why do newer age engines last longer than older?

What are the main reasons that newer high performance engines can go much longer without a total rebuild than older engines we build? For example, the 485hp SRT challenger motor compared to a fresh built 500 hp aluminium headed 440 running less than 10.5:1 compression. . In most cases the 440 would need a rebuild or at least bearings and maube rings at a much shorter interval than the 392

Progress in assembly, oil formulation, fuel management, etc.

Back in the day, piston rings were a big one. Old cast rings versus moly rings, the difference is huge. Even in the late 318's and magnum engines, cylinder bore wear is night and day versus the old ones.

Also, fuel management. If you've ever cracked the head off a carbed engine compared to the same engine with port EFI, the pistons and valves on the fuel injected one are very clean. On the carbed one they are all junked and carboned up. All that raw fuel, running rich, poor fuel distribution, takes it's toll on engines.

1: Moly faced piston rings 2: Oil technology 3: Fuel management

4: AND this is probably the most important one, more so than the rings, harder bore sleeves. In 1981 it became federal law that cars had to pass emissions for 5 years/50000 miles. Old engines that were shot at 100K miles had significant bore wear at 50000 miles too (and were sometimes in need of a rebuild then). Bore wear leads to oil consumption and other nasty things that show up in emissions testing. So manufacturers had to make the bores hard enough to not be significantly worn at 50000 miles. A bore that is hard enough to not wear .001 at 50K miles doesn't wear much more at 100K miles, or 150K, and so fourth. Thats why we have engines with 300K miles that don't burn any oil and still make great cranking compression.

Overdrive transmissions are another reason that the engine last longer.

The cruising rpms on the highway are now 2k or less when they used to be 3-4k.
You've slowed the revs down by 50%.

As already stated with fuel injection keeping the a/f to where it needs to be there no more ring wash out and carbon build up.

EFI don't dump as much raw fuel on the cylinder walls because it atomizes better and is more precise. Fuel is a bad lubricant. The EFI on modern engines also has the ability to turn on a CEL and let average people know when there is an issue, with a carb the vast majority of people will never know when it gets a little out of whack.

Better oil control means they can run lower tension and thickness rings and that means less friction.

OD trannys keeping RPM down when not needed to be high.

Hypereutechtic pistons are used in most engines now and the alloy is more slippery as well as tighter fittin in the bore at cold starts thereby reducing blowby of carbon and other harmfull substances. It expands less than forged or even old school cast.

Machining precision, the machine tollerances are held to a lot tighter standard again reducing friction.

Oil is much better now than 50 years ago, there was such wide variations in oil back then that you could not mix different brands a lot of times.

Better ignition systems like coil on plug ensure more complete combustion.

Better material in the bearings block and rings and cranks...

More thought is put into getting the engine to warm up faster thereby lowering emmisions caused on cold starts, also the cars are heavy forcing the engine to warm up faster to a more efficent temp. Higher temp thermostats also make the fuel evaportate faster keeping it out of the oil. Hot parts also generate less friction.

There is more also and some of these things are easily added to old engines and some are not.

I've seen 727's go 100k+...

With zero fluid changes...


I've been in 225's with over 450k...

Seen 318's go 150k before I could lift the chain off the plastic cam gear...


Folks who did the maintenance, got the life...


Today???

Much improvement, no doubt...

Driven by 'warranty'...

It's the Japanese manufacturers fault AKA aside when the Japanese car invasion started back in the late 1960s they forced the American car makers to make better cars that lasted as long as the much cheaper Japanese cars and engines did the Datsuns and Toyota engines and bodies lasted way longer and used a lot less fuel than the Pinto and Vega cars did Of course progress and competion has a lot to do with any industries progress and development Mopar engines and drivetrains lasted a lot longer than the GM and Ford car lines did back then, Mopar started the Five and Fifty warrentee program in either 1963 or 1964, all the other cars had a 12000 mile or one year warrenttee back then, if my memory is correct. All of the other American car makers had to follow suit the next year to keep Mopar from getting all the new car and light truck sales that year
Edited, don't forget that the American car companys had large stakes, partial ownership, in a lot of foriegn car companys over seas, Mopar was in bed with Mitisbushi, Ford had Mazda, GM was in with Isuza in Japan and all of them where making cars and trucks in Europe and other country all over the world

unleaded gas is probably the biggest factor. overdrive transmissions drastically reduce rpm. better parts and better engineering.

Don't forget about manufacturing tolerances and processes.

Todays processes for machining are far more accurate than what was used "back in the day".

Ed

My opinion is fuel injection - but I am just some dude.

Interesting, whats the overall effect?

Lead sludge from blowby, also lead buildup on rings, combustion chambers, etc can gum up the works.

