CP4 to CP-ISB21S3 (revised CP3) change for 2021 6.7L Diesel Trucks -- Merged Threads

[erichonda30]

This will be interesting.
Only 13,600 miles on my 19 ram 3500
Motorcycle is my daily rider.

 

[erichonda30]

I don't buy the emmisions excuse for using the cp4.
2021 meets emmisions with cp3.

 

[bigcitymike]

I don't buy the emmisions excuse for using the cp4.
2021 meets emmisions with cp3.

I've heard that the CP3 at the time didn't produce enough pressure (~24k PSI MY2013 - 2018), so the CP4 was used (30k PSI). You need higher pressure for power, and probably more importantly to meet ever tightening emission standards (cleaner burning, less EGR issues). I've also read that what everyone is calling the new/old CP3 today is actually called a CP-ISB21. While CP-ISB21 might be a CP3 inspired pump, I'm guessing it's not really the same part as the old CP3. They had to do something different to up the pressure from 24k PSI to 30k PSI.

 

[98GTSViper]

I’m sorry as this has probably been answered, but it’s hard to search as it’s 64 pages..

Can the pumps from the 2021 and 2022 Rams not just be the prescribed solution to the 2019 and 2020 HD rams?

 

[Brutal_HO]

I’m sorry as this has probably been answered, but it’s hard to search as it’s 64 pages..

Can the pumps from the 2021 and 2022 Rams not just be the prescribed solution to the 2019 and 2020 HD rams?

The timing cover back plate and mounts are different. It's not a direct bolt on swap.

The 3rd party CP3 adaptations use an adapter ring and a relocation bracket for the ECM.

 

[UglyViking]

I've heard that the CP3 at the time didn't produce enough pressure (~24k PSI MY2013 - 2018), so the CP4 was used (30k PSI). You need higher pressure for power, and probably more importantly to meet ever tightening emission standards (cleaner burning, less EGR issues). I've also read that what everyone is calling the new/old CP3 today is actually called a CP-ISB21. While CP-ISB21 might be a CP3 inspired pump, I'm guessing it's not really the same part as the old CP3. They had to do something different to up the pressure from 24k PSI to 30k PSI.

I'm quoting this for the sake of argument, not directly against you FWIW.

I just don't see how that can be possible. The new engine is basically identical to the outgoing engine in every major way, the HP/TQ numbers did jump a little on the HO trucks, but considering the aftermarket had been doing as large/larger numbers with the factory CP3 and tuning only, I just don't see a great argument here. I understand that the CP4 is capable of a higher pressure according to Bosch, although I'm honestly unsure what makes that so, it seems as if it would be a specific version of the pump, and not the max capabilities.

My understanding is that the stock CP3 should be good to around 600hp give or take, so since these new trucks aren't even remotely close to that, I don't see that as an obvious answer either.

What is very obvious, is the fact that the CP4 is much cheaper than the CP3, it also saves a bit of weight I'm assuming, so those are two major reasons. I'd be curious if someone bench tested the two, or was somehow able to get a test between the two. If the reason that Ram went with a CP4 was indeed for higher pressures, one would expect that the CP3 trucks have a notable acceleration delay, yet I've not heard anyone comment that yet.

I agree about the ever tightening emissions, and that may have been the driving factor along with cost. If they are truly worried about EGR issues, well I'm curious why we aren't focusing more on the Cummins EGRless 6.7 currently available. New versions supposedly have a 50% smaller SCR/SPF as the unit is now combined (no clue what this does to reliability or replacement cost, which would be my largest concern).

 

[steve49]

UglyViking, "If they are truly worried about EGR issues, well I'm curious why we aren't focusing more on the Cummins EGRless 6.7 currently available."​

Unless something has changed, I read sometime back about this new Cummins EGRless design that could meet EPA parameters, but the EPA still turned it down saying it had to have an EGR?

 

[H3LZSN1P3R]

I'm quoting this for the sake of argument, not directly against you FWIW.

I just don't see how that can be possible. The new engine is basically identical to the outgoing engine in every major way, the HP/TQ numbers did jump a little on the HO trucks, but considering the aftermarket had been doing as large/larger numbers with the factory CP3 and tuning only, I just don't see a great argument here. I understand that the CP4 is capable of a higher pressure according to Bosch, although I'm honestly unsure what makes that so, it seems as if it would be a specific version of the pump, and not the max capabilities.

My understanding is that the stock CP3 should be good to around 600hp give or take, so since these new trucks aren't even remotely close to that, I don't see that as an obvious answer either.

What is very obvious, is the fact that the CP4 is much cheaper than the CP3, it also saves a bit of weight I'm assuming, so those are two major reasons. I'd be curious if someone bench tested the two, or was somehow able to get a test between the two. If the reason that Ram went with a CP4 was indeed for higher pressures, one would expect that the CP3 trucks have a notable acceleration delay, yet I've not heard anyone comment that yet.

I agree about the ever tightening emissions, and that may have been the driving factor along with cost. If they are truly worried about EGR issues, well I'm curious why we aren't focusing more on the Cummins EGRless 6.7 currently available. New versions supposedly have a 50% smaller SCR/SPF as the unit is now combined (no clue what this does to reliability or replacement cost, which would be my largest concern).

