rockjeep73

Ya, are we even headed in the right direction

Bushy

Fill time....the amount of time available to fill the head before the plunger begins to compress....this is an interesting one cause I'm just tinkering with this on a test mule....

pb...

rockjeep73

Come on man, one step at a time. Here we are talking about dynamic timing control and rotor control collar movement and now you bring up rotor fill time

rockjeep73

PB,
I am still curious as to if you have an answer to my question in post #21.

At least that way we can eliminate further research in certain areas if someone already has the answers

frostie

So, we have went from diaphram lift pumps, to industrial piston pumps for VE injection pumps. So why not run a second gen lift pump and find out how to seal the VE to take the extra lift pump pressure. More pressure in the pump would mean more fuel available for fill time. Would this be correct or am I in left field.

rockjeep73

I dont think that a lack of pressure or volume has anything to do with the issue we are dealing with here. What PB is talking about is the amount of time that the rotor port has to fill, as RPM goes up the window of time gets shorter. But what is actually happening if the time is physically too short for the rotor to fill?

Bushy

If the "start value" of fueling is used like you suggest, that is pump max fueling like the start cycle, then the plunger must make a full working stroke = max fuel delivery....
Either way the plunger stroke is maxed and the fuel delivered is maxed as in WOT...
If you have a heavily tweaked pump running at 'max fueling', and alot of us do, then the control collars ability to dump fuel and actually control engine speed is extremely limited...we actually end up with the pump kind of force drawing/feeding itself...that is your runaway...
On the topic of runaway, my brother and I have kinda tinkered with that condition, ya I know...on purpose, are you CRAZY !!....

This testing was done with the '366 governor spring installed and stock valve springs, timing tweaked, modified cone etc...
What we did, and this may go to your question 'rock, ...is this..we went thru a process of turning in the fuel screw in 1/4 turn increments...we started with a fairly aggressive setting to begin with since it was already a tweaked pump hence the 1/4 turn value..

After each adjustment we slowly, manually, raised the idle value to approx 2200 RPM (this just turned out to be the threshold)...and held it there while waiting to see if the engine would continue to gain RPM...at a certain point we found that if we raised the idle slowly to 2200 RPM the engine would continue to climb upwards in RPM at a fairly quick rate....kinda scary to be honest...The first few times natural instinct took over and we quickly released the throttle...we overcame that finally...

After 4 or 5 runs at this we found that the engine would run up as far as approx. 3600 - 3700 RPM then quite suddenly the governor would grab hold real quick and pull the RPM back down towards the original 2200 mark or close to it....
It (the governor function) would then release and, up she'd go again to the 3600'ish range then grab hold and come back down. It did this repeatedly. We did not actually manage to achieve a true runaway condition but it was pretty nerve wracking since we did not have the heavy valve springs in at the time...

This is something to consider too...the 366 spring was tough enough to refuse governor counterweights effects well into the mid/high 3000 RPM range and not just 3000 or 3200 as the nickname for this spring suggests.
The effect of the governor kicking in and out was much like a big cam gasser that is surging up/down only with alot more RPM's....

So as for runaway and control collar position, I honestly don't know what the eventual outcome would be.....it WOULD be interesting though...

As an aside....a while back (and I can't recall which web site I posted this) I posted a question for all the guys who'd been on the/A dyno. I asked at roughly what RPM they made the best peak/highest HP reading. I was not intending take into account the duration (in terms of RPM) that the max HP was held to drop off point since I really wanted to see when the max was initially reached/achieved.
(The data for how far/long the max HP was maintained as the RPM climbed would likely be more of an issue for guys who want to some sled pulling since tire speed is critical in that game.)
As I recall it was in/around the 2600- 2750 RPM range (yours may vary). I was looking to see just how far up into the RPM range we needed to pull or draw absolute max fuel flow from the pump.
I asked this with the thought that it would likely be in the mid to high 2000's for RPM/HP peak and it seems that was born out by the few replies I got.
So, what we need to do is "aim" the pump/engine/governor to do it's thing up and into that range and the rest (some guys saw an increasing HP as RPM continued to climb but not alot as I recall) is wasted wear and tear etc...Yes?? No??


Does this help at all..???

pb...

edit: recent preliminary testing/tinkering has shown that the larger 14mm plunger/barrel assembly from KTA Cummins produces a real healthy amount of fuel delivery at an RPM that is inside the "rational mans RPM world" for the most part.
We have not finished our testing on this new unit and have some other ideas to work on once we have nailed down some basic settings/values.

We also want to make sure that we do not duplicate either on purpose or by accident the condition(s) (I'm pretty sure it was lubrication related) that cause the plunger/barrel assembly to spontaneously weld/seize/lock/fry together....it was brutal man..even the pum guy who's been in the business a LONG time said he'd never seen one lock up that bad...ballpeen hammer time to get things apart, literally...

