When am I lugging?
 

Hi guys.

I've only been driving stick for 3 months, and I want to learn more. I've heard many things about lugging your engine, and how it can lead to Transmission stress and Engine pings/knocks.

However, I really don't know when I am lugging my car. Is there a sound I should hear when I'm lugging my engine?

Here are some scenarios I think I lugged my engine:
-48mph in 6th gear at 1.8k rpm
-12mph in 3rd gear at 1krpm
-16mph in 3rd gear (forgot the rpm)
-30-35 mph in 5th gear (forgot the rpm)

Are any of these lugging the engine? Is it better to over rev?

Thank you!

You are probably lugging any time that you are dropping much below 1,000 regardless of what gear you are in. If the engine starts rattling and the car is sort of lurching then you need to bring the revs up. I personally try to keep my RPMs at a minimum of 2,000 all the time although you can go lower without lugging. The other benefit of keeping down a gear with slightly higher revs is that if you have to motor out of an issue you can get some speed up way faster.

Below 2k is lugging territory.

I can't even picture doing 12 mph in third. Gotta go try that and see what happens.

For me, the lowest MPH I can cruise in 6th is 36mph. Anything under that and you're lugging the engine even while cruising...

Either way, I wouldn't accelerate in 6th at all (its very stressful on the drivetrain) unless you are over 70mph.

Listen for the sound of baby Jesus crying.

No, over revving isn't good either. Keep in the normal/correct rev range for the speed.

Clues that I was lugging when driving stick:
1. Engine revs were too low to hear, but could hear clunking noises when I tried to accelerate.
2. No acceleration - just deep vibrations.
3. Almost stalling/ lurching.

Don't do it!

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only time i get below 1k is in first gear. think stop & go traffic on relatively flat road less than 10 mph, you can creep along without pressing the gas (eventually) to avoid clutch in clutch out, brake, repeat just to go 15 feet. even then when accelerating from that low of a speed, its easy on the throttle to get it back into operating range. i believe when your car starts bucking back n forth is lugging. m2c.

a) over rev is not the right term, and no, it's not any better than lugging, in fact it'd be worse

b) if your car is under load (moving) and your car is near idle engine speed, it's not good.

c) picture yourself on a bicycle, if you are in a high gear and you're going too slow, your legs are gonna feel a lot of stress. just like the rods in your engine will feel if engine speed is too slow in relation to road speed.

Finally, FRS engine is not very tolerant of low RPM and you'd get a ratchety sound at low rpm under load. you have an entire safe rpm range from 1000 to 6000 (7000 if you really wanna rip it). Use it, over shifting your gear box doesn't do it any favors.

higher RPM up a hill is easier on your drive train as the engine can get the torque to apply to your wheels on a hill.

for educational purposes, you might try an obdII Bluetooth dongle to watch how much your timing gets retarded (knock) when you give the throttle input in the higher gears.


i drive most cars about 3000 rpm unless i am on the interstate. most cars seem the most efficient in the 2800-3000 range.

Turn on the shift indicator might be able to help you.

I've done 12MPH in third a few times, usually when cruising to a stop due to traffic on the highway. Only tried to accelerate from 12MPH in third like once... also due to traffic on the highway. The car was not happy.

I accidentally started in third from a stop the other day. The car CAN handle it every now and then.... It's just not good overall.

OP, you're unlikely to do real damage in the short term by lugging. Just don't make it a habit to put the car in a place where the car shudders or vibrates as though it is having a hard time.

Thank you guys! It now gave me a better understanding of lugging. I was just worried, since I want to keep this car for a long time. Maybe in three years I'll do an engine and tranny rebuild, but for now I'll save them as much as possible.

As for the 12 mph, I was breaking into a traffic from 25mph. And then I was cruising at third with 12mph for 30 seconds or so. I didn't hear any horse dying. So I guess I was good? Hahaha

If you think you're lugging the engine ....... you probably are ......;)


humfrz

it depends on the displacement of the engine to determine what's lugging. For example my ford ranger 4.0 SOHC is happy to putter at 1K rpm, but the BRZ is a lot happier to be no less than 1600-1800rpm. This is the rpm that will allow you to accelerate, albeit not aggressively

My two cents.

Displacement has little to do with it. It is more in the gearing. Yes a larger displacement may be able to go a bit lower since it does not make power through revs but it still needs that minimum based on gear.

So If im going say, 5mph should I put it into 1st or just accelerating from 2nd is okay? Like I always accelerate from say 5-7mph and the engine does vibrate but quickly recovers.

5mph in 2nd gear is like under 1k rpm no? I downshift back to 1st gear when I'm going under 10mph

Shoot, I keep my rpms low all the time. I routinely beat every EPA estimate in the book that way.

As for lugging... well just listen to the engine. It'll let you know what it doesn't like. The car will start hopping forward and falling on its face.

You can run a low rpm just cruising, just remember to gear down before accelerating. High 30s seems to be the lower limit for sixth in mine.

I've noticed the BRZ clatteres like a diesel when I'm creeping through parking lots in second. I think that's just the direct injection kicking in though.

Really though, don't think about it too much. It'll let you know when you're doing it wrong, by hook or by crook. If the engine doesn't, the clutch will, lol. I think everyone remembers that smell from when they were young.

A lot has to do with either rolling downhill or climbing uphill.
This is with driver only in car.
Rolling down at 60kph , 6th is fine.
On a level road 70kph minimum for 6th.
The slightest hill climb will need downshift.
With a passenger and a load of luggage , add 10kph for 6th.
Try driving with the backseat down and you can hear if there is any lugging.

