Tell me if I have this right...pump saver question

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by Scouder, Jan 29, 2011.

  1. Blownalky

    Blownalky Top Sportsman

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    Pat thanks, you bring up some good points. Yes, I have one -10 coming out of the barrel that feeds the flow meter and from there it goes to a combined Gorr distribution block that feeds the hat, the dribblers and the ports. The way the barrel (Enderle K) is built, it is like a "Y" fitting and that is after the spool so from the way I see it, it is just like pluming it in a distribution block. It's just the "Y" is at the barrel instead of downstream where you would split it to go to the hat and port distribution blocks. Both methods have the pressure from the pump facing the outlet of the pump saver check valve.

    Looking through the hole on the top above the spool, you can see the pump saver hole in the spool and it is open until about 1/4 - 3/8 throttle and then is blocked off. But as Mike pointed out, there are no seals in there so some fuel could slip around the spool. When the throttle is shut, that hole is wide open letting pump pressure hit the pump saver check from the side where it would push it open while the spool is closed (except for the small part of the "V" slot). With the spool closed, the only pressure after the spool would be the idle ~6LBS and whatever the pump saver check would bypass. At this point, with my combined distribution block, the hat, dribblers and ports would all see this. On my setup, only two hat nozzles have no check valves so I would think that the majority of the fuel would feed them, followed by (because of increasing check pressures) the dribblers, then the ports and finally the remaining two hat nozzles as these have 30LB checks in them. Since this is PSI-C, I don’t need as much fuel in the hat but the principals that I outlined should still be the same. I’m still open to be talked out of it if I could understand plumbing it this way would cause issues.

    Tom
     
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  2. Alkydrag

    Alkydrag Sr. Dragster

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    The idea of Davenports program is to help you make adjustments for atmosphere changes. The program shows you what you have to do to keep the same fuel pressures despite the altitude. This keeps the fuel curve the same and also keeps the crack pressure the same.
     
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  3. pat Iley

    pat Iley Member

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    I understand what you are tring to do however the port valve is blocked off due to get proper fuel flow to motor by having it y after flow meter but the port outlet will have fuel pressure and flow going against the pump saver poppet during the run if you plump into this port, will it damage the poppet or with the pressure their how will it affect its opening when its required. you should have two distribution blocks still one for the hat and one for ports. With the k-valve it can only flow so much fuel at idle to the motor and you will not relieve fuel pump pressure as the spool is designed to reduce fuel flow to the motor at this time. the only way to insure excess fuel goes to motor is thru hat distribution block. as you seen looking at your valve is correct and that is why some racers use this poppet to control fuel flow at part throttle and during burnout to help keep piston temp correct for max horsepower as some blowers make good power and require less fuel unless at full throttle.
     
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  4. OzAlky

    OzAlky New Member

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    Hmmm.. If a significant amount of fuel were able to leak through the clearance between barrel valve body and the spool.. then why doesn't this affect the engine at idle and stage ?

    I set the pump saver considerably lower than maximum fuel pressure (around 140 lbs, as per Norm Drazy's recommendations) and have never seen a problem.
     
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  5. Mike Canter

    Mike Canter Top Dragster

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    The reason it doesn't effect the idle and overall running when it leaks pass the spool is the Pump Saver Poppet is blocking it. Yes, there is always some leakage around the spool regardless and when one adjusts the idle mixture it is compensated for. At wide open throttle if it is dumping fuel then one probably wouldn't know it and would change the tuneup to compensate for it. If this happens then the car is probably not running at its full potential because the fuel curve below a certain fuel pressure would be one way and above a certain fuel pressure would be another way. The car would still run.

    The reason Norm Drazy, way back when, set his Pump Saver Poppet at 140 psi was to purposely dump fuel back into the hat during the burnout to stop a lean backfire caused by a part open throttle. Norm was actually using that leakage pass the spool to take care of that lean spot. Todays fuel systems don't seem to have that problem anymore.
     
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  6. Blownalky

    Blownalky Top Sportsman

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    I think I see where we might be getting crossed up. At idle, the pump pressure is low and the hat and port distribution blocks are seeing what pressure the idle poppet lets it have and that is delivered through the idle/part throttle “V” groove cut in the spool. Normally it is around 6-7LBS depending on the setup. This same 6-7LBS is sent to the hat distribution block and because there is no check valve there, is feed back to the outlet of the pump saver check valve. That is if you run a line from the pump saver to the hat distribution block.

    When you have the throttle wide open, this path for fuel flow is still there as it has not changed. The line from the barrel to the hat distribution block is still there as well as the line from the hat distribution block to the outlet of the pump saver. At this point, the hat distribution block sees full output of the pump (say 150LBS constant for illustration purposes minus a little loss at the barrel) and because of the connection from this block to the pump saver, the outlet of the pump saver is seeing full pump pressure or this same 150LBS for the duration of the run.

