A fresh approach to Fuel Pressure Regulator and Dampers
10-12-2022, 08:05 PM
#63
Rennlist Member
Thread Starter
I'm glad you asked.
A tapped hole in the cap, a set screw and a flat cap that centers in the cap and the spring.
But, if you know the static fuel pressure you need I can source a spring with the spring rate you need.
Kevin
A tapped hole in the cap, a set screw and a flat cap that centers in the cap and the spring.
But, if you know the static fuel pressure you need I can source a spring with the spring rate you need.
Kevin
10-13-2022, 04:25 AM
#65
Rennlist Member
Whilst these lads go at it again... I was more asking in regards to when needing to replace them. Instead of running two and outlaying that cost, and if they are fighting each other anyway reverting to one. Great info however regards injectors as I am heading down that track.
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Kevin in Atlanta (10-13-2022)
10-13-2022, 12:59 PM
#67
Rennlist Member
10-13-2022, 04:12 PM
#68
Former Sponsor
As we both know, you've been working off of my product, from the beginning...with Hans' goal to make it different, visually.
It's still just an American diaphragm, with an appropriate spring.....exactly like mine. The shape is different.
Currently, you are where I was at, ~two years ago.
And you've got one hell of a learning curve left...
And I'm not about tell or show you what that learning curve is.
Way too much of that has already occurred!
Like I said, I'm perfectly and completely happy to supply my clients with my dampers and regulators.
Completely "in house", on "in house" cars.....where no one will ever have the opportunity to tear them apart and "learn" how it's done.
I'm completely over having my stuff copied....
As a matter of fact, I've got a couple of cars headed down into your general location and I'm installing stock dampers/regulators on those cars. (If you've been paying attention, I have a huge inventory of Bosch/other parts that no one can currently get. I "saw" the writing on the wall, was privy to some information, and planned way ahead.)
The rest of the market is all yours and Roger's...
while I smile.
'Cause I don't care, anymore...too many people that don't have the intelligence to think up their own unique products, take my ideas, and make essentially the same product.
I'm over trying to build things for the "general 928 community".....because of people, like you.
Guess who suffers? (Clue: It's not me. There's 37 928s here, today, with 42 more on a waiting list....)
Last edited by GregBBRD; 10-13-2022 at 04:25 PM.
10-13-2022, 05:20 PM
#69
Rennlist Member
Thread Starter
Thanks for your offer, Kevin, but I'm going to decline.
As we both know, you've been working off of my product, from the beginning...with Hans' goal to make it different, visually.
It's still just an American diaphragm, with an appropriate spring.....exactly like mine. The shape is different.
Currently, you are where I was at, ~two years ago.
And you've got one hell of a learning curve left...
And I'm not about tell or show you what that learning curve is.
Way too much of that has already occurred!
Like I said, I'm perfectly and completely happy to supply my clients with my dampers and regulators.
Completely "in house", on "in house" cars.....where no one will ever have the opportunity to tear them apart and "learn" how it's done.
(As a matter of fact, I've got a couple of cars headed down into your general location and I'm installing stock dampers on those cars. If you've been paying attention, I have a huge inventory of Bosch parts that no one can currently get. I "saw" the writing on the wall, was privy to some information, and planned way ahead.)
The rest of the market is all yours and Roger's...
while I smile.
As we both know, you've been working off of my product, from the beginning...with Hans' goal to make it different, visually.
It's still just an American diaphragm, with an appropriate spring.....exactly like mine. The shape is different.
Currently, you are where I was at, ~two years ago.
And you've got one hell of a learning curve left...
And I'm not about tell or show you what that learning curve is.
Way too much of that has already occurred!
Like I said, I'm perfectly and completely happy to supply my clients with my dampers and regulators.
Completely "in house", on "in house" cars.....where no one will ever have the opportunity to tear them apart and "learn" how it's done.
(As a matter of fact, I've got a couple of cars headed down into your general location and I'm installing stock dampers on those cars. If you've been paying attention, I have a huge inventory of Bosch parts that no one can currently get. I "saw" the writing on the wall, was privy to some information, and planned way ahead.)
The rest of the market is all yours and Roger's...
while I smile.
Gosh, no matter how many times I say it you don't listen. I have never used your FPR or FPD offerings to come up with mine.
