High RPM, below redline. Good? Bad?

subaru
outback

#1

I posses a 2001 Subaru outback 4-cylinder automatic transmission with about… 170,000 miles on it.

It has a spread of minor problems, but the main topic of this discussion isn’t related to them. The thing has a redline of about 6,200 RPM, which I believe is fairly common among similar engines.

My question is:

There comes a time where one just has to stomp on it. Is it bad for the engine to run between 5,000 and 6,000 RPM for a short time? (Mostly whilst accelerating)

I have noticed that the ECU tries to avoid running the engine above 4,000, so I am just wondering if that is likely to cause problems down the line.

Another thing is engine braking (as best you can in a car, anyway)

is it bad to run the engine into higher RMPs when using it to slow down?

I just like to put the thing in 2nd gear and stomp it sometimes,

(I mean come on, once it hits 5,000 RPM, it sounds cool)

Is that a bad idea?

Another thing is the exhaust system. Recently, the ‘check engine’ light came on. This was right after the exhaust system started to come apart somewhere under the passenger area of the car. I have also noticed a reduction in power of the car. Could the exhaust leak be related to either of those?


#2

It’s always a bad idea to expect a high mileage engine or automobile in general to have the same capabilities as when it was new or in mid life.


#3

If I owned a Subaru with 170K miles on it I would be afraid to take it much over 3500 RPM. Flogging tired, old, engines might be “fun” but I’m afraid the fun won’t last very long…When a rubber timing belt snaps at 6000 RPM, Ka-Ching!! That will be Four Grand Please…


#4

You have an exhaust leak somewhere, a Check Engine Light lit, a reduced power situation?

You should be asking how to fix these problems rather than whether you can “stomp on it” safely.

If the engine were operating properly and properly maintained, running it up between 5,000 and 6,000 during acceleration would be no problem whatsoever. But you do not have an engine operating properly. You have an engine with unknown problems. So we cannot tell…but I’d go easy until I got it diagnosed and fixed. Start by getting the codes read.

By the way, how out of date is the maintenance?

Why am I getting the impression that this poor car has been badly pounded on?


#5

How does the ECU try to avoid running above 4000rpm?
Could it be clogged exhaust,timing off,in need of tuneup, cheap gas or dirty air filter is keeping it from reving much past 4000rpm?
What are the minor problems?


#6

I seriously doubt the Tensil/Fiber and polymer reinforced timing belt has 170k miles on it. Quite sure it was replaced LONG before that.

If the engine was well maintained…then I see no problem what so ever revving this engine past 4000rpms. Did it several times on my wifes 87 Accord with well over 250k miles…Wouldn’t hesitate one bit.


#7

I still believe that an engine that never sees 5000 Rpm will last longer than one that often sees 5000 rpm. Oh I know that engines are better than they used to be, but high rpm is not good for an engine. I also know that I’ll get a lot of disagreement about this. There’s no way we can tell how much longer an engine will last if given a little mercy.


#8

What you say is almost certainly true, but where do you draw the line. An engine that is never run above 1000 RPM will last even longer, but not as long as one that is never started.


#9

Respectfully, I’m not sure I agree. With the exception of engines plagued with design or manufacturing deficiencies (like my '72 Vega was), a properly maintained engine should be able to be brought up over 5,000 RPM routinely while accelerating without problems and without prematurely wearing out.

I’ve owned cars for over 40 years, the last three dacades of which have been largely spent as a commuter. I’ve never babied my cars, feeling free to punch the gas to pass as desired, and to accelerate from the toll booths (they’re like the start of Indy on the Everett Turnpike). I’ve never worn an engine out. Some I’ve even owned for a few hundred thousand miles.

Theoretically a kindly treated engine will last longer. But longer than what? If the engines already outlast the vehicles, where does the lone get drawn?

And for those engines that are pushed, is it really the RPMs or the higher cylinder temps and pressures brough about by the wide open throttles? I respect the theories involving higher inertial forces from higher RPMs and I know I’m getting deeper into theory here, but I wonder if it’s really the RPM itself.


#10

“If the engine was well maintained…then I see no problem what so ever revving this engine past 4000rpms. Did it several times on my wifes 87 Accord with well over 250k miles…Wouldn’t hesitate one bit.”

I agree as 4K is well below the read line…but here we’re talking about 6000 rpm in a motor that the operator thinks is “cool” at that rpm "mostly whilst accelerating.
Give me a Honda race bred motor any day and slightly rev to 4k over a Subaru Fuji Heavy Industry smudge pot at 6K (just kidding VDC) :slight_smile:


#11

My feeling is that my cars exist for my convenience, not the other way around. So, I don’t baby them either. Of course, I can afford to replace them as needed. Otherwise, I might feel differently about it. I’ve never worn the mechanicals out either. I usually retire one because I want the features now available on the newer ones, or something like that.


#12

Most of mine have been traded because my needs changed.

My '72 Vega…well, it was a Vega. I got rid of it when the rear axle came out of the housing.

My '76 Corolla got traded when my son was born. Ever try to put a baby in the rear of a '76 Corolla coupe?

My '82 got traded for a Toyota minivan when my second was born.

My '79 Toyota pickup got junked after 10+1/2 years when the frame rotted out. The engine was still going strong.

My '89 Toyota pickup (given to my daugheter at 295,000 miles) ran well until it got totalled…at 338,000 miles.

My '91 Camry I gave to my son when I gave the '89 to my daughter…seemed only fair.

There’re more vehicles and more stories, but the idea is that they get traded for reasons other han worn engines.

I’m keepin’ my '05 Scion…forever!


#13

Just have mercy!!


#14

With many years driving many miles in all manner of vehicles it seems there is a seat of the pants sense for when an engine is being over revved. Mazda Miatas seem to be lugging when below 2500 rpm and don’t have much power until near 3500 but they don’t feel very willing to run behond about 5500 even though the red line is somewhat higher. Old MGs seem to enjoy sitting at the red line for hours. I rarely drive Subarus though.


#15

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#16

I don’t know if it’s such a good idea to force your old car as if it is a new one. A friend of mine who works at a used car dealers Des Moines service used to tell me: “when in Rome, do as the Romans do”. I suppose that if you have an old car try to treat it like this.