Thread 28680532

What the fuck is "low RPM".

I've been told by people driving at low RPM is bad for the engine and that you should drive it at higher RPM to keep the engine happy.
Then the next day the same people will tell me that when I start the engine after a cold night I shouldnt drive it at higher RPM and instead should keep it at low RPM to keep the engine happy.

In both cases not a single time will the threshold of where low RPM end and high RPM begin be stated.
Is it 1000 revs? 1500 revs? 2000?

If I have a choice of driving at a speed of X in 3rd gear at 2750revs and a 4th gear at 1900revs which one is optimal when I'm not trying to drag a healthy sized american family and their snacks up a hill? I don't like the noise the car is making in either scenarios because the factory exhaust has a weird resonant frequencies around 1850 RPMS

I'm retarded but I'm not that retarded so you don't have spend time to explain me the concept of mechanical advantage of lower gearing and I'm not asking about hard acceleration. Just normal driving conditions where it's sometimes flat, sometimes going downhill sometimes going uphill


Talk to me like I have an intelligence of an average brown person mkay.

>>28680532 (OP)
If the car is vibrating, you’re lugging the engine. Drop a gear Or go faster.

Makes no difference to the engine. The reason people say to drive at high revs time to time is to blast all the shit out.

Also wtf is it with grown men playing with dolls i see this gay shit all over /k/

>>28680560
Lugging the engine will damage the engine and transmission mounts. Vibrations are never good.

>>28680532 (OP)
Low RPM=higher cylinder pressure

>>28680565
Yeah after a million miles. They're designed for the average brainless moron to drive it any way they can hence anti vibration mounts exist to counteract vibration effects.

Lugging an engine is generally worse than redlining it.
You'll know because you give it more throttle and it doesn't make enough power to accelerate. It puts a lot of what's called load on the engine. It will vibrate and throw the harmonics out of whack which is very bad for bearings of all kinds.
Do not do this. If you're driving an automatic it will just downshift for you.
...When an engine is cold the tolerances are fucked-up since different metals expand at different rates (it's not just about the oil). You don't want to put too much load (either revving too high or low-rpm with more throttle than usual) on such an engine, let it warm up a bit.
I've been in full-vehicle test engineering and we never started a duty cycle until the engine had flat-lined cycling in operating temperature range for at least 5 minutes.
This all really does make a difference, if it's "worth considering" is hard to say for sure but I think about it.

>>28680560
We're all little girls here

>>28680532 (OP)
Basically don't lug the engine you autistic weeb. Or better yet, get an auto. Manual is clearly not for you.

>>28680532 (OP)
Generally you want to keep low RPM, just enough so that your engine can pull the car along easily at the speed you are doing. This is dependant on engine size, gearing, car weight, but usually 2000 rpm is plenty for a petrol engine, diesels are happier even lower than that.
However every once in a while it's good to accelerate hard and let the engine spin fast to keep everything nice and clean. Only do this when the engine is nicely warmed up though, if you do it from cold it will not do anything good.

>>28680565
>>28680606
>Lugging
Define it. Can you lug a modern (made after 1996) naturally aspirated gasoline engine at 1900 RPM in 4th gear cruising at 32 miles per hour on relatively flat ground?

>>28680718
1900 is fine for any of the engine configurations I can think of.

As for what it is, generally speaking, it's when the combustion event exerts peak pressure at a steep crank angle, reducing torque efficiency, and imparting a high rocking force on the crank instead of trying to turn it. That's not the worst of it, either. The flame front spends more time in the cylinder, increasing chamber temperatures, and exerting extreme stress on the piston rings. A little lugging here and there won't kill it, but it prolonged instances can lead to detonation and pinging, which is never good.

Tldr if your engine can freely accelerate, it's not lugging.

>>28680532 (OP)
I try to cruise between 1800-3000 rpm. At cold starts I'll keep it between 2000-2800 so it warms up quicker. Once a month I take it to the redline after its properly warmed up. Works for all my shitboxes

None of this matters btw, my coworkers rev the shit out of the company cars at -5c straight aftet a cold start and all are fine

>>28680718
not sure, my 2 litre Toyota starts to shudder if I'm in the wrong gear and going too slowly, ie, if revs drop below 2000rpm.
If you can't work out how to be in the right gear for the conditions, as others said, get an auto.

>>28680632
fuck off oingo boingo

>>28680782
No, they love little girls

>>28680575
And look at all of those million+ mile cars on the road.

>>28680718
>Define it.
Chug-chug-chug *no power here* a bit of a rattle as if you're about to stall out then if you're not dumb you'll downshift and give it the throttle to get back into operating range.

>>28680757
>Tldr if your engine can freely accelerate, it's not lugging.
But what If I stab the throttle and it starts to accelerate but slowly? Is it lugging?

>>28680921
means you're in the wrong gear, shift down
lugging is a vibration you experience when you're in a high gear, going too slow, with low rpms.

>>28680924
do you mean those tiny vibrations that you feel always just slightly increasing with amplitude as you put load on the engine or the vibrations that shudder the whole body of the vehicle

>>28680929
it's more like a shudder. they'll go if you shift down (or if you insist, you can accelerate through them, and they'll go when your rpms get high enough). They can damage your transmission over time. Learn to drive properly, be in the right gear.

>>28680932
that thing doesn't happen unless it drops down below 1600 in 4th but between 1600 and 2000 you can feel those tiny vibrations on the steering wheel through your fingers

>>28680942
that could be a million things. when did you last balance your wheels?

>>28680946
Oh please dont start with this bullshit I know what an off-balance tyre and bad bearing feel like.
There's a clear and definite difference in how a car feels at 1800rpm and 2800rpm when it comes to vibrations from the motor regardless of displacement or whether it's a turbodiesel or gasser.
I'm asking whter it's already lugging or not yet.

>>28680952
You'd know if it were really lugging. It's very obvious. Might be a mild form, ~1600 is where it starts happening on the underpowered shitboxes I drive.

>>28680958
I also drive underpowered shitboxes. I wouldn't be making this thread if i drove a big fuck off v8 with enough power to shred tires at idle.

>>28680961
why can't you just change gear?

>>28680968
I could spend all day in 2nd reving the tits out when below highway speeds but whats the point?

Is it really so difficult to simply entertain the question I'm asking instead of trying to default to recommendation not backed by anything?

>>28680532 (OP)
Depends heavily on the car, so you might want to check your owners manual. Mine specifies to keep it under 3000 for a little on startup.

>>28680972
we've answered the question. low rpms, in a high gear, at low speed, cause lugging, which is noticeable as you'll get shuddering. small vibrations could be anything.
simple

>>28680972
It’s a less pronounced version of the sound your car makes if you stall it in first gear. Same root cause though.

Some engines love being lugged.

>>28680532 (OP)
Low RPM is fine as long as you run high RPM once in awhile. I'll just floor it on occasion like when I'm going onto the highway to blast away carbon buildup.

>>28680532 (OP)
IMO I would define low RPM as below 3k. You should be between lugging and 3k most of the time, but there’s nothing wrong with going above 3k if the engine’s warmed up.
That said you can develop issues if you NEVER take the engine out of low rpm. So you do want to get it above 3k every now and then.

>>28680532 (OP)
>What the fuck is "low RPM".
Anything under 8000 rpm is considered idling
life begins at 12000

>>28685688
>life begins
Interesting choice of words for an organ donor.