You need to read a book and learn something. not one of your points is accurate or relevant.

The engines in question are in the same family, burn the same fuel, and are within 50 cubic inch of each other.

These "big rig" and "tractor" engines you keep reverting back to are DIESEL for one.

A 500Hp big rig engine is going to be in the 800 or more cubic inch range. This big block chevy you talk about is what ?? 454 cubic inch?
OF COURSE THE torque is going to be at a Way different RPM, and way less for the 454.

You really need to learn what Torque, horsepower, and RPM are really all about.
You should have been introduced to this at the latest in middle school. Its called work, power, and energy.

 

Your the one who does not quite get it,you cannot compare a Diesel to a gas engine why not? A DYNO TELLS THE STORY PERIOD!!!!!!!!!!!!!!

You did not explain why the moped could or could not pull a 200 pound passenger with a 2 HP 40,000 RPM RC model airplane motor attached to a proper gearbox and do the same work as a 50cc moped engine.

A 2 HP RC engine could probably not even get the custom gearbox needed rolling without even being hooked up to the moped itself because it does not have the torque ( MUSCLE ) to get it rolling.

You are not going to see a 330 cubic inch gas motor moving 80000 pounds down the road at a good clip.

ITEM C = You could build lets say a 1500 HP bigblock Gasser that made 1500 foot pounds of torque DRAG CAR MOTOR and the dyno would say you can now pull 80000 pounds and move the loaded rig at lets say 150 MPH ( BECAUSE IT IS 1500 HP IT COULD DO THIS ). And it would then smoke a big rig and blow it off on top end for an hour and then need to be rebuilt! It would excellerate to 80 MPH pulling 80000 at about the same rate as the diesel engine because the torque is somewhat the same but then the extra HP of the race gasser would walk away from the diesel engine.

That is why big rigs use a diesel engine, it makes the power where it needs to be to move the load efficiently and for 100's of thousands of miles before a tear down.

What you are saying is correct but you are leaving a major equation out and that is your inability to read and understand what a motor dyno is telling you and what it means in real world application.

Your torque and torque curve are as important as the gearing.

Like I said if people could build a gasser 454 and get it to do what a big rig does it would have been done along time ago but they have not because refer to item C !

 

I give up! You can't teach those who THINK they know it all. This is like this old saying;

"Never argue with an idiot. He will drag you down to his level and beat you with experience."

 

realslow your right.
you need to get a van with a big rig diesel for your needs.


you asked the question. why did you ask if you already had your mind made up that the 4.6 was not good enough.

 

Your the one who does not quite understand. I understand as the ratio of a gearbox goes lower the torque goes up. The cubic inches has nothing to do with this argument your lack of understanding real world application does.

A gear box can do nothing by itself it must be powered by a power unit and the power of that power unit ultimately determines what you can do effectively( IN REAL WORLD APPLICATION ) and not.

Like I said you are right about the gearing multiplying torque but what you do not understand is the gearbox relation to a running motor and the engines torque HP power output and at what RPM range it does it in.

Here is a simple explanation since you do not know how to understand what a engine dyno is telling you and what it means in the real world.

Lets say you have the old thing again since you fail to get it. A 500 HP diesel that makes 500 HP at 2700 RPM and you have a 500 HP 454 Gasser that makes 500 HP at 7000 RPM the 500 gasser is capable of making the 500 HP (BUT ONLY IF YOU ALLOW IT TO UNDER ITS WORKING PARAMETERS and the rpm range where it makes the 500 HP determines this) but the Diesel does it much more effeciently and does not require itself to work ( TURN RPM ) to do it. RAW PULL MUSCLE!

Lets say you put a 50 speed gearbox on the Gasser and a 15 speed on the Diesel. The diesel with the 15 speed will pull the 80,000 pound load much much better.

You drop the clutch on the diesel at 2700 RPM in first it gets the load moving the RPM drops a little but it does not faze it why because it is always making about 500 HP no matter what RPM it is at. The gasser on the other hand has got to be reved up to 7000 RPM to get the 80000 pound load moving and even if 1st is alot lower you still have to rev it up much higher to make 500 HP. You cannot let the gas motor rev below lets say 5000 RPM because there would not be enough HP below that to pull the load and keep it moving up in MPH and on the diesel it makes 500 HP just above idle so when you shift the motor it really is not losing any real power it keeps applying 500 HP effieciently!!

So you shift on gasser what happens the RPM drops and so does all or most of your Horsepower. You would have to smoke the clutch and keep the RPMs way up and there goes all your power smoking the clutch to keep it rolling and when you are doing this your speed is dropping the whole thing would just crash to a stop.

When you shift 50 or 60 times the power is not being applied to moving the 80000 pound load to keep it excellerating so the motor falls of the power curve and dies!

500 HP at 7000 RPM is not like having 500 HP 2700, no contest no matter how many gear ratios you try on the gasser the diesel will move the load much better!

How do I know this because I have been working with and building motorcycles the last 25 years and they will teach you more about HP and gearing faster than just about anything out there because how fast you can make changes in them in set up.