After market CP3 kits are stroker or overdriven pumps not the same old cp3 that topped out at 26k psi HP means nothing other than flow

 

[bigcitymike]

I'm quoting this for the sake of argument, not directly against you FWIW.

I just don't see how that can be possible. The new engine is basically identical to the outgoing engine in every major way, the HP/TQ numbers did jump a little on the HO trucks, but considering the aftermarket had been doing as large/larger numbers with the factory CP3 and tuning only, I just don't see a great argument here. I understand that the CP4 is capable of a higher pressure according to Bosch, although I'm honestly unsure what makes that so, it seems as if it would be a specific version of the pump, and not the max capabilities.

My understanding is that the stock CP3 should be good to around 600hp give or take, so since these new trucks aren't even remotely close to that, I don't see that as an obvious answer either.

What is very obvious, is the fact that the CP4 is much cheaper than the CP3, it also saves a bit of weight I'm assuming, so those are two major reasons. I'd be curious if someone bench tested the two, or was somehow able to get a test between the two. If the reason that Ram went with a CP4 was indeed for higher pressures, one would expect that the CP3 trucks have a notable acceleration delay, yet I've not heard anyone comment that yet.

I agree about the ever tightening emissions, and that may have been the driving factor along with cost. If they are truly worried about EGR issues, well I'm curious why we aren't focusing more on the Cummins EGRless 6.7 currently available. New versions supposedly have a 50% smaller SCR/SPF as the unit is now combined (no clue what this does to reliability or replacement cost, which would be my largest concern).

I could be wrong about the performance side (I thought I read that somewhere), but according to this video the CP4's may be cheaper to make and are need for emissions reasons.

CP4 ---> CP3 Swap video

 

[erichonda30]

I'm a little confused so the 2021 trucks didn't come with cp3?
Did they already have the cp isb21?

 

[Dwilly]

I'm a little confused so the 2021 trucks didn't come with cp3?
Did they already have the cp isb21?

The CP3 is an ISB21. Just likely a bit overdriven to reach the pressures needed.

 

[H3LZSN1P3R]

The CP3 is an ISB21. Just likely a bit overdriven to reach the pressures needed.

Its not a CP3 like the past its a variation of one and not overdriven

 

[UglyViking]

Its not a CP3 like the past its a variation of one and not overdriven

Do you have concrete details about the difference between the two? I'd imagine a different cam, maybe slightly stroked, but what else could be different?

 

[Dwilly]

Do you have concrete details about the difference between the two? I'd imagine a different cam, maybe slightly stroked, but what else could be different?

The concrete details are that it's close enough to a CP3 that it might as well be called one.

 

[bigcitymike]

How is it no detailes of the recall (parts list or repair procedure) have been leaked yet? It's not like this is some Skunk Works project.

 

[flan]

How is it no detailes of the recall (parts list or repair procedure) have been leaked yet? It's not like this is some Skunk Works project.

As I type, there’s test trucks out there running the potential replacement pump. They have been doing so for a couple months now. They want to be sure the pump and it’s replacement parts are going to be a success before releasing the kits to the dealers. Up until the first forum member rolls out of the service dept we still won’t know what that specific pump will be (although there is/will be speculation). The recall letter you will be getting more than likely won’t even mention it. It will just give you the explanation of why there is a recall in place and to schedule your service.

 

[jkempken]

As I type, there’s test trucks out there running the potential replacement pump. They have been doing so for a couple months now. They want to be sure the pump and it’s replacement parts are going to be a success before releasing the kits to the dealers. Up until the first forum member rolls out of the service dept we still won’t know what that specific pump will be (although there is/will be speculation). The recall letter you will be getting more than likely won’t even mention it. It will just give you the explanation of why there is a recall in place and to schedule your service.

This does not give me a warm and fuzzy feeling we are getting a CP-ISB21, but time will tell. Only a week away until the letters should be coming out and we should be able to get our trucks scheduled for the swap.

 

[UglyViking]

This does not give me a warm and fuzzy feeling we are getting a CP-ISB21, but time will tell. Only a week away until the letters should be coming out and we should be able to get our trucks scheduled for the swap.

I would not be concerned. The testing trucks are likely monitoring the software and mounting solution, not the pump itself. Frankly, after all this I expect this to be a pretty clear homerun.

 

[H3LZSN1P3R]

As I type, there’s test trucks out there running the potential replacement pump. They have been doing so for a couple months now. They want to be sure the pump and it’s replacement parts are going to be a success before releasing the kits to the dealers. Up until the first forum member rolls out of the service dept we still won’t know what that specific pump will be (although there is/will be speculation). The recall letter you will be getting more than likely won’t even mention it. It will just give you the explanation of why there is a recall in place and to schedule your service.

Its a CP3.3 according to an inside leak from a FCA employee his was the 2nd truck (company truck owned by ram) to get the kit he had pictures on FB

 

[flan]

Its a CP3.3 according to an inside leak from a FCA employee his was the 2nd truck (company truck owned by ram) to get the kit he had pictures on FB

Ok I saw the post, but no pics. Seemed like a credible source after FB fact checked his employment history haha!