WOT Driving and Engine Wear

[Srt20]

I actually did my verison of an ITU to a 06 Impala 3.5L a few weeks ago.

The car was my grandmother's. It had 40k miles on it and had probably never seen 3k rpm. And I would bet that most of those miles were within a 2 mile radius of her house in town.
Anyway it burned about 1 qt per 2-2200 miles.

My ITU was driving around in 1st gear going from 3k rpm up to 6200ish rpm. It would shift to 2nd gear at 6400 rpm. Then let off down to 3000ish rpm then roll back into it, once it started pulling forward, I would go WOT to 6200 rpm again. I rolled into it until it grabbed because the motor mounts werent liking the WOT stab after coming down from the higher rpm.
So I did this for 30 mins straight on country backroads.
Now on this OCI Im at 2300 miles and the oil level is still full. Im assuming the oil control rings were pretty gunked up. I bet they are fairly free now.
ITU worked for me. lol

 

[Panzerman]

I don't think it really hurts anything. I used to get brand new big trucks and I would think brand new engine and first hill with a load on and your into the governor for every gear pulling a mountain.
Granted they are diesels but they get run hard from the first load for the rest of thier lives. No babying the motors.

 

[CR94]

The Mazda listed below spent a lot of time at or near WOT, but not at high speed, or at very slow (near idle) speed. The stresses associated with running WOT are very different at different engine speeds. (I.e., challenging the limits of the hydrodynamic film at low speed "lugging," vs. high temperatures and inertial loading at high RPM)

 

[SwampSurvivor]

I took a junkyard engine that was sitting for a few years and stuck it in a pickup and towed 6500 pounds through the hills. Running that engine hard was beneficial for it. The engine definitely blew some smokke and burned some oil at first, but by the end of the trip, it had gained quite a bit of power. There was one section where it was running 4000 RPM foot-to-the-floor for 4 or 5 minutes straight.

I definitely think they are beneficial for the reasons mentionws above. All of my vehicles are expected to work so it happens frequently out of normal use. My forester gets one every day leaving work getting on the highway.

 

[ShotGun429]

Originally Posted By: gfh77665
Originally Posted By: ShotGun429
old police cars get the [censored] run out of them and then go on to be taxi's and then back to public, I have seen many with 400,000 miles on them running fine.


Did the WOT driving extend their life? Or, was it lack of thermal cycling (no cold starts) and a dedicated maintenance department funded by tax dollars (that likely ignored repair costs)?
THE Above is correct!!

 

[Virtus_Probi]

Originally Posted By: BalticBob
Originally Posted By: ShotGun429
old police cars get the [censored] run out of them and then go on to be taxi's and then back to public, I have seen many with 400,000 miles on them running fine.

I agree, run it fast and furious. Jake and Elwood Blues (the Blues Brothers) car was still running fine, out-ran most of the newer police cars.


Only because they were on a mission from God!!!

 

[Ducked]

Originally Posted By: CR94
Originally Posted By: eljefino
... Newish Prii also seem to have piston ring problems. They never engine break, either, ...
The first statement there seems to be true, too often. The second is false.


That might depend on whether the spelling is deliberate, or a mistake.

 

[FCD]

WOT does not produce more wear, if you have a warm engine and your don't just stomp on it from a standstill no harm should be done.
In old carbureted cars with point ignition systems the italian tune up really works, because they run really rich when cold and generally have weaker ignition systems usually means the combustion of the air/fuel mixture is not as complete and produces more deposits, i know in my carbureted cars, a little "spirited" driving at high revs generally makes them run smoother.

 

[ragtoplvr]

about 30 years ago I worked with a retired auto engineer, they did wear tests, one was 100 hours at wide open in the desert, and the other was cold start, idle until warm, then shut down. His claim was the idle test did more wear than WOT. He did say the WOT was [censored] on alternator bearings, fan clutch and power steering pumps without oil coolers This was in the carburetor era, so fuel wash down was probably a item.

Rod

 

[ARCOgraphite]

There is hard data; weve seen the graphs: high load and higher RPM cause the highest engine wear. Steady state (light load) mod-high RPM has slightly more wear than moderate rpm.

On a street car you (likely) don't drive it hard enough to influence the wear.

I toasted my 86 MR2 WOT 5000-6000 highway stone cold. Burning oil like a bandit at 35K miles.

But that's just me.

 

[fenixguy]

I would just like to add to this conversation that I paid for all of the available RPMs in each of my vehicles and I frequently use the entire range. If that's shortening their life, then they need to hurry up and die because I don't want them taking up space in my driveway. I bought them to work for me, not the other way around.

No, I don't drive them like a stole them every day. I feed them a good diet of top tier fuel and (usually) synthetic oil. I expect my cars to do what I ask.

 

[UncleDave]

Prolonged WOT under load does cause accelerated wear.

It cannot be categorized as "premature" because you are causing it. Accelerated is more accurate.

A perfect example of this is the huge number of half ton truck I see that have spent 5-10 years towing boats up and down the desert hills.
After about 100K and a decade of this they start losing compression and consuming oil.
Its normal to be at 100% throttle for extended times in scorching heat with a huge load on the entire system with this kind of workout.

I see tons of clapped out trucks at 10 years and 100K .

A more severe example would be a high performance boat engine - take a mercury 525 big block.
Almost all need a top end job around 250 hours and a full lower rebuild between 5 and 6.
paltry hours compared to what that engine is a sedan can last.

A common BITOGGER myth of wearing out the vehicle before the engine doesn't apply to trucks that work all the time.

Driving 100MPH in a car for extended times is relatively easy on it by comparison

UD

 

[mightymousetech]

Originally Posted By: UncleDave
Prolonged WOT under load does cause accelerated wear.