@Da Brz

No, that clattering is your flywheel rattling against your pressure plate. Downshift to 1st before that happens. It's not hard to downshift to 1st under 10 mph. I also noticed you've made posts about your car knocking when coming to a stop. Perhaps you are keeping your rpms too low. I think the lowest rpms you should cruise at safely should be about 2500 rpm. There's no reason to almost lug this engine just for muh mpg's when it runs efficiently enough when driven right.

True.

Back-on-the-farm we had a 1941 Ford 1.5 ton truck with a flathead V-8.

When put into the "granny gear", even with a half load of hay, I could let the clutch out, in a rough hay field, and not touch the gas pedal and it would just jug right along.

Why did I do that ....?? Because, I was so small, I had to open the door to see out ...... and I couldn't reach the gas pedal while leaning out to see where the next bale of hay was.

(ohhhh......I think I've told that story before ...... :sigh:)


humfrz

Oh, I'm not so sure your engine likes that. The engine in my car seems to like being at 3,000 rpms or above .......once it gets warmed up.

:iono:


humfrz

Actually ...... since the flywheel is bolted to the crankshaft and the pressure plated is bolted to the flywheel ....... what is chattering is the clutch disk rattling against the pressure plate and/or the flywheel ..... :D

(I'm practicing on being like @Tcoat ....... :bellyroll: ........ now THAT should get a rise out of SOMEONE ......:popcorn:)


humfrz

Most clutch plates have springs to help keep the system from bucking, but at that low an RPM they just can not handle the changes in the engine speed. (They also help with mismatched shifts).

Actually the springs can exacerbate the problem at that low a speed

^^^truth^^^

OP, when you're operating the car with the engine between idle and 2K, the trick is to not give it any more gas than it would take to gradually rev up the engine in neutral.

While standing still in neutral with the engine at normal idle, gradually step on the gas. Raise it to 1000 RPM and hold it. That's as much gas you should give it when you accelerate from a crawl at idle.

Now gradually go from 1000 to 2000 RPM. ...

Practice that and you'll get how to not lug the engine. If you ever make it chug below 2000 RPM, you're doing it wrong.

The knocking when coming to a stop is when the car is in neutral and the clutch out, actually.

It also knocks at idle with the clutch out sometimes.

12 mph in 3rd gear?! Please don't tell me you floor it when the rpm are that low. Turn your 'upshift' indicator on. It'll let you know when you shift for best fuel economy. As far as your question, anything under ~1500rpm I would say your lugging the engine. Also you're not going to 'over rev' this car unless you go north of 7200rpm. If you can keep it between 3000 and 7000, you'll be fine.

I leave my shift indicator on and going easy down the 40 mph road I work on, it tells me to go into sixth around 38 or so and that's about 1700rpm.

Keeping it at 3k or above at all times would require a lot of clutch modulation, I'd imagine. Like a motorcycle. Sounds like a good way to burn up a clutch early.

You have to remember your throttle input is a factor. If you're only using enough throttle to remain at speed, you may as well use the most efficient gear. Just shift down before accelerating.

I've never burned up a clutch in 20 years of driving and 5 different DD stick shifts.

Mine never wants to go into first without being <5mph. :iono:

And IMO, if the engine's own tune allows it to run low enough to knock at idle and when coming to a stop, then I don't mind letting it happen a bit while modulating a tight spot in the parking lot.

I mean, even first will do it, too, in the right situations. Again, it doesn't even have to be in gear to do it! lol

How does keeping the revs up require more clutch than keeping them low?

I guess if you don't mind looking obnoxious, it doesn't.

Most of the time, if you're in too low a gear and running high rpm, the vehicle will buck some.

That's why clutch modulation is a necessity on a motorcycle. And why they have a wet clutch.

I don't want to get into a fight about how best to negotiate low speeds in these cars.

I just want to point out that you guys running 55mph in your cars at 3k rpm or whatever don't need to do that and are basically just being wasteful.

First off, I disagree with the shift indicator ....... that's the reason I don't activate mine..... :)

More clutch modulation at above 3000 rpms ??........ I think you got that backwards ...... ;)

YOU have to remember ??........ :sigh: I may be old ...... and my short term memory ain't what it used to be ....... but ...... I do remember how to use the throttle ....... most of the time ...... :D

Well, after driving clutched things since I was 5 years old ...... that would be .... wait one till I consult with my paper and pencil ........ roughly, 69 years, I have never burned up a clutch.

When you start off shifting thinks like this, pulling heavy stuff ...... you get and remember clutch/gas things real well .....:respekt:


humfrz

I can drive a tractor too! High five.

And if you're so experienced (which I believe you are), you should already know that too high an rpm makes low speed stuff tricky which requires clutch modulation. If you go too fast in first, you get a herky-jerky throttle. You should know that.

To illustrate by exaggeration, imagine trying to navigate a parking lot with the throttle stuck at 7 grand. You think that's going to be a smooth experience without slipping the clutch some?

And as for the shift indicator, well, I trust the engineers at Subaru (a little) but, again, to me, it all comes down to listening to the engine. Is my motor trying to hop forward and die at 1700 rpm? No. Is it even struggling or knocking? No. Sounds to me like it's doing just fine. Gear down to romp and you'll be fine.

No. If you are in too high a gear and your revs are too low the car will buck. Higher revs in a lower gear should give you a nice smoother acceleration or cruise.
We are not talking about motorcycles here.

Which is called lugging. Something I'm not suggesting or doing.

This is one of those things where if you could ride around with me, you'd say, "Okay, yeah, not my style, but sure."

But since that's not happening we're just gonna have to let this drop.

55mph at 3K is just about where you want to be for good economy. Lower RPMs do not always equate better mileage.
Driving around pushing the stall speeds all the time will damage the car and cost more in the long run than driving in the proper gear at the recommended RPMs.


If you want to lower the RPMs to just about stall and drive around thinking you are saving $20 a year then there are better alternatives.


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