Cruising RPMís - BMW Luxury Touring Community
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  #1  
Old Jul 1st, 2012, 8:11 am
SteveW SteveW is offline
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Cruising RPMís

Iíve had my 03 LT for close to a year and have been a watching this site daily to learn things about this beast. I keep reading here about how these machines like to be run at much higher revís than my other bikes so I just have to ask, do they really?

Iím talking about normal everyday riding here. As an example, at 50mph in fourth gear the engine runs at around 3k RPMís, and compared to my other bikes except the Triumph thatís screaming. Iíd like this LT to last me for a lifetime, so should I continue cruising around in lower gears and higher revís, or should I shift?
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  #2  
Old Jul 1st, 2012, 8:35 am
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Re: Cruising RPMís

I don't even think about shifting until 5500 RPM.... That's where my girl loves to sing.... Third LT, ZERO issues with winding her up...
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  #3  
Old Jul 1st, 2012, 8:51 am
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Re: Cruising RPMís

cruising down the highway at 50 the bike dosent care if you are in forth or fifth but in fifth u will have less throttel responce but you dont need to run in forth.
i think when guy are talking about the big rpm is when you ask the bike to perform
hard cornering you want the rpm around 5000 or up so you can make it really handel.
also if you have never driven the bike in the upper rpm you have a big plesent surprise
comeing the big girl will suprise you when shifted at 7000 . i dont live by the 5500 rpm rule but definatly take it well above that on occasion
without any fear of damage
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Old Jul 1st, 2012, 8:54 am
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Re: Cruising RPMís

Quote:
Originally Posted by bobst2
cruising down the highway at 50 the bike dosent care if you are in forth or fifth but in fifth u will have less throttel responce but you dont need to run in forth.
i think when guy are talking about the big rpm is when you ask the bike to perform
hard cornering you want the rpm around 5000 or up so you can make it really handel.
also if you have never driven the bike in the upper rpm you have a big plesent surprise
comeing the big girl will suprise you when shifted at 7000 . i dont live by the 5500 rpm rule but definatly take it well above that on occasion
without any fear of damage
+1 on everything. Well said.
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Old Jul 1st, 2012, 9:00 am
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Re: Cruising RPMís

The LT has a rev limiter......Use it...

I was getting on the highway once when suddenly I realized I was still in second...The rev limiter caught me....

I've never heard of an LT engine being damaged by being run too hard...
Just doesn't happen....
You don't necessarily want to run it hard all the time..

But when you're in the twisties. Second gear is all you need.. Roll on to speed up... Roll off to slow down.. Very little braking required....She'll go 85 in second gear... So dont' think you're going to be slow...
She really doesn't start pulling till about 5K....

Have fun..

John
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  #6  
Old Jul 1st, 2012, 9:07 am
SteveW SteveW is offline
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Re: Cruising RPMís

Thanks for the replies guys. I just wanted to be sure that 50 MPH in fifth gear wasnít lugging the engine; I know thatís not good for it.

Well, I wanted a touring sports bike and it seems thatís just what I got. Now that I have the cruising part down pat itís time for me to start exploring the sports bike side of this beast.
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Old Jul 1st, 2012, 9:45 am
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Re: Cruising RPMís

Quote:
Originally Posted by SteveW
Iíve had my 03 LT for close to a year and have been a watching this site daily to learn things about this beast. I keep reading here about how these machines like to be run at much higher revís than my other bikes so I just have to ask, do they really?

Iím talking about normal everyday riding here. As an example, at 50mph in fourth gear the engine runs at around 3k RPMís, and compared to my other bikes except the Triumph thatís screaming. Iíd like this LT to last me for a lifetime, so should I continue cruising around in lower gears and higher revís, or should I shift?

even back in the 70's with the boxers there were guys who insisted the proper way to drive was to shift at the redline - those engines did not have rev limiters - which meant 1st gear in the city all the time - I never liked to listen to all the noise - BMW builds an engine that is perfectly happy chugging around in the city in 5th or staying in gear until you hit the rev limiter - it just needs long runs on the highway to be at its best
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  #8  
Old Jul 1st, 2012, 10:00 am
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Re: Cruising RPMís

I think I'm getting better fuel mileage by staying in forth while cruising 55-60 mph.

chris ogle
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  #9  
Old Jul 1st, 2012, 10:05 am
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Re: Cruising RPMís

This is one of the things I love about the LT--great comfort and smooth ride. However, if you want her to take off her skirt and become a sportbike--hold on, she can make you sizzle!
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Old Jul 1st, 2012, 3:27 pm
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Re: Cruising RPMís

Interesting discussion, I have been thinking about this very thing. I don't think the motor really cares what RPM you're at, as long as it isn't knocking.



