So you need good springs to pull the plunger down and to keep it in contact with the cam. Beyond that critical aspect of design I don't see the concearn. I feel it is advantageous and necessary that the plunger be pulling a vaccum at high rack travels so that when the plunger gets back to port opening the vaccum created would help to draw the fuel into the plunger cavity so that you have suffecient time to fill the plunger before it starts to close the fill port again and injection starts. When you consider the amount of time there is to get the plunger full of fuel at 4000rpm and how small the fill port hole is it is a miracle it happens! This is why more fuel pressure is of benefit as it allows the plunger to more effeciently fill itself and to maintain its charge across a broad range of rpms.

Hi Tom your colleague Peter just email'd me -The expensive metal objects are on their way, How many other sets have you supplied to American Benz guys? Is this the only set here?
Thanks and I appreciate your help supplying these.

Josh (Biohazard), Ca, got one set but David did not finish the IP as far as I know. I am running these for about 20.000 Km in my SD (but still with the bloody stock turbo).
Then 4 other guys in other countries have them installed but no feedback.

Took some time to get the elements to you but it was the best I could arrange during my trip.

Thanks,

Tom

I am going to be using some stronger springs when I build my 10mm MW for sure.

I am also going to reduce the total lift of the cam because I see no benefit to pumping fuel in and out of the barrel beyond that which would be, as the result of the deceleration ramp. However, I have considered the momentum of the plunger being a factor in getting through the sealed portion of the downward stroke, and reducing the total stroke would reduce the momentum. Since I am not going to be lifting the plunger as far, I can be more aggressive with the deceleration ramp and the downward ramp, which, along with the stronger springs, may effectively do the same thing as the stock set up does. Running a pump on a test stand will tell if I am right or not.

With the shorter lift, and quicker return, the plunger will spend a lot more time below the fill port, and I am thinking that the additional time, along with higher supply pressure, will result in a more complete fill before plunger starts to go back up.

the thing you should care about is the shortened range of rod travel for a proper governor operation. In your set up it needs only small increments of rod travel to alter the delivery and you risk that the governor can't handle it.

The other thing (that you will face later) is the increased residual pressure in the hard lines that cause post spray of the injectors due to larger elements depending on the pop pressure.

Be prepared to use delivery valves with increased "release volume".

Tom

The largest you can get. Going with stock 5.5mm or huge 10mm makes no difference to the price of rebuilding a pump with new elements.

145hp is the physical maximum, and that will cause damaging exhaust temperatures very rapidly no matter how much boost you feed the engine.

The information is freely available on several forums. If anybody needs to know what/how to adjust I can help.

I bought it and have not installed it yet. No time as I work in NY without my garage/tools. Shortly after X-mas ought to be the time it'll go on my 84 wagon.

Don't forget that I am modifying the end of delivery helix angle to comparatively reduce the volume displaced per degree of plunger rotation.

The goal is to be able to use the full range of the rack without delivering more than 90cc / 100cc, (for my application), at full, (useable), rack travel. This should provide stock fueling in the lower end of the range, but with a very short delivery time, and allow additional fuel delivery at the top end of the range, (you will have to have your foot into it), with a very short delivery time.

I am going back and forth on what pop pressure I want to start with, and the affects that different pressures may have on injection quality and control.

My thinking is that a higher pressures, (150 + bar), would help to reduce the pintle over travel from the initial pressure serge, (I have seen this during bench tests at 120 bar), along with a larger nozzle orifice that will allow enough flow to maintain the regulated injection pressure.

I will pose a question. For a given delivery valve, say used in the stock MW, is the amount of post injection residual line pressure, (that is regulated by the delivery valve), a percentage of the injection pressure, (in this case the lines would be expanding, (volume potential of the lines would determine the change in residual pressure)), or, is it determined only by the volume of the lines.

If the residual line pressure is percentage of the injection (pop) pressure, then different delivery valves may very well be needed to achieve the best outcome. However, if the line pressure is strictly a result of the combination of the delivery valves displacement and the volume of the lines, then the stock delivery valves should work as they flow more than enough fuel to handle the increased volume of the modified 10mm elements.

Perhaps going with a lighter delivery valve spring may have a benefit?

