[protovack]

I know you aren't supposed to lug the engine and that it is tough on internal components. I am wondering what exactly qualifies as "lugging" and what will happen if I do this.

For example, many times I am driving at highways speeds in 6th gear and it feels like the engine is lugging when I go to increase my speed, say, from like 60 to 70mph.

Should I be downshifting to 5th to increase my speed? Or is it fine to stay in 6th.

Thanks

[torqueaddict]

Lugging stresses the internal components of the engine as it tries to turn the crank that's much harder to turn because of too high gearing for the given speed. Think of it as trying to ride a bicycle at really low speeds in the highest gear. Or to start off in the highest gear.

I try not to pass in 6th or increase speed drastically. Gentle increases should be ok. I make it a habit to downshift for passing.

[JamesNoBrakes]

It's fine unless you are having to depress the pedal all the way to the floor. At 60mph it will pass just fine in 6th, although not very fast. It really seems to lug if I let the speed decrease to about 45 mph in 6th, but it does just fine around 50mph. Again, if I have to depress the pedal more than about halfway to get acceleration, then I should shift. The other thing to consider is that while the car will purr along at 1000rpm all day long, you do need to exercise the RPM for the rings, so lots of highway miles at low RPM without ever revving up isn't the best thing, it should see higher RPMs too. The torque on tap though means you can get decent mpg without having to go to high RPM to maintain speed.

[Reddy1LE]

Originally Posted by JamesNoBrakes

It's fine unless you are having to depress the pedal all the way to the floor. At 60mph it will pass just fine in 6th, although not very fast. It really seems to lug if I let the speed decrease to about 45 mph in 6th, but it does just fine around 50mph. Again, if I have to depress the pedal more than about halfway to get acceleration, then I should shift. The other thing to consider is that while the car will purr along at 1000rpm all day long, you do need to exercise the RPM for the rings, so lots of highway miles at low RPM without ever revving up isn't the best thing, it should see higher RPMs too. The torque on tap though means you can get decent mpg without having to go to high RPM to maintain speed.

I do the same, I normally shift @ 50mph to 6th gear and car pulls fine. If i let it go below 47,46 it seems to feel sluggish and need to be downshifted.

Exhaust gets louder..but in a "hurting" sense if that makes sense..

[Boost Creep]

Originally Posted by protovack

I know you aren't supposed to lug the engine and that it is tough on internal components. I am wondering what exactly qualifies as "lugging" and what will happen if I do this.

For example, many times I am driving at highways speeds in 6th gear and it feels like the engine is lugging when I go to increase my speed, say, from like 60 to 70mph.

Should I be downshifting to 5th to increase my speed? Or is it fine to stay in 6th.

Thanks

Lugging puts a lot of load on the bearings when you have the least oil pressure down near idle.

Really you don't want to do any kind of heavy acceleration under 1500-2000 or more. Light throttle is fine down low, but the more throttle you want, the more rpms the engine wants.

[VinnAY]

Originally Posted by torqueaddict

Lugging stresses the internal components of the engine as it tries to turn the crank that's much harder to turn because of too high gearing for the given speed. Think of it as trying to ride a bicycle at really low speeds in the highest gear. Or to start off in the highest gear.

I try not to pass in 6th or increase speed drastically. Gentle increases should be ok. I make it a habit to downshift for passing.

Great post.

[VinnAY]

I won't grab 6th unless I'm over 75, 6th has no RPM for the driving situation I find myself in on the freeway/highway around here. In 6th @ <70 the pedal is just too mush for my power needs; low RPM.
Most guys can't or won't grasp the concept that just because it's running and going down the street the <2K RPM range is indicative that you need to downshift at least one gear. A huge part of driving a manual is selecting the gear for the RPM range.

[Vtor_ZL1]

Better swap in that ZL1 1LE 6MT... 6th gear 2500 rpms at 80mph, you'll go looking for 7th gear.


As other said, high loads, low-ish oil pressure, althought mine seems to read 35+ all the time, cold, hot, etc. fancy variable displacement pumps.

[JamesNoBrakes]

Originally Posted by VinnAY

I won't grab 6th unless I'm over 75, 6th has no RPM for the driving situation I find myself in on the freeway/highway around here. In 6th @ <70 the pedal is just too mush for my power needs; low RPM.
Most guys can't or won't grasp the concept that just because it's running and going down the street the <2K RPM range is indicative that you need to downshift at least one gear. A huge part of driving a manual is selecting the gear for the RPM range.

You do realize why they put a 6th gear on the car, right?

[Ryephile]

Go drive an automatic transmission version of the engine you have. Observe the ratios selected for given engine loads and torque request. This gives you evidence of what the OEM deems acceptable engine operation. You will find that at low load the RPM is at low BSFC / high fuel economy, and at high load the RPM is at peak torque to the axle.


You won't find an OEM admitting exactly what "lugging" is, it's too vague a term and is mainly a catch-all term to give them an easy legal path for warranty denials. If the oil pressure is too low and causes metal-metal contact in the bearings, then the engineers failed to design the pump correctly. If there's LSPI, then the combustion chamber was incorrectly designed and ECU calibrators failed at their job.

[Vtor_ZL1]

Comparing automatic and manual for load is... not the same.



Where torque converter acts as damper for loads, clutch... NOT so much.


Try again.

[RedHot_1SS_1LE]

Originally Posted by Vtor_ZL1

Comparing automatic and manual for load is... not the same.



Where torque converter acts as damper for loads, clutch... NOT so much.


Try again.

No... Ryephile is right.

The TC is locked above 2k RPM (not sure of exact RPM) so for peak torque at high load, the auto programming will be very close. Even for low RPM high efficiency driving, a computer controlled TC clutch will 'lock' the TC so that should be close too. Maybe not exactly the same, but definitely close enough to get a good idea of where the powertrain engineers feel the engine is happiest/safest.

[kropscamaro16]

lol i never even use 6th gear because the drone is so bad

[Boost Creep]

Originally Posted by Ryephile

Go drive an automatic transmission version of the engine you have. Observe the ratios selected for given engine loads and torque request. This gives you evidence of what the OEM deems acceptable engine operation. You will find that at low load the RPM is at low BSFC / high fuel economy, and at high load the RPM is at peak torque to the axle.


You won't find an OEM admitting exactly what "lugging" is, it's too vague a term and is mainly a catch-all term to give them an easy legal path for warranty denials. If the oil pressure is too low and causes metal-metal contact in the bearings, then the engineers failed to design the pump correctly. If there's LSPI, then the combustion chamber was incorrectly designed and ECU calibrators failed at their job.

I was going to post something similar.
Low load low rpm, high load high rpm.
If you are just cruising it's inefficient and un-practical to cruise in a lower gear turning 4000 rpm, doesn't make sense unless you are waiting on the third horn beep while driving in Mexico. And when trying to pass someone on a hill going 40, sixth gear and 900 rpm aren't going to help you gap that Prius.