VE Tech

Just an fyi.... on a test bench, we gained absolutely nothing (not a single cc at 280cc) with increasing case pressure over stock. If one has large enough injectors to affect things, I would suspect it to be different though.
 
Yes it was... which is why I emphasized that it may change with very large injectors.

I run an injector that flows about what a 5x16 does. I ended up with 80psi of idle case pressure due to it being the best place that I found with the least pressure drop, AS WELL as the most case pressure sweep. Any higher and I was losing a sweep percentage.

After the adjustable timing spacer, different springs, changing pressures.......I ended up with 80 at 800rpm idle, with an 89 timing spring (in my 92 pump) and an M&H spacer with zero shims (not even the one they send). I then put the ksb on a toggle. Do I know what the sweep is? No, I honestly didn't care... I tune by how it acts on the truck. Anymore timing was completely un necessary (sweep that is) and only caused it to drive stupid pathetic. And less and I was losing in the top or bottom.




Edit - Once I got the timing dialed in... I noticed that I was gaining zero fuel with increasing case pressure... the only change I had was due to simply changing my timing curve (which changed the smoke and how the turbo hit).
 
Last edited:
The reason I ask is that the return orifice in the regulator is calibrated to the intended out put of the rotor and injectors, it is designed to supply a repeatable and reliable timing curve for the given flow, as you have said and I also assume that with larger injectors you will loose the calibration and then overall case pressure will drop. for interest I did the same graph with a 14mm rotor. everthing else the same. You can see case pressure doesn't recover well until over 2500rpm.

14mm ve pump graph.jpg


With larger injectors that's when every thing goes to ****. Bumping the base setting of the reg cracking pressure up to 80psi (is this what you did?) will keep it at that setting anything above is not really possible with out some sort of changes to those regulator hole sizes. That becomes pretty hit and miss I would suppose.

Good thread I love this sort of tech stuff. Cheers.
 
It is due to the system becoming overwhelmed, it can't catch back up.... slow the fueling down, and it all raises in unison a little better. (talking about the graph again).

And yes, you have a very large adjustment range with adjusting the regulator (knocking down the center changes the spring tension). Is that what you're asking?
 
Yep that was what I was asking. Yeah raising case pressure that way will only set the minimum pressure it will open but wont compensate for the larger flow rate of the injectors any where else in the rev range.

I need to figure a way to have the pump out put percentage raise as it goes up the rev range in my little spread sheet. There is no way you can have 80% fueling at 1250 rpm same as you cant have 10% fuel at 3500rpm. Wont make any difference in the scheme of things but it would make the graph reflect reality a bit more. Plus could give a better ball park size for orifices to begin experimenting.

Exploding cases start at what pressure?:badidea:
 
I know nothing of the VE pumps, but reading this has led me to believe that the VE builds its own case pressure via its vanes which in turn has an effect on timing? Still being fed by a low pressure diaphragm pump?


Sent from my iPhone using Tapatalk
 
Yes. The timing piston has a spring on one side, and case pressure on the other. As case pressure rises, it overcomes the spring and advances timing.
 
9724VF350 said:
Yes. The timing piston has a spring on one side, and case pressure on the other. As case pressure rises, it overcomes the spring and advances timing.
Click to expand...


Ok so being able to change spring pressures and case pressure could effect the timing advancement etc. But input pressure and injectors have an effect on case pressure as well as rpm. I think I'm beginning to understand.


Sent from my iPhone using Tapatalk
 
For what it's worth, (sometimes I just put information on here so I can find it in the future LOL) A stock 2.8mm cam plate, from 0-2.8mm lift is 25* of pump rotation.

Here's a pump number of a 6.7 RGT engine 0 460 426 375 3288249.

I'm told they have a considerably faster cam plate. Anyone able to use that number to find out any details? If I had one off I'd check myself, but they're a major pain to remove from a tractor.
 
Someone remind me tomorrow and I'll see if I can't find some information about it... see availability and price as well.
 
The pump shop we normally deal with is supposed to be sending me a few cam plates he thinks is faster than normal to check out. Also, a junk head that I can press the inner sleeve out of so I can take a look around.
 