    When you close the throttle, that 150LB pump pressure is not at the outlet of the barrel anymore but it is still at the inlet as the pump RPM has not changed. At this point, that hole in the spool is exposed to the 150LBS (plus whatever spike) at the inlet of the barrel. Because of that, the pump saver will open and deliver that fuel to the hat distribution nozzles. Because the hat block is still connected to the barrel with no check valve, that pressure will also be felt at the outlet of the barrel valve until the fuel flows into the hat. That is the same exact point where I would plumb the line into on my proposed setup; I’m just connecting it closer to the barrel instead of the distribution block.

    I used to run the pump saver into the hat distribution block. That same distribution block is pressurized by the pump when the barrel is open as it is "Y'ed" off the main line after the flowmeter. Even before I had a flowmeter, I ran the two lines out of the barrel, one to the hat block and one to the port block. Both of those outlets are after the spool and this is the "Y" part of the barrel I was talking about before in my previous post. Both port and hat outlets flow fuel when the barrel is open and fuel output is reduced to both when it is closed. So if you plumb the pump saver to the hat distribution block, the pump saver check valve will see full pump pressure when the throttle is open, with or without a flowmeter.

    I’d like to understand how you would use the pump saver poppet for part throttle and the burnout and still retain its purpose as a pump save?

    Tom
     
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  7. SoDak

    SoDak Active Member

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    The best example of part throttle I can think of is a sprint car. Going through the corner they may need to back off the pedal to slow down to stay on the track. When they do this the engine RPM(pump RPM) stays higher in comparison to throttle position, now the engine gets temporarely flooded because the butterflies are somewhat closed but the fuel psi is higher. The barrel valve hole is somewhat open and let's "excess" back to tank.(if the poppet isn't set too high)

    When the race is over, they go past the checker flag at screaming RPM, than let completely off the gas pedal, the fuel psi would spike pretty high if the barrel valve hole wasn't open and the "pump saver" poppet was not correctly set.

    This is how I think of it.
     
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  8. pat Iley

    pat Iley Member

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    you cannot use this poppet for both applications. but due to its location it serves both purposes depending on which you require, i would assume that if they were plumbing it for part throttle they would use a poppet on top of fuel pump for pump saver as these are the racers that need all the performance not bracket racers.now if i understand you correctly you have a plug in your port oulet in k-valve right now and want to plumb your pump saver poppet back thru the port outlet thru K valve and the only line going to the distribution blocks is the top hat port outlet that is y' after flow meter. the problems i see are what is the effect of the flow going to the poppet that will be caused during the run as that line will pressure up during the run and when you go to a idle that line will still be full of fuel at what pressure , working against your pressure that you are trying to reduce to save fuel pump. as the spool is closed you have minor pressure that can excape via the port outlets going out as designed not into barrel valve. This would ack like a plugged line not operating proper or will it alter the pressure requires to open poppet correctly .when you plumb into the distribution block the excess pressure is forced to go thru hat nozzles into blower to aid in cooling to help strips in blower last longer.
     
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  9. Mike Canter

    Mike Canter Top Dragster

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    When you say part throttle are you talking about what I said in my post that was an answer to OzAlky's post on setting his pump saver poppet at 145 psi as per Norm Drazy in the PSI Manual? If so then read my answer again because Norm only set it at 145 psi because he was afraid of getting a lean spot when the BV was partly open in a burnout only. I have never seen that problem occur. Has anyone else? My recommendation OzAlky if that is why you set it at 145 psi then you should reconsider changing it to 200-220 psi but since your tuneup is already set you may want to just leave it at 145 psi.
     
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  10. OzAlky

    OzAlky New Member

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    No Mike, I didn't mean the fuel would leak into the pump saver, I meant that if there was significant leakage around the pump saver hole between spool and housing, then there would also be significant leakage around the spool at the barrel valve outlet which would affect the ability to set fuel volume at idle and stage.

    I understand that the pressures are lower at idle and stage, but the hole is also much bigger (nearly twice the circumference) and therefore the potential leak area is also much larger.

    The idle bypass on a PSI setup is usually around 20 lbs, and our car has over 32 lbs of pump pressure at idle and around 95 at stage (I realise that will be a little lower at the barrel valve, but still it's significant pressure).

    Yes that's why Norm was doing this (and that recommendation is still in the latest revision of the PSI Manual), although I'm not sure he was relying on leakage, but rather that the pump saver port would be partially uncovered during a burnout with a large area hat.
    I don't believe he would have done this if he thought it would affect full throttle flow.

    I don't know what would have changed since then in the fuel systems that would make this unnecessary.
    Our fuel system is essentially the same now as it was then.
    .. and I've definitely seen cars backfire during the burnout and when feathering the throttle coming out of the water from this.

    Anyway.. it's an interesting one.
    It'd be interesting to either try a flow meter on the pump saver line, or test it on a flow bench.
    When I get a chance I'll measure the clearance between spool and body which will make it easy to see how much area we're talking about.
     
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    Last edited: Jan 31, 2011
  11. OzAlky

    OzAlky New Member

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    I just read your post more carefully Tom, and had an "Aha" moment.
    You're saying the pump saver can't pass fuel during the pass because it has high pressure at both ends.. right ?
    It can't open unless there's a pressure differential equivalent to it's setting.