This is how I got here:
- At the RENDEZVOUS 928 a few years back here in Atlanta Hans showed me his rails with dampers.
- I asked if we could make dampers and fuel regulator bodies to use the inserts.
- He said yes.
- I was unaware that you were also doing this until you mentioned it.
As for my latest version...
- I have had an adjustable FPR on my desk at work for a few years.
- I took it apart to see if I could understand how it works.
- Along the way you and Jim C. criticized my first version of the dampers for their lack of volume and not being designed for batch firing.
So, I took your critique to heart and looked at the adjustable version from 928 motorsports more carefully.
That is where the new version came from. It had a specific volume, spring rate, preload and an aftermarket diaphragm.
I bought a Radium FPR and took a peek at it, too. I almost used the Radium version at as starting place but there were limitations to it's design.
Then I disassembled every FPR and FPD Bosch markets for our cars. I calculated their volume and spring rates, preload and the surface of the diaphragms.
So, there you have it . At no time did I use or need anything related to your FPD's
One thing you have right is where I am in terms of development. Not quite 2 years is my hope. So, enjoy the head start. :-)
And lastly, there are only two ways these regulators dampers can work. Either you continued with the Bosch post design or you went with the non-post version used by Radium.
KB
P.S., And in the end I may go open source and provide the STP files.
P.P.S, Please buy Greg's fuel and clutch lines. If I didn't have need for them in my cars I would frame them. Better than Porsche by a mile.
10-31-2022, 07:10 PM
#70
Rennlist Member
Thread Starter
First testing update
I am making progress dialing in the spring rate for the S4 fuel regulator. Static fuel pressure rings in with 58psi. This is the same as my stock Bosch FPR on my 88.
When I apply vacuum in 5psi increments 0-20 fuel pressure drops 3psi each time. The good news is it is linear. That suggests I am close to the desired spring rate.
But, I am shooting for a 5psi decrease for each 5 psi of vacuum. Sourcing an off the shelf spring for the range is limited. I am looking at custom springs.
And the other good news is once I get the spring rate and PSI decrements right I'll have a spring rate and spring that I can use for 84-95 model years. All I will need to do is adjust the preload.
And with known preload I will be able to add a capability to adjust fuel pressure internally or externally. Kind of like Konis. :-)
While playing with spring preload I learned it does not take much to increase the fuel pressure. In one of my tests I managed to generate 150+ PSI on the fuel rail (oops).
My fuel regulator held the pressure. Alas, my used Bosch front damper did not as evidenced by the bubbling mineral spirits coming from the vacuum port in a later test.
I have a fuel injector tester on its way. It can adjust the injector timing to mimic RPM changes.
With the tester and a relay I should be able to fire the injectors in batch and use a data logger to measure damper performance over the RPM range. Then I can dial in the correct spring preload.
Kevin
When I apply vacuum in 5psi increments 0-20 fuel pressure drops 3psi each time. The good news is it is linear. That suggests I am close to the desired spring rate.
But, I am shooting for a 5psi decrease for each 5 psi of vacuum. Sourcing an off the shelf spring for the range is limited. I am looking at custom springs.
And the other good news is once I get the spring rate and PSI decrements right I'll have a spring rate and spring that I can use for 84-95 model years. All I will need to do is adjust the preload.
And with known preload I will be able to add a capability to adjust fuel pressure internally or externally. Kind of like Konis. :-)
While playing with spring preload I learned it does not take much to increase the fuel pressure. In one of my tests I managed to generate 150+ PSI on the fuel rail (oops).
My fuel regulator held the pressure. Alas, my used Bosch front damper did not as evidenced by the bubbling mineral spirits coming from the vacuum port in a later test.
I have a fuel injector tester on its way. It can adjust the injector timing to mimic RPM changes.
With the tester and a relay I should be able to fire the injectors in batch and use a data logger to measure damper performance over the RPM range. Then I can dial in the correct spring preload.
Kevin
Last edited by Kevin in Atlanta; 10-31-2022 at 11:47 PM.
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Adamant1971 (10-31-2022)
01-21-2023, 01:10 PM
#71
Rennlist Member
Thread Starter
I am making progress dialing in the spring rate for the S4 fuel regulator. Static fuel pressure rings in with 58psi. This is the same as my stock Bosch FPR on my 88.
