Common misconceptions

[Lakeside53]

What does this have to do with CHAINSAWS?

I think you're being ignored

 

[2Coilinveins]

when i was looking at new internationals they had high output diesels that were only available in emergency vehicles.

I can understand why that'd be possible. Emergency vehicles don't rack up nearly the miles OTR trucks do, and (hopefully) get meticulous maintenence. Higher output for less time. The ones at the local volunteer fire station are always on a block heater, even in the summer. No cold starts.

 

[kf_tree]

http://www.web-cars.com/math/horsepower.html

 

[Vman]

(and it's genius).

it is "Jenius"

 

[Simonizer]

http://www.web-cars.com/math/horsepower.html

Nice link. By now you understand that diesel horsepower vs gasoline horsepower is as asinine as comparing hydroelectric watts to nuclear reactor watts. A horsepower is a horsepower.

 

[spacemule]

One of my favorite misconceptions is the people who mistake great volumes with great pressures. You know, the ones who call you a liar when you tell them that big tractor tires only cary about 20 psi of pressure.

 

[spacemule]

Which weighs more, a lb. of feathers or a lb. of lead?

 

[ray benson]

Horsepower - Gas vs. Diesel. An interesting comparison.
http://www.buymytractor.com/HP vs Torq.htm

 

[PWB]

We've got some F450's at work with the powerstrokes, way too hard on fuel and gutless. I have an old GMC at home I repowered with a 354 Perkins (a natural!) that beats them both ways, power and mileage. This 354 is rated at 120 hp at 2800, and if I remember right, 345 ft/lbs of torque. Why can I outrun/outwork a powerstroke for less fuel?

The latest version of the 6 l ford seems pretty good, finally got the bugs out. Still think a diesel should be inline though! Never seen a V6 or V8 diesel yet that could match an inline (although some of the old Detroits could make power when cranked!)

 

[Lawn Masters]

its about torque not horsepower in a diesel. you cant pull something with sheer horsepower alone, you need torque behind that hp to pull it.

 

[Simonizer]

its about torque not horsepower in a diesel. you cant pull something with sheer horsepower alone, you need torque behind that hp to pull it.

Please explain. What is a transmission for? What is the relationship between torque, RPM and horsepower? I am confused.

 

[Mange]

Please explain. What is the relationship between torque, RPM and horsepower? I am confused.

It is called Rolls and it fits the description exactly!

 

[JohnL]

Horsepower is Horsepower
Torque is Torque

The only differences are where in the rpm band they peak. In Diesels the torque peaks at a lower rpm.


More specifically, the difference is in the HP vs RPM and Torque vs RPM graphs look like, how flat they are, how much of the RPM band has high enough HP or Torque that is usable for doing work.

 

[kentuckydiesel]

phillip

what kind of rims are on that rig? they look like alcoa ........

Yep, alcoa classics. -Phillip

 

[kentuckydiesel]

clean looking truck for that many miles.........but you have the 7.8 unlike the new recalled 6.0 getting 12 miles to the gallon. i'm only at 241,000 on my 97 dodge. i've had some performace up grade's like cold air kit, 4in exhaust and cam plate in pump. i've had to replace 2 starters and a throttle linkage but other than that eveything on the moter is origional.

on some of the new trucks they offer 300hp diesels. that why ford put that 6.0 out before it was ready bugs and all to compete in the hp war a few years ago. i'm pretty sure theres a 350hp cummins/dodge available , but it's only sold in certain state's. i haven't been on the turbo diesel register forum in a while.

i love my 7.3, but the 6.0 is a really good engine. A friend has a 2003 with a 6.0 and he loves it. He put a box on it and it's FAST.

As far as HP goes, I believe Dodge and Ford are tied for first at something like 325, but that's at the crankshaft, not at the rear wheels. Rear wheel HP will be probably 25-35hp less. -=Phillip

 

[MotoBoyMatt]

A horsepower is a horsepower and horsepower is proportional to Torque and RPM's mulitiplied together. Since diesels put out more torque they can generate more HP at lower RPM's. This is why diesels are generally rated for a more continuous duty cycle than gasoline engines. How long do you think a Corvette would last if you expected it to put out 400 HP continually considering it needs somewhere near 7000 rpm to do this.

 

[Al Smith]

550 ft lbs per second,equals 1 horsepower.Now that was simple. Of course you could go farther and say 746 watts equals 1 horse power,or perhaps 30,500 btu per hour etc etc.Then you could bring in tractive effort,drawbar horsepower,belt horsepower and go on and on.

 

[chowdozer]

A horsepower is a horsepower and horsepower is proportional to Torque and RPM's mulitiplied together. Since diesels put out more torque they can generate more HP at lower RPM's. This is why diesels are generally rated for a more continuous duty cycle than gasoline engines. How long do you think a Corvette would last if you expected it to put out 400 HP continually considering it needs somewhere near 7000 rpm to do this.

Since you brought it up...

I know a normally aspirated Winston Cup NASCAR engine with a restrictor plate in the intake will put out ~780 HP all day at 200+ MPH. A 6.0L Winston engine weighs about 500 pounds.

Now, a question for you:
How much would a normally aspirated diesel weigh to put in an automobile and push 200 MPH?

If you want to talk turbo'd, http://www.turbomagazine.com/tech/0202tur_extremeedge/

Horses for courses.
I'm glad my saws aren't diesel.

 

[Patrick62]

While we are way off topic

Diesel, gas, whatever. I have a question for the gearheads (that is most of us, right?)
We use trucks for a living, and it has been my observation that a inline 6 engine will out pull a comparable V8.

The reverse is also true, the V8 will out run the I6

"seat of the pants dyno here"

Why?? If we are comparing Diesels the Cummins in spite of the fact that it is 1 1/2 liter smaller than the PowerStroke, can keep up with, and pull just as hard. gasoline? Think about this:

Ford 300/6 vs 302/8
GM 292/6 vs 327/8
Dodge 225/6 vs 318/8

There are other combo's but it must have to do with crankshafts, rod lengths, and other oddities, but unless the V8 is geared way different, or really HUGE the inline will out pull it.

My $0.10 worth

 

[J_Ashley]

Uh Oh, time for a 19 year old's POV.

Horsepower is a function of torque. Torque can be described as force applied through a rotational movement. When, you turn a screwdriver, you are applying torque to the fastener to turn it. Horsepower, refers to how fast work has been done. If I turn the screwdriver with the same amount of force (torque) in half of the time, I have effectivley doubled my Horsepower.

Horsepower more specifically is 550 lb./ft. per second. Meaning that If you rotate an object with 550 lb/ft in one second, you have produced 1 HP. If rotate the same object twice, in the same one second timespan, with the same 550 lb/ft of torque, then you have produced 2 HP.

HP is therefore equal to Torque, times the RPMs, all divided by 5252. < HP = ((Tq. x RPM) / 5252) > When you look at a Dynograph, at 5252 RPM, Torque and Horsepower will ALWAYS be equal. Below 5252 RPM, Torque will ALWAYS be greater than Horsepower. Above 5252 RPM, Torque will ALWAYS be less than Horsepower.

When you look at a diesel engine for example, they make typically 2-3 times more Tq than HP. This is because they make an abundace of torque (Force that does the work) at relatively low RPMs, and don't need to rev high to make what would be useless HP. This is why low-revving diesel engines, are suited for truck use.

Justin