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Control Pressure Dampener from 930SE

Chris at Turbo Craft posted a picture on another thread Is this a factory intercooler? of a pice that comes on some of Porsche's special high output 930's.

It is called a 'dampener' and is plumbed into the center of the Fuel Distribuitor's bled line that goes to the WUR. The WUR acts as a regulator valve to maintain Control Pressure which it central to determining our AFR's.

It is my thought that this it there to 'dampen' the metering arm from 'over-swings' that comes with control pressure quickly dropping when boost enrichment is experienced on modified 930's or those running over .8 bar boost.

If so this could be Porsche and Bosch's effort to correct the same issue we see with that 'pig rich' section we see in the AFR curve with first boost on high HP motors.

Anyone have any info on this?




Quote:
Originally Posted by totle View Post
This is very interesting.
This seems to be a 928 factory part

Did some search and found some installation pictures on an italian site. Used Google translator, so wording might not be perfect.
-----------------------
PorscheMania Forum: ARRICCHITORE BENZINA 930

THIS mounting on dell'arricchitore fuel injection pump 930 turbo
- ACTS AND WORKS when the pressure exceeds the turbine or 8 bar opening injects gasoline --
This original device is fitted as standard on the Turbo S 930/66.
Not having an electronic control that automatically adjusts the fuel pressure this device prevents the higher pressure, or 8 bars become "LEAN"
avoiding breakage of the motor -
Council:
1 - to all those using the spring bar-1
affordable --
2-all in porsche kit costs about 280 + assembly -
disadvantages:
1-mounting is not easy because it is applied behind the pump, however, does not need to lower the engine
2-important after redo the carburetion in um Porsche Center.
here are the pictures of the mounting








Old 03-30-2010, 07:53 AM
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More great info from Chris:

Quote:
Originally Posted by TurboKraft View Post
Parts & numbers are listed in the PET program (workshop manual) for ROW-spec models. It's everything with the M148 option code, "Engine with Increased Efficiency 930.66."




They call it a "diaphragm damper" and MSRP is $137, still available. Fuel lines are $130 and $166, also showing still available.

I'm usually a picture freak with 100+ shots of an engine as it comes down and apart, but I don't have a picture of whether or not there's a vacuum line attached to the damper, and if so where it attaches (above or below throttle body).
Old 03-30-2010, 07:55 AM
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Larry at CIS Flowtech believes the nipple on the dampener is there in case it should leak. I suspect it is also a vent to let the dampener work. We have found no pictures of this hooked up but Larry thinks it should be hooked to the intake in case it dose leak and dumps fuel.

It would be nice to find out if it is ever connected. I would hook a drain to it away from the exhaust or plumbing it to the air cleaner I am thinking if we do not find it has a purpose.

For what it is worth, i believe I have seen this on RUF's CIS 930's also.
Old 03-30-2010, 07:59 AM
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Someone hook this thing up and tells us what it did.
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Old 03-30-2010, 08:45 AM
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Like Chris mentioned, this is part of the option code, M148, for 930.66

What other modification did this option code include?

- Bigger intercooler
- Diaphragm damper (928-110-231-02)
- ???
Old 03-30-2010, 09:02 AM
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Bosh call this part "fuel pressure regulator" and Bosch part number is "0280161007"

Mercedes used the same regulator and had MB part number (000 078 05 92)

Last edited by totle; 03-30-2010 at 09:14 AM..
Old 03-30-2010, 09:07 AM
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The indy mechanic that I have used a few times here in NJ mentioned this thing to me.

The sense I got from him is that it helped protect the diaphragm inside the WUR and made the WUR last longer.
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Old 03-30-2010, 09:15 AM
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Quote:
Originally Posted by jwasbury View Post
The indy mechanic that I have used a few times here in NJ mentioned this thing to me.

The sense I got from him is that it helped protect the diaphragm inside the WUR and made the WUR last longer.
+1

I in agreement with Jacob's remark. Since the device has no pressure bleed-off capacity, it would hardly qualify as a regulator. Damper would be more accurate since it has nothing more than a diaphragm which absorbs pressure oscillations or spikes that could be present in the fuel system. These oscillations could come from the rotary fuel pumps, NA engines (4 to 6 cyl applications) where there may be metering plate oscillations of a minute nature from the timing of the intake cycle.

This would allow the Control Pressure Regulator (WUR) to more accurately meter fuel to engine demand than misread oscillations as a change in demand (engine load).
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Old 03-30-2010, 09:40 AM
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+2
The WUR diaphragm is known to be iffy at 1.0bar and spikes beyond, translating to sudden fuel pressure changes which is what I understand this device helps to smooth.
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Old 03-30-2010, 12:14 PM
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The only diaphram thats "iffy" in a 930 WUR is the boost enrichment diaphram and it never see's fuel, only air pressure around .8 to 1.2 bar depending on what boost you're running.
Brian Leaske will install a heavy duty boost enrichment diaphram that laughs at 1.4bar if you want when he rebuilds them.

