themaincop
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Just to clarify: sometimes in light traffic I'll be driving around in third and then traffic will slow down a bit and my revs will get down to like 1500-1750 or in around there. Is there anything wrong with gently accelerating from low RPMs if I want to gradually get back up to speed or should I always downshift? I never aggressively accelerate if I'm below 3k but I've been unsure about getting back up to speed in just light driving while at a gearing disadvantage.
charleswrivers
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Again... the key word being 'gently'. If we're talking about the engine under minimal load, and load being able to be gauged by manifold pressure... as in still being in a vacuum... *I* don't see any problem with that. I do it myself.
With the car unloaded w/just me in it on a level grade... I'll go 35 in 6th. RPMs are very low... but so is engine load. It requires virtually no throttle and manifold pressure is pretty much bottomed out at 10 (can't remember if it's inHG or psi...).
You sound like you have the right idea at using minimal throttle and accelerating slowly if you're going to stay in a higher gear vice downshifting. Obviously, if you need to give an aggressive amount of throttle and build a lot or full boost... downshift. The driving style you're describing sounds like one which does not put excessive strain on your powertrain.
I'm not the end all be all authority... (I'm not an authority at all!) but based on what you're describing, I'd toss you the keys to my own car and be comfortable it'd be driven just fine.
tehSteve
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I have a bumper to bumper commute in NY/NJ traffic. Too much being on and off the clutch in slow moving traffic, you will notice your engine will lug every time you come on and off the clutch. If you are climbing a hill rather slowly and decide to shift into 4th, you will feel your entire car vibrating until you gear down.
In traffic, I always leave about a cars worth of space in front of me. This helps in those situations where traffic begins to move, but in 3 seconds it is at a dead stop again. The additional space allows me to be less aggressive with the clutch.
Not sure what gear you are in during your commute. But you can literally make a 2nd gear start without much issues.
Will require a tiny bit more revs and you will notice a slight vibration. That is completely normal (unless you really rev it out a lot).
You can be rolling at 5mph (never clutching in) and you can still press the gas and move in 2nd.
It may shake a little little bit, but that is completely normal.
If you clutch in during this situation and decide to stay in 2nd and clutch off, you might experience a little buck.
To get rid of the buck, you can give it tiny AF amount of revs as you hit the bite point.
If you are rolling under 5mph to a red light and all of a sudden it turns green, you can either drop to 2nd or slowly slowly continue to apply gradual gas in 3rd. Do not WOT it.
You won't even notice the engine lug. The downfall of this is it takes longer to get up to speed, but it works.
Key here is to NEVER mash 3rd.
I also was able to pull this off in 4th gear too. Although it took me like 20 seconds to get up to speed LOL. Remember no WOT.
However, it is not a habit. I usually drop gears as I really enjoy giving the throttle a slight blip for a satisfying rev match.
As long as you aren't WOT in these situations, I think you are fine. Minimal lugging is negligible especially if you know how to modulate it. Go WOT and you will have a bad time with the connecting rods. If you do it right, the only long term effect I see would be increased wear on your mounts from some shaking. Just like from normal everyday driving over bumps and whatever, but at a slightly more increase rate.
In traffic, I always leave about a cars worth of space in front of me. This helps in those situations where traffic begins to move, but in 3 seconds it is at a dead stop again. The additional space allows me to be less aggressive with the clutch.
Not sure what gear you are in during your commute. But you can literally make a 2nd gear start without much issues.
Will require a tiny bit more revs and you will notice a slight vibration. That is completely normal (unless you really rev it out a lot).
You can be rolling at 5mph (never clutching in) and you can still press the gas and move in 2nd.
It may shake a little little bit, but that is completely normal.
If you clutch in during this situation and decide to stay in 2nd and clutch off, you might experience a little buck.
To get rid of the buck, you can give it tiny AF amount of revs as you hit the bite point.
If you are rolling under 5mph to a red light and all of a sudden it turns green, you can either drop to 2nd or slowly slowly continue to apply gradual gas in 3rd. Do not WOT it.
You won't even notice the engine lug. The downfall of this is it takes longer to get up to speed, but it works.
Key here is to NEVER mash 3rd.
I also was able to pull this off in 4th gear too. Although it took me like 20 seconds to get up to speed LOL. Remember no WOT.
However, it is not a habit. I usually drop gears as I really enjoy giving the throttle a slight blip for a satisfying rev match.
As long as you aren't WOT in these situations, I think you are fine. Minimal lugging is negligible especially if you know how to modulate it. Go WOT and you will have a bad time with the connecting rods. If you do it right, the only long term effect I see would be increased wear on your mounts from some shaking. Just like from normal everyday driving over bumps and whatever, but at a slightly more increase rate.
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dblotii
Member
It seems we have different definitions of lugging around here. For me (an automotive powetrain engineer with over 30 years experience), I define it by 2 things:
1) a high enough load at low engine speed that you feel significant powertain vibration and/or noise
2) a high enough load at low speed that you will get better fuel economy by downshifting
There is nothing wrong with being in top gear with little of no pressure on the gas pedal. In general, the lower engine speed you can make the necessary power, the more efficient. The other thing to note is that with a modern engine, you can't actually damage anything by lugging. The calibration is sophisticated enough to prevent any damage including low-speed preignition or super-knock. The young engineer in the video is correct that it is a concern at high load and low rpm, but I would not worry at all about that unless you are at continual full-load at low engine speed in warm weather and you stay there for a couple of minutes.