On the other hand, I have killed TWO gear boxes in my '02 K1200LT/ Hannigan 2+2. Both times it was the bearing on the front of the input shaft. The first time I thought it might be lubricant related, like maybe the lube I was using got past the seals on the sealed bearing & washed its grease out. Now after having a second gear box fail, I think maybe I need to learn to drive stick. I should keep the RPM up to at least 3,250 - 3,500 under a light load, & 4,000 or more under harder acceleration. My LT is a fulltime sidecar rig, & that extra 500 lbs on the side puts a lot strain on the drive train.



In town I would tend to dog it, & the RMP would drop to maybe 2,500. Then when speeding up coming out of a town, I would just crank it on. The bike accelerated OK like that, but I now believe it put too much stress on the input shaft. If I would have back shifted a gear or two, & spun the motor up some. It would have put a lot less stress on everything, the input shaft especially. It was just easer to be lazy, & leave in a higher gear. But now, this timeÖ when I finish putting my rig back together I plan on keeping the RPM up.
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  #11  
Old Jul 1st, 2012, 4:03 pm
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Re: Cruising RPMís

I am in no higher gear than 4th, unless I am on the interstate@65 or higher in speed. It just feels natural. The only time I am at 2,500 rpm is on my way up or down in the shift pattern, never steady at that rpm.
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  #12  
Old Jul 1st, 2012, 4:22 pm
gary45 gary45 is offline
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Re: Cruising RPMís

Quote:
Originally Posted by Patric
Interesting discussion, I have been thinking about this very thing. I don't think the motor really cares what RPM you're at, as long as it isn't knocking.



On the other hand, I have killed TWO gear boxes in my '02 K1200LT/ Hannigan 2+2. Both times it was the bearing on the front of the input shaft. The first time I thought it might be lubricant related, like maybe the lube I was using got past the seals on the sealed bearing & washed its grease out. Now after having a second gear box fail, I think maybe I need to learn to drive stick. I should keep the RPM up to at least 3,250 - 3,500 under a light load, & 4,000 or more under harder acceleration. My LT is a fulltime sidecar rig, & that extra 500 lbs on the side puts a lot strain on the drive train.




In town I would tend to dog it, & the RMP would drop to maybe 2,500. Then when speeding up coming out of a town, I would just crank it on. The bike accelerated OK like that, but I now believe it put too much stress on the input shaft. If I would have back shifted a gear or two, & spun the motor up some. It would have put a lot less stress on everything, the input shaft especially. It was just easer to be lazy, & leave in a higher gear. But now, this timeÖ when I finish putting my rig back together I plan on keeping the RPM up.

altho there is no comparison between your LT sidecar rig or mine, in the city I shift at very low rpms but if I have to accelerate fast as in going onto the HWY I run very high rpms going thru the gears - no tach but they tell me it has a rev limiter, Yamaha seems to have a very robust motor
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  #13  
Old Jul 1st, 2012, 7:26 pm
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Re: Cruising RPMís

I'll be the first to admit that I don't know much about the physics of engine size and power and it's relationship to revolutions and the weight it has to pull, but common sense tells me that the faster a machine runs--the more the wear. On the other hand, if it doesn't run fast enough to generate enough torque, and it struggles, that may even be worst. You can easily tell when on engine is dogged down and runs free when it reaches a certain rpm. At this point, you have good trottle response and I keep that, as a guide. I have never seen the need to run the LT, over 5000 rpm,s.
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Old Jul 1st, 2012, 7:36 pm
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Re: Cruising RPMís

Quote:
Originally Posted by SteveW
Iíve had my 03 LT for close to a year and have been a watching this site daily to learn things about this beast. I keep reading here about how these machines like to be run at much higher revís than my other bikes so I just have to ask, do they really?

