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

 

[enginesrus]

BrianPetersen (Mechanical)
---------------
What usually fails on them? Needle bearings? The roller ? The pin? Have they determined if it is a material issue, or a quality of lubricant issue?





LionelHutz (Electrical)
13 May 22 11:45
You find a new forum complaint thread somewhere?
--------------------
This particular area is about Engineering Disasters, meaning some huge failures caused by bad engineering, so this is the correct place.

 

[TugboatEng]

All of these engines get torture tested before going in to production but the testing is done with the manufacturer supplied oil. The manufacturer has no control once the product is in the hands of the consumer. For all we know, these failures are caused by consumers running the Shell Rotella oil because it's the best.

 

[enginesrus]

Some of the failures are on low mile engines, for warranty reasons, not many folks want to mess up with factory recommended oil changes.

Something that marine engines do that auto engines don't, they run all the time.

 

[GregLocock]

The first thing an automotive engine design has to do before it gets any real development is to run for 100 hours continuous at peak power. If it survives that (some engines (eg Austin A+ turbo) do first time, others take months to get to that point (redacted), and others never get there (many SI to CI conversions in the 80s)) then it is deemed worthy of further development.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[TugboatEng]

Talk about problems. All this to get to the radiator drain.

 

[enginesrus]

GregLocock (Automotive)
14 May 22 09:40
The first thing an automotive engine design has to do before it gets any real development is to run for 100 hours continuous at peak power. If it survives that (some engines (eg Austin A+ turbo) do first time, others take months to get to that point (redacted), and others never get there (many SI to CI conversions in the 80s)) then it is deemed worthy of further development.
------------------------------------------

I suppose that is also why the conservative HP ratings on some automotive engines. I wonder if the high HP engines like the Hell Cat Hemi had to do that? Or do they "adjust" to a lower HP for the test?

 

[BrianPetersen]

The drive-by-wire and fully electronically controlled nature of modern super-high-power-output engines allows for the possibility of automatic de-rating based upon whatever sensor readings and mathematical models the calibration department deems appropriate.

Disclaimer, I don't know Chrysler ECU calibration, but it's pretty likely that it'll make that power level for as long as you can keep engine oil temp, trans temp, and coolant temp within range, and as long as internal mathematical models for certain critical component temperatures are satisfied. I do not know if the stock radiator and oil coolers are sufficient for continuous output at that rating ... I tend to suspect not.

Bear in mind that at 707 hp, those cars will drain their entire petrol tank of fuel in about 15 or 20 minutes, so there's an automatic time limit on how long one can sustain that ... and that's assuming Mr Policeman does not have a thing to say about it.

In the motorcycle world, the little 125cc scoots have quite a bit less specific power output than the 1000cc superbikes. It is presumed that the 125cc bikes (which usually have 12 or so horsepower) will be ridden flat out all the time except when a stop sign or traffic signal dictates otherwise, or perhaps in school zones. (Mine is ...) whereas it is presumed that the 1000cc superbikes cannot be ridden at max power output for significant lengths of time, even in track-day service.

My two-cylinder 321cc Yamaha R3 has key cylinder and valve dimensions that are within a millimetre or two of those of a four-cylinder Yamaha R6, but the rev limit is some 3000 rpm lower, and the specific power output is quite a bit lower (it makes about 40% of the power despite having 54% of the displacement). If "all else were equal" this is a bit more than half of an R6 engine ... but it's de-tuned in the interest of driveability and longevity.

 

[GregLocock]

On a serious engine dyno you have unlimited cooling (including cooled oil), and also as much ventilation as you need, including spot cooling with eductors. As such running full power tests is not especially traumatic. Having said that fires are perhaps an annual event.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[LionelHutz]

Hellcats have interesting torque management during transmission shifting, cutting most of the power during the shift.

 

[Lou Scannon]

Yeah, they took away half the fun

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[LionelHutz]

The sweeping up of transmission bits fun?

 

[BiPolarMoment]

Hey, perhaps snapped half shafts too?

 

[CWB1]

At least on early cars, the differential has a nasty habit of ripping itself loose of the chassis before the halfshafts break.