My recommendation for shifting strategy is as follows:
There is no one correct answer to what rpm you should upshift. It all depends on what you want to do with the car in the next seconds of driving. If you want more power, then you might want to downshift or stay in your current gear. If not, upshift to keep the engine revs down to save fuel and wear and tear on the engine and accessories. Don't upshift if that will result in lugging the engine. It doesn't matter if you are driving a sports car, motorcycle, or family car; the following is the basic logic to follow for shifting a manual transmission for both efficiency and performance:
· Try to think ahead about the next 10 seconds or so of driving
· If you upshift to the next higher gear will you have enough power to do what you want to do with the car? (this all depends on how fast you want to accelerate and whether you are going uphill or downhill)
· If so, go ahead and upshift, but not if that will result in lugging the engine
· If not, then decide if you can attain the level of power you need in your current gear or you need even more power
· If you need more power than is available in your current gear then downshift
Keep running this algorithm in your head as you drive. You always want to strive to get in top-gear, but not at the expense of not having enough performance, or lugging the engine, or not having fun!
Dave
1) a high enough load at low engine speed that you feel significant powertain vibration and/or noise
2) a high enough load at low speed that you will get better fuel economy by downshifting
There is nothing wrong with being in top gear with little of no pressure on the gas pedal. In general, the lower engine speed you can make the necessary power, the more efficient. The other thing to note is that with a modern engine, you can't actually damage anything by lugging. The calibration is sophisticated enough to prevent any damage including low-speed preignition or super-knock. The young engineer in the video is correct that it is a concern at high load and low rpm, but I would not worry at all about that unless you are at continual full-load at low engine speed in warm weather and you stay there for a couple of minutes.
My recommendation for shifting strategy is as follows:
There is no one correct answer to what rpm you should upshift. It all depends on what you want to do with the car in the next seconds of driving. If you want more power, then you might want to downshift or stay in your current gear. If not, upshift to keep the engine revs down to save fuel and wear and tear on the engine and accessories. Don't upshift if that will result in lugging the engine. It doesn't matter if you are driving a sports car, motorcycle, or family car; the following is the basic logic to follow for shifting a manual transmission for both efficiency and performance:
· Try to think ahead about the next 10 seconds or so of driving
· If you upshift to the next higher gear will you have enough power to do what you want to do with the car? (this all depends on how fast you want to accelerate and whether you are going uphill or downhill)
· If so, go ahead and upshift, but not if that will result in lugging the engine
· If not, then decide if you can attain the level of power you need in your current gear or you need even more power
· If you need more power than is available in your current gear then downshift
Keep running this algorithm in your head as you drive. You always want to strive to get in top-gear, but not at the expense of not having enough performance, or lugging the engine, or not having fun!
Dave
alpineshepherd
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Wondering the same, lol. Mine has been minmal but after reading this, I kinda regret upshifting shifting below 2k while the car is warming up. Also wish I would've fosnshifted a little more often up yo this point.
dblotii
Member
Take it from an engine engineer, while there have been a few automotive engines that could have the bearings overloaded by lugging, there are no modern engines that won't survive continual full load at any speed above 1500 rpm. You can't do anything worse to your engine than what an OEM does during hundreds of hours of General Durability testing, which engine have to pass without any significant wear. The entire lower-end of the engine is designed to be safe at full load across the entire speed range. The only bad things about lugging are that it may be sub-optimal for fuel economy and of course noise and vibration
ToastedSi
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quick question about lugging. This is my first manual.
Lets say i'm cruising at 6th gear at 60mph and want to increase my speed to lets say: 65-70. Would it be okay to ease in my throttle to eventually get to those speeds or do I have to downshift?
Obviously, I won't WOT at 6th gear
Lets say i'm cruising at 6th gear at 60mph and want to increase my speed to lets say: 65-70. Would it be okay to ease in my throttle to eventually get to those speeds or do I have to downshift?
Obviously, I won't WOT at 6th gear
ricepaperscissor
Member
keep it in 6th
10GenPearlSi
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You don't have to baby it, just don't abuse it. It is fine to go 1/2 or even 3/4 throttle to pass. Pushing it to the floor might be a bit much.
360glitch
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That is probably going to be dependant on your tune. Many of our cars are commmanding full boost at 3/4 throttle, which is what you want to avoid in a “lugging” situation.
tacthecat
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Peanut Gallery input - This is an Si; unless you're on a significant uphill (think Mt Washington, Donner Pass, or I-77 north of Charlotte) you're into the meat of the motor at 60 - go for it!
Lesser designs beware.
Lesser designs beware.
dblotii
Member
There is nothing to fear. Isn't there a shift light?at 6th gear, I've been afraid of push throttle more than 30%. but that's just me
but thanks for the input guys
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