Keeping revs down - a good thing?

warriorpluto

Original poster
Member
Apr 12, 2012
215
So i guess not taking it over 2k rpm to save gas is hurting the engine? So i should drive it regular like 3k? I'm scared now lol I'm at 152k. If i start driving it above 2k i know my alternator will crap out since it's stock. Guess I'll get a new one and start driving it like it should be driven
 

Sparky

Member
Dec 4, 2011
12,927
warriorpluto said:
So i guess not taking it over 2k rpm to save gas is hurting the engine? So i should drive it regular like 3k? I'm scared now lol I'm at 152k. If i start driving it above 2k i know my alternator will crap out since it's stock. Guess I'll get a new one and start driving it like it should be driven

How do you not go above 2k RPM? I can't accelerate close to normally without it getting to at least 2500 RPM, let alone merging onto the highway.

Actually, letting it hit 2500-3000 RPM on some shifts isn't going to burn that much more fuel - if any, as you are getting up to cruising speed and higher gears faster. In heavier city traffic I can see not getting up to speed much because you'll just stop at the next light again in a couple hundred feet. No sense in being that guy who floors it light to light lol :tongue:

FWIW my normal driving I'll not hit 3000 RPM too often (aside from highway merges) but every so often (a few times a month) I'll accelerate a little harder and get it in the 3k-4k range. Once in a while I'll really nail it and it'll go upwards of 5k RPM. I've never mashed it enough to hit much above that. I'm at 162,500 right now.

Also I'm not sure why your alternator would die if you get in the middle of the RPM range :confused: It should be designed to take full engine range fine.
 

warriorpluto

Original poster
Member
Apr 12, 2012
215
Sparky said:
How do you not go above 2k RPM? I can't accelerate close to normally without it getting to at least 2500 RPM, let alone merging onto the highway.

Actually, letting it hit 2500-3000 RPM on some shifts isn't going to burn that much more fuel - if any, as you are getting up to cruising speed and higher gears faster. In heavier city traffic I can see not getting up to speed much because you'll just stop at the next light again in a couple hundred feet. No sense in being that guy who floors it light to light lol :tongue:

FWIW my normal driving I'll not hit 3000 RPM too often (aside from highway merges) but every so often (a few times a month) I'll accelerate a little harder and get it in the 3k-4k range. Once in a while I'll really nail it and it'll go upwards of 5k RPM. I've never mashed it enough to hit much above that. I'm at 162,500 right now.

Also I'm not sure why your alternator would die if you get in the middle of the RPM range :confused: It should be designed to take full engine range fine.

Normal driving i never go over 2k but highway merges i get to 2.5k. Only took the truck to 4k when i was on a rage because of stupid drivers. That was five months ago. I was thinking the alternator might go because of the old age. It's never been changed.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
I split this discussion off of the head removal "How-to" thread because that other thread's destiny is to be an article. Better to not have back and forth discussions in an article because they could be indexed differently. And articles may be frozen once complete and we don't want to "trap" any questions inside them.
 

Sparky

Member
Dec 4, 2011
12,927
I've heard of engines that don't get out of the low RPM ranges getting gummed up with deposits as it is never breathing enough to "flush" the system out. Constant low airflow can lead to carbon deposits falling out of the airstream and piling up or something like that. Not really sure. But it can't hurt to get the RPMs up higher every so often, especially right after putting something like seafoam or techron in the gas tank to help break carbon deposits and stuff down.
 

MacMan

Member
Mar 3, 2012
194
warriorpluto said:
So i guess not taking it over 2k rpm to save gas is hurting the engine? So i should drive it regular like 3k? I'm scared now lol I'm at 152k. If i start driving it above 2k i know my alternator will crap out since it's stock. Guess I'll get a new one and start driving it like it should be driven
Just drive it normally......keeping it at 2K or below will save gas, but you're going to be a "problem" for people behind you going on the ramp to the freeway.

Keeping RPM's low will have nothing to do with the alternator going bad.....if it wants to crap-out, it will regardless.

My TB has 193K, has the original alternator too, and I just drive it like I want to. Had the RPM's up to almost 5K the other day passing a truck on a side road.....no problems.
 

MacMan

Member
Mar 3, 2012
194
Sparky said:
I've heard of engines that don't get out of the low RPM ranges getting gummed up with deposits as it is never breathing enough to "flush" the system out. Constant low airflow can lead to carbon deposits falling out of the airstream and piling up or something like that. Not really sure.......

Nonsense. Computer adjusts fuel/air mixture regardless of speed.

