How much does RPMs affect engine life?

[njdevilsfan87]

If I were to drive on a highway, and keep my RPMs down roads with a lot of traffic lights, how much engine life be effected? Is it a really big deal? If I accelerated at something low like 2k RPM instead of pushing the engine up to 3k, before it usually switches to the next gear on it's own (yeah yeah I don't know how to drive a stick... yet) - is it a big deal on a 3.8L V6?

Reason I'm asking is because I'm 20, and really can't afford car repairs at this point in my life, so I have to do my best to make sure my car keeps running well until I leave college with a well paying job.

Thanks!

 

[fbrdphreak]

Which 3.8L V6? The GM Series II, or the Mitsu motor? If it's the GM, that thing will run forever as long as you change the oil. Seriously, just follow the scheduled maintenance to a T and you shouldn't have anything to worry about.

To answer your question more directly, it would be interesting to look at Mean Time Between Failure for engine parts like rod bolts & other critical components. My friend said he saw such data at one point for a GM V8 and the MTBF dropped dramatically in the upper RPM range. So basically don't leave it in 2 on the highway and you'll be fine...

 

[Jeff7181]

The difference between 2000 and 3000 RPM is insignificant. Now, if you were to cruise in 3rd gear at 5000 RPM, yeah, that would definitely shorten engine life.

 

[Billb2]

Think of piston travel per mile vs pounding the rod and mail bearings with low RPMs. It's a tradeoff, probably different for every engine design.

 

[thedarkwolf]

My miata runs 4k rpms on the interstate so I wouldn't worry about it too much unless you are cruising near redline.

 

[alimoalem]

Originally posted by: thedarkwolf
My miata runs 4k rpms on the interstate so I wouldn't worry about it too much unless you are cruising near redline.

i was about to say...people made me feel better about my high revs in the freeway but 4k rpm is closer to 5k than 2k...so would a constant 4k rpm reduce the life of any part?

 

[overst33r]

Originally posted by: alimoalem

Originally posted by: thedarkwolf
My miata runs 4k rpms on the interstate so I wouldn't worry about it too much unless you are cruising near redline.

i was about to say...people made me feel better about my high revs in the freeway but 4k rpm is closer to 5k than 2k...so would a constant 4k rpm reduce the life of any part?

Considering there are tons of 200k+ Miatas with no major issues, I'd say there's not too much more stress on the components at 4k vs 2k.

 

[Throckmorton]

The speed of the actual piston is more important, I would think. Your 3.8L V6 has a longer stroke than a 1.8L Miata, so the pistons are moving faster at a given RPM.

 

[Demon-Xanth]

It really depends on the engine. For mine, I don't see anything under 4k being a big deal, over 5k, and it's a very very big deal though (4.7L SOHC V8). For my dad's truck, anything over 2500 becomes an issue (5.9L I-6 diesel), 5k is just something that is expensive

 

[DivideBYZero]

Right up to 8K for me.

 

[Dudewithoutapet]

While I don't know the age or mileage of your car and this discussion is great, IMHO, you probably don't need to worry about the revs right now. You're 20, so I'd assume your going to graduate in a year or two. I would imagine with routine maintenance, you're car will last at least that long or die from something else rather than revs.

Otherwise, avoid the redline and because its an automatic, you can't control the RPMs that much anyways right? I'm sure the car manufacturers put a "dependable" timer into their engines to switch gears when appropriate for the longevity of the engine.

 

[alpineranger]

sounds like you've got an automatic. Don't worry, the transmission will keep the engine in a reasonable rpm range for cruising on basically any road unless you're constantly testing the car's top speed on the autobahn. With the stock transmission programming, and stock drivetrain, as long as you maintain it properly and use some common sense you won't have to worry about rpm related engine wear. By common sense I mean things like drive gently until the engine is warmed up and the oil (not just the coolant) is up to temperature. After that, feel free to go to town. You'll burn more gas, but for most people's purposes, engine wear is negligible.

Look at it this way, if you maintain the car properly, the drivetrain will not likely fail within the warranty period (60k mi?) regardless of how hard you drive it. Consider how much less stress your driving involves (an order of magnitude less, probably), rest assured you'll be fine.

