Engine designs that have problems 22

[enginesrus]

Since the one thread I started, is headed way off topic, reason for this.
Engine designs that have problems or have had them.
I'll start with the 3 valve Triton.
This guy explains. Has data from others that deal with the same problems.

https://www.youtube.com/watch?v=xcN_WcGr4BU

 

[BiPolarMoment]

That's a fermented capsicum pubescens sauce.

Verdict: Great on Sausage pizza and Sausage Egg and Cheese Bagels.

 

[TugboatEng]

Awesome. I was hoping to get some feedback. Two users took me up on the offer.

 

[SwinnyGG]

I disagree. Open deck allows for die casting of the block. There are benefits to this other than cheapness. Remember, it was only Subaru that had problems with their head gaskets, open deck or not. All other manufacturers have successfully and reliable open deck designs in their portfolio. Even some Formula 1 engines are open deck.

There was an entire thread about this like 2 years ago, started by you-can-guess-who, where the exact points you're making were made. And here we are again.

In all seriousness why does anyone on this forum continue to engage with this guy

 

[TugboatEng]

Where do you draw the line? The environmental catastrophe comments have the same level of credibility. I prefer a forum where everybody can share their thoughts so that they can all be exposed to equal criticism. I have been banned from parts of this forum for questioning the status quo. I think the best part of this forum is the local knowledge that quickly shoots down any conspiratorial comments. None of my own idiotic comments have withstood the test of peers.

 

[SwinnyGG]

I'm not advocating for the banning of anyone - but at this point I fail to understand why anyone attempts exchange. There is none; only the statement of 'facts' which are almost always wrong, and then a disappearing act when challenged.

 

[CWB1]

Where do you draw the line?

Given ownership of the sandbox I'd draw it at politics and discussion of non-engineering/trades media articles. Ignorance will always abound and I'd be afraid of discouraging students or others genuinely trying to learn if mods tried to regulate ignorance otherwise.

JMO as an engineer, avid hot-rodder, and rebuilder of junk but open-deck blocks, fractured caps, etc are all serious performance improvements.

 

[enginesrus]

Fractured caps are a one time use item. If a bearing spins, the rod or block is junk, unless very expensive machine work is done to retrofit new caps.

 

[TugboatEng]

Spinning a bearing isn't very common. You want to spend more for every rod you buy for the odd chance that you spin a bearing in a way that doesn't condemn the rest of the engine? A fracture split rod only costs around $75.

 

[Brian Malone]

I find modern engine designs to be highly reliable with longevity of 200K+ miles easily achieved by most brands with a minimum of maintenance - just follow the OEM recommended oil changes and drive. Certainly, as has been pointed out by some of the posts, there are situations where access to ancillary gear is restricted or a pain in the rear but for the greater percentage of the consumer market engine tech is amazingly bulletproof. With the mention of fracture-split connecting rod caps I had to do some research. I have not rebuilt a modern engine that uses this type of hardware and I am only familiar with machined and doweled caps and rods. Everything I have looked at indicates fracture-split caps provide a significant cost reduction with improved cap/rod stiffness and roundness thus improving performance. The only downside is the loss of traditional rehab/remachining capability - which is not a high frequency item for most consumer-use engines.

eEuroparts has a good write-up:

https://eeuroparts.com/blog/engine-might-cracked-connecting-rods/

Yamaha has their original technical paper on the fracture technique. Technical Review - Technical Review | Yamaha Motor Co., Ltd.

https://global.yamaha-motor.com/design_technology/technical_review/

Look for the title 'Development of Fracture Splitting Method for Case Hardened Connecting Rods' - it is the 9th article from the last in this list. Yamaha has some interesting research articles posted. I am amazed the fractured surface provides a perfect alignment of the cap to the big end - equivalent to a doweled and match-machined cap.

SAE has extensive preview articles on their website - viewing the complete paper requires a purchase:

https://www.sae.org/publications/technical-papers/content/2003-01-1309/

The metallurgy and engineering is amazing.