    Only when the barrel valve shuts and the pressure in the distribution block drops can the pump saver open.

    Thank You, that makes perfect sense.
     
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  12. secondwindracing

    secondwindracing top alcohol

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    Someone in the past post said to block off the pump saver!!! will I think it might blow the pump apart or something else..don't think that would be a good plan...dave
     
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  13. aj481x

    aj481x Member

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    Did you ever notice that the Enderle instruction sheets calls this outlet "optional" ?
     
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  14. Blownalky

    Blownalky Top Sportsman

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    Yes, that is pretty much the case. I'm using an all in one Gorr distribution block but for discussion purposes we can leave that out.

    http://www.rbssuperchargers.com/Store_Detail.cfm?ID=220766&InfoID=3921


    Tracing the line, plumbing it in either place will be the same. Pat, I see what you are saying now but I don't agree. The pressure against the outlet of the pump saver is the same going down the track with plumbing it into the hat dist block or taking it and putting it into the port outlet of an Enderle "K" style barrel valve, it's logically the same place pretty much if you take out the flowmeter. The same for when you close the throttle, the pressure aft of the barrel would flow out the hat nozzles (because there is no check) and through the ports and dribblers (as long as the fuel pressure overcomes the crack pressure) reducing the pressure there and then will also get a kick in the shorts from the opening of the pump saver.

    Tom
     
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  15. Mike Canter

    Mike Canter Top Dragster

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    Well you would have to ask why it is optional. Probably means in some applications of the barrel valve the pump is different or the pressure is lower or they don't shutdown abruptly like we do. With our immediate shut down and with our high fuel pressures we need to get rid of that pressure spike so it is not felt back on the pumps rotating teeth and breaks the pump's drive shaft. It may not break the shaft right away but it will keep hammering it.
     
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  16. Scouder

    Scouder New Member

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    Tom,

    I'm sure you are correct. It doesn't matter where, on the outlet side of the BV, you dump your pump saver. Even if you dump it at the hat block it's going to flow through the port nozzles as well, assuming that your saver crack pressure is greater than your port check crack pressure. The only way to prevent this would be to put a very light poppet on the hat block, so it would open during idle, but not allow the pressure from the saver to back flow. (I'm a roots guy, so there are a few differences in our stuff, but the basics are the same).

    I am now a little more educated about the pump saver circuit than I was when I made the post. So my concerns are gone. I have learned that:

    1. The saver circuit is closed at full throttle. So it really doesn't matter where I set my crack pressure, as long as it's more than the pressure the system sees while it's open at idle and part throttle.
    2. The clearances around the spool which would allow fuel to see the saver poppet are very small, so the amount of fuel that might get to the saver at full throttle is inconsequential, and would have no effect on full throttle performance.
    3. The pressure spike on my car is only 1/10 of a second, then the pressure drops back to or below the normal peak pressure. So we are talking about a very tiny time window to start with.

    Since I want a pretty good slug of fuel at the lift to cool things off, I want to set my saver crack pressure very close to my peak pressure at the finish line. That way it opens immediately at the lift, and stays open until I return to normal pressure.

    -Brian
     
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  17. secondwindracing

    secondwindracing top alcohol

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    Brian I know alot of racers plumb there saver back to the dis. block and so do I but make sure you dont put a lot of fuel there it could bend some rods or even try to keep the motor lite,,just something to think about. Dave
     
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  18. pat Iley

    pat Iley Member

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    There is two problems you are failing to realize the pressure that fuel pump is putting into barrel valve will be so great that the outlet line for the hat port is already maxxed out and will only flow a set amout of fuel, that is where you fine tune the leakdown for idle settings it won't change even at the end of a run. the second is the port outlet is designed to flow fuel out and line will be full of fuel so when you shut throttle off it is full of fuel with the spool blocking off the return fuel with fuel pressure from the fuel pump your fuel will not go anywhere to relieve fuel pump pressure. when you route return line to hat distribution block the motor will act like a vacuum sucking fuel into blower just like starting motor with a bottle it will suck fuel. as in the enderle option sheet if a person had a smaller pump they may not need this as the smaller square barrel valves do not have this option but with a bigger pump i would advise using it . if anybody can explain otherwise please post
     
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  19. pat Iley

    pat Iley Member

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    Just need to change a few of your thoughts
    1- the open pressure you want in poppet should be higher than your top fuel pressure seen during your run. its main purpose is to relieve pressure in pump when you shut your throttle off and pump is still turning high rpm, if you set it higher than your idle and part throttle and it opens it will affect your tuneup by making it richer on the hat if that is where it is plumbed.
    2- as long as the poppet pressure is set correct no fuel will flow until that time when pressure builds up
     
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  20. pat Iley

    pat Iley Member

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    i have given some thought to your question and i believe that you can use poppet for both applications the reason is the crack pressure that you have set will be much lower that your peak fuel pressure so it will be open the only difference is the fuel will be returned to fuel tank not hat distribution block. this post has caused me do to i lot of thinking. Now if winter was done we could get back to racing. this is keeping me interested until that time
     
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