Life expectancy of 3.5

[FordTechOne]

I disagree. As you mentioned, there are millions out there so bringing up the 5 you know is not a sufficient representation of the population.

Turbocharged engines have lower reliability (in comparison to their naturally aspirated counterparts) due to the increased temperatures at which they operate at, the increased pressures inside the combustion chamber, intake/exhaust manifolds, the more sophisticated control technologies (and associated sensors they are dependent on) and the basic statistics of having more parts, each of which has its chance own chances of failure.

There are far more “flight critical” parts on any turbo engine. These are the parts that are required to work correctly for the engine to function. More parts = more chances of having any one part fail.

Turbocharged engines create more heat which leads to higher temperatures. Operating at higher temperatures in general degrades material properties and will cause them to fail earlier every time (except for some high nickel super alloys). “Earlier” may still be at 200,000 miles or more. Just stating that it’s earlier than the same part that is not exposed to such extreme temperatures. For example, I have the spec for A-286 pulled up and it shows that the yield strength drops by 35% at just 1200F. I have seen EGT’s over 1600F on my turbo Jeep.

Also, repairs on turbocharged engines are likely to cost more than NA engines. For example, my buddy’s 2015 3.5EB had the exhaust manifold gasket blow out. It was found that the exhaust manifold had warped. This is due to the higher temperatures and pressures that turbo engines run at. Repairing it required removing the turbocharger on that side as well. A NA engine is less likely to have this happen and if it happens, it’s not nearly as critical to get it fixed since it’s not feeding in to a turbine.

Engines today are very reliable so even if you pick an unreliable design, chances are that it will still not fail on you, at least for a while.

After all, if the 3.5 was as reliable as any NA engine we would see it being used in many other places (e.g heavy duty trucks, work trucks, etc.)


Having said all this, I’m still A huge proponent of the 3.5EB but there is no getting around the numbers and the physics that it is less reliable than an equivalent naturally aspirated engine.

It sounds like you're more of a critic than a proponent. Do you own one by chance?

You discredited @goblues38 personal experience as anecdotal, and then brought up "your buddies" 2015 3.5 as evidence. You can't have it both ways.

You are making the assumption that the necessary engineering was not incorporated to ensure that these engines remain reliable while being turbocharged. All Ford engines, as with most OEMs, must pass severe durability testing whether they are N/A or forced induction. This isn't the aftermarket; they can't just throw a turbo setup on and worry about the durability later.

You may not be familiar with the Terminator 4.6 that came out in the 03/04 Cobra, but they couldn't hold them together with the off the shelf powdered metal connecting rods available at the time. The engine would make it through hours worth of maximum output testing, and then grenade. They ended up going with Manley Forged H-beam rods in order to pass durability testing, regardless of the fact that each rod cost 7 times more than the standard one. Durability testing has become more, not less, stringent since then with the increased duty cycle of trucks and the increased capability.

The 3.5 is not used in HD applications because it's not designed for HD applications. It's a 1/2 ton truck engine that can reliably tow up to 13,200lbs, just as it was tested for. It's not designed to tow 20,000 or 30,000lbs like the physically large HD cast iron gas and diesel engines are.

 

[TurboTJ]

It sounds like you're more of a critic than a proponent. Do you own one by chance?

My only point is that when adding more parts that you depend on that have a non-zero failure rate, your reliability will always go down. It's just math.

I do have a 2020 Raptor and I love the 3.5EB. The pro's of the 3.5EB strongly outweigh the cons for me. It will never be as reliable as an equivalent engine without forced induction but that engine will never make the same power either. In short, the (most likely small) decrease in reliability is well worth the increase in performance and fuel economy.

I have never owned a car/truck in my entire life that was left naturally aspirated or that didn't come with some sort of forced induction. I turbocharged my first vehicle (A Jeep wrangler TJ 4.0L) and did a lot of prototyping various turbos and data logging on it trying to make it better and better.

You discredited @goblues38 personal experience as anecdotal, and then brought up "your buddies" 2015 3.5 as evidence. You can't have it both ways.

Maybe I wasn't clear enough in my post - I mention that anecdote as an example of the difference between turbo and NA engines, not as point about how the 3.5 is/is not reliable. It shows how even a small gasket on a turbo engine is harder to fix, more likely to fail and has greater consequences of a failure than on a non-turbo engine. Again, I am not using that story as a data point about reliability

The 3.5 is not used in HD applications because it's not designed for HD applications. It's a 1/2 ton truck engine that can reliably tow up to 13,200lbs, just as it was tested for. It's not designed to tow 20,000 or 30,000lbs like the physically large HD cast iron gas and diesel engines are.

Why do you think none of these trucks feature a turbo gasoline engine? Why not just design a turbo gasoline engine for the 3/4 ton and 1 ton trucks? I know you have a lot of experience and knowledge about these trucks so I'm genuinely interested in what you think.