The fuel metering diaphram is a stainless steel metal disc against an orifice under the control pressure and return lines on the top of the WUR and it is not damaged by the system or control fuel pressures in a 930, even when raised with a modified fuel head.

The dampener device discussed is absolutely a fuel pressure regulator, apparently being used as a sort of pressure dampener in this situation.
It is exactly like the fuel pressure regulator on the end of the fuel rail on Bosch L-jetronic fuel injection used on mid to late 6 cylinder seventies BMW's right down to the in and out flare fittings. Some BMW's had a barbed fuel line fitting for rubber fuel line on the fuel exit/return line.

On those cars the small vacuum line fitting on the end would go to intake manifold vacuum and intake manifold vacuum would work against the internal diaphram and spring - lowering fuel pressure by bleeding it off the fuel rail and returning more of it to the gas tank when manifold vacuum was high during idle and steady cruise, and moreso during deceleration.
Open the throttle and there's no manifold vaqcuum pulling against the internal diaphram and spring so the pressure regulators needle and seat holds some fuel back from the return line and raises fuel pressure to it's default level which was around 38-42psi so more fuel squirts out the electronic injectors while they are open (dwell time) with L-jetronic.

If you hooked that fitting up to intake manifold vacuum/boost on a 930 the thing would do the opposite to control pressure of what you want it too just like Keith mentioned above.

There are adjustable wide range aftermarket fuel pressure regulators for L-jetronic that you could experiment with in this application if you were so inspired.
Bosch Motronic uses a similar fuel pressure regulator but it fits into the fuel rail with a special 0-ring fitting.
With this little Bosch FPR you can only raise fuel pressure a little at a time by sqeezing the end with the vacuum line fitting inwards with 2 proper size sockets in a vise.
Doing that bends that end of the stamped steel housing inwards a little concave around the vacuum line nipple and increses the spring pressure inside > which raises the default fuel pressure.
Old 03-30-2010, 12:55 PM
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I can see that this might protect the WUR. There was a series that had such an issue. I recall Lee Rice that used to make the Rice Fuler saying that he added a dampener to his Pressure Sensing WUR's that ran lower on boost Control Pressure to protect the diaphragm.

Larry of CIS Flowtech said it acts more like an accumulator. That with quick changes in the movement of the metering pin, system pressure and control pressure can be effected. He felt that this helps rebuild pressures quicker. He has seen them on CIS Ferrari's to.

So far we have not found any evidence the little nipple hooks up to manifold pressure.

Remember, fuel flows from the Fuel Distribuitor to the WUR. If we add any restriction in that line, which is where this unit is attached, it would increase control pressure and the motor would run leaner.

I would not think that it would have much to do with soothing out variations from the fuel pump side of things. The big fuel Accumulator before the Fuel Distributor should take care of that.

Not one seems to think this regulator/accumulator might slow the response measurably to changes in control pressure that comes with boost enrichment?
Old 03-30-2010, 01:45 PM
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Dampers are used on EFI cars to dampen out pressure pulses, insuring that the injectors receive a consistent volume of fuel. I'm sure that the CIS damper is meant to do the same thing, except that it's hooked to the control pressure port on the fuel head.
The nipple is a vent to atmosphere.
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Old 03-30-2010, 01:53 PM
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Makes sense to me.
Old 03-30-2010, 02:10 PM
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Keith, if this FPR/dampener in the control pressure line is there to slow down the speed that hydraulic control pressure on the top side of the control plunger drops under boost then it goes against your repetitive theory that the early vacuum sensing WUR that drops control pressure completely and instantly as soon as intake manifold vacuum is zero, would be an improvement over the 1978 thru 1994 boost enrichment WUR's

From what you've said many times before the early 1976-77 vacuum sensing WUR has no boost sensing hardware in it, it is intake manifold vacuum sensing instead so it drops the control pressure as soon as manifold vacuum hits zero and thats right when the throttle butterfly opens part way > wayyy before boost even starts.
You've said many times this lets the air flow meter open faster and sooner, and eliminates the "lean surge", and in theory that sounds correct but because there is no boost sensing it also seems very inaccurate because it will give the same control pressure at .1bar, or .5bar, or 1bar.

If this dampener device does what you say it does, it's going to completely cancel your theory.
Old 03-30-2010, 04:46 PM
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I really do not know what this thing dose.

I am only guessing and hoping for good input from others.

It's function could be very minor and quick acting to just protect the WUR.

Larry believes that its function is to stabilize System & Control Pressure in the FD when the throttle is quickly closed and the metering pin moves quickly. That control pressure in top of the metering pin can not instantly reestablish its self and this acts as an accumulator and helps with that.

