What I was saying was to talk to Mahle and ask their opinion about gapless rings.

I just hunted for the subject; lots of "promotional" videos and articles, which are all biased. My career was in the automotive field, OE, and the aftermarket simultaneously. Lots of aftermarket BS out there. Most times, if you want to understand a subject, you need to buy and go through many SAE articles on the subject.

So I found a video that enforces my speculation that I had last night when I questioned why, if this is so great, it's not used in production vehicles. Yet, there are counterarguments in the comments section. So we are left to sort out the crap, as we always are. I'm biased because my R&D work can be classified as product testing. After more than three decades, it was rare to find claims that rang true.

If you are in the OE production arena, things get really inexpensive due to the production scale. Sorry, but that does not translate to over-the-counter parts at the dealership. Way more overhead, and the vehicle manufacturer adds a markup for having their name on the product despite most vehicle parts are not made by the vehicle manufacturer, and the dealer has markup, too.

So I go back to the question, if this was so great, and the automotive world is hell-bent on improving fuel efficiency and emissions, which better sealing rings would do, and the in-production costs would be minimal, why isn't it done? Mahle might give you a straight answer.

 

Figured I'd drop this by for all of you and any future readers of this thread, I'll keep my opinions/questions out of this post for now.

I finally heard from Mahle! Unfortunately, this is all still undecided for me, and Mahle's response hasn't helped push me one way or the other. I appreciate hearing what they had to say as a company who doesn't necessarily gain from gapless ring sales, which hopefully limits SOME bias. I've listed my questions and the answers I received below, with the answers in bold. Keep the opinions coming!

1. Do gapless rings have a significant impact on compression sealing on a diesel engine? Is blow-by a big enough concern to justify them?

To start, MAHLE does not manufacture gapless rings but many of our customers run them with our pistons. Gapless rings can improve ring seal and reduce the amount of blow by.

2. I've read that gapless rings can keep oil cleaner and cooler. Is this actually a significant improvement? Clean oil in this engine is everything to us, considering the injectors are fired by oil in the HEUI system.

With less blow by, there will be less contaminants transferred into the crankcase that end up in the oil.

3. Could a street/heavy-load towing engine benefit from these, or are they only beneficial in the race world?

Both street and race driven vehicles use gapless rings.

4. These diesel pistons can only have gapless second rings. Ring flutter has been listed as a concern for gapless second rings, and the issue is sort of debated. How exactly does ring flutter occur? I know there is a concern with sealing and top ring lift, but even if the ring lifted, how would it lose seal? Would the RPMs on an engine like this get high enough to create an issue?

The risk of ring flutter is there. Ring flutter can happen two ways. First type, is from inertia. When the rpm hits a certain high point, the top ring cannot stay seated to the piston groove. The second type is from buildup of inner ring pressure. If the pressure between the top and second ring is greater than the pressure pushing down on the top ring, it will lift the ring off the groove. Both of these can also happen together.

Conclusion of Email: Ultimately, there are some benefits to running a gapless ring but also some risks such as inner ring pressure. I know many of our diesel customers run them successfully.

 

Hmmm.... Interesting discoveries in the YT comment section that I've not heard anywhere else, but it makes sense. When you think about it, the downward pressures alone (not to mention the added benefit of boost) that the diesel engine's top compression rings experience would make it unlikely for the ring to lift during compression. Not to mention this engine will rarely see the high RPMs typically required for the phenomenon to occur.

MAHLE never mentioned anything about this, but how can we expect them to.... They're not in the gapless ring business. At the same time, we can't always believe every claim made by Total Seal (they're trying to sell a product).

Another theory I had is that these could aid in cold-starts. In my mind, the gap is most open when cold, and closes under heat. Therefore, when cold starting without gapless rings, you're trying to compress the air (and heat it ofc) with a greater possibility of compression loss. Especially in an older, more worn engine. It's something to consider, and I reached out to Total Seal with that question.

Thoughts are always appreciated. This thread is not only for me, but for others who will look into these in the future, so I want to conclude it as much as I possibly can, whether I choose to use them or not.

 

I think I've finally made my decision, after about a month and a half of reading the same things twice and communicating with you guys and other companies.