That's not to say all the old engines were used up at 100k, the IH sv series was known to go 300k between rebuilds. Those were carbd in the 60's. They were also industrial engines mmeant to chat away at 3 to4 thousand rpm all day everyday. High nickel blocks, forged cranks and generally heavy construction got them there.

lead wears an engine out. i don't think any metallics are good for them long term.

Not true about the lead additives wearing motors out, that is a bunch of horse pucky spouted by a lot of the enviormental haters If you go back to the engines made originally in this country for our cars and trucks before the lead additives where being used in the fuel the motors needed valve and ring jobs long before 30,000 to 50,000 miles The lead additives added to the gas stop the need for the valve jobs and also help increase the ring life along with better valve life The lead additives, Tetra Ethel (SP?) was a lubricant for the valve seats and cylinder walls that reduce metal to metal wear, it didn't increase the engine wear

lead and other metallics due wear engines out. i doubt that the intended introduction of "lead" in gas was a valve seat lubricate but more of an octane boost. before lead compression ratios were stuck in the 7:1-8:1 max. as compression ratios increased during the fifties more lead was dumped in the fuel. non-detergent oils were a big factor in engine failures prior to detergent oils which were developed around the same time as "ethyl" was introduced. but, believe what you want.

Without a doubt overdrive transmissions is the biggest factor.

EFI is better yes, but even they have to get run out on the highway to "blow the carbon out" every now and then.

Hmm. Had a 68 GTS 340, around 72-73 blew a head gasket with 125,000 miles on it. After pulling head, no ring grove at all, bores very smooth. I was expecting some wear but found none, lead gas and that bad oil, changed at 10-12 thousand mile intervals. Maybe I was on to something. Guy I sold it to turned it into a race car. 4.10 gears and headers, car ran low 12s for next two years. Lost track after that.

Here's what an engine designer says.

“The California Air Resources Board and the E.P.A. have been very focused on making sure that catalytic converters perform within 96 percent of their original capability at 100,000 miles,” said Jagadish Sorab, technical leader for engine design at Ford Motor. “Because of this, we needed to reduce the amount of oil being used by the engine to reduce the oil reaching the catalysts.

“Fifteen years ago, piston rings would show perhaps 50 microns of wear over the useful life of a vehicle,” Mr. Sorab said, referring to the engine part responsible for sealing combustion in the cylinder. “Today, it is less than 10 microns. As a benchmark, a human hair is 200 microns thick.

“Materials are much better,” Mr. Sorab continued. “We can use very durable, diamondlike carbon finishes to prevent wear. We have tested our newest breed of EcoBoost engines, in our F-150 pickup, for 250,000 miles. When we tear the engines down, we cannot see any evidence of wear.”

-----

“Competition is part of it,” said Peter Egan, a former auto mechanic and now editor at large of Road & Track magazine. “Japanese cars kind of upped everyone’s game a bit. With some exceptions, the engines would go a long time without burning oil or having other major problems.”

Hyundai and Kia, the South Korean carmakers, now include 100,000-mile/10-year warranties on their cars’ powertrains. If a relatively abusive driver can count on no major mechanical failures before 100,000 miles, a careful owner can — and does — expect his car to go much farther.

“My parents, with their ’56 Buick, used to have the wheel bearings repacked with grease before a long trip. Nobody does that anymore. The lubricants are better, the machining is better.”

from:
http://www.nytimes.com/2012/03/18/automobiles/as-cars-are-kept-longer-200000-is-new-100000.html?_r=0

Removal of lead, and reduction of sulfur from the fuel helped tremendously.

Finite element modeling of the engine structure and cooling system reduce assembly and operational distortion which reduces wear.

Ever look at how the head bolts are designed on a modern engine? they no longer are threaded to the top deck, but rather are long with counterbores to reduce bore and deck distortion.

Thermal modeling of pistons, valve bridges, and cooling systems is s.o.p now

Computer modeling capability wasn't available in the 50s and 60s. There was a lot of trial and error engineering back in the day.

Engines only wear appreciably when the fuel mixture is off....Lean and they run too hot....Rich washes oil off cyl walls....I think Fuel infection is the single biggest reason.

Fuel injection, better rings and overdrive.

Less fuel washing down the cylinder walls, less ring wear, less high rpm operation on the highway.

2.2 engines came carb'd, TBI and Turbocharged.

The turbo engines came with PFI and better rings. The turbo engines held up far better than the carb and TBI engines bore wise.

Lead in gasoline is not metalic, it is a compound chemical with the lead only being one ingredient sort of like how hydrogen is one ingredient in water, the other being oxygen, neither would work well in your cooling system by themself but combined make a good chemical compound for cooling the engine.

My Magnum with the 3.5 v6 uses about 1.5 quarts between 5000 mile oil changes. It has done that since new- and has 182,000 on it now.

