Pump saver

Hi all,
I'm trying to understand the pump saver function on a K-style barrel valve. As far as I know you connect a poppet to the top with an opening pressure of around 200 psi. When you shut the throttle it should open and dump the excess fuel in the top or return it to the tank.
Now for my question: If the throttle is slammed shut, the opening through the spool to the return port will also open, so the fuel pressure will be kept low anyhow.
What am I missing here?

TIA

 

saver

I have been told it is for burn outs ect where the rpm is high and the blades are slammed shut. There is not enough flow trough the spool to take care of all of the extra fuel. I hope this helps

 

When using large fuel pumps, both of those holes in the rotor are needed to relieve enough fuel to have the desired effect. If you are using a smaller fuel pump, it isn't necessary to run that upper relief check valve at all, the idle check valve will do the job just fine.

Since that upper check valve is only exposed to fuel pressure when the throttle is shut, there's no reason why it can't be set to a much lower pressure than that. I think 200 PSI is higher than it needs to be.

Spud
www.fuelinjectionent.com

 

I should have realised that the opening through the spool was too small to dump all that fuel. We'll be running a 1100 enderle pump on a 500ci blown hemi, so I think that qualifies as a decent size pump for which we should install the pump saver. The spring kit is on its way to fiddle with the pressures so we should be able to get a decent starting point.
With the datalog pressure sensor in the inlet port we should be getting enough information to sort it out.

And thanks for setting up the calculators Spud. I already did some guessing on where to start with this engine, and your calculator gives me the extra confidence that I'm on the safe side. One thing I don't trust is the system pressure, which is said to go over 400 psi where I'm quite certain I won't even reach half that, but we'll find out soon enough. I can PM you the data if you want.

Thanks

 

I'm not so quick to agree with setting the pressure lower than that.
What happens if you spin the tires and peddle the car and when the RPMs are up and you spike the pump and the the pump saver dumps off the fuel pressure? Now when you immediately go back to the throttle wont the engine be lean and more aggressive and harder to hook back up?

 

ding ding ding... we have a winner

but heck with being hard to hook back up... what about lean and eating parts?

don't take anyone elses word for your fuel system... educate yourself. put a gauge on it and watch it on the run... AND put a check in the line to catch your peak (it will be when you snap the blades shut) pumpsaver needs to be somewhere in between

and if you've ever pumped a firetruck (i have) you'll know what water hammer is... and you'll know it's bad. it breaks things. so will hi-velocity, hi-volume moving fuel... hydraulics can be an unforgiving bitch

 

The PSI manual suggests 140 psi and looping it back to the nozzles to prevent a lean spot in the burnout / peddling.

 

PSI manual

Sounds like an interesting manual.
Is it available on-line somewhere?

 

Altered boy...you have the (A) for today..Dave
www.myspace.com/daveloweswr

 

http://www.psisuperchargers.com/viewproduct.php?id=28

They don't list the book: It comes with the supercharger.
You could email the sales rep.

 

Well, it depends on your setup...if you are hitting 400 PSI going down the track, then yes, 100 PSI for the pump saver is way too low. If you're running an Enderle internal gear pump and run 100-130 PSI like a lot of folks do, then setting it to 200 PSI means it isn't going to do you much good.

Running the relief back to the top of the hat distribution block as mentioned is a good thing to do not only get rid of that possible lean spot, but also to help save the strips in your blower during the shut down. Unless you shut off the fuel at the finish line...then the relief does nothing for you.

You're welcome TWD! I would indeed be interested to hear what kind of pressures you really see. The pressures reported are just approximate. For a supercharged setup running high boost, the AFR it uses tends to be lean which means you'll be using a smaller pill than it suggests...which means pressure may be even higher than it reports!

Spud
www.fuelinjectionent.com

 

OK now I have a question. On tv I've seen fuelers with the bdk coming off the pump saver port. I assume they slot the hole in the spool so its open wot.
have I answered my own question?

Spud
On your website the supercharger tuneup caculator sets up a methanol motor @ 5:1 air/fuel ratio. Shouldn't it be 4.2:1 ? Do you sell pistons??? lol

 

online calculator

It really is a wonderful toy in all it's splendidness and I read the warning label.
it would be super cool if you could move the air / fuel around by itself for different compresion,load ect...
I have another question though. Someone over on promodzone was asking about a two step on a mallory mag. Do you think a PSI rev limiter could be turned down enough to 5000 rpm and run though a clutch switch or a through a relay off the trans brake to mag +.

 

Hi Marty,

The AFR decreases as boost and/or dynamic compression increases. Around 5:1 works just fine for boost levels up to 15 PSI or so and then it needs to be a bit richer. 4.2:1 is pretty rich unless you're up above 30-35 PSI or running lots of compression.

You didn't think a free web tool was going to be "everything to everybody" did you?

It does spit out all the numbers you'd need to calculate whatever AFR you prefer.

Spud
www.fuelinjectionent.com

 

Hi again Marty,

Nope, I sure wouldn't do that...a PSI kills everything, it isn't selective or intelligent at all. It would oscillate - meaning it would kill it, drop a few hundred RPM, then climb, kill it, drop...I don't think things would last very long doing that.

If I spent hours and hours programming that stuff into the web calculator, some people would begin to trust it too much and blindly use what it delivers. There are a lot of other factors involved that keep a tool (or toy) like that from ever being perfect. One of those is the load on the motor (vehicle weight, gears, tire size, etc.). More load requires more fuel too. That would be hard to build into the algorithms. No matter how good the programs or computer tools are, there will always be some head scratching and common sense required. I haven't found a Perl programming module yet for common sense

It does illustrate the relationships between nozzles, fuel, pressures, boost, air, etc. and lets people quickly see how things change when one or more of those factors is tweaked. That's really all it's supposed to do.

Spud
www.fuelinjectionent.com

 

Spud how will the new Hampton 2 lobe 8/ 71 blower affect your calculater ?

 

Enderle pumps are sensitive to high fuel pressures, there is no support on the cresent between the gears. I personally set my pump saver to the max fuel pressure on the run, approx 160lbs. On a roots style blower, I return the fuel from the pump saver to the hat to lube the blower.
When you step off the throttle , engine rpm is high, doors are closed, very little fuel goes to the engine. When fuel is returned from the pump saver to the blower, if you pedal the car the engine goes rich, and in my opinion may save parts.
Just my 2 cents. Ken

 

since all i ever ran was enderle pumps i thought i was stupid until i read your post
Ken
couldn't agree more

 

stopping lean out

I put a check valve, something like 100#, I then ran the line to the top of the hat distribution block. That way it prevented lean out when the valve was open and closed.

I tried to up load a picture, but I do not have the expertise to reduce the size of the up load, all i succeeded in doing was making the picture to small to see with MS office picture editor.

 

Richard,

You can e-mail the photo to me and I can resize and host it for you.

ericdavidbru@yahoo.com

EDB

PS Long time no talk to, I hope all is well.