When I apply vacuum in 5psi increments 0-20 fuel pressure drops 3psi each time. The good news is it is linear. That suggests I am close to the desired spring rate.
But, I am shooting for a 5psi decrease for each 5 psi of vacuum. Sourcing an off the shelf spring for the range is limited. I am looking at custom springs.
And the other good news is once I get the spring rate and PSI decrements right I'll have a spring rate and spring that I can use for 84-95 model years. All I will need to do is adjust the preload.
And with known preload I will be able to add a capability to adjust fuel pressure internally or externally. Kind of like Konis. :-)
While playing with spring preload I learned it does not take much to increase the fuel pressure. In one of my tests I managed to generate 150+ PSI on the fuel rail (oops).
My fuel regulator held the pressure. Alas, my used Bosch front damper did not as evidenced by the bubbling mineral spirits coming from the vacuum port in a later test.
I have a fuel injector tester on its way. It can adjust the injector timing to mimic RPM changes.
With the tester and a relay I should be able to fire the injectors in batch and use a data logger to measure damper performance over the RPM range. Then I can dial in the correct spring preload.
Kevin
When I apply vacuum in 5psi increments 0-20 fuel pressure drops 3psi each time. The good news is it is linear. That suggests I am close to the desired spring rate.
But, I am shooting for a 5psi decrease for each 5 psi of vacuum. Sourcing an off the shelf spring for the range is limited. I am looking at custom springs.
And the other good news is once I get the spring rate and PSI decrements right I'll have a spring rate and spring that I can use for 84-95 model years. All I will need to do is adjust the preload.
And with known preload I will be able to add a capability to adjust fuel pressure internally or externally. Kind of like Konis. :-)
While playing with spring preload I learned it does not take much to increase the fuel pressure. In one of my tests I managed to generate 150+ PSI on the fuel rail (oops).
My fuel regulator held the pressure. Alas, my used Bosch front damper did not as evidenced by the bubbling mineral spirits coming from the vacuum port in a later test.
I have a fuel injector tester on its way. It can adjust the injector timing to mimic RPM changes.
With the tester and a relay I should be able to fire the injectors in batch and use a data logger to measure damper performance over the RPM range. Then I can dial in the correct spring preload.
Kevin
When I pull 20 in/hg the PSI on the rail drops from 58~ to 48~.
The fuel system operates such that there is a constant differential pressure between the fuel rail and the inlet manifold at the point where the injectors are fitted. This is necessary so as to ensure that the amount of fuel injected per pulse is correctly calibrated. At idle a good motor will pull a vacuum of about 20 inches Hg and that is equivalent to an absolute pressure of about 5 psia. Thus the differential pressure at idle will be the test value of 3.3 barg [48 psig] plus the pressure equivalent of the vacuum pulled which is 10 psi to give a total differential pressure of 58 psi. When the engine is at full throttle most of that vacuum is lost by the friction losses in the runners so for discussion purposes let's assume that at full throttle the absolute pressure in the inlet manifold is 14 psia. To maintain a constant differential pressure the fuel rail pressure therefore has to increase to 58 + 14= 72 psia or 57 psig which equates to 3.9 barg and that is where the 3.8 barg comes from allowing for rounding errors in the numbers I have used for illustration purposes.
I think I'm ready to toss the FPR into the 88 S4 test mule.
Last edited by Kevin in Atlanta; 01-21-2023 at 01:12 PM.
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ROG100 (01-21-2023),
Zirconocene (01-21-2023)
01-21-2023, 03:10 PM
#72
Rennlist Member
Thread Starter
Our design is modeled after the Bosch units. But, we think there is a design fault in the Bosch version that leads to their premature failure.
We believe our change will increase the life of the diaphragm.
We believe our change will increase the life of the diaphragm.
01-21-2023, 03:33 PM
#73
Rennlist Member
I've always chuckled at Tesla's hand-waving of their meltdown problems by comparing them to gasoline engine fires, as a whole. Except for Ferraris and Lamborghinis, new cars are VERY resistant to catching fire. It's usually the old cars with aging or modified fuel components. Hence the question.