Oh and please tell us what car you're talking about. Lots of manufacturers make or have recently made 3.8L v6s (gm, ford, chrysler, hyundai come to mind immediately). GM's, which is most numerous of all those, is also the best.

 

[themisfit610]

Exactly. Just let the car do what it wants, and keep up with maintenance and regular oil changes.

~MiSfit

 

[njdevilsfan87]

Yeah it's automatic. The only thing I can do to control my RPM is to either floor it so it goes way past 3k until I left off, or accelerate slowly and have the gears change early (they usually change around 3k normally). It's a GM II engine for fbr who asked, so it's good to know it'll last forever as long as I take care of it.

I wasn't really referring to cruising for those talking about highways, as I've got an automatic, and at 70mph it's at about 2k RPM. I'm more concerned with stop-go traffic light highways... Should I step down on the pedal and have some fun, or take it easy? That was pretty much what my question was because I've got a 97 Camaro with 160k miles on it... and I just really need to last me another 2 years. It was serviced about half a year ago. Blinkers weren't working properly, suspension needed some tuning. Re-alignment, etc. But after that service, the car seriously felt a few years younger. I was just wondering if stressing the engine might have an effect on other parts, but it sounds like it doesn't too much, so that puts me at ease.

Thanks.

 

[Blackjack200]

Doubt it will affect your engine, but I would still take it easy at the traffic lights. If you wind it up at the green, and then stomp on the brakes at the next red, you will be putting unnecessary wear on the brakes, suspension, and maybe transmission (I don't drive an automatic so someone might have to confirm that), and you'll be burning more gas.

Try to time the traffic light so you never have to actually stop. slow down to 15-20 mph or whatever is appropriate and watch the opposing signal. If you can do that your car should have much fewer problems.

 

[Dudewithoutapet]

While I might be wrong, I believe it is ALWAYS better to take it easy or accelerate slowly, especially since your worrying about the longevity of your engine. I'm not gonna lie, its fun to floor it sometimes, but lets be honest, it aint good for the engine in the end. Maybe some of them racecars are best floored and continue to function at their best that way, but I doubt a commuter truck was created with the same things in mind.

 

[thedarkwolf]

Need to do an Italian tune-up every now and again. Clean that carbon out.

 

[Vic]

Originally posted by: Billb2
Think of piston travel per mile vs pounding the rod and mail bearings with low RPMs. It's a tradeoff, probably different for every engine design.

Yep. Engines run best and longest in their mid-range. It is different for every design, but all of them have a sweet spot in the rpm range where everything is smooth and balanced and there is little stress.

Plus, it's not that fast or spirited driving is inherently bad for your car, it's just that most people don't do it right. They drop the clutch, hamfist the gears, slam the brakes, dump it into the turn, and that's all hard on the equipment, and for nothing.

Remember the racing mantra: "Smoother is faster."

 

[jagec]

Originally posted by: Dudewithoutapet
While I might be wrong, I believe it is ALWAYS better to take it easy or accelerate slowly, especially since your worrying about the longevity of your engine. I'm not gonna lie, its fun to floor it sometimes, but lets be honest, it aint good for the engine in the end. Maybe some of them racecars are best floored and continue to function at their best that way, but I doubt a commuter truck was created with the same things in mind.

Trucks aren't for commuting, they're for hauling.

You're mostly right. There are a couple of exceptions--driving for too many months without ever stressing the engine/going into the high RPMs can leave carbon deposits and even cause oil leaks on some engines (Northstar V8 comes to mind)--but for the most part slower acceleration and taking it easy is the key to long engine life.

 

[Eli]

As others have echoed, it really depends on the engine.

RPMs kill, though, no doubt about it. Just think about it. All else being equal, the engine that saw higher average RPMs over its life will wear out first.

Of course, in the real world all else isn't equal, so as it turns out.. most engines wear out due to other things, like improper maintenance.

Edit: Oh, and the people touching on actual piston speed are right on the money.

That is really what matters.

Engine reliability is very critical in the aviation industry, and you will not find a piston engine with a high piston velocity used. The lower the better as far as longevity goes.