It sure does. Normal maintenance on a racecar is rebuild head every 100 hours, rebuild entire engine every 200 hours. Would not want to do that with my street car.

 

[UncleDave]

Yup.

The only cases where that isnt the case are when the engine is exceptionally watered down and you basically need WOT almost all the time - something like an old honda trail 70 where the powerband can be described as one continuous flat spot on what should be a curve.

Auto guys here often swear you can run cheap oil, and cheap filters, and have the engine outlast etc car.
There is merit to this simply because the loads are so low on most auto engines thats close to true it matters very little.
At the 14% load at freeway speed most of its life cheap stuff at regular intervals works fine.
You can have crud go right through the bearings and never streak or grind because it isn't pushing hard.

Take an engine with some beans in it and put some real load on the system for appreciable time and all the little things you do to keep oil cleaner and cooler help the ecosystem actually matter and really payback.



UD

 

[SilverSnake]

Originally Posted By: UncleDave
Prolonged WOT under load does cause accelerated wear.

A common BITOGGER myth of wearing out the vehicle before the engine doesn't apply to trucks that work all the time.

UD


Great post. I love it. I would say the myth also applies to the following cars:

1. Those that regularly get "the snot beat out of them." (I see an image of dirty oil and antifreeze dripping off the grill. The oil is dirty because many BITOGGERS routinely try to get the last mile and day out of a change of oil)
2. Those that are frequently driven like they are "stolen." (These cars are also likely to have body damage similar to those driven by thieves who wreck them trying to evade the police)
3. Performance cars driven by drivers that think they were "made to be abused." (If you look up "abuse" in the dictionary you will find it refers to "improper and excessive" use)

 

[CR94]

Originally Posted By: Ducked
Originally Posted By: CR94
Originally Posted By: eljefino
... Newish Prii also seem to have piston ring problems. They never engine break, either, ...
The first statement there seems to be true, too often. The second is false.
That might depend on whether the spelling is deliberate, or a mistake.
Good point! A few probably have broken. I should've said the second statement would been false if he'd spelled "engine brake" properly.

 

[DoubleWasp]

Originally Posted By: UncleDave
Prolonged WOT under load does cause accelerated wear.

It cannot be categorized as "premature" because you are causing it. Accelerated is more accurate.

A perfect example of this is the huge number of half ton truck I see that have spent 5-10 years towing boats up and down the desert hills.
After about 100K and a decade of this they start losing compression and consuming oil.
Its normal to be at 100% throttle for extended times in scorching heat with a huge load on the entire system with this kind of workout.

I see tons of clapped out trucks at 10 years and 100K .

A more severe example would be a high performance boat engine - take a mercury 525 big block.
Almost all need a top end job around 250 hours and a full lower rebuild between 5 and 6.
paltry hours compared to what that engine is a sedan can last.

A common BITOGGER myth of wearing out the vehicle before the engine doesn't apply to trucks that work all the time.

Driving 100MPH in a car for extended times is relatively easy on it by comparison

UD


You sure are right about that 525. True race engine lol.

 

[SteveSRT8]

As is typical here the folks who actually touch an engine know that true, continuous full throttle is very different from a typical drive in the hills.

Most modern higher performing cars simply cannot stay at full throttle for long or you hit something!

 

[Artem]

Originally Posted By: eyeofthetiger
ITU can be good for some things, and bad for others. The worst thing you can do is redline a high-mileage engine that spent its whole life putting around at 2000 RPM or less. As the piston rings and cylinder wall wear together, a lip (or ridge) forms on the cylinder wall at the furthest point of the ring's travel. At high RPM, the rotating assembly may stretch so that the piston ring impacts the lip worn in an engine that has previously only seen low speeds.


I agree with the above statements about giving a granny driven powertrain the good ol' Italian Tune-up.

I believe in exercising the machine daily for good health, just as a human needs exercise. Take that 50 year old buff Bowflex guy and tell him to run all out for a mile. He's make it just fine and can run another if needed. Now ask a similar 50 year old couch potato fatty to run a mile... yea right!!! Someone call an ambulance, we have a coolant / oil leak on runway #4.

Engines and transmissions need to be put thru their rev range frequently. I find that merging onto the highway is the best and safest way. You've got plenty of road and can legally run thru several gears on your way to that 65 - 70mph speed limit. I usually Make a quick stop and start off in first gear @ WOT. Nothing like feeling a rush of power from that engine and blow out the carbon from the pipes in the morning (once fully warmed up, of course
I run the snot outta all my cars and have gone thru several cars that had excellent UOA doing so. No signs of engine wearing out to be seen in the report and all engine ran healthy and gave excellent, better then EPA rated gas mileage.

 

[fdcg27]

Running an engine really hard all of the time will obviously shorten its life.
This is no more than common sense.
As one A&P wrote in one of the AV rags, horsepower wears out engines and this is also the reason that two thousand hours before overhaul is considered a good life for an aircraft piston engine. These do get run hard most of the time.
Fortunately, there is no road venue in this country where an engine can be run hard enough long enough to hurt it, with the exception of towing through the hills.
Only very low specific output engines can be run hard all of the time and their low specific output protects them from any harm cause by being run near their power peaks for long periods of time.
I'm thinking of diesels here, both OTR and old Mercedes. OTR diesels don't have very high specific outputs and are also built to absorb many hours of running close to their power peaks.
SI light duty vehicle engines aren't built for this sort of use but have enough power that they'll never be subjected to it for very long, except when towing something heavy through hilly country.
I myself think that the occasional hard run through the gears is probably a positive for the engine and tranny. Doing so all of the time and everywhere can only shorten the life of these assemblies.