Iím talking about normal everyday riding here. As an example, at 50mph in fourth gear the engine runs at around 3k RPMís, and compared to my other bikes except the Triumph thatís screaming. Iíd like this LT to last me for a lifetime, so should I continue cruising around in lower gears and higher revís, or should I shift?
3,000 is nothing for the LT. However, it isn't just RPM, it is how much load you have on the engine. If I am just cruising along on the level, I will shift into 5th as slow as 45 MPH as the engine is just loafing along. No reason to run at 5,000 in 2nd just to be at 5,000 RPM. However, if you are pulling a steep grade or accelerating up an on ramp to blend in with 70 MPH traffic, then crank up to to 6 grand and get on with business.

As with most things in life, there is no precise formual for all situations. I just try to match the RPM to the load. High load = high RPM, low load = low RPM. That is my style.
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  #15  
Old Jul 1st, 2012, 7:44 pm
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Re: Cruising RPMís

While ridding across Texas I compared the mpg use 4th and 5th which wound up being the same.

We have had people with LTs that have put 200K to over 300K on their LTs. I don't remember any of them having to rebuild the engine?

Gliding through twisties in second gear is delightful.

Best from Tucson
Bob
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Old Jul 1st, 2012, 8:33 pm
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Re: Cruising RPMís

Quote:
Originally Posted by Voyager
3,000 is nothing for the LT. However, it isn't just RPM, it is how much load you have on the engine. If I am just cruising along on the level, I will shift into 5th as slow as 45 MPH as the engine is just loafing along. No reason to run at 5,000 in 2nd just to be at 5,000 RPM. However, if you are pulling a steep grade or accelerating up an on ramp to blend in with 70 MPH traffic, then crank up to to 6 grand and get on with business.

As with most things in life, there is no precise formual for all situations. I just try to match the RPM to the load. High load = high RPM, low load = low RPM. That is my style.
Voyager,
you made perfect sense to me. The onlything I could add is : sometimes the gear you'r in maybe more important than the rpm,s.
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  #17  
Old Jul 2nd, 2012, 7:00 am
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Re: Cruising RPMís

90% of my riding is in max. mpg mode. I'm almost always in 5th gear by 35 MPH on flat ground. My last fill up back & forth to work was 55.98 MPG.
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  #18  
Old Jul 2nd, 2012, 7:10 am
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Re: Cruising RPMís and mpg

Quote:
Originally Posted by saddleman
90% of my riding is in max. mpg mode. I'm almost always in 5th gear by 35 MPH on flat ground. My last fill up back & forth to work was 55.98 MPG.
My digital displays says I am getting around 50mpg but when I fill my gas tank
it is more like 45mpg and when check it by miles ran since last fillup.
The biggest problem I have is filling it to the same level in the tank each time
so I can accurately check it.
I use the side stand and try to have the bike on the level with front wheel straight when I fill up, but it still seems to vary as to how much I can get in the
tank and how high the bar goes on the LCD display.

I guess it is a work in progress to learn how to do it accurately.
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  #19  
Old Jul 28th, 2012, 5:25 am
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Re: Cruising RPMís

Think Aircraft engine; Long distances at high speeds will not hurt the engine. Aircraft engines routinely run at 55-75% power.

Regards,

Will
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Old Jul 28th, 2012, 6:39 am
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Re: Cruising RPMís

Very low RPM will wear out crank and rod bearings faster than higher, especially if you routinely are at high throttle settings at low speed. That is commonly called "lugging" the engine. Lubrication of the bearings is based on the "hydrodynamic wedge" principle, where the oil being "sheared" between the bearing surfaces creats a wedge between the surfaces. At lower RPM this wedge is much shorter, beginning where the oil is introduced between them (at the oil hole in the crank, and somewhat at the edge of the bearing insert that is beveled). This can allow the bearing surfaces to touch, where at higher RPM the wedge is much longer, and the wedge creates higher pressure between the surfaces. As the crank rotates, the oil introduction hole moves around the bearing, and when it is approaching the non load side, the pressure created by the shearing action of the oil will not reach the other side of the bearing where it is really needed. There will usually be a microscopic film of oil there, hopefully keeping the bearings from touching, but this can be tenous. Best to keep the high pressure shear wedge as far around the bearing as you can to keep the bearings seperated as much as possible.

