "well good enough"?
Regardless of public knowledge and opinion, it is my believe that there is a better/more stable way, and lots of options and solutions to get there.

For the record: The in-depth sharing here is only a result of my commitment to Pronto. I may need to take it to PM with him as following some thought, there is a point where too much tech info may create a certain level of liability. Need to think this through.

 

[SloGN]

Interesting stuff here Jerryl. The design of the stock Bosch regulator is a bit different from the aftermarket regulators. Subtle differences at that.

I run a fuel pressure transducer and log it, with an Accufab FPR. The pressure does jump around, I thought that this was due to the pressure fluctuations of the positive displacement pump(s). Now I'm not so sure, need to post filter the heck out of the data to smooth it, even with a tiny orifice at the transducer (mechanical filtering).

RemoveBeforeFlight

I think the issue of the fuel pressure jumping around could be related to how big the injectors are.....

This would be due to the amount of fuel being injected at various rpms....in the import world they have a damper atteched to the fuel rail to help ease the pulsating effect on the regulator...

Try this I'll bet when you put the car into batch fire mode the fuel pressure moves a lot more vs Sfi.



There could be other factors at work to. Like how smooth of flow is the fuel up to the rail and thru the rail. If there is any turbulence in the fuel along the way that energy is being shown in the fuel pressures moving around. The best way to test this is use the same test car for different regulator so the testing is done in the same repeatable manner .

I might set up a complete fuel system and do some testing I'll just have to create a way to drive injectors...

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[we4Mateo]

...I might neutral set up a complete fuel system and do some testing I'll just have to create a way to drive injectors...

Posted from the TurboBuick.Com mobile app

RC should be able to do that right?

 

[captndave737]

Atrocious quality!
This is PRV 100. Accufab should be embarrassed.
The seat is metal, not aluminum. . .

Aluminum isn't metal??

 

[Pronto]

Jerryl, being a Captain Obvious kind of guy, the big difference is the spring pressure being less on the Kirbans and worse on the Accuflub. That is pretty much what the logs of the fuel pressure showed for me. The Bosch 237 was almost a flat line, Kirbans has some bouncing and the Accuflub was the highest. Not knowing the science and ramifications of all this, my uneducated self thinks a flat line would be better for overall performance of the injectors.

How about trying the Bosch spring in the Accuflubber?

 

[Jerryl]

Jerryl, being a Captain Obvious kind of guy, the big difference is the spring pressure being less on the Kirbans and worse on the Accuflub. That is pretty much what the logs of the fuel pressure showed for me. The Bosch 237 was almost a flat line, Kirbans has some bouncing and the Accuflub was the highest. Not knowing the science and ramifications of all this, my uneducated self thinks a flat line would be better for overall performance of the injectors.

How about trying the Bosch spring in the Accuflubber?

Exactly my thoughts.
Thinking:
Kirban disk/diaphram, 233 spring, in Accuflob
Or
233 Spring in Kirbans

 

[Jerryl]

The mating surfaces to the diaphram were not flat on the Kirban regulator. Probably "flat enough", but a handfile clearly exposed the high spots.

 

[RmvBfrFlght]

Another item to measure is the diameter of the diaphragm that is exposed to the fuel pressure. This is more or less the diameter of the FPR bore where the diaphragm sits. From this the area can be calculated, which is directly affecting or affected by the spring pressure.

On another note, notice how the fuel pressure chamber of the Accufab FPR is small. While the Kirban's is larger, and the Bosch appears to be even larger still. This may be the key to damping the fuel pressure fluctuations.

RemoveBeforeFlight

 

[Jerryl]

Yes, there is definitely a correlation between the spring rate and diaphragm diameter.

 

[Jerryl]

Pretty sure eventually, all the air will be bled out of the regulator, but not sure how long that takes as it will naturally rise and sit against the diaphragm.

 

[toofastforyou]

If someone wants a stock "crushed" regulator, I have one, works great gives about 40~45 psi. Let me know…

Claude.

 

[Jerryl]

Update for those still interested in this;
Had many discussions and there are couple of things that can be done to reduce fluctuations with the current stock location aftermarket FPR's.
Of course, the team recommends designing and building one from scratch , which will be guaranteed to minimize fluctuations, but I am tying the hands and want to focus on a solution for the Accuf. and KB. FPR's in the field.

Hope to be testing in the next few months as we are setting up a test rig and criteria. Need to calculate bypass fuel at max flow. This is a challenge as set-ups and flows differ. Thinking about a medium type set-up with 340 Walbro, 25 PSI, 60lb injectors, 93 octane. (Will use a non flammable media with similar SG).

Any thoughts on test criteria?

 

[delcowizzid]

I can send you a GM inline pulse dampner I think I have 1 non adjustable and one adjustable in the shed off our newzealand and Australian Buick v6's.I use them on imports with big injectors that rattle the fuel lines against the floor in time with rpm as the injectors open and close causing fuel hammer like water pipes in your wall normally after big injectors pump and aftermarket regs fitted..sometimes the fluctuations hit the injectors as they try to open and do nasty things making tuning fun lol.

Sent from my LT26w using Tapatalk

 

[Jerryl]

Cool. I will send a pm . . . and incorporate it into the testbench.