Remembering when oil/filter(some cars oil filters were factory options) change and 'grease' jobs were scheduled for 1 to 2K intervals on all new cars. Working in gas stations as a kid.

Much has changed.

Im not working on late model stuff everyday but I have noticed that most of the later model engines have much higher oil capacities. My HEMI Ram truck took 7 qts,my wife 3.5L V6 Edge takes 5.5 which seems like a lot for the size of the engine. More oil keeps it cooler and cleaner, I am sure that also plays into the longer oil change intervals.

How many miles are you guys seeing from b/rb rebuilds that use Chromoly rings, updated bearings, hypereutectic pistons, fuel injection, synthetic oil and overdrive transmission?

Also, Can the cylinder walls be "hardened" without using sleeves?

Very interesting debate in leaded fuel! I always was taught it helped decrease valve seat wear, and was only gotten rid of because it of environmental impact.

Well my little daily driver runs 3500 rpms at 75 mph and gets about 36 mpg, so it runs a lot higher RPMs than many of the larger displacement engines that have more torque. It only has 105 hp so it has to make up the lack of torque with RPMs. Tim

Main reason....Tolerances and capability.....plain and simple.

I worked at one of the largest US based engine plants in the country....Control the tolerances thru in-process gauging, and it will last...Knowing what tolerances have to be held is one thing, measuring them & holding them is another.

I don't know about the significance of overdrive. Lots of new 4cyl cars still buzz at 3000rpm down the highway and they have to still meet the same standards of longevity as lower revving engines.

Also, if you've ever worked on an engine with carbon build up, you'll see why a full throttle run on the highway isn't blowing anything out. Don't know where that myth came from....

4 cylinders tend to have light pistons and rods which reduces loads on the bearings. 3000 rpm is nothing for a 2.2 and still turning 500 rpm less than my Duster cranking down the highway at the same speed.

Those little 4 cyls also have very short stroke so the piston speed is not that high.

Pinion snubber-angle has to be set right also

I had a 1985 Nissan 300ZX that I put 315,000 miles on with factory recommended maintenance, i.e., 3000 mile oil changes. I finally let it go because it failed a state emission test after 25 years. I currently have a 2000 Toyota Camry V6 that has 318,000 miles and passed it's last emission test and is still going strong. My guess is that lubricants are much better and the metallurgy of engine components also has something to do with it.

My $.02.

Most import engines are assembled with select fit bearings and rings.They measure the bore and crank journals and install the correct bearings and pistons. Although I really have to question the use of low tension rings lately though. Oil consumption is an issue with some Toyota 4 cylinder engines and I have been doing quite a few ring jobs lately. They have changed the piston design on the new ones I am installing.
I built my 493 s it will go over 100k easily

Gus

What are low tension rings?

Better everything. Electronic engine controls, more accurate engineering and design, better casting technology, better machining ability, lower rpm operating ranges. All these are just normal technological evolution. As far as the single biggest factor? Over drive. You can seal it better, make it tighter, oil it better, and be perfect in metering, and there are still only so many trips up and down a bore before it's not longer able to be efficient at it.

I'd like to hear more about Lead vs. lead free gas. I always thought it was a lubricant for the valve train and valve seats. Today they use "hardened" valve seats eliminating the need for lead in gasoline, but my 340 does not have hardened seats I was told I need to put a lead additive in to prevent wear.

Moparts Mythbusters.... What's the true story?

Low tension rings put less pressure on the cylinder wall and create less friction. That is good for a high performance application where engines are routinely torn down for inspection. They seem to loose their tension after about 80-100K in a daily driver. The oil rails let oil past when they stick in the ring grooves of the piston and and the engine starts to use oil.
Some car companies are using the low tension rings because it makes for a very efficient air pump when it's new and you get better fuel economy and you can raise your fleet economy numbers.

Gus

link http://www.history.com/this-day-in-histo...in-auto-engines

Some of the explanation in there

Gus

F.I. is a huge deal. And, remember those nasty rich cold start and warm ups that were "normal" on all but the best maintained cars, Pumping the gas pedal, Chokes that didn't choke, or chokes that wouldn't stop choking. People trying to double the miles between those tune-ups that seemed to be due weekly.

Think about the extra life we get today from knock sensors. Knock sensors, with F.I. and 100K spark plugs protect good engines from human beings. We as a group can't be trusted.

Lead in fuel destroys catalytic converters. A primary reason is banned. Lead in atmosphere is another.

one thing to consider is that raw fuel that washed down cyl walls -ended up- in the oil pan.....naturally , if you thin your oil with gasoline .... well.....---todays fuel injection coupled with excellent piston/ring improvements have almost eliminated that deal...keeping the oil clean is priority #1 in diesel engines and even they have improved over the years.