"Constant low airflow can lead to carbon deposits falling out of the airstream and piling up or something like that."

:crackup:
 

McGMT

Member
Jun 17, 2012
621
MacMan said:
Nonsense. Computer adjusts fuel/air mixture regardless of speed.

"Constant low airflow can lead to carbon deposits falling out of the airstream and piling up or something like that."

:crackup:

Actually, it wasn't very well put but there is something to keeping these newer engines at low rpm and low load all the time. I mentioned this in another threat before that GM had experienced this issue with the northstars especially.... Constant idling and low RPM usage would buildup carbon and in severe instances the rings would not seat and the engine would excessively burn oil.... It is not nonsense, it is the truth to an extent...
 

Denali n DOO

Member
May 22, 2012
5,596
McGMT said:
Actually, it wasn't very well put but there is something to keeping these newer engines at low rpm and low load all the time. I mentioned this in another threat before that GM had experienced this issue with the northstars especially.... Constant idling and low RPM usage would buildup carbon and in severe instances the rings would not seat and the engine would excessively burn oil.... It is not nonsense, it is the truth to an extent...

Ya great theory, then In my case throw in a 5.3 with 4 cylinders not even firing all if not most of the time. That's probably contributes to why my old 5.3 burned soooo much oil it damn near ran itself dry! :confused:
 

McGMT

Member
Jun 17, 2012
621
Denali n DOO said:
Ya great theory, then In my case throw in a 5.3 with 4 cylinders not even firing all if not most of the time. That's probably contributes to why my old 5.3 burned soooo much oil it damn near ran itself dry! :confused:

The fix was really simple back then (03) do an engine clean (seafoam) and run the livin begeezus out of the vehicle for an hour or two to set the rings in ... Worked every time on those... SO, yes, running your engine low rpm all the time will cause increased carbon buildup.... Its the truth...
 

Sparky

Member
Dec 4, 2011
12,927
Denali n DOO said:
Ya great theory, then In my case throw in a 5.3 with 4 cylinders not even firing all if not most of the time. That's probably contributes to why my old 5.3 burned soooo much oil it damn near ran itself dry! :confused:

Except when in DoD mode with 4 cylinders off the reason they are off is mainly because the fuel has been shut off to them. No fuel = no burn = no carbon build up :wink:
 

OctaneRider03

Member
Jul 31, 2012
430
Remember when I said something about my engine vibrating at lower rpm's while it idled? Once I gave it more gas the misfire stopped right away, but as I would slow down to a slower speed, it started again due to the deposits of carbon in the head. Food for thought. Don't worry about going slow man! The alternator will go bad when it's time regardless!
 

MacMan

Member
Mar 3, 2012
194
McGMT said:
... SO, yes, running your engine low rpm all the time will cause increased carbon buildup.... Its the truth...

So, what part of the OP's 150,000 miles caused the carbon build-up?
 

McGMT

Member
Jun 17, 2012
621
MacMan said:
So, what part of the OP's 150,000 miles caused the carbon build-up?


What are u going on about... Are you reading the same discussion the rest of us are?
 

warriorpluto

Original poster
Member
Apr 12, 2012
215
McGMT said:
What are u going on about... Are you reading the same discussion the rest of us are?

The thread was spilt because the roadie said he didn't want the discussion to get too far off in the other thread. OP of that thread had carbon build up in his head which led to constant misfires. I think a loose intake manifold bolt caused it. Thanks for the information guys. Ill run my truck up to 3.5 here and there. I don't take short trips. This is my daily driver so I'll keep the revs up a bit more so carbon doesn't build up
 

dougman

Member
Mar 15, 2012
20
Man, I drive the heck out of mine at times. 95% of the time, I try to keep my acceleration constant and reasonable. I never look at the tach to keep it below a certain number. Recently, I was towing a pop-up trailer up an 8% grade. I had good speed (70 or so), but got caught behind a truck that pulled out in front of me doing about 25 MPH, to pass a semi which took him 4 MILES to complete! I was so ticked that I punched it. I was wide open through first and second gears - topping out at 6K. Yes, that is hard when pulling a trailer up a huge grade, and my temps got a little hot, but it felt good. Of course, I had a Silverado with the DuraMax towing a much larger camping trailer pass my like I was standing still after I pass the semi and the other truck. That is NOT something I do very often, and was truly a rage inspired event. The guy didn't even gain any speed on the semi for the first mile.

My engine doesn't burn more than 1/2 quart of oil between changes (I change at 10% oil life using Mobil1), and I still have my original alternator (and original transmission) at 182K miles.
 

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