how much are you supposed to open up the restriction in the return...

[Don Tanklage]

GL, what does that have to do with the return line coming out of a ve pump?



daniel, you really think it is that high of a percentage? hummm, imagine if you could get the thing to use all that fuel instead!



i started the topic because cerbie said you have to open up the return when you turn up the pump. i didnt ask which return..... my bad.



cerbie, which return were you talking about???



thanks, don

 

[Stomp]

Man you guys are confusing the heck out of me. Why again are we trying to drill out the return? I have left all of mine stock. I have never had a problem with a stock pump. Is this why some of my 14mm pumps have failed??? Who knows… I do have a case pressure gauge hooked up and it will go to about 160+/- psi at 3200 rpms or so. It’s not really in my line of sight so I have a hard time looking at it when playing around. I usually set the case pressure up when I have it on the bench. I wish I had some more time to play around with different pressures, but I don’t anymore. It would be interesting to see what happens.



Stomp

 

[Don Tanklage]

Why again are we trying to drill out the return? I have left all of mine stock. I have never had a problem with a stock pump.

we're not...



it was suggested to me by cerbie, no, it was said to be 'mandatory'...

I wish I had some more time to play around with different pressures, but I don’t anymore. It would be interesting to see what happens.



Stomp

yes it would...



apparently kta is running some really low case pressures with his system



i guess that works too...



don

 

[cerberusiam]

After a little digging around, and more than a little swearing , all the great plans and stuff I had collected for a pump build evidently has been lost in one of several computer crashes/reformats/swaps etc. Oh well, back to the drawing board again.



What I had drawn up, and for the most part rattling around in my head, was a theoretical design to increase the lube/cooling flow in a VE pump that was running at 250-270 cc's of fuel delivery at ~ 3200 rpm's. At that level I was assured the pump would eat itself up in short order due to lack of lube and heat stress. Why? Becuase the stock system was unable to handle the increased flow needed to offset the extra heat created AND supply the extra fuel needed above and beyond the injection needs.



All of the radial pumps, VE and VP even the CP3, suffer the same fate when pushing them beyond the design limits in fuel delivery. Fuel is routed to injection first and lube/cooling second generally thru a set of presized orfices. When you push the limits of fuel delivery you must increase the flow to lube/cooling to offset the increased heat and that generally means resizing the passages used to route fuel into and out of the cooling portion. With the VE its not only external port but also internal ports that need to be addressed.



I have not seen the effects on hundreds of pumps, only a few. What I did see suggested that more cooling and lube was a good place to start. PB on the other hand had seen a lot of pumps and the effects and we were headed down the same theoretical path. In fact, he had been tinkering with a design for over a year before he passed away, and, I believe he and his brother had incorporated some of the ideas into a pump build that was working nicely.



Thats the theory and a germ of an idea to build a reliable, long lived, high HP VE pump. Will it work? Good question, but thats what R&D is all about. Currently, I am like Jeremy and lack the time and resources to pursue this to its bitter or glorious end. :-laf I break too much stuff and with several trucks to play with some things just take a lot longr than I want.

 

[Greenleaf]

What does fuel rate of a pump have to do with the return?

When a pump is set to "x" cc's, it is properly noted as "x" cc per 1000 strokes. Look on your (or any Cummins) engine data tag- stock fuel rate is in mm3 or cubic millimeters. Some p-pumps can pump 1000-1200mm per stroke, or 1-1. 2cc/ stroke.



Look at the cam plate, the 12mm head, and do the math. It is impossible to pump 160cc per stroke. That is over a deciliter, or 3oz!!!!! Talk about over fuelling.





DP

Probably that, I'd guess.

 

[Jgolden]

Does a guy like me who has only turned in the fuel screw and got some pretty good results have to be concerned with return flow and internals, or is it only in the case of all mods maxxed that it is critical?

Thanks

 

[Stomp]

apparently kta is running some really low case pressures with his system



i guess that works too...



don

Hey I am not saying that it wont work I just havent had time to really expiriment with it. I do know one thing I dont get any advance from the pump because of the pressures that I run. When I start mine the pressure is allready up and overides the internal advance. I get max from the start. I need to either use a different spring or shim/shave the piston. Someday I will get around to doing that.

When you push the limits of fuel delivery you must increase the flow to lube/cooling to offset the increased heat and that generally means resizing the passages used to route fuel into and out of the cooling portion.

How about cooling the fuel before it gets to the pump??



Jeremy

 

[Don Tanklage]

i was wrong... . again



i heard he has a inline check valve on the fuel going in to that port (the return). so as soon as the vane pump is makin more than his supply pressure that port is closed off. looks like my stock banjo has a ball n spring in it too? whats the for? to keep return fuel from the inj from entering the pump?



thats a nice cooler. i ordered a small cooler yesterday, but nothing like that. just going to throw it on the return from bypass reg going back to tank, and mount it under truck. (wanna leave as much room up front as possible, for a bigger intercooler)



JGolden, i dont see how opening up the return could help in your case...



don

 

[cerberusiam]

How about cooling the fuel before it gets to the pump??



