Raising FP on stock regulator & Accufab junk

[Jerryl]

Changing relief pressure requires primarily a change in spring pressure. I get that part.
Has anyone been successful in squishing a 233 regulator to 45 PSI base?

 

[mikestertwo]

I have done it. FWIW It's easier just to get a 237 regulator. The junk yards are filled with them on late 80's front wheel drive cars.

 

[Jerryl]

You are correct.
I happen to have 4 spare 233's and they are really “good for nothing” at the stock rating.
Based on a recent post, the 237 is the most stable regulator ...... which started my thought process.

 

[Jerryl]

So I thought I'ld revisit this. I am not convinced the Accufab regulators are the way to go. I had vacuum leaks in the threads and lost pressure immediately after shut off. At boost the pressure was choppy too. This was after sending it back to them to rebuild it too. So here is a back to back to back comparison of the Accufab, Bosch 237 and the Kirbans regulators. The numbers in the box for the Bosch 237 are not correct but the graph shows the story.
Accufab:
View attachment 225584
Bosch 237
View attachment 225585
Kirbans
View attachment 225586
So, the Bosch is the steadiest of all three but the base pressure is 45 line off. If your chip can adjust all the fueling aside from WOT (unlike the TT 6..1) then this looks like it's a winner. If you need to adjust the pressure to 43 then the Kirban's one beats the Accufab in my test. I would like to see others do this test to compare to my results. For now I'm going with the Kirbans. If I change chips to the SD2 then I would definately give the Bosch a try, Ebay has them for $50.

 

[Jerryl]

What I would like to do is determine the reasons for such wide fluctuations in the aftermarket units.
I have access to +150 years of combined pressure relief valve design and testing experience and already have some ideas.

I need to search for picture of the cutaway of the stock, Accufab and Kirban units for further analysis. I will also need dimensions . . . .

 

[Pronto]

PM me your address and I'll send the Accuflub to you.

 

[Jerryl]

PM me your address and I'll send the Accuflub to you.

Thanks pronto. PM send.

 

[Jerryl]

Pictures.

 

[Jerryl]

More pics.

 

[Jerryl]

Last one.

Note:
This is refered to as a hard seated valve which are never leak free. The seat and poppet are always highly polished.
A close look at this seat indicates leakage. The poppet is mounted on a 360 deg pivot to ensure alignment.

The gouge on the OD of the seat was "as is".

 

[RmvBfrFlght]

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

 

[Pronto]

http://www.turbobuick.com/forums/threads/paging-all-powerlogger-experts.406907/page-5#post-3413602
See post 98.

 

[Jerryl]

http://www.turbobuick.com/forums/threads/paging-all-powerlogger-experts.406907/page-5#post-3413602
See post 98.

Hey Pronto,
The info I posted was from your work. Not sure why your id wasn't posted with it. By all means, the credit belongs to you. Thanks for posting the link!

 

[Jerryl]

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

Based on data from Ponto it sure is strange.

There are a few things that will induce fluctuations in PRV:
-Media and specific gravity
-Operating temp
-Inlet design
-Spring to Seat OD ratio
-"Plenum" volume
-Outlet orifice and design path
-Spring ratio

It is my intention to look into the variables related to the FPR wich we can control, to minimize the fluctuations.

I will share the findings (read facts) with the board, regardless of the outcome.

Last but not least:
BIG THANKS to Pronto for sharing his results, and the FPR for the greater good of the sport and community.

 

[Jerryl]

Here is the Accufab/ 233 comparison
Observations:
Size of the boost signal connection is smaller. 0.087 / 0.117
Spring is shinier , but definitely weaker. (need to test this)
Seat definitely has a burr, and poppet/disk will not seal.
Poppet/disk is larger dia. 0.540 / 0.318
Seat hole dia is larger 0.178 / 0.132
Inlet at fuel rail is the same 0.238 / 0.238
Inside dia above membrane is smaller 1.248 / 1.405

Poppet uses similar tech. as in "full 360 deg of alignment freedom"

 

[BEATAV8]

Excellent Thread

 

[Jerryl]

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

 

[Jerryl]

At first sight, there are a few design issues as well, and I can see why the pressure would be unstable. The pressure pulses from the fpr inlet hit the diaphtlram and definitely work against the spring and will cause "chatter", especially against a weaker spring.

I will verify and confirm with my Team.

 

[Jerryl]

Thinking about this last night . . .
One of the issues is the lack of volume under the diaphram.
Larger volume or inlet sizing would greatly reduce fluctuations.
There may be some mods that can be done to help stabilize the pulses.

 

[Pronto]

At first sight, there are a few design issues as well, and I can see why the pressure would be unstable. The pressure pulses from the fpr inlet hit the diaphtlram and definitely work against the spring and will cause "chatter", especially against a weaker spring.

I will verify and confirm with my Team.

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.