Low RPM engines, like V-Twins, normally have much larger crank journals, so that the surface speed of the bearing surfaces is still reasonably high at lower RPM. The crank journals on higher performance engines are typically much smaller so that the pearing surface speed at their normally higher RPM stays in a reasonable range at red-line. They do NOT like high power settings at low RPM.

If you want to expect the best life of the LT crank bearings, do not do high throttle at under 3,000-3,500 RPM! It is perfectly fine to loaf along on the highway at low RPM, but if you need to use high power, as to pass, DOWNSHIFT! You will pass much faster, and be doing the engine a big favor.

When accellerating at high throttle settings, keep the RPM high enough so that when you shift to the next higher gear it does not drop below 3,500. Better for the engine, and a heck of a lot more fun.

About the only time my LT ever saw below 3,000 RPM was on start from stopped. Never did that at high throttle, waited until the RPM was up a little before the "big twist". Even on the highway, I did not use 5th gear until I could do so at above 3,500. I would downshift at above 3,000.

When you have a basic understanding of mechanical engineering and engine design principles, you tend to drive/ride differently. Others do it because it is more fun.
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  #21  
Old Jul 28th, 2012, 9:46 am
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Re: Cruising RPMís

Hmmm, this thread has me thinking I need to change my style. My LT almost never sees anything about 4000 on the tach, I never really thought I was lugging the engine because when you shift at 4000 you end up in the next gear between 2,500 and 3,000 but now I think I might need to reconsider.

While I ponder a major life-changing event (see previous paragraph) this next thought kind of dovetails with it. Is there any truth whatsoever to this 'carbon build-up' thing? I have a riding partner who insists that the inside of the engine on my R1220C and LT are getting all gucked up because I don't 'blow out the carbon', meaning that I never hop on and really run the bike hard. I just always thought this was an excuse invented by people who wanted to justify racing all around.
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Old Jul 28th, 2012, 2:25 pm
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Thumbs up Re: Cruising RPMís

Quote:
Originally Posted by jzeiler
I am in no higher gear than 4th, unless I am on the interstate@65 or higher in speed. It just feels natural. The only time I am at 2,500 rpm is on my way up or down in the shift pattern, never steady at that rpm.
+1
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  #23  
Old Jul 29th, 2012, 12:31 am
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Re: Cruising RPMís

I do lug my motor around town but I don't ask it for much while lugging it. And I always find a reason to get the rpm's up before putting her to bed, carbon build up can hurt fuel efficiency as well. My mechanic out of Daytona claims that lugging these motors can contribute to other problems from clutch to final drive. So go to the whip every now and then.
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  #24  
Old Jul 29th, 2012, 1:23 am
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Re: Cruising RPMís

Quote:
Originally Posted by JPSpen
The LT has a rev limiter......Use it...

I was getting on the highway once when suddenly I realized I was still in second...The rev limiter caught me....

I've never heard of an LT engine being damaged by being run too hard...
Just doesn't happen....
You don't necessarily want to run it hard all the time..

But when you're in the twisties. Second gear is all you need.. Roll on to speed up... Roll off to slow down.. Very little braking required....She'll go 85 in second gear... So dont' think you're going to be slow...
She really doesn't start pulling till about 5K....

Have fun..

John
++1
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  #25  
Old Jul 29th, 2012, 9:08 am
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Re: Cruising RPMís

I have always done a lot of city driving with my BMW's, wonder how many people who drive motorcycles drive standards in 4 wheel vehicles, with automatics you can "floor it" because the torque converter stall speed in a car is around 2K rpm's. If you only drive standards in cars and trucks you learn to just give it enough throttle at low rpm/speed otherwise you are asking for trouble = $$$

had a friend who was a really good rally driver but could not keep a clutch in his car - you only had to listen as he started forward or backed up to understand why

lugging is too low rpm with too high throttle for given load and speed and the LT motor is really good at letting you know by the way it acts if you listen to it
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Old Jul 29th, 2012, 8:36 pm
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Re: Cruising RPMís