I have been through this on racing engines and there is no substitute for torque being applied at the crankshaft! ( REAL WORLD APPLICATION not a computer program or a chalk board)

 

And this is coming from a guy who was asking us how the 4.6 compares to the 5.4 for towing? Good Grief - since you already obvisouly know everything (or think that you do), why did you ask for opinions in the first place. In two identical trucks with identical transmissions and gearing, the 5.4 will outpull the 4.6, period. However, not everyone who tows needs the 5.4, it all depends on what you need to do.

You need to compare engines of the same basic layout and configuration if you want to compare diesel and gasoline engines.

Why do you think the 300 I-6 Ford pulls so strong? That is an in-line engine design, and I'd say a very durable engine. It produces torque DOWN LOW where you need it for pulling (sort of similar to your "big rig" diesels, eh???)

So, if you want a fair comparison, then you need to design and build a 800 CI inline 6 GASOLINE engine to compare to your "big rig" diesel engine. Why did most heavy trucks to go diesel? I can think of two short answers. 1) They are more durable and do not have to rely on an ignition system and 2) Better fuel mileage, but this one is questionable in my mind if your dealing with engines of similar displacement.

As one other poster mentioned, your comparing an apple with an orange so it's not a fair comparison.

 

I have a 7.3 e 250 van that I am restoring but it is a 1989 model. These were made the best with by far the most metal in the bodies.

 

I need the 4.6 for light work and to get descent gas mileage for pulling my bikes on the highway. i did some research and the general conclussion was the 5.4 pulled better but you payed a price in overall gas mileage. thanks for the reply!

Old whipper snapper here is dreaming,if you can make a tranny that can shift 50 or 60 times and not fall of the power curve then it could work. Maybe whipper snapper needs to go invent it so he can laugh at me and say I told you so!

 

He was saying the power is not as important as the gearing and it is. You are right you can build a gasser to do the job but at that point for moving heavy loads a diesel makes more sence economically speaking. And a diesel would still get the load moving off the line better with out being strained. They still make a bit more off idle torque. Like I said a dyno tells the story right up front. Alot of people do not understand HP and what it means that is why the RC engine is a great teacher. 2 HP out of a motor smaller than your hand but it turns 40000 RPM to do it.

 

You can't fix stupid! Fortunately stupid is almost always self correcting, that is if society keeps it's hands off.

 

lets take your argument you keep implementing and incorporate it to you.
your 89 econoline. 7.3 vs an identical van with a 7.5L
which has more torque and horsepower?
just a hint. you have to go to a first gen PSD to get comparible numbers between it and a 7.5L of the same era.
I've owned both in trucks. 7.3 IDI, and a 460.
the 460 has more power and gets similar fuel economy.

 

You fail to understand the argument go back and read the first post, he was saying gearing is much more important than the power driving the gearing and it is not. The gear box is just the means to apply it.

Here is one for you, a 500 five hundred cubic inch V8 gas and a 500 inch V8 diesel. the gasser way more HP but the diesel will make more torque earlier in the RPM range and get the load moving off the line with less effort and not burn your clutch out.

Do not pay attention to factory specification, you need to see an independent dyno graff and all test's have to be done on same dyno same day to truly get a real accurate rating if you are doing a race application where a foot pound of torque can be the difference between winning and losing a race.

On average if you convert a gasser to diesel the torque will go up by about 30 to 33 % and be stacked much lower in the power band but you lose HP because you no longer turn RPM.

Now you may very well have a gasser that makes more peak torque but it is going to be way higher up in RPM and spread over a narrower RPM RANGE making the torque not as good for pulling off the line. In order to access it off the line pulling a heavy load you will have to smoke the clutch alot more to get the load moving.

So in general all things being equal a higher torque lower HP engine will excellerate the load up to speed faster but then die when it runs out of HP and the lower torque higher HP motor will lose off the line pulling a load and on the big end out run it when it starts to apply the MORE peak HP than the other motor and run a bigger MPH!

A dyno tells the story it is not in alot of cases how much PEAK and I mean PEAK HP and torque you make but where it makes it in the RPM range and over how many RPM! It all depends on what you are doing and for pulling a lower RPM torque and HP curve is superior to a motor that makes more peak HP and torque but does it much higher up in the RPM range and over a narrower RPM spread..

 

The only one failing to understand is you. You are either too dense (you can read that as STUPID) or too arrogant to understand that you have no clue about what you are talking about.

 

I do not see any explanations coming out of you and all I see is insults. I will leave it at this, did you know only around 3 % of this countries european settlers fought for our independence from England? The other 97% walked around picking it's a ss. You sir are part of that 97 % known as the sheople.

The power's that be have made their point. They need to do a round up and get this ignorent mass into the cities then kill it as quickly as possible and then start over and maybe humanity will have a chance!

 

Sonny boy, you know less about me than you know about cars, trucks and torque and how it works. I was defending this country before you could get around without diapers. I survived two combat tours and another 40 years on top of that as a disabled veteran. I carry a side arm everyday, everywhere and you clowns that want the big change are in for a shock when it comes, cause it ain't gonna be anything like you imagine. Oh dumb ***, it is spelled "SHEEPLE". I know this because I am one of the sheep dogs that holds the wolves at bay. When we do start over, I have no fear that you will not be among us.