 

[Lou Scannon]

Back in the old days of bear skins and stone knives, (almost) everything was so over designed that it could take it.
Now they have optimized the weight and cost savings of the drivetrain components, just to consume all these weight and cost savings with hardware that has nothing to do with propelling a vehicle from A to B.



"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[enginesrus]

Lou Scannon, You hit the nail on the head, and how true.

 

[Spartan5]

Back in the old days of bear skins and stone knives, (almost) everything was so over designed that it could take it.
Now they have optimized the weight and cost savings of the drivetrain components, just to consume all these weight and cost savings with hardware that has nothing to do with propelling a vehicle from A to B.

They consume it with unnecessarily high performance capabilities as well. Your average grocery getter family sedan has 0-60 times that rivals that of the muscles cars of the 70’s. Why? I guess because that’s what the markets want. That’s what the commercials tell us anyway.

What kind of reliability (and, dare I say, efficiency) could we get out of an engine/vehicle that had a top speed of <80 MPH and a 0-60 time that wasn’t suited 1/4 mile comparisons?

 

[TugboatEng]

It seems that economy, low emissions, and power go hand in hand. If you have one you can have the others.

 

[enginesrus]

I see no reason for the average vehicle to have to weigh in at close to 2 tons. The old VW beetles, and GEO Metro's tip the scales under 1 ton, given that, there is no reason to have more than 140 HP.
The old 235 Chevrolet inline 6 was rated at 140 HP, and could move a fairly heavy car or truck just fine. Absolutely no reason for 700 HP in any normal road car especially where high speeds are not allowed.
High HP? There are very few class 8 heavy trucks that have 700 HP, and for one to come close to a GEO Metro one of those trucks would need close to 2500 HP. MPG ? All this battle to get to high miles per gallon?
GEO Metro has been getting over 40 MPG for the last 33 years or so.

 

[CWB1]

If you want to prioritize efficiency then buy an economy car. The OEs all make them, baby Ecoboosts, Ecotecs, etc are ~100 hp and the cars sell for under $15k brand new. Personally I'm like most and prefer a bit more power and am happy to settle for less economy if I must, but that's not a direct correlation without maintaining the same gearing. In the commercial truck industry for example there are many examples of higher-horsepower trucks having taller gears and getting better fuel economy than the same model with a smaller engine.

Comparing HD diesel power curves to light-duty gas tho is apples and oranges. A 15L making 700 hp is doing so for half the RPM range and will be producing ~2k lb-ft of torque at high idle. The aforementioned Hellcat's making 300 lb-ft at high idle and only producing 700 hp at its peak.

 

[BrianPetersen]

Part of the weight increase is due to better crash structures, part of it is from people not wanting the car to sound and feel like a tin can when opening or closing the doors or when driving over bumps, part of it is from every vehicle generation having to be bigger than the last one so that the marketing people can advertise "more trunk space", "more legroom", etc ... "less trunk space" is not a good marketing plan. Hence, a Honda Fit nowadays is bigger than the second-generation Civic was, and the Civic today dwarfs Honda's original (1970s) "big car" Accord.

Couple vehicles ago, my 2006 VW Jetta, VW's compact car in that era, was very close to the same size as what it replaced, a 1996 Passat - VW's big car of its era.

The modern Fiat 500 that is my daily-driver today is roughly the same size as the first-generation Honda Civic that I learned to drive in, but it weighs almost 50% more. I'd sure take the odds of surviving a crash in the modern car versus the old one ... the crash structures are enormously stronger and it has much better safety equipment, 30 years of development will do that.

Powertrains? The engine sizes are almost the same, 1.4 in the Fiat, 1.5 in the Civic. The newer engine makes more power, although given the weight difference in the vehicle, acceleration is probably about the same. Fuel consumption is also about the same. The Fiat weighs more but the aerodynamics are better. The factor that is orders of magnitude different, are the CO, HC, and NOx emissions.

Durability? The Honda started burning oil after about 120,000 km, and it went to the junkyard with 12 years and about 180,000 km on it, completely rusted out and with nothing good left on it whatsoever. I put on more annual mileage now; the Fiat still runs practically like new with almost 230,000 km on it and the paint and interior are in great shape as well.