EDIT: I also wanted to mention that Ford has done a lot to make the engine more reliable than other manufacturers. For example, the cylinder head temperature sensor. There is a table in the ECU to retard timing with increased temperature. Most cars have to rely on coolant temperature for this table but having one in the head gives you far better readings with drastically reduced reaction times. The end result is reduced chances of engine knock compared to a legacy coolant temp sensor.

 

[Flatom]

Disclaimer I have not read this entire thread, in my opinion current discounting and intrest promotions you would be better buying new. Search Georgia dealers.

 

[NASSTY]

I think it’s very telling that Chevy/dodge/Toyota/Nissan aren’t doing turbo truck engines.

I would guess that the biggest threat to longevity are the turbos themselves and the additional complexity. I don’t think electronically actuated waste gates and bypass valves will last as long as the engine.

Chebby has a turbocharged 2.7L 4 cylinder engine option in the Silverado. It's gutless compared to Ford's 2.7 V6 Ecoboost.
There's a 2.7 Ecoboost on the F150 forum with 400K miles. Aside from normal maintenance , the only part replaced was a purge solenoid valve

 

[John813]

The used market isn't that great for a buyer. Especially when talking about high mileage ones. You'll be paying a lot for a truck out or almost out of warranty.

IMO either hold tight as the market has exploded, or up your budget a bit for a lower mileage/optioned one.

The 3.5 isn't some glass engine. Take care of it and it should take care of you. Ford has spent millions upon millions on these engines and almost a decade of R&D/real world testing on the ecoboost lineup.
JMO, I would just change the oil faster than what the computer recommends but don't want to start an oil war in this thread

 

[goblues38]

any engine designed before say 2010....both pro and con in terms of reliability does not equate to a modern engine. software, metallurgy, and overall design is completely different.

A lot of the anecdotes @TurboTJ was using may have been true 30 years ago for turbo motors, but do not match up to todays motors.

 

[1BAD454SSv2]

Watch the Mike Rowe Ecoboost videos gen1 on Youtube . Ecoboost torture testing they do is unreal chilling engines to -30 deg start up and run full throttle to 240 deg . over and over. Towing at 90 mph for 24 hours . I honestly believe you need change oil at least every 3000 miles and spark plugs every 10,000 miles if you run your truck hard. Did that formula on my modded 2014 tremor and it was problem free 35,000 miles , been to dealer 1 time for brake booster recall.

 

[TurboTJ]

any engine designed before say 2010....both pro and con in terms of reliability does not equate to a modern engine. software, metallurgy, and overall design is completely different.

A lot of the anecdotes @TurboTJ was using may have been true 30 years ago for turbo motors, but do not match up to todays motors.

What anecdotes? Also, what metallurgy advances have been made since 2010?

 

[Badgertits]

What anecdotes? Also, what metallurgy advances have been made since 2010?

They’re being Made all the time. Different die-casters ask for varying tweaks to even standard Secondary AL alloy designations to make them their “own” for whatever internal specs they’re trying to achieve

there’s been a gravitation towards higher pressure casting techniques to raise the bar even higher in terms of preventing micro-fissures & enhancing the overall strength of the casting In general.

using more A319 in place of A380 in higher compression smaller displacement FI engines, adding Ni & Sr additions during the smelting or casting process to increase strength etc

 

[TurboTJ]

Watch the Mike Rowe Ecoboost videos gen1 on Youtube . Ecoboost torture testing they do is unreal chilling engines to -30 deg start up and run full throttle to 240 deg . over and over. Towing at 90 mph for 24 hours . I honestly believe you need change oil at least every 3000 miles and spark plugs every 10,000 miles if you run your truck hard. Did that formula on my modded 2014 tremor and it was problem free 35,000 miles , been to dealer 1 time for brake booster recall.

That’s a great video. Accelerated aging tests are always fun. I’m happy to see they do thermal shock too. Makes me feel better when I remote start at -10F in the winter and hear an unusual whine for the first 10-20 seconds. I used to do thermal shock testing on nuke components and always wanted to stick car parts into the chamber!

They’re being Made all the time. Different die-casters ask for varying tweaks to even standard Secondary AL alloy designations to make them their “own” for whatever internal specs they’re trying to achieve

there’s been a gravitation towards higher pressure casting techniques to raise the bar even higher in terms of preventing micro-fissures & enhancing the overall strength of the casting In general.

using more A319 in place of A380 in higher compression smaller displacement FI engines, adding Ni & Sr additions during the smelting or casting process to increase strength etc

There certainly have been advances in surface treatments but I hadn’t heard that and A-380 is not in my references (besides the jumbo jet) but I don’t work with castings on a daily basis either. I’ll have to read up on this. Maybe they find a material less susceptible to warping than the current exhaust manifolds.

As I’ve said before, I think the 3.5EB is a great engine and very reliable but given the extra complexity and parts, it’s just not possible to be *as* reliable as a non turbo engine. That’s just math/statistics.