For another $100 I can put in a nice ring set from a company with a great reputation. I am this deep in the motor, so I might as well put in a good product that will hopefully give me:
-Longer ring life
-Cleaner Oil
-Little to No Blowby (for a long while!)
-Possibly Slightly Improved Cold Starts
-Possibly Cooler Oil

With my concerns of ring flutter now reduced, I am less hesitant to give it a shot.

If I was building a typical rice burner engine, I couldn't justify spending the extra $100. However, I am building a turbodiesel engine with a HEUI injection system, and that makes it different for me.

NOTE: HPOP oil shearing is still an issue, so cleaner oil doesn't mean I can or would ever want to go longer intervals. But cleaner oil is still healthier for everything.

Not only will I hopefully see these benefits on my truck, but I will be sharing my experience and oil change test results and observations for a while, to help others decide if the benefits are good enough for their motor. I would like to thank you all for your help, and I hope this works out well! This thread is far from over.

 

I haven’t had to rebuild any 6.0 engine. Our engine just passed 300k miles. I haven’t read of ring wear being a big concern with these, at least compared to other items. So I wouldn’t think swapping in a different style of rings would benefit from a longevity point of view.
As far as cold starting, there are so many things that have to be correct. In Mn ours has sat outside, not plugged in and still fired off when it was well below zero. I think if you have cold starting issues, there are other places to look first.

 

Sorry I took a bit to respond, I've been insanely busy!

Yeah, the cold starts likely won't be improved that much. Others have mentioned it here and there, so I put it here as a "possible slight benefit".

Oil cleanliness is goal number one, and we'll see how that goes, but I'm confident that I'll notice.

As far as ring life, if the rings do their job properly, I expect to see no blow-by at all, even with 300K put on the post-build engine. They should seal completely for a very long time considering how the rings are designed, unless I am incorrect?

 

Time will tell…..

 

For sure.

Worth a shot I guess!

 

Oh, I think it's an interesting home R&D!

 

I hope it will be!

I plan to save a little oil from each oil change, as well as a sample of what I took out of it pre-build, so that we can see how the oil's cleanliness changes over time, if at all.

I also plan to send oil off for analysis, but I've never done that before.... Is it something that is done at every oil change, or would I do it every 3-5 oil changes?

If I am ever deep into the motor for something like glow plugs, I could probably attempt some leak down tests at varying mileages to see if ring issues develop and how long it takes.

Any other suggestions? I want to make this as informative as possible for anyone reading in the future!

 

Well, I wanted to update this a little. Still not back together, but the machine shop is finally working on our block! He ordered the rings, Total Seal S4914 (Standard; No Boring Needed) and wants to have them in hand before the hone job.

He was talking about specialty hone stones being required for Compact Graphite Iron blocks, which I believe, but I don't believe the 6.0L is CGI, unless I missed something. I let him know about that. The 6.7L was the first CGI Powerstroke block, correct?

I'll try to update this thread when I know more about the hone job and rings overall.

 

I know a SLIGHT amount about oil analysis through my job. Anytime a piece of equipment comes in for a service, we take a sample of all oils; hydraulic, transmission, and engine. Doesn't matter what were doing work on, how many hours it's been since its last change, whatever. If it's a piece of CAT equipment and were doing a service a sample WILL be taken.

With that being said, I have carried that same idea into my personal life. If I am doing an oil change, that little cup gets stuck under the drain hole and sent off every time. That way I get the best track of how my engine wear is trending and it gives me that little extra piece of mind to know everything is normal every 5,000 or so miles. I'm sure you could do every other, but for me it makes the most sense to do it anytime you change the oil.

Proper sample taking is a big deal if you do plan on sending them off, though. I like to have my oil nice and hot before I change it, and the sample is taken mid-drain. Too early and you get sediment gathered around/near the drain plug, and too late the oil is picking up a lot gunk from the bottom of the drain pan... or, so we were taught in class.

 

I got the gapless rings and engine block from the machine shop today. I'll have more to come soon about their installation and more research I've done on them since last posting here.

 

I know it’s been awhile, but any update to how this engine shook out for ya?