Useful engine life

[PLeon]

I have come across this web page that reports engine life expectancy according to manufacturers and I was wondering if it's true.

http://www.synlube.com/viscosit.htm

Quote from page
FORD which has previously designed cars to have 10 year or 150,000 miles life has reduced the mileage life expectation to "beyond 100,000 miles" on vehicles that are operated on SAE 5W-20 Motor Oil.
HONDA only claims "useful life" as 7-years or 70,000 miles in EPA certifications for their CIVIC which uses SAE 5W-20 Motor Oil, while the previous model that utilized SAE 5W-30 Motor Oil was certified for 10 year or 100,000 mile durability.

 

[ivymike]

perhaps if you told us what was meant by "useful life" in those EPA certifications, we might have an easier time commenting. My suspicion is that their aftertreatment systems have to last for the entire "useful life" of the vehicle, and that having a shorter u.l. makes the vehicle less of a warranty risk.

Why do hondas only go 10k/yr, while fords go 15k/yr? Seems odd...

 

[PLeon]

(I think what EPA wants is useful life to be the same as warranty period.)

If manufacturers are reducing u.l. because of warranty risks then synube (a thick oil advocate) is twisting the meaning and attributes the lower u.l. to thin oils.

 

[WGJ]

Pleaon, as a European Frod Mutter Co employee, who has been invovled in the so-called 'sign-off' of durability on certain vehicle systems, I can say that this particular company still hasn't properly got to grips with durability in its day-to-day business.

Sure, you can find numerous SAE and internationally published papers on specific durability development exercises, Taguchi studies, applications of Deemings principles, et al, but there's still a dearth of understanding and capability amongs many engineers, lower and middle managers - the ones that should be the 'enablers'.

So, I'm not surprised at the contradictions from that particular company.
In my own system/sub-system work, I could never get management to publicly nominate a target, so I set it for myself as a 10% failure rate (i.e. Weibull B10) with 90% confidence, of 150,000 miles, as modelled by the company's data used for correlating their test tracks. Clear as mud?

Total system reliability, like an engine 'life' in a particular vehicle platform even when it's been serviced as specified, will be affected by the number of starts experienced, accels, torque reactions, loading profiles, fuels used, environmental temperatures, blah, blah blah.

From what I see these days, the power of CAE and the increasing power of desktop computing has a lot to do with the straightforward stress/strain-related durability issues and friction/lube issues are still not quite so well supported in that direction.

 

[ivymike]

Sure, friction/lube/wear/transport are not modeled as well currently as one might like...

but I can tell you with great certainty that the PRL packs for at least one diesel OEM have a B10 life well beyond 1,000,000 miles for on-hwy HD applications. The key for PRL wear is to run many endurance (cyclic) tests to a significant fraction of the engine life, and track wear closely throughout. Alongside that battery of tests you run a field follow program, and you pay close attention to any parts you can get back from the population at large, and at the end of the day you know darn well how your parts are performing (or at least you can draw a floor on it). You do sometimes get really odd results back which you can't readily explain (like a cylinder with 1,000,000mi projected life next to 5 others with 5,000,000mi projected life), but with enough data those guys fade out.

I can't say how Ford do their evaluations, but if they can't spare a few bucks for the above, I don't know who can. (so it would be a shame if they're as clueless as you suggest)

 

[ivymike]

back on the EPA stuff... I had a client call up one time asking for any suggestions as to what he could tell the EPA to convince them that the useful life on his engine family was LESS than 10,000hrs... the motivation was similar to that discussed above (emissions conformance at end of "useful" life). We did finally come up with a few good reasons, but it wasn't as easy as one might think (he had a pretty good engine).

 

[WGJ]

ivymike
My statements are based on direct experience of that particular manufacturer's business in Europe and experience as part of the full-service supplier business they set up a few years back. That company's business was to supply so-called 'tier-one' products back to Ford. What I saw there was what I described and I had already experienced similar in Ford. I once went through a cam and follower development process, aimed at eradicating a cam wear issue in heavy truck diesel engines. I got to a conclusion which significantly improved durability and was supported by a statistical analysis. The trouble was, the cam came from supplier A and the followers from supplier B. The purchase dept gave all the business to supplier B, cutting the durability advantage significantly and negating about 9 months work.
More recently, a product which features an electric motor that runs all the time the engine does was having the motor validated in the USA by just running it !!
I managed to get budget to do the same work for European applications, but with the assembly on a triaxial vibration rig and with recorded road-load fed in. Result, a b10 of about 60% of the US tests.
Management in organisations like this often just want 'the bottom line' and won't give time to understand the parameters. If 'their man' says it's OK, it's OK. It's only when the warranty starts to mature that the revisions and revalidation start again.
I am guessing from your description that the engines you refer to are used in earth movers, locomotives, real heavyweight trucks or similar?
The customers for these are a different breed altogether. Downtime to them is real money and not an just an inconvenience. Proper validation, results and evidence are acknowledged.
I think some auto manufacturers get a lot of mileage from never doing anything too radical - radical design needs thorough validation.

 

[bigmo460]

Can't recall the exact no. of miles that the EPA requires but I think it was 120,000 miles. This meant that the engine emmissions would be with in spec for that no. of miles. (Typically warranties for the automotive engines are less than this) Where I worked (OEM), we'd run Dyno. and in car testing to simulate the 120k at 90% driver. Upon test completion engine emmissions must be well within spec and at tear down the engine must not have any part at or near failure. If a problem was found, steps were taken to not have the problem occur again. And to validate the changes further testing was done til no failures.

 

[drwebb]

"(Typically warranties for the automotive engines are less than this)"
The EPA don't care if the engine quits, since then it has zero emissions.