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What revs?
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=25223		 Page 1 of 1
Author:  ed. [ Tue Oct 09, 2007 1:12 am ]
Post subject:  What revs?
What revs do you consider as working the CRD hard?
Am I babying it too much by keeping revs under 2500rpm?
Author:  Sir Sam [ Tue Oct 09, 2007 1:29 am ]
Post subject:  Re: What revs?
ed. wrote:
What revs do you consider as working the CRD hard?
Am I babying it too much by keeping revs under 2500rpm?


I dunno, when you floor it where does it shift at?
Author:  onthehunt [ Tue Oct 09, 2007 1:45 am ]
Post subject: 
Working the engine hard really has nothing to do with revs. How much you are loading it is where the work comes in. I would say you are driving it way too nice if you never go above 2500 rpm's. How did you break it in?? Hope you at least pulled something. You need boost to seat the rings. Does your crd have excessive oil consumption?
Author:  ed. [ Tue Oct 09, 2007 1:59 am ]
Post subject: 
Nah I bought it with 66,000kms on it.
I try not to go over 2500 when just daily driving but offroad I think it's been up and over 3k as I can hear the turbo flutter when you back off. IIRC it's called compressor surge?
Author:  RTStabler51 [ Tue Oct 09, 2007 8:49 am ]
Post subject: 
I don't like to go over 3k, but mainly because seems like all the hp/tq is below that....other wise I don't care what it revs at as long as it ain't over 4k in this thing!
Author:  nursecosmo [ Tue Oct 09, 2007 9:19 am ]
Post subject: 
Diesels like to rev fast now and then. The ECM won't allow you to rev it too high.
Author:  gmctd [ Tue Oct 09, 2007 4:10 pm ]
Post subject: 
The sweet spot is on the map - 295tq @ ~1900rpm, and ~160hp @ ~3800rpm - the engine is designed to run in those ranges continuously, if properly maintained - the lower the rpm, the better the fuel economy, which is where Diesel's excel.

An EGT guage would be a better indicator - you should regularly get EGT up around ~650degf for extended periods to clean out the soot trap so the engine can breathe
Author:  ed. [ Tue Oct 09, 2007 5:29 pm ]
Post subject: 
Sounds like I need to give it a bit more stick. :lol:
Author:  gmctd [ Tue Oct 09, 2007 6:53 pm ]
Post subject: 
G'Day, mate - yep, a monthly walk-about at hiway speeds ought just about doit fer ya, right?
Author:  Saber [ Tue Oct 09, 2007 7:07 pm ]
Post subject: 
about once a week I get on it. Most of the time on a up hill on ramp I take it to a 100. Blows all the soot out :D Fun to do when a Japanese vehicle is behind you:twisted:
Author:  Tinman [ Mon Oct 15, 2007 9:27 am ]
Post subject: 
High load, low rpm is far more deleterious than the same load a higher rpm. "Lugging" puts a lot more force/wear on bearings and engine internals than rpms. Of course, the higher the duty cycle, the more wear/shorter life. Hard to lug a automatic though. Don't worry about it, drive it. It's probably good to do a full throttle run every now and again to get the cylinder temps and pressures up to clean out the combustion chamber.
Author:  BioJeep [ Thu Oct 18, 2007 7:12 pm ]
Post subject: 
Never baby turbodiesels. Rrunning regularly at high rpms and high loads helps keep the movement of the turbine vanes & piston rings free. This may be particularly important given the oil CRDs have in their intakes (soot + oil = black cement). However, if you have a manual, do not run it at high rpm for any extended length of time. This can result in cylinder wall glazing, which sucks. And, never, ever let your CRD idle unnecessarily for any extended period of time. I run it to redline at WOT regularly, probably once every 30-50 miles, often under moderate load. Think of it as exercise.
Author:  ed. [ Thu Oct 18, 2007 9:39 pm ]
Post subject: 
Thanks for the replies guys.
I've heard about the idling for extended period of time but what is considered an "extended period of time"?
1min? 5mins? 15mins?
Author:  ATXKJ [ Fri Oct 19, 2007 10:35 am ]
Post subject: 
A lot of the big rig drivers let them idle overnight - or at least hours at a time, that's where the warnings show up.
The ~ 5-10 min (don't remember exact numbers) time is recommended in the manual for cooldown if you've been running hard (trailer at speed)
So I'm guessing excessive is greater than 30min or so.
Author:  dgeist [ Fri Oct 19, 2007 11:26 am ]
Post subject: 
ATXKJ wrote:
A lot of the big rig drivers let them idle overnight - or at least hours at a time, that's where the warnings show up.
The ~ 5-10 min (don't remember exact numbers) time is recommended in the manual for cooldown if you've been running hard (trailer at speed)
So I'm guessing excessive is greater than 30min or so.


