Engine cavitation in ISB

[Johnstra]

direct from Cummins...

I received the following response from Cummins regarding engine cavitation in the B/ISB engines...

Summary: ram b/isb cavitation erosion considerations



Solution:

Thanks for the email John. Your understanding of the sleeveless (parent bore) nature of the B/ISB engines is correct, as is incorrect your concerns for future cavitation issues with this engine. Marine ratings are far higher than Dodge ratings. We have no liner pitting issues on these engines, and we wouldn't expect to.



"..... but other sleeveless diesel engines do still require additives to prevent cavitation problems. "



We have not heard of this and doubt that it's true, unless the sleeveless design has sufficiently 'thin' castings to allow the kind of ringing/flexing that induces cavitation bubble in the first place; casting precision is not sufficient to give reliable "thin-ness" such that this is an issue on any reliable, durable production engines that we know of. Design for durability does vary with market - we know of some lawn trimmer motors that have target durability of 25-50 hrs.



The primary diesel market for our products is the commercial, high-durability, lowest total cost-per-mile or -hour of operation; the only issues we note with cavitation erosion are on removable, free-standing cylinder liners and we have no issues with this phenomenon with parent bore designs.



No worries on current or future versions of your engine. (you're not a surgeon living in Central IN by any chance?)

 

[SilverFox]

Am I reading the email from Cummins right?



Marine ratings are far higher than Dodge ratings. We have no liner pitting issues on these engines, and we wouldn't expect to.



Do the Marine ISB's have liners? It seems to me Cummins says they do and they don't have a cavitation problem, even with sleeves. What is the Marine rating for the ISB?



"..... but other sleeveless diesel engines do still require additives to prevent cavitation problems. "



Is the above a quote form your email, John? If it is, Cummins goes on to say they have not heard of this and doubt it's true. How can that be, Cummins must know the Navistar T-444 requires the additive as well as the sleeveless Caterpillar engines.



I must be reading this wrong?

 

[Johnstra]

Yes, that's a quote from my email to Cummins and, yes, you're reading it right. I hesitated before posting this because, like you, I found it kind of confusing and contradictory to some of what has already been posted concerning this.



The way I took it was, neither the marine nor the Dodge ISB have liners, and even with the higher rating on the marine ISB, they still have no pitting problems... so we don't have to worry with our RAMs. I took it this way because in my original email to Cummins I asked if they thought as the Dodge ISB HP numbers continue upward do they forsee this becoming a problem in the future.



I'm definitely puzzled that he's not aware of these other engines and their recommendations.



I've replied to him, asking for some clarification. I'll post when I hear back.

 

[SilverFox]

Thanks John, I just added 5 oz. of FW-16. With statements like that coming from Cummins, I'm going with my intuition. Usually not the thing to do but I'm just conditioned to use the stuff. That's the only additive I use.



I'm looking forward to hearing what Cummins has to add to your original email.

 

[moorepowercoatings]

Guys, read the e-mail again. It said the isb is sleeveless and it also said the only problem with sleeveless design would be a thinwall casting, ie; navistar. Grasshopper, Don't try to read between the lines, or you may not see the trees for the forest.

 

[abledog]

I'm with Pat