Jeremy

Can't hurt in a warm environment. In the colder climates the fuel should be warmed for optimum performance but a thermal switch can take care of that.



There is already and excellent heat sink in the form of a fuel tank. Unless you are chasing the max HP a fuel cooler is probably overkill most of the time but it has possibilities.

 

[CSchafer]

So If this cooling circuit is just a series of fixed orfices then in therory going from like 9 to 14psi of fuel pressure to somthing like 30 or 40 psi with a boost referenced regulater under full throttle would squeze more fuel through the fixed orfices and promote cooling. So I guess what in the pump would 30 or 40or 100 psi of fuel pressure at the inlet hurt. I know that the front seal will let go but i've heard of retainers for that, is there anything else inside the pump it will hurt.



P. S. Don thank you for pushing this subject, probobly would of done a couple things differnt but I'm definently learning some stuff now

 

[Don Tanklage]

your welcome



they say if inlet pressure (thru the regular inlet) goes above mid 20's it will damage the pump. i dont know what it damages tho... .



i hear the damage will first present itself in the form of hard starting



but i think that is constant high pressure at the inlet



mine is at 22 psi now, that is what my fass produces with a clean filter and what ever spring it has in it, that is why i am putting a bypass regulator in line. i dont think it needs to be that high for starting and idling around.



as for putting fuel into what was the return orfice goes, i dont know...



it looks like there is a already a check valve inside my return banjo



even if there is not the hole is only . 018"



stomp says he sets his pumps up at 160 psi max cavity pressure



i dont see the benifit of installing a check valve there and putting 15-65 psi of fuel pressure on the other side of it if the vane pump is just going to close the check valve as soon as the thing starts to spin up



maybe i am missing something?



don

 

[Don Tanklage]

ps - a local shop here says the cavity pressure is supposed to be 20 psi at idle - but i dont know it they know that for sure or just made it up! (same guy said 30 psi at 2000 rpm and i dont think that cant be right)



and if you convert the return into a intermittent inlet the fixed orifice that you mentioned, it is no longer there, you replace that with a an fitting

 

[Stomp]

i was wrong... . again



i heard he has a inline check valve on the fuel going in to that port (the return). so as soon as the vane pump is makin more than his supply pressure that port is closed off. looks like my stock banjo has a ball n spring in it too? whats the for? to keep return fuel from the inj from entering the pump?

don

as for putting fuel into what was the return orfice goes, i dont know...

Ok I am pretty sure that KTA has his set up that if the case pressure drops to low it will push fuel into the case through the return. Think about it unless you have a case pressure gauge you can’t see what is going on inside of the pump. When you stand on the throttle the case pressure will significantly drop and then go back up when it gets close to the governor or when it catches back up. If it gets too low you know that you are not getting enough fuel in there to help keep things cool and lubricated. That is why he has his set up the way he does. I had mine set up the same way, but I am still chasing an unknown problem for about a year or so know. I have mine back to stock because I thought that somewhere along the line by doing this I messed up. I just haven’t had time to change it back yet.



I hope this clears things up for you guys.





Jeremy

 

[Don Tanklage]

so you ran a bypass reg with a 1:1 boost reference, a check valve on what used to be the return side, and fuel to both ports...



what was your intitial fuel pressure?



how much boost did you run? (what was the max pressure)



thank you so much for sharing jeremy



tank

 

[Don Tanklage]

ps - without a check valve it would be 'messed up' cuz the case would never get higher than intial + boost pressure



you did run a check valve, right?



don

 

[CSchafer]

What I was thinking is teeing into the line before the regulator and giving it 50psi all the time with a check valve so that the 100+ psi of case pressure doesnt push back out the line. I was going to put a regulator on my boost line to the reg to limit fuel psi to about 25 to 30 at max boost but KTA said that he is running 40+ into his with a seal retainer. So I guess the question still goes, what in the pump can be hurt with big inlet fuel pressure.

 

[Don Tanklage]

i dont know buddy, maybe the vane pump? maybe the piston?



i do know that if you tee into the line BEFORE the reg that line will still only see the same pressure as the line you have going from the reg to the inlet (on a return sys)

 

[CSchafer]

yeah your correct on the pressure with the return system. Oh well I think I'll just run it to the inlet and we'll see what happens. I think I will be messin with a case pressure guage though.

 

[Don Tanklage]

thats what i am doin. plz update when you get a gauge on it



don

 

[bgilbert]

Cade, I've been running mine at 12psi idle and at big boost, my VE see's all the pressure the A1000 will produce. I've seen it produce as much as 80psi on a buddies p-pump truck. Knock on wood, no leaks yet, front seal still intact- no retainer, just the seal pressed in as normal.