Quote:
Originally Posted by dshealey
Very low RPM will wear out crank and rod bearings faster than higher, especially if you routinely are at high throttle settings at low speed. That is commonly called "lugging" the engine. Lubrication of the bearings is based on the "hydrodynamic wedge" principle, where the oil being "sheared" between the bearing surfaces creats a wedge between the surfaces. At lower RPM this wedge is much shorter, beginning where the oil is introduced between them (at the oil hole in the crank, and somewhat at the edge of the bearing insert that is beveled). This can allow the bearing surfaces to touch, where at higher RPM the wedge is much longer, and the wedge creates higher pressure between the surfaces. As the crank rotates, the oil introduction hole moves around the bearing, and when it is approaching the non load side, the pressure created by the shearing action of the oil will not reach the other side of the bearing where it is really needed. There will usually be a microscopic film of oil there, hopefully keeping the bearings from touching, but this can be tenous. Best to keep the high pressure shear wedge as far around the bearing as you can to keep the bearings seperated as much as possible.

Low RPM engines, like V-Twins, normally have much larger crank journals, so that the surface speed of the bearing surfaces is still reasonably high at lower RPM. The crank journals on higher performance engines are typically much smaller so that the pearing surface speed at their normally higher RPM stays in a reasonable range at red-line. They do NOT like high power settings at low RPM.

If you want to expect the best life of the LT crank bearings, do not do high throttle at under 3,000-3,500 RPM! It is perfectly fine to loaf along on the highway at low RPM, but if you need to use high power, as to pass, DOWNSHIFT! You will pass much faster, and be doing the engine a big favor.

When accellerating at high throttle settings, keep the RPM high enough so that when you shift to the next higher gear it does not drop below 3,500. Better for the engine, and a heck of a lot more fun.

About the only time my LT ever saw below 3,000 RPM was on start from stopped. Never did that at high throttle, waited until the RPM was up a little before the "big twist". Even on the highway, I did not use 5th gear until I could do so at above 3,500. I would downshift at above 3,000.

When you have a basic understanding of mechanical engineering and engine design principles, you tend to drive/ride differently. Others do it because it is more fun.
Mr. Shealey, My hat is off to you sir! I get it! Thank You!!
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Old Aug 4th, 2012, 11:08 am
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Location: Lawrenceville, PA, USA
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Re: Cruising RPMís

Quote:
Originally Posted by will3hawks
Think Aircraft engine; Long distances at high speeds will not hurt the engine. Aircraft engines routinely run at 55-75% power.

Regards,

Will
Most piston aircraft engines are NOTHING like the engines in our LTs and most cars. Airplane engines are designed for low RPM (most don't run above 3,000 RPM and often 2,700 is the limit) and they cruise at 2,200 to 2,400. They are also highly understressed on a HP/CI basis. My Skylane had a 470 cubic inch engine that developed only 230 HP. That is way less than most auto engines develop from that displacement.

The LT displaces 71.52 CI. Stressed the same is my O-470 Continental, it would produce only 35 HP!

Airplane engines are designed to fun at low RPM, yet produce high torque. Yes, they cruise at high relative power outputs, but we are talking 75% of a relatively small max power output for the size of the engine. So, comparing airplane engines to an LT is not only apples to oranges, it is probably more like comparing fruits and vegetables!
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  #28  
Old Aug 4th, 2012, 11:13 am
Voyager Voyager is online now
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Re: Cruising RPMís

Quote:
Originally Posted by Samir
I do lug my motor around town but I don't ask it for much while lugging it. And I always find a reason to get the rpm's up before putting her to bed, carbon build up can hurt fuel efficiency as well. My mechanic out of Daytona claims that lugging these motors can contribute to other problems from clutch to final drive. So go to the whip every now and then.
It sounds like you are confusing low RPM with lugging. They are not synonymous. I run my LT at low RPM all the time, but I rarely lug it. Cruising through town in 4th gear at 40 MPH on the level isn't lugging. It is only lugging if you whack the throttle wide open when at low RPM in a high gear.

It is much more about how much power you are asking from the engine at a given RPM, then the RPM itself. Otherwise, the engine would be "lugging" the most when idling.
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  #29  
Old Aug 4th, 2012, 11:45 am
gary45 gary45 is offline
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Re: Cruising RPMís

Quote:
Originally Posted by Voyager
.

It is much more about how much power you are asking from the engine at a given RPM, then the RPM itself. Otherwise, the engine would be "lugging" the most when idling.
+1 100%
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