I have been too busy to make any progress beyond that of thought, but the better thought out a project is, the better the initial result.


On a side note, went to court last Monday, and to give you an idea of what the judge thought of the case, I got fees and expenses.

my understanding is:

opening the DV and flow is not an issue.
During injection fuel is pushed through the opened DV and the line pressure increases until the nozzle opens.
I think (could be wrong) that the line pressure during injection is about the pop pressure, maybe a little higher but not much otherwise the nozzles are too small to exit the fuel and something will brake or the line would expand too much (*).

End of injection: the helix connects the pressure "chamber" to the gallery.
Now we have a pressure difference pre and post the DV, that closes the DV with help of the spring. By moving of the little plunger with the "ring" and cone into the DV barrel the ring separates the two pressure zones but the plunger moves further until the cone closes. This further movement takes away volume from the (already separated) line and reduces the pressure in the line.
Don't know when exactly in this scenario the nozzle closes, at least when the DV plunger moves into the barrel, maybe already when the helix opens.

The nozzle closes because the line pressure is below the pop pressure.
As the fuel column is moving (and the DV plunger backward movement with taking away volume from the line still allows the fuel movement because the volume taken out is too small to stop the fuel movement) the fuel column runs against the closed nozzle, the pressure in the line is reduced so the nozzle is really closed. Now we get a pressure wave reflecting at the nozzle and running backwards to the closed DV, reflects there and runs again to the nozzle to open it.

Forget here the orifice in the DV holder as the larger MWs don't have them.

To close the nozzle it takes only a reduced line pressure so it must be the pressure wave running in the line that opens the nozzle again.

The higher the pop pressure the harder it is to open the nozzle a second time but the overall pressure is higher so I can not see a solution only in pop pressure.
A weaker spring on the DV plunger might help in theory but the pressure difference will close it rather than the spring.

For precise injection we want a high residual line pressure. A too low line pressure has to be "filled" before the fuel pressure reaches the nozzle.
This might also be a reason for the orifice in the DV holder for faster engines and better emissions.
At the end of the day this stuff is more acoustics than mechanics and limited somewhere. The development goes CDI and in general control of injection directly in the nozzles without hard lines in between.

Increasing the inner volume of the hard lines could reduce the risk of post spray but makes the pressure build up mushy.

Tom

It will be interesting to see how the engine responds the modded 10s via the EGTs, and sound.

There may very well be secondary injections, but because the end of injection will be so much sooner that stock, the secondary injection might take place before the stock end of injection time frame and may be unnoticeable.

For injectors I will have the nozzles extrude honed to increase the orifice diameter, and set the pop pressure to at least 150+ bar. My thinking is that a larger nozzle along with a higher pop, (injection), pressure will allow for an increased volume to be injected in over given period of time, (in a very fine mist or fog), as the pintle moves at a higher frequency, maintaining a more consistent, (smoother), line pressure during injection.

With a smaller nozzle and lower pop, (injection), pressure, the pintle has to lift farther to flow an increased volume of fuel in a given period of time. The higher the pintle lifts, the lower the quality of the injection, (spray or stream instead of a mist or fog). I am hoping that a larger nozzle will allow for an increased volume of fuel to pass with a lesser amount of pintle lift, maintaining a very small, (tight), gap between the pintle and its seat, causing the fuel to be injected in a very fine mist, which should ignite better in larger quantities, (less or no nailing).

Additionally, the higher pintle frequency might have an effect on the post injection acoustics. If the injection line pressure stability is increased, (regulated to more of a constant, higher frequency pressure, as apposed to having larger pressure swings at a slower frequency from a smaller nozzle and lower pop presser), with the larger nozzle and higher pop pressure, the post injection "signal" wave may be lessened.

Why not put some detailed pics up of these, please?

At least its going on a wagon :)

I'll see about taking some side by side pictures of the three 10mm ones I have. Not sure about the detailed part though, the differences are pretty self explanatory.

I am assuming your interest is purely academic since you have some 6.5mm MW elements.

here are some pictures of three different 10mm elements that I ordered.

The thin one came is one of a set that is running in a 617a. You can find the thread over at STD.

The two thick ones are for a PS pump.

As you can see the plungers are quite differnt.

I could only uploade 5 picks. There are two more in the next post.