After finally seizing up my 14mm head and rotor after 2.5 years of countless 3500-4000 rpm pulls, races, and dynos, I have come back to the drawing board. I'm pretty sure my 14mm seized from crappy watery fuel though and not from rpm and abuse after finding rust in my pump and what didn't look like fuel coming from my airdog. The rotor seized in the head, had to tap it out with punch, broke the cam plate ears, coupler, and pump shaft ears, and thats as far as I dug into it before I threw it all in a box for a rainy day.

So...I got my old original ic 12mm pump back out and went into it a little. After finding a broken return spring (it still ran). I ended up putting a non ic head and rotor in it (originally from my 14mm pump) since it has much deeper cuts in the rotor. Also my old 12mm always idled low after the truck got warm which i was always told was from a worn out head and rotor. This picture is probably old news to most people but may be useful to some.
picture.php

Intercooled rotor on the left, non intercooled rotor in the middle, and 14mm rotor on the right. To me the non intercooled rotor seems to have just as deep of cuts as the 14mm rotor does.

After putting my 12mm back together along with non ic delivery valves (they are a deeper cut, but not by much) and adjusting the regulator valve quite a bit, it took me quite a few runaways before I finally got it dialed back in. Main cause was throttle indexing. Cuz my fuel screw feels like its bottomed out and it won't runaway. I've had this happen on many other intercooled pumps/trucks. Once I got it dialed in, this 12mm pump flat out rips, and I almost like it as much or more than my 14mm pump, and it seems to run just as good or better. It has no afc and spools my big single much easier than my 14mm pump did with a tight afc setup. The 14mm did fuel much much harder down low though. I still need to get a case pressure gauge installed....

Going back to rotor comparison, in my thinking, the 14mm rotor is bigger, which would allow more time or duration in between ports to fill the ports with more fuel, which in higher rpm would benefit? Maybe I'm thinking of this wrong, but in my head it made sense. I'm not afraid to try the 14mm pump again, as I had good luck with it even with high rpms. I've already got another under the shelf waiting for a rainy day and extra coin. I've still debated on trying the 4mm camplate with it as well even though I haven't heard many good things.

Most people say the problem with VE pumps is that the vane pump can't keep up. I tried doing some research on vane pumps a while back to see if modifying the one in the ve would benefit (more vanes, bigger vanes, etc.) but didn't come up with assuring answers. I remember reading once about a guy using a power steering pump to supply the VE pump with its high pressure, but then never heard much of it again. I've heard many different theories and even the the theory of cavitation causing these pumps to fail which is highly believable at high rpm.

We are all in this for something a little different, for me its mostly just for curiosity, and I'd love to gain much higher rpms with a VE and compete more with the looked down upon pump. I know there is a lot left on the table and much more trial and error to be had.

Things I've already thought of include:

-running an external pump and possibly dual feed through the timing check port in middle of head. Could have it rpm or boost controlled so that it didn't affect low rpm timing.

-lightening up the flyweights for more rpm, (heard of p pump guys doing this and got me curious)

-tractor/ag governors, are they different? would they better?

-delivery valve options, could there be more options out there, or would custom made ones be worth it?

-an even bigger head and rotor, would more than 14mm be worth it?

I'm just as curious as the rest of you but I seem to learn things best with trial and error. :pop:
 
The depth of the cuts in the rotor I think is minor, what's more important is the quantity of the openings in the head.

Tip speed on a larger rotor is going to be greater, which I think would allow less fill time.

Feeding through the timing port in the back would be a problem, since it would be backfeeding during injection, not sure if there's a type of check valve that would be up to the task and not absorb too many cc's when it closes.
 
The gap between fill ports is wider on a 14mm rotor so maybe it would "even out" as the outside tip would be going faster. The deeper cuts in the rotor are delivering much more fuel per stroke vs a intercooled rotor.

For what its worth, when I worked on standby generators, we worked on some standby fire pump engines. Some had 6 cylinder VM Motori engines on them about the same frame size as a 5.9. (Not sure what liter).They had a Detroit Diesel tag on them but they ran at 3600 rpm. They had a HP rating of 165hp @3600 rpm and ran at that constant rpm. I got the numbers off those engines and was gonna call Detroit to see if I could get one of those pumps but never got around to it. I'm very curious as to what type of governor system they have to run at that high of rpm constantly and still make more HP than our engines from the factory when the pump looks identical from the outside with afc housing and all.
 
You must log in or register to reply here.
Back
Top