"Lugging" an engine?

[DCTFAN]

Honda designed and tuned the NC700 engine for efficiency in low and mid range rpms. If the owner's manual and the DCT software both agree that operation under 2000 rpms is OK than it is OK. This engine was developed by the Honda MOTOR Company and they know what they are doing and the engine will provide a long service life when operated under the owner's manual suggestions.

As far as suddenly opening the throttle to accelerate from a cruising speed of 1800-2000 rpm - the DCT does downshift up to 4 gears. A rider on a manual transmission is expected to do the same.

Folks on manual transmission Honda models which offer the DCT option should
etch these words into their left hand and onto the windshield.

Lugging is not harming the engine if the DCT computer maintains the gear at low rpm.
On a manual transmission, you are harming the engine, if you don't shift when the DCT ECM would shift.

Did I get that right?

 

[670cc]

myself, as far as I have been reading through the years and failing to have saved URLs at hand to show you, many of the aforementioned wear issues may manifest under situations of continual severe laboring of the engine - it's all about too abrupt acceleration pulses of the pistons slapping down the drivetrain accumulating too high point loads over various parts - think how an engine is made up from its parts and it is easy to understand. Inadequate oil feed under lower pressure makes the bearing oil wedge formed by the rotating crankshaft and rods thinner thus less heat absorbing and this could mean trouble there particularly when the bearing tolerances happen to be on the tighter side of their specifications. You can find examples of scorching marks on car engine crank bearing suggesting such laboring abuse over many thousands of miles - not that they cause a real life problem per se during an expected vehicle's timeline. On the camshaft driveline, acceleration-decceleration pulses put strain on the adjuster and chain - an extreme situation as told to me by a fellow hands-on racing mechanic on DOHC motocross/supermoto models is of often timing chain troubles and wear (jumped teeth or too much accumulated slack that directly affects timing) caused by the abrupt engine deceleration when landing from jumps. Of course these MXers and supermotos are no NCs in any way.
For the NC and similar designs I guess that mild pulsing should be OK oever many years but severe laboring should deteriorate the engine's possible lifespan.

Still no data. Too much "could this", "may that."

 

[dduelin]

I can't help but think Honda took all the expected wear and performance factors into account when they designed this engine. It was said by the leader of the NC engine project that the design team met once or twice a month with automotive counterparts for the two years the NC engine was under development. All the wear factors mentioned in a prior post are opportunities to be examined, met, and overcome, not immutable problems that restrict long service life.

I could be wrong but it's a smart bet that Honda knew exactly what they were dealing with and designed & built accordingly.

 

[Mi_ka]

Still no data. Too much "could this", "may that."

I am sure you can google around be yourself - I have better things to do and I do take my expert mechanic friend's hands on experience on multiple racing machines as well as thousands of bikes passing by his shop for grounded - you may as well toss all this away, fully lug your bike for 2-3 months or so and then report back - if you report no problem (feasible enough for this engine design vs the lower mass of the motorcycle vs a double the size car engine against 5 times the vehicle mass) I am also free to throw your report away as I may just say you did not lug enough for me to hear it half a globe away. When/if I ever buy my NC I will not be lugging it and under no way laboring it for sure (the DCT would help me for sure).

 

[Deleted member 5383]

I lug my dualsport all the time. Provides some traction control and allows me to ride through changing terrain without doing more shifting. There's a lot of times when tractoring though is better than ripping. But when I LUG my dualsport, that usually results in bucking until I get up to an RPM that is actually more appropriate for the conditions -- or even a stall-out unless giving a little clutch relief. Certainly neither the engine nor the rider is being well-served by LUGGING, but lugging is a useful tool in the toolbox ; }

The same principle applies on the pavement. The results are what determines which is which.

 

[showkey]

Guess grandpa's JD model 50 should have failed 20 years ago.............it never saw more than 1500 rpm in its life time. Another long stroke engine witha very flat torque curve.



Not even sure what defines lugging on the NC......but.......Bottom line the NC will tell you when your lugging ............well in advance of any possible or potential damage or wear.

 

[dduelin]

From mechanical point it makes sense to think that unbalanced engine work is harmful to some extents.
This is pretty popular discussion on web.
Here is one of many examples:

Save 9:13 of your life and watch the Cliff Note version of 45 to 55 seconds and 6 min 15 seconds to 6:30.

 

[Mi_ka]

Another long stroke engine witha very flat torque curve.

View attachment 31449

same flywheel mass as well results in the that same revvy feel to the NC

and that gear driven camshaft driving pushrods(?) is also designed to the same tight tolerances as the NC-Jazz engine as it is well known all over the world that farmers are the best users of precise machinery

better find a better example to support the argument

 

[lootzyan]

Save 9:13 of your life and watch the Cliff Note version of 45 to 55 seconds and 6 min 15 seconds to 6:30.

