Originally Posted by RUFFSTUFF

True statement. Dynojets are relatively cheap, therefore popular. My experience has been with Factory Pro eddy current dynos, and I have greater respect for their results. Dynojets are great for when its time to brag since they tend to have a significantly higher result. But again, comparing Dynojet dyno numbers under most conditions is futile.

Originally Posted by RUFFSTUFF

I've had a PSD for 2 weeks now after 5 years with a 5.4 and all I can say is I don't see a reason to ever buy a gas truck as long as I have to tow or haul something. Gassers just don't know what's up.

Originally Posted by fabmandelux

Still not convinced?

[SIZE=+1]"Here is an example of another way horsepower could be directly measured. Say you have a horse hitched to a plow. In the hitch is a spring scale (like a fish scale). The horse pulls the plow one foot every second and you see 550 pounds on the scale. That horse would be generating one horsepower

Originally Posted by RUFFSTUFF

It's all about the torque. Horsepower is a calculation. Torque is like being able to bench press 400lbs. Horsepower is like being able to bench press 400lbs 10 times in a minute. Since the vector for a bench press is near 0, no "real" work is done, since the displacement is near zero.

Originally Posted by PorchFarms

Take the same engines and load them to their max gcwr and see which one will accelerate faster. A 235 hp tractor will not win a race but can pull a 30ft disc. Now i know weight is a difference and so is gearing but all gearing does is multiply torque and weight controls slippage. you cannot multipy horsepower

Originally Posted by tgreening

I don't see the point of having a shatload of HP if you dont have enough torque to even get the load moving. I don't see the point of having a shatload of torque to move a megaload if I've only enough HP to move it at 5 mph.

Maybe a couple of the arm-chair engineers in here can fill me in.

Originally Posted by Argo

The Scottish Engineer and inventor, James Watt (1736-1819), introduced the term "horsepower". The term was and is used to indicate the rate at which an engine can deliver work. As such, it is a measure of power, that is, energy produced or work done by an engine per unit of time. Mr. Watt wanted to tell how powerful his engines were. So, after some tests (not with engines but with horses) he established that on the average, a horse could haul coal at the rate of 22,000 lb-ft per min. In order to conservatively rate his engines, he decided the raise this number by 50% to arrive at 33,000 lb-ft per minute.

So, if an engine can push 33,000 Lb of something one foot in one minute, we say that is a one-horsepower engine.

So horsepower is not an "imaginary" number. It is in fact, a conservative number grounded in sound scientific fact. It is therefore a measurement of work performed over time. This is opposed to torque, which is the amount of work which can be done per revolution at a given engine RPM. So If two engines are geared for their optimum horsepower, the one which has the highest numbers will in fact pull a heavier load at the same speed as the lower horsepower engine, or will pull the same load as the lower horsepower engine at a faster rate of speed. That is why to you PSD guys, a V-10 sounds like it's going to "blow up" when hauling a heavy load. It is geared for it's optimum RPM range and therefore is revving up to a higher RPM than the diesel is to get into it's powerband. Now, if we dropped a V-10 into a truck that has PSD gearing, it will not pull, because it can't get into it's powerband. However, if both engines are geared appropriately, the one with the higher horsepower will pull the heavier load or the same load faster. You can argue the point all you want, but this is basic physics. Power is real, whether it is low RPM grunting power (torquey diesel), or high RPM screaming power, it is the same thing. If it weren't, Navy destroyers wouldn't be powered by gas turbine engines (little torque, tons of RPM). FYI, diesels would have never supplanted steam locomotives in railroading either, since steamers produce max torque at 0 RPM. However, diesels rev higher and produce more horsepower than steamers do, and therefore, diesels replaced the steamers, because diesels aren't driving the drive wheels directly, but they are driving the wheels through either a mechanical transmission (smaller switchers) or through a generator/electric motor arrangement (larger passenger and freight engines) that allows the diesel engine to run at it's optimal RPM to produce horsepower which is used to do work. Period.

Originally Posted by tgreening

I'm just curious as to the actual point of this argument. HP is better to have than Torque? Other way around??

Maybe I'm just simple minded but it's always been my understanding that they go hand in hand. It was once explained to me in what seemed simple yet logical terms that if you want the load to move you need torque. If you want to move it faster you need some HP. Makes sense to me. Divvy 'em up however you see fit to get the overall performance you want.

I don't see the point of having a shatload of HP if you dont have enough torque to even get the load moving. I don't see the point of having a shatload of torque to move a megaload if I've only enough HP to move it at 5 mph.

Maybe a couple of the arm-chair engineers in here can fill me in.

Originally Posted by Lead Head

Gasser: 400 HP @ 5000 RPM = 420 lb-ft.
Diesel: 400HP @ 2500 RPM = 840 lb-ft.

Put a 2:1 reduction drive on the gasser, and you'll get an effective speed of 2500 RPM with 840 lb-ft of torque. That 2:1 reduction could be realized in transmission gearing or rear end gearing.

High RPM and low torque can be made up for with gearing, low HP can not.

Originally Posted by Kajtek1

Very simple as samples were already given.
The first one is very important in light vehicles like F1 racing, the second in tractors for earth movement. My JD tractor/backhoe is 21 HP . I can move a house with it (or outtow Bill), but will not drive 60 mph on the freeway.

Originally Posted by Argo

When I posted this last night, by the time it went on line three pages had passed. Since several of you have asked questions or requested an "armchair engineer's perspective" I am just bumping this forward.

Originally Posted by 2001400ex

All this arm chair Wikipedia stuff is cool and all, but show me one time a v10 outpulled a psd. There was the one pulloff where the psd started smoking, and still pulled even with the v10. There are too many other factors besides horsepower to say it is purely about hp.

Sorry v10 guys, but you need to stick to real arguments for your v10, not manufacture them.

Will someone with a 7.3 please swing by Bill's house and show him around?