Twins with Twins, Anyone?

[Chevy1925]

i would put half the run hours on the new pumps and send them back to be opened up and fully inspected. Duty cycle on these pumps at or damn near max pressure for his length of time is hell. What ken explained earlier as to likely cause of failure makes total sense.

 

[darkness]

Without going back thru this, are you pre-cooling the fuel before the cp3’s? I don’t remember if there was an optimum temp for diesel. Could help keep the pumps cooler maybe.

 

[kidturbo]

Checked the separators again, just a couple drops of water, so doesn't look to be contamination related. Everything goes through a 1micron before the pump.

Had a nice chat with Randy from Exergy today. Learned a lot more about CP3 pumps and how these are modified. Which raises some new question if anything. But short of it is, there are some higher stresses applied to the followers and eccentric when you increase the volume and or pressure on the plunger. As stated above, these stresses aren't a big deal when your talking 10sec blasts. Nobody has studied the effects after 10 minutes at full pressure and high RPM outside of a bench setup. And what's left on this pump is a study in catastrophic failure. This eccentric actually exploded, seized the shaft, and the 80lb flywheel said, we ain't stopping that quick. So it removed a couple teeth off the pump wheel to make a point.

Fuel temp and lubricity might come into play, or it might just be metal fatigue. All things to study. So the best plan is also as listed above, pull the pumps after 10-20hrs and crack em open to see if anything looks stressed. Also log some temps on input, output, and returns at speed. Finally get to put the IR camera to good use.. Pre-chillng the fuel could be an option. Currently it only gets cooled on the return to tank.

Here is the two points of failure we've noted, along with an exploded view of a CP3. Found these easier to understand then the exploded views I produced..

 

[zakkb787]

Never seen an exploded view of a CP3 before. Makes more sense how it works now. Looking at the failure points in the first set of pics, I can definitely see how heat from the extended high RPM runs could cause that type of failures. Looks to me like part number 204 rides directly on the plunger. Maybe the fuel doesn’t have enough publicity properties and cooling ability to negate the friction between the two parts, much like how over revving an engine can spin main or rod bearings causing a similar locking up situation. Curious to see what Exergy comes up with to combat those effects! Very cool stuff Ken

 

[JoshH]

Can you run lower rail pressure to reduce the stress on the pump?

 

[2004LB7]

What about some needle bearings between the shaft and eccentric?

 

[kidturbo]

Can you run lower rail pressure to reduce the stress on the pump?

Yes that's an option, but reduces max power potential. In which case going to 10mil would likely land us in the same range.

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[2004LB7]

Sounds like you are better off with duel CP3s. Less demand from each pump to achieve the same pressures, lessening the stress on the internals of the pump

 

[kidturbo]

I sure like the clean fit of a single valley pump. Trying to hide another pump on the front cover is gonna be a trick. However first trick I've gotta perform is pulling this fluidamper off the Callies crank.. Not sure if anyone else noticed this, but either FD was a couple thou tight on their first batch of Neutral bal units, or Callies was a couple thou over on thier Ultra Billet snout. Plus they are double keyed.. They went on so dang tight 4yrs ago that Dustin and I both said, "hope these suckers hold together, cause I don't wanta be that sucker who tries to pull these off..."

Well today found myself buying two bearing style puller kits from Jegs, after spending 4hrs Monday trying to lightly warm the hub, feeding the keysways with PB Blaster, while bending a cheap puller around a grade 5 bolt, waiting for it to pop and take out an eyeball any moment. Ah the fun ya that comes with being the first test dummy on all this hardware. Belt drive pumps don't look so bad at this moment..

 

[JoshH]

Yes that's an option, but reduces max power potential. In which case going to 10mil would likely land us in the same range.

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You could bump up the injector size to make up for the lowered rail pressure. What sort of rail pressure do you run at full load?

 

[Fingers]

IMO, you are over spinning the pump. The simplest solution would be to under-drive a single belt driven 12mm pump. Keeping the max pump shaft speed around 3000 RPM. The "Cool" solution would be to change up the gearing on the valley pump and under-drive it.

 

[2004LB7]

IMO, you are over spinning the pump. The simplest solution would be to under-drive a single belt driven 12mm pump. Keeping the max pump shaft speed around 3000 RPM. The "Cool" solution would be to change up the gearing on the valley pump and under-drive it.

That's what I was saying. Maybe not as elegant as you. Also was kind of hinting that he would have to belt drive them too

 

[kidturbo]

You could bump up the injector size to make up for the lowered rail pressure. What sort of rail pressure do you run at full load?

Currently 190MPA above 3200 or so.

 

[kidturbo]

IMO, you are over spinning the pump. The simplest solution would be to under-drive a single belt driven 12mm pump. Keeping the max pump shaft speed around 3000 RPM. The "Cool" solution would be to change up the gearing on the valley pump and under-drive it.

I've thought about that option, but yet to calculate actual pump RPM as is.. To the naked eye the pump gear looks similar to the dia of a crank gear, so guessing they run pretty close to engine RPM. IF anyone has both crank gear and a pump gear on the bench, please give me a tooth count. I'll do the same if my puller tools arrive before I leave town tomorrow. So far I'm letting the pump guru's research a couple other options.

 

[2004LB7]

I count the crank and CP3 gears both at 43 teeth. So that puts the pump RPMs the same as engine RPMs

 

[PureHybrid]

Is changing the pump gear size really feasible at this point? You'd have to mount the pump further up correct?

 

[2004LB7]

Is changing the pump gear size really feasible at this point? You'd have to mount the pump further up correct?

Without messing with the crank/cam relationship, I can't really see another way. Unless you figure out how to install an idler gear along with reducing both crank and cam gears

 

[kidturbo]

Yes would have to reinvent the wheel per say. Fingers belt drive idea would obviously be the best solution to maintain the 12mil. But ultimately easier to just stick a stock one in the water pump hole and call it done.

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[kidturbo]

The damper puller kit didn't arrive today. Jegs running a bit slow getting orders out this week it seems. So we decided to go ahead and prep the engine bay to start on the drive swap next week. Pulled the turbos and tail pipes off once again. Finally get that one V-band to stop leaking, and now time to break the seal..

Also pulled all 16 injectors tonight. Sending them out tomorrow for inspection and a good cleaning. First since changed tips after the dyno days. Had one stick on the Port engine that jumped up from a +4.5 to a +6.5 on bal rate after that pump failed. Noticed EGT on that bank running a bit low at WOT also. Stbd engine had so much metal in the valley after the pump failure, I'd be amazed if nothing made it out the plungers. Maybe something will jump out that helps solve this problem..

Had a helper show up today, Tyson who owns the big Skater cat with twin Industrial 6.7's. Those also runs single stroker pumps, and is about even with me on hours. While I know the C pumps are slightly different internals, I also read where they increase the bore rather than just offset grinding the eccentric to gain stroke. Which makes me wonder if that might be a better internal mod. Since that's what exploded in this second pump, I'd love to hear from someone who knows all the aftermarket mods better than I..

 

[JoshH]

Industrial Injection has their XP line of CP3 pumps that are both bored and stroked. From what I understand, they have 2 levels. Stock plungers are 7.5 mm, the standard XP pump bumps that up to 8.5 mm, but I hear they also have one that is 9.5 mm. They are all a 12 mm stroker pump, but I'm sure they could do something custom for you if you called them. I installed one of their 8.5 mm pumps in a customer's truck after talking to a few people who have run them, and it is working good so far, but I have very little run time on it and can't speak to the reliability or longevity.