PSDExcursion
Millstone NJ
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Quote:Quote:Look at this and see that after 2000 rpm the torque starts to drop on my 6.0 PSD. So at 2000 rpm I am at my maximum torque and that is were my rpm's are in OD when towing at about 65 mph.
I didn't question at what rpm any particular engine develops its max torque or HP. I just asked what the throttle position would have to be at a praticular rpm in order to develop the max torque at that rpm. In order for your PSD to develop its max torque at 2000 rpm, it must be at WOT. If it is not, it will not develop its max torque.
Bert
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2002 Chevy Express 3500 8.1 155" WB passenger van
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slorebo
San Pedro, Ca. USA
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Quote:Quote:Look at this and see that after 2000 rpm the torque starts to drop on my 6.0 PSD. So at 2000 rpm I am at my maximum torque and that is were my rpm's are in OD when towing at about 65 mph.
I didn't question at what rpm any particular engine develops its max torque or HP. I just asked what the throttle position would have to be at a praticular rpm in order to develop the max torque at that rpm. In order for your PSD to develop its max torque at 2000 rpm, it must be at WOT. If it is not, it will not develop its max torque.
Bert
Bert,
I think you're confusing torque and horse power at WOT
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tgatch
Meridian, ID
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Joined: 08/13/2003
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You folks all need to understand that dyno runs are done at wide open throttle. Basically they start from idle and then slam the throttle to wide open. These numbers are then plotted into the graphs you see.
If you are cruising along at a quarter throttle at 1800 RPMS your truck is not producing max power at that rpm. The only way for that to happen is the truck has to be receiving maximum fuel as it goes through that RPM. The only way to be receiving maximum fuel is wide open throttle.
I don't agree with much of what bert has to say, but he is right on this one guys. Sorry ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/frown.gif "frown")
Tom
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Ag Teacher
Oklahoma
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I think if people would stop and read the posts closely, more folks would agree with Bert instead of arguing with him. Some of you just can't believe that a diesel owner like Bert would dare say a gas engine has positive merits.
If he had originally asked: What has more power? An engine with 345 horsepower or an engine with 300 horsepower. Everyone would agree the engine with 345 HP has more power. But when you diesel guys find out that the Vortec 8.1 has 345 horsepower and the Duramax has 300 everyone says there is no way a gas engine tows better than a diesel(talking older engines here, not the newest, latest, greatest because it doesn't matter). But noone said the gas tows better - the statement is simply the gas has more power because power is measured in horsepower.
Just because you have to justify spending $5000 for an optional engine to your wives doesn't mean you have to convince the whole world to own a diesel too. Let everyone get the TV that best suits they're needs, towing enviorment, and price range. Not everyone wants to tow a 36 foot fifth wheel up pikes peek and it doesn't take the same truck that is used to tow 14,000 pounds up pike peek to tow a pop up around the Gulf Coast. Of course the diesel guys will say to the pop up guys "What if you want a bigger camper someday."
What if? I guess they'll buy a new truck and have a new truck to tow they're big fifth wheel with instead of a 10 year old diesel that they wore out driving back and forth to work and pulling they're pop up.
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sack1
Kent, WA
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Correct you are. Published HP and torque figures are max numbers taken on an engine dynamometer. Those torque numbers are plotted all along the rpm band. From that the math is done to indicate HP which is the work an engine can deliver over time.
I graphically look at torque and HP this way: Take two engines, one produces a greater amount of torque but does not rev as high and produces lower HP numbers. Apply that to a sewing machine attached to both those engines. The engine with higher torque will be able to punch through thicker material but do so only up to a certain rpm where torque drops. The second engine cannot punch through as thick of material but can do so through more repetitions over time. The second engine could complete the job sooner. It is simplistic but I think it works. That is what HP indicates.