I don't think I would give even 1 second of my life to look for 25 sec. of CliffsNotes explanation to how combustion engine works.

 

[mrdcmills]

I agree. Mine will pull just fine at 1000RPM, but sounds terrible. That rattle is hammering from the crank through the transmission all the way to the back sprocket. You might save $.30 on a tank of gas.

 

[bvogel7475]

Don't try lugging it at 60 mph while trying to climb a decent size hill. I tried that yesterday and the bike started shaking like crazy. Scared me a little bit but it's happened before. This bike has a very week top end. So, big hills at 55 trying to get to 75 are quite a challenge. I'm used to it. So, it's no big deal.

 

[ST13Fred]

^^^^^^^^^^^^^^^^
Question these theories.............any data, articles, SAE papers, instructions, warnings, engine failure analysis.... to back up the theories ??????

This is a fact regarding engine lugging......not theory. Higher RPMs lowers bearing pressures/heat......Opening the throttle at low RPMs increases pressure/heat. It's simple physics.
Air passing through a carb venturi or over an aircraft wing does the same thing. As air speed increases, pressure lowers. That's how a plane flies.

 

[VE258]

Don't try lugging it at 60 mph while trying to climb a decent size hill. I tried that yesterday and the bike started shaking like crazy. Scared me a little bit but it's happened before. This bike has a very week top end. So, big hills at 55 trying to get to 75 are quite a challenge. I'm used to it. So, it's no big deal.

As it has already been said-auto transmission would shift down, on lower gear. on your car or bike. with manual tranny it is expected that you do same. another valuable quote comes to mind- "stay in responsive gear"

 

[670cc]

This is a fact regarding engine lugging......not theory. Higher RPMs lowers bearing pressures/heat......Opening the throttle at low RPMs increases pressure/heat. It's simple physics.
Air passing through a carb venturi or over an aircraft wing does the same thing. As air speed increases, pressure lowers. That's how a plane flies.

The question is not about the physics; the question is more about data on engine failure or damage to the NC engine. If there is more heat and pressure, who cares?, as long as the engine is designed and built to operate that way.

 

[showkey]

This is a fact regarding engine lugging......not theory. Higher RPMs lowers bearing pressures/heat......Opening the throttle at low RPMs increases pressure/heat. It's simple physics.
Air passing through a carb venturi or over an aircraft wing does the same thing. As air speed increases, pressure lowers. That's how a plane flies.

This bearing temperture chart says something different :



As many other posts are repeating the engine lets you know when the rpm is to low for comfort. Lugging below a certain low rpm makes no sense and is not comfortable for the rider or the bike. The NC can and does operate well at a low rpm compared to many other bikes.

A recent article in Rider tested two bikes in the retro scrambler category.

Bike 1

Torque at 2500 rpm.......20 ft lbs. (not a misprint)
Torque at 3000 rpm........60 ft lbs
Torque at 6500 rpm........72 ft lbs. MAX

Max horse power 99.5 at 7800 rpm. Redline 8200

Bike 2
Torque at 1800 rpm.........62 ft lbs
Torque at 3000 rpm ........72 ft lbs
Torque at 3300 rpm.........74.4 ft lbs. MAX

Max horse power 74 at 6200 rpm. Redline 6200 rpm
63 ft lbs from 2000-6000 rpm

Question which bike is going to more comfortable at low rpm pull ???
Which bike would you have to rev to get it going ?


Bike 1 2016 BMW R NINET 1170 cc
Bike 2 2016 Triumph T120 1200cc


Just as a comparison NC700 numbers are almost half due to engine size but the rpm range is comparable

Torque at 2500........38 ft ft lbs
Torques at 4700......42.5 ft lbs. max. Redline 6550 rpm

Over 40 ft lbs from 3500 to 6000 rpm
Max horse power 47.5 at 6250 rpm


Beating the dead horse a little more. Chart shows oil temp vs RPM with no load,half load and full load and thinning of the oil with temperture. Assumes the parts in the oil are going to about the same temp as the oil.

 

[Mi_ka]

Interesting - article URL for the first image?
I must note that no mention of load & throttle opening are mentioned in conjunction to journal temps so it is half the story.
During LUGGING and not lugging pulses, the journal loads should be spiking in an abrupt way not showing in the average graph which may not cause high average thermal loads but could provoke great oil film thinning and scorching instant thermal loads again not showing in the average graph, I theoretically imaginatively think myself.
Have they studied a not heavily lugging multi cylinder engine with heavy flywheel maybe?