 

[Brian Malone]

More I read on fracture-split connecting rods and caps the more I think this should not be in a 'failures and diasters' section but should be in an 'engineering triumph and success' section. The technology embodies metal alloy processing, precision metal sintering and forging, post-forging cooling, controlled positioning of fracture initiators, controlled application of a high impulse force to create the fracturing stress (old school falling weight no less!). The understanding required to determine the correct crystal structure, metal treatment, and physical geometry is engineering at its most fundamental level. Laser displacement measurements and scanning electron microsopy is thrown in for good measure! If the combination of all the experimental and theoretical disciplines involved doesn't add to an engineering success then this house is a tough crowd to play.

 

[enginesrus]

Brian, the failure of these designs is not for the manufacturing end. The failure is always on the end user of the product. Its all win win for production and fabrication. I always fall back on do you see that practice used for large industrial engines or aircraft engines? If not then it is a corner cutting design that cuts manufacturing costs. Yes some modern automotive engines are reliable but many are not. Just enter "Engine problems" into a search engine and you get a good idea of which ones are not. Maybe Tugboat can explain why we don't see cap fracturing used on the industrial engines.

 

[BrianPetersen]

I have yet to see a con-rod after a spun-bearing situation that was properly salvageable. Every one that I've seen looks like it has been adversely heat-treated to the point of no longer trusting it to be original strength ... Only trustworthy repair (on a high-performance engine) is to replace the rod and the crank.

If you are going to the trouble of tearing down the engine to replace parts after a spun-bearing, in most cases, the cost of a new con-rod for peace of mind is a trivial part of the build.

I've never spun a bearing on any street-application engine and I've taken a couple past 400,000 km.

I've only spun a bearing on a race engine once and that's because I bought a used engine from someone else and neglected to do a complete teardown to see what had been put together wrongly. Evidently, someone didn't torque the three bolts that hold the oil pump together.

If someone spins a bearing because they never check the oil level on the dipstick and they ignore red warning lights, that's on them.

Most cars nowadays go to the junkyard with near perfectly functional engines ...

 

[Brian Malone]

I'll look a little bit to see if I see trends that are substantiated - and not related to street racer boosted engines or cars that are being put on the track.

 

[CWB1]

Sintered/fractured rods are indeed used on some large industrial engines, and are remanufacturable by grinding. Its not the metallurgy or the fracture that prevents remanufacturing some rods, its the lack of material to remove. 99% of light-duty automotive is driven by cost so there's no excess material on parts anymore. Turn most brake rotors or grind light-duty rods and you'll usually be compromising the part structure.

 

[btrueblood]

Tug, sorry not to reply sooner. Sauce is delicious, I have a bottle here at work to season my typical sardine lunch. Usually not a fan of hot-hot peppers, but the sauce is a good blend of flavor and heat. Thanks.

 

[SwinnyGG]

I always fall back on do you see that practice used for large industrial engines or aircraft engines?

There are LOTS of industrial engines which use cracked rod caps. Perkins 1000, since the mid 90s (30 years ago). Cummins ISX and QSX since their introduction in 2001 (over 20 years ago).

 

[TugboatEng]

Thanks for the feedback, glad I sent two bottles.

As for remanufacturing fracture split rods, the process on doweled or fitted bolt connecting rods involves shaving the mating face of the cap and rod to undersize the bore and then finishing to the correct diameter. This can't be done on a fracture split rod unless one were ambitious enough to add dowels.

In my experience, rods simply don't require resizing anymore. The quality direct from the manufacturer is high. The bore doesn't change during use. The rods can be placed right back in the engine during overhaul with no recondition necessary.

Large industrial engines cut a saw tooth pattern on the mating surface. That technique is expensive and never made it to automotive applications.

 

[SwinnyGG]

That's precisely why the cracked cap process was invented - it provides the full benefit of match machined mating surfaces at much lower cost - and since there's not a machining operation involved which is subject to machine and tool wear, it's much more consistent.

This is case number 500 of a certain someone labeling a given innovation as a sign of reduced quality or even an 'engineering disaster', when in fact it makes the end product significantly better.

 

[BiPolarMoment]

Thanks for the feedback, glad I sent two bottles.

First one is half gone, I'm afraid for my health because of the lack of a Prop 65 warning!

 

[enginesrus]

Cracked cap technology is not just for connecting rods they are also used for main caps on some of the disposable automotive engine blocks as well. If memory is correct OMC and Mcculloch used cracked rods in the 50's I'd have to study that to be sure. Spinning bearings not common you've said? I have dealt with it a lot back in the day on off road industrial engines.