Ok one last item....pump fuel volume values (keep in mind that these values were acheived using the Bosch recommended "test orfice": One pump tested ran approx 168cc of fuel as it's "start value", woth a decline rate to 102cc's with boost fueling on line at 850 pump RPM.

A second pump produced the following: a start value fuel supply of 214cc's and, a value of 149.7cc at 850 pump RPM....that's a fairly large variation in my view...
The third pump tested did the following: start delivery value of 142cc's and 138cc's at 850 pump RPM.
So you can see there is a significant variation in the values from one pump to the next. Since Bosch uses an "acceptable range" for these settings we can and do tweak to the upper end of the value ranges just to have a baseline starting point to begin our tweaking and testing.
I also admit that if a larger test orfice or injector nozzle was used you'd see a significant difference in the cc's supplied.
Currently our testing is being done a proper stand with "applicable" sized nozzles feeding into marked beakers to determine accurate volume/rate/variation, if any.
I think you'll be surprised at the end result when the testing is completed on the new 14mm head/plunger assembly from KTA Cummins' product. The preliminary numbers, and I stress perliminary only were such a surprise that we actually need to find some tricks to reduce the fueling at certain RPM's if you can believe that......lottsa fun..

Bushy

By looking at the Bosch schematics for the pump, can we see/find a way to start the "fill cycle" sooner and/or make it last a tad longer....that is what we're working on or actually just getting started with now...
My apologies for the fill time post as it did end up hijacking the topic guys...sorry

pb...

G1625S

''My apologies for the fill time post as it did end up hijacking the topic guys...sorry''

No apologies necessary, Pastor. I think I can safely say that we're all looking for the right direction to go to get more juice from these pumps. If the thread has to change direction slightly in order to produce results and answers, then so be it.

''By looking at the Bosch schematics for the pump, can we see/find a way to start the "fill cycle" sooner and/or make it last a tad longer....that is what we're working on or actually just getting started with now...''

It seems like the plunger would have to be physically altered, as the length and width of the fill slot seems to determine the onset of the fill cycle...or maybe the fill port in the distributor head itself could be machined differently to produce similar results?

Alec

I think you are on the right track, Greg, as there are only two ways to make that plunger fill faster: Increase the feed pressure or decrease the flow resistance of the feed port.

Increasing the feed pressure has the unwanted side effect of raising fuel temperature before injection.

When the plunger doesn't fill, there are a couple of things that could be and probably are happening:

The fuel is actually slightly compressible, so the fuel in the plunger is less compressed than the fuel in the pump body. Indeed, it is probably under a slight vacuum -- the plunger doesn't have to fill with anything, it can draw a vacuum! It is also possible that the cam return springs start to "float" a little, which just can't be good for the cam or rollers.

Does that make sense?

G1625S

All I could picture in my mind was a vacuum, so yeah, that makes sense

rockjeep73

No apologie needed. I was just givin you a hard time for bringing up so many different ideas...but isnt that what we want

rockjeep73

Maybe not all plungers are created equal?

Top left is a 12mm that KTA has in pic for comparison.
Top right is his special 14mm.
Bottom is my spare pump.

The slots are much shallower on mine, making it harder for the fuel to enter and fill the plunger barrel?

G1625S

How about that. The plot sickens...

rockjeep73

I figure that youre asking this question because the fill time has become a limiting factor on fuel delivery. Deeper slots in the rotor, like in the picture, will give the incoming fuel a larger and less restrictive path to fill the barrel. Also, wider slots in the rotor will do the same.

But what will this actually gain us. In order for the plunger to fully "pull back" (for lack of better terms) in the barrel, the area where the fuel is compressed has to be completely filled with fuel. It makes sense to me that this process is assisted by the incoming pressurized fuel AND the plunger return springs which draw the plunger back in order to "suck" the fuel into the barrel. If the window of time for the barrel to fill becomes too short, due to high RPM (I cant think of any other reasons why it would be), and the fill port closes before the barrel is done filling with fuel then the plunger will not fully retract causing it to float off of the face cam. If this is the case, then this is an issue that needs to be dealt with. BUT, if the barrel will always completely fill with fuel, then reducing the restrictions to incoming fuel and/or modifying the fill time or fill window will not gain us anything. Meaning, as long as the barrel can and does completely fill with fuel on each stroke, then it doesnt matter if the fuel is "pulled" in by the plunger or "pushed" in under pressure because fuel is not compressible so as long as its getting where it needs to be, it doesnt matter how it got there, meaning the volume will always be the same for the given area.

So, is fill time a key to more fuel...I have no idea, but I hope someone does