Hannibal
Tampa Bay Area
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5200rpm for 100k miles? Why? Even with my lethargic 5.4L, I only occasionally turn 3800-4200rpm on the uphills. Easily less than 1% of our travels. Also, using gear reduction takes the load off of the engine by the percent of the gear ratio so although the engine is running at higher rpm well below it's peak hp rpm, it's doing less work letting gear reduction take the load. Like 2:1 rope and tackle to lift a load. You might have to pull the rope twice as many times but, it will require half the effort on each pull. As for the 5200rpm wearing an engine out, during R&D, Chrysler ran the 5.7L Hemi 300 hours at peak hp rpm full load. Upon dissection, it showed only normal wear and nothing broke or melted. The Cummins can also be run full load at peak hp rpm for hundreds of hours with no ill affects. Loading at low rpm puts more load on the lower end bearings. It's not "easier" on the engine as your ears might suggest.
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rhagfo
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transamz9 wrote:Sport45 wrote:If you run a diesel at 5200 rpm for a mile it will come apart.
A gasoline engine at redline is not tearing it itself apart any more than a diesel operating at redline. (But it may sound like it.)
HAHAHA!! O.K what ever. You win...... ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/smile.gif "smile")
The whole point is a Diesel doesn't need to turn 5,200 rpm to move a large load.
Just remember that the land speed record towing is held by a diesel, 140+ mph towing a TT trailer with all necessary equipment to camp.
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RFOneWatt
Detroit, MI
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I'll say it again -- this thread is the best example of beating a dead horse so I might as well join in the fun once again.
I'm pretty sure I'm one of the very few that has read EVERY post & reply for the last five years. I must say that if you are trying to decide between a diesel and gas TV there is some very valuable information buried in this thread. (Along with A LOT of BS!)
I've posted this before but for those that missed it, and for what it is worth: (NSFW Warning: If you have kids in the room or are easily offended, don't watch -- Eminem was playing on the stereo)
2007 5.4L towing 7000LBS in the mountains of Utah & Wyoming.
Didn't Einstein say "The definition of insanity is doing the same thing over and over and expecting a different result."
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transamz9
Lawrenceburg Ky
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Hannibal wrote:5200rpm for 100k miles? Why? Even with my lethargic 5.4L, I only occasionally turn 3800-4200rpm on the uphills. Easily less than 1% of our travels. Also, using gear reduction takes the load off of the engine by the percent of the gear ratio so although the engine is running at higher rpm well below it's peak hp rpm, it's doing less work letting gear reduction take the load. Like 2:1 rope and tackle to lift a load. You might have to pull the rope twice as many times but, it will require half the effort on each pull. As for the 5200rpm wearing an engine out, during R&D, Chrysler ran the 5.7L Hemi 300 hours at peak hp rpm full load. Upon dissection, it showed only normal wear and nothing broke or melted. The Cummins can also be run full load at peak hp rpm for hundreds of hours with no ill affects. Loading at low rpm puts more load on the lower end bearings. It's not "easier" on the engine as your ears might suggest.
I'm sorry about the 5200 RPM's. I just used that number because it was in a previous post. The way that I look at this is that when a motor is turning 4200 rpm's then it is turning 2X's what I'm turning at 2100 rpms. That's 2X's the wear any way you look at it. When you are turning that 4200 in your truck your torque converter is unlocked and that is a lot of wear on the trans and parts also. You say they test the Hemi for 300 hrs? That's only 18,000 miles at a 60 MPH average. At 40 MPH average (which is more realistic for a vehicle)it's only been tested for 10,000 miles. Now I know you are thinking that you don't run your motor under full power all the time but you would be surprised at how much you do. You don't have to put your foot on the floor to put full power out.
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Hannibal
Tampa Bay Area
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My previous '05 Hemi powered 2500HD at 120k miles when I traded it still used it's usual .5 qt of oil between 5k mile OCIs. Still ran as strong and quiet as it did new. Odd, 4200 rpm is also twice what I'm turning at 2100 rpm! Gotta love math! My '03 Cummins Ram turned 2900rpm on the same uphills the Hemi turned 4200rpm. Neither suffered any ill effects from it.
300 hours at peak hp rpm full load is a good indication of an engine's ability to handle work no matter the engine or how you want to downplay it. How did you arrive at 18000 miles at 60 mph? If running in O/D, that would be 140+mph non stop for 42000 miles. But the engine was in the lab.
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Hannibal
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rhagfo wrote:transamz9 wrote:Sport45 wrote:If you run a diesel at 5200 rpm for a mile it will come apart.
A gasoline engine at redline is not tearing it itself apart any more than a diesel operating at redline. (But it may sound like it.)
HAHAHA!! O.K what ever. You win......
The whole point is a Diesel doesn't need to turn 5,200 rpm to move a large load.
Just remember that the land speed record towing is held by a diesel, 140+ mph towing a TT trailer with all necessary equipment to camp.
Err uh, neither does a gas engine. And the tiny little camper was towed with empty tanks and no propane. If someone with too much money decides to build a gas engine to make 1000 hp to tow a tiny travel travel trailer 140mph, have no doubt it can be done. The diesel was nowhere near a stock production engine.
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rhagfo
Portland, OR
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Hannibal wrote:rhagfo wrote:transamz9 wrote:Sport45 wrote:If you run a diesel at 5200 rpm for a mile it will come apart.
A gasoline engine at redline is not tearing it itself apart any more than a diesel operating at redline. (But it may sound like it.)
HAHAHA!! O.K what ever. You win......
The whole point is a Diesel doesn't need to turn 5,200 rpm to move a large load.
Just remember that the land speed record towing is held by a diesel, 140+ mph towing a TT trailer with all necessary equipment to camp.
Err uh, neither does a gas engine. And the tiny little camper was towed with empty tanks and no propane. If someone with too much money decides to build a gas engine to make 1000 hp to tow a tiny travel travel trailer 140mph, have no doubt it can be done. The diesel was nowhere near a stock production engine.
It wasn't the HP it was the Torque necessary to pull that ultra slick little flat backed trailer, it was a stock production model just with speed rated tires.
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Sport45
Not far enough from Houston, TX
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Quote:It wasn't the HP it was the Torque necessary to pull that ultra slick little flat backed trailer, it was a stock production model just with speed rated tires.
Do stock production models blow that much smoke?
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Hannibal
Tampa Bay Area
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Far from stock production model...
http://news.pickuptrucks.com/2012/11/the-fastest-trailer-tow-in-the-world.html
All the torque in the world without rpm is no motion. Torque and rpm together are known as horsepower in our application. If the truck would have had enough torque to produce the necessary horsepower at 2000rpm, he wouldn't have had to blaze along at 4k rpm.
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transamz9
Lawrenceburg Ky
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I agree with Hannibal on this one. I don't have a doubt in my mind that a gas motor turning the same 1000+ hp as the truck in the video would break the record. I would say that he ran out of RPM's before he ran out of power. All he was doing was trying to beat the old record. That truck had stock gears so he would probably run that, no more empty. A gas motor would be turning north of 10,000 RPM's to get that HP. It would just take twice if not more to build a 1000+ hp gas engine than it would a diesel. I would say the bottom end of that Duramax was stock. That video doesn't impress me and that's not what we are discussing here. We are talking about real world everyday performance with-in the laws of the road. Hell, I've seen semi's grossing 80,000# running 110+ MPH on the hi-ways so I know with a taller final gear they could break the towing record with a light load. That record means squat to me.
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