I am wondering if it it a little longer acting and might reduce over swing of the metering arm with the drop in enrichment.

As to a vacuum sensing WUR I am sorry if I keep pitching it. No one else seems to get it. I feel confident in its advantages as expressed by Lee Rice who was a very good tuner of 930's. and from my experience with my fueler.

If I was running a D-WUR I would not think one would want this as it might slow response to control pressure changes. I feel the same way about using this with a Vacuum Sensing WUR.

As to lean surge, check out the AFR curve on Brians last Dyno plot for his headers. It is clearly evedent. A Vac-Sensing WUR could help reduce this also.

Good stuff.
Old 03-30-2010, 06:13 PM
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ps: RUF and Porsche on there special turbo motors seem to use this.

I still wonder why?
Old 03-30-2010, 07:10 PM
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The PET calls it a "diaphragm dampener" maybe that is all it is.

The translation from another language using an automated translator above states:

Quote:
THIS mounting on dell'arricchitore fuel injection pump 930 turbo
- ACTS AND WORKS when the pressure exceeds the turbine or 8 bar opening injects gasoline --
This original device is fitted as standard on the Turbo S 930/66.
Not having an electronic control that automatically adjusts the fuel pressure this device prevents the higher pressure, or 8 bars become "LEAN"
avoiding breakage of the motor -
Council:
1 - to all those using the spring bar-1
affordable --
2-all in porsche kit costs about 280 + assembly -
disadvantages:
1-mounting is not easy because it is applied behind the pump, however, does not need to lower the engine
2-important after redo the carburetion in um Porsche Center.
here are the pictures of the mounting
What do we think this mean?

Is it talking about a 1 bar boost spring?

It sounds like it protects the motor from a lean issue that might brake the motor.

Maybe there is a situition where the fuel head sees a spike in pressure to 8 bar that makes it to the area above the metering pin and leans the motor.

Maybe with throtle lift under hight duty when the fuel pumps are running full blast, the metering pin is fully extended and then slams shut, there is a pressure spike.

If there is a chance we might see an elevated pressure spike of up to 8 bar in the area above the metering piston (control pressure area) this would create a lean issue. If this happens under race duty between shifts, this could create a lean condition just when we do not want it. This could kill a motor.

An 8 bar pressure spike in the control pressure area, this would likely make it to the WUR and rupture the diaphragm.

If this is the case, a stronger diaphragm might keep the WUR from going but not the pistons from a lean burn.

This might make some sense.

???????
Old 03-30-2010, 07:31 PM
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I use to break the warm up reg diaphram if I was running low on fuel on the track. Pump would suck air and then when fuel hit the reg it would crack the diaphram and leak fuel through the vent into the air cleaner. I had a dampner laying around (off of a RUF BTR) installed it and the problem went away.
Old 04-03-2010, 07:53 PM
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Got some info on these little things today. And those guys on that website in Italy should be pretty familiar with it. Or any Mercedes mechanic for that matter. Today I was busy in my buddy's Ferrari shop installing a muffler on my car. After I was done, I asked him if he was familiar with a little dampener between the WUR and the fuel distributor in a 512BB? He is like, 512BB? Nah man, it's in the 512, 308, every big K-Jet V8 Mercedes like the 450 SEL 6.9 and others. I've even seen them in Rolls Royces, he says. Hell, even my 89 Testarossa has 1 of them for each fuel distributor. He is like, you car does not have one? Ferrari and Mercedes put them in so nothing funny happened with the sensor plates or high rpm lean situations. I'm like, nope. Hey is like, ****, why not? I'm like, beats me. But they put them in the 930S. But hey, he says, I have a bunch over here. You want one? I'm like, yeah, sure. Just let me check the part number and see if I can get a Bosh corresponding number. Nonetheless, every Mercedes which had one, had the same part number. Here is one off of a 512 Boxer.

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Old 06-22-2010, 01:43 AM
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Quote:
Originally Posted by Ed Bighi View Post

... Ferrari and Mercedes put them in so nothing funny happened with the sensor plates or high rpm lean situations...
Ed,

Can you get a more technical description what they do.

Also, where is the vac connection attached? After the throttle plate, to atmosphere, or to the section between the air filter and sensor plate.

I do not think it add any fuel enrichment per say.

It might protect against a condition that can make for a lean response.

I have been suspecting a couple of different possibilities:

One that they protect the WUR that with a failure could create a lean condition.

Or that there is some type of potential to experience a high presser response above the control plunger that would slow sensor reaction between full on shifts, momentary throttle lift, or some such.


As the flow is from the Fuel Distributor to the WUR which is the circut this it conected to, I just do not see it as being able to lower control pressure such that it might contribute to a fueling improvement.

Any details you might discover would be very much appreciated.

Interesting stuff.
Old 06-22-2010, 07:46 AM
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