You can tell that gas engines get their generally higher HP numbers through rpm that's significantly higher than what the diesels can turn. Now before one makes the comment that rpm is bad and that diesels hold the sweet spot remember that there are mechanical limitations to engine rpm. It's generally measured in piston speed, or distance traveled over a minute. Gas engines generally have designs that allows extra rpm safely. If torque is maintained or drops off more gradually through the rpm range then HP will increase with rpm. If you look at most diesel torque curves they rise quickly at a specific rpm, may plateau for a couple of thousand rpm and then drop like a stone. Gas engines that are not overly tuned generally have more gradual torque curves that extend farther up the rpm range.
For example, while the 8.1 gas engine develops a peak torque reading of 455 ft/lbs @ 3200 rpm, fully 90% of that max is obtainable from about 1700 rpm on up to about 4200 rpm. That makes for a very broad torque spread. (and yes, at wide open throttle) But then I don't have to call down for WOT throttle when I tow so the actual power produced and needed for that situation is reduced. Gosh, I'd hate to think of any of our fuel mileages if we towed with our foot buried in it all the time.
I have to agree though, too much of the time on this forum it's diesel this and diesel that. Almost to the point that some do more than infer that gas engines just don't cut it..ever! Well I guess we're all entitled to our own feelings but let's get real here. If you aren't towing the heavier trailers or do so often up steep mountain passes, for example, a big HD turbo diesel is overkill both in power and cost. But again, to each their own.
There was a fellow here asking about suitable tow vehicles for his 3500# tent trailer a while back. I just knew a diesel fan would chime in..and he did. Unless the guy just had to have a diesel where is the sense in that? We towed our tent trailer of similar weight with an Astro van. It was perfect for it, carried all our stuff plus the family and returned 17 mpg doing it. A diesel would have had more torque but the truck itself could have easily cost twice what the Astro did. Let's face it, diesels are all the rage here and in print. They have come a long way from where they were just a few years ago. But that does not mean that gas engines all of a sudden can't handle the load or have any redeeming features. They are being developed too. The 8.1 develops more power over a broader span than the 7.4 it replaced while being more efficient. It still uses spark plugs and has short coil wires and coils but no longer has a distributor, cap, rotor or points, etc. like some diesel fans here make issue over gas engines about.
Lastly, I'm sure most gas owners who have well matched rigs find they do just fine with their tow vehicles and feel the added expense of a diesel is unwarranted. I don't have the diesel bug so I knew up front that I'd do just fine without one and I do.
I believe to serve those inquiring best one has to temper their emotions about their own choices and look at the broader picture.
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Tincan931
Eden, NC, USA
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It does not matter what brand of truck you buy, as long
as you are happy. If you ever go with a diesel powered
truck, you will throw rocks at any gasser you ever towed
with. I did. Strokin it and lovin it!
Tincan
2005 Jayco Eagle 322FKS, 2004 Dodge Ram 2500 QC, Cummins
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slorebo
San Pedro, Ca. USA
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"I think if people would stop and read the posts closely, more folks would agree with Bert instead of arguing with him. Some of you just can't believe that a diesel owner like Bert would dare say a gas engine has positive merits"
I agree to a point, but in high mileage vehicles I see NO positive merits!
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PSDExcursion
Millstone NJ
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Quote:"I think if people would stop and read the posts closely, more folks would agree with Bert instead of arguing with him. Some of you just can't believe that a diesel owner like Bert would dare say a gas engine has positive merits"
Maybe I should have took his advice on my first Excursion and purchased a 5.4 gasser instead of a 7.3 PSD to tow my 41 ft TT since he says it has more balls.![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/rolleyes.gif "rolleyes")
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Tincan931
Eden, NC, USA
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I have towed with both and there is no comparison when
it comes to towing. It is simple. If you want 0 to 60
in a few seconds, gas is the way to go. If you want work
and torque, up a mountain at a low rpm, diesel is BOSS!
Real truck have GLOW PLUGS!
Tincan
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BertP
Edmonton, Alberta, Canada
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Joined: 11/07/2003
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Quote:Bert,
I think you're confusing torque and horse power at WOT
I don't follow. Can you explain that for me, please?
Bert
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