twin P-pump?

[cetanefreek]

I know there was an H pump that had electronic variable timing, a member on here is working on putting one on a cummins.

 

[biggy238]

That was the first thing that came to mind when I first read your post. Not sure how it ended up.

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[cetanefreek]

I think his pickup got stolen, he posted that he's still working on it.

 

[camarokiller]

Must be where i heard of it then

 

[cetanefreek]

I'm still liking the belt drive idea just for the tunability, and I could build it all with off the shelf parts and not spending a week machining things.

 

[camarokiller]

Im sure it would have to be a cog belt atleast. No way a v or rib belt will spin a p pump. Then you have to account for the harmonics from the belt also.

 

[Scooter's Roofing]

a serp belt isn't going to run a P-pump correctly

and if you run a cogged belt, there's no way to advance or retard the timing without jumping a tooth at some point

 

[cetanefreek]

I'm picturing a cogged gates belt, no way you could keep it in time otherwise.

 

[cetanefreek]

Sure there is, you move the slack from the back side of the pump pulley to the front side of the pump pulley

 

[Cozze44]

Sure there is, you move the slack from the back side of the pump pulley to the front side of the pump pulley

The belt would have to physically gain teeth or loose teeth to change timing, regardless of if the belt slack is on the top side or bottom side. I may be wrong but I don't see how changing where the slack is could effect timing with out either changing teeth count or actually slipping on one of the pulleys...

 

[cetanefreek]

Not if you are moving the slack while it's running, set base timing with a spring tensioner keeping the slack on the backside like you would normally. Now another idler on the front side mounted with an actuator pulls the slack around to the front of the pulley, the spring idler gives up the slack, and the driven pulley effectively advances.

 

[GOT-Torque]

It would work great.

 

[khaoskustoms]

Richards twin p-pump truck had an air actuated variable advancer working off the belt tension of the cog drive belt for the second p-pump. I think it would advance pump timing 20 degrees or so. This last year he was running the cog drive setup in a single pump only configuration with the variable timing advancer.


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[cetanefreek]

Huh, exactly what I was picturing, any idea if he liked that setup?

 

[khaoskustoms]

Yes he did. He's planning on using it again next year. Not sure if he's going to put on the twin pumps or stay with the single pump and cog drive.


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[cetanefreek]

Cool, that's good to know, I'm going to pursue this route I think, the cam phaser still intrigues me, but I don't see it being as tunable.

 

[RockinRam96]

So at an idle will both pumps be timed the same?

What about a centrifugal advance? Kind of backwards of how a snowmobile clutch works?

I don't see why a mechanical advance, similar to a caterpillar advance wouldn't work. Obviously you'd need a new timing cover and pump gear, but I think you could start with an adjustable pump gear to build the advance. All points/ magneto ignitions use a mechanical advance.


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[Cozze44]

Not if you are moving the slack while it's running, set base timing with a spring tensioner keeping the slack on the backside like you would normally. Now another idler on the front side mounted with an actuator pulls the slack around to the front of the pulley, the spring idler gives up the slack, and the driven pulley effectively advances.

I'm seeing this now :Cheer::doh:

 

[zfaylor]

So at an idle will both pumps be timed the same?

What about a centrifugal advance? Kind of backwards of how a snowmobile clutch works?

I don't see why a mechanical advance, similar to a caterpillar advance wouldn't work. Obviously you'd need a new timing cover and pump gear, but I think you could start with an adjustable pump gear to build the advance. All points/ magneto ignitions use a mechanical advance.


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This. it seems everybody has tried to go every route possible to do dynamic timing on a p7100 except copying what has already been done by CAT. Sometimes reinventing the wheel isn't necessary to be revolutionary.

 

[9724VF350]

Part of the problem with copying the cat setup is just the sheer amount of force it would take to advance a P pump and have it not back off during the injection event when the advance is under significant load, then snapping forward to advance position, creating a long, slow injection that actually results in lesser performance than a non advance gear.

The stock P7100 drives much harder than most of the cat pumps. Start adding fast cams, big plungers, and big rpm and the force required to make a effective advance increases exponentially.