I was under the impression that the cooldown period listed in-manual is more-so for the intercooler and turbo components, which depend partly on air flow for cooling, although I'm not sure what the effect of the EGR being shut down has on this. Slower warm-up, faster cool-down I suppose. Ultimately, the VM has a heavy iron block anyway, so once it gets up to temp, it's pretty darned warm for HOURS after you shut it off.
Author:  Sir Sam [ Fri Oct 19, 2007 6:14 pm ]
Post subject: 
dgeist wrote:
ATXKJ wrote:
A lot of the big rig drivers let them idle overnight - or at least hours at a time, that's where the warnings show up.
The ~ 5-10 min (don't remember exact numbers) time is recommended in the manual for cooldown if you've been running hard (trailer at speed)
So I'm guessing excessive is greater than 30min or so.


I was under the impression that the cooldown period listed in-manual is more-so for the intercooler and turbo components, which depend partly on air flow for cooling, although I'm not sure what the effect of the EGR being shut down has on this. Slower warm-up, faster cool-down I suppose. Ultimately, the VM has a heavy iron block anyway, so once it gets up to temp, it's pretty darned warm for HOURS after you shut it off.


You dont want to shut a HOT engine off and let HOT oil sit and cook in a HOT turbo, that can drastically shorten turbo life.
Author:  Cowpie1 [ Sun Oct 21, 2007 10:53 pm ]
Post subject: 
Tinman wrote:
High load, low rpm is far more deleterious than the same load a higher rpm. "Lugging" puts a lot more force/wear on bearings and engine internals than rpms. Of course, the higher the duty cycle, the more wear/shorter life. Hard to lug a automatic though. Don't worry about it, drive it. It's probably good to do a full throttle run every now and again to get the cylinder temps and pressures up to clean out the combustion chamber.


I have been reading these statements and I am trying to figure out who came up with the info.

Most modern (last 5-6 years) are designed to lug and putting them at high RPM or redline is not a good idea.

Case in point... ALL CAT, Cummins, Volvo, International, Mack, etc engines are designed to operate at lower RPMs than earlier models. It is not uncommon to "lug" them down to 1000 RPM even under an 80K lb load. They operate best and most effectively at 1300-1400 RPM. This is the middle of the power band.

Likewise, the VM reaches it's peak torque at 1800. The torque drops off starting at 2500. Therefore the power band is between those two values. The engine is designed to operate best in that range and diesels do not need to be run up to "clean" them out.

I know that some may disagree, but having put close to 3 million miles on various diesels including 1.4 million on my last Freightliner and not EVER having a major problem or losing a turbo I got a good feeling about my comments. I presently have over 300K on my Volvo and REGULARLY "lug" it down to 1000RPM and NEVER rev it above 1600 and it runs like a champ and pulls the hills great. I regularly operate it at about 1300 RPM and it purrs like a kitten.

Some of those out there need to get out of the 20th century regarding diesels and catch up to the new technology. Thing have changed quite a bit in the last few years. Since this is important to my business, I put in a lot of effort in studying the newer engines. at $25K a pop for an engine, I can't afford to play games with how they are supposed to operate.
Author:  Tinman [ Sat Oct 27, 2007 9:32 pm ]
Post subject: 
Perhaps we should define "lugging". I've been told it is running and engine at a rpm that it can't pull out of. Such as running up a hill with a load, low rpm, heavy fuel (wot) and the engine is not able to accerlate. I agree that running at redline a lot isn't good for longevity but heavy duty engines are dyno tested and full load, full throttle and redline for days on end. I don't like to rev my engines and perfer to drive in the "meat' of the powerband like a diesel is meant to be driven, lower RPM. That's one reason I like diesels, they don't have to rev high to make power. I bet my older truck hasn't seen 60sec at redline total it's whole life (150K miles). But it isn't going to hurt these engines the run them at high rpms some. No need to run around in second gear but no sense in avoiding 4k rpm on the little VMs to pass someone either.

As for "blowing' out the engine. I agree it's a stretch of logic but these newer engines (in the trucks at least) have had some issues with carbon built up on the injectors. I've heard of voided warrenties for too much idling. Trucks that run empty and easy a lot sometimes have had issues as well, so that's why I said that. But I've heard it from older diesel drivers too. I try to run a double strength stanadyne conditioner at oil change to keep the insides clean. You obviously have a lot more experience driving diesels than I ever will, so your point is well taken.


"Forget the Demicans and Republicrats.... vote Libertarian!" :D :D Right on, brotha'
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