I am comparing the 360FE to the 351W. the FE wieths 650lbs, the 351 weighs 510 lbs.I know it takes more enerty to move more weight but weight generates momentium and momuinium can be helpful. I have heard on a Diesel forum that the momentium generated from the heavy engine makes up for the extra weight you are carrying around. I think that the 360 is bulletproof because it is heavy and I am not convinced that weight is terrible. IH engines weigh over 700 lbs, 720 lbs of the 304, and 800 for thier 392 I think.

 

I vote both, takes more energy to slow down, and takes more energy to speed up...comparing to a lighter engine.

 

My stock 351 F-150 accellerates as quicly as my B2 2.9L but I feal it more in the truck. I think that the weight has kenetic energy loading up on the passengers bodys.


I wonder if a 10,000 lbs truck with 875 lbs of torque could out run a 6000 lbs truck with 525 lbs of torque both bineg identical trucks with the wieght % displaced the sam just 4000 lbs more iron on the other truck with equal aero dynamics.

I am comparing running the 360 vs. 351W along with adding extra lbs of rollcage and other iron or steel to improve my kenetic energy. I know making a vehicle lighter quickens the speed. However I would not make a 10,000 lbs unless it was a 6.9L diesel or similar. Probably 5000-6000 lbs for a -420 cid gasser.

 

Weight is the enemy of fuel economy.

 

I believe that but that truck weigs 4500 lbs accoding to the vin tag and the B# weighs 3900 lbs and they get equal gas mileage. The truck has a c6 and 4.11 gears with 29" tires. while the bronco has 3.73 gears with a 4 speed auto and 28" tires.


But I believe you that the heavier I go the more gas I can expect to use. Probably 6 or 7 mpg out of that 8000 lbs truck cruising.

 

Looking at this by reffering to Newton's laws, we have situation were it takes a lot of energy to effect a change in motion, the greater the mass.

Newton stated that a object does not change it's motion, speed, or direction of motion , unless something makes it change. If a object is sitting still, it takes energy (or thrust) to accelerate it up to a certain speed. It also requires negative energy (in this case drag) to slow it down, and the greater the weight, the more drag is required. The heavier the object is the more energy it takes. That's why stop and go driving requires so much more fuel than highway cruising does. More weight just agravates the problem.

Once an object is in motion it will stay in motion at the same speed and in the same direction, unless something (an energy) makes it slow down, or makes it change it's direction. For example, an object in outer space could continue to travel the same speed and the same direction forever, without any additional energy input. This is because there is no friction or drag acting upon the object.

A truck on the road does have both air drag and friction drag acting upon it constantly though. It takes a constant supply of energy (or thrust) to counter act this drag.

There are essentially four main forces acting upon a truck moving on a level road: They are drag and thrust, along with gravity and lift. Although it's not an airplane with wings suppling the lift, the tires and wheels are acting against gravity. This bleeds off some energy just as more wing lift increases the total drag on an airplane. Larger wheels and tires have greater drag.

Less weight is always better, if possible. It just takes less thrust, or drag, to effect a change in the object's motion state.

Kentic energy can be quantified as the velocity squared, multiplied by the mass. Although mass (weight) is one main factor, it's not nearly as important as speed in the total kentic energy, because mass isn't squared, and speed is. How much surplus kentic energy is on hand to effect a change in direction, or to carry a truck through a bog, or to help it start up an incline ..ect.. can be determined using a simple formula used in rocket science since the 60's:

Surplus energy={thrust minus drag/weight} multiplied by the residual velocity.

If you could plug in the numbers, it becomes clear that the more weight there is, the more energy must be used, and more of it becomes wasted.

 

I get 7.5-10 depending out of my 460, it's in a 94 F-350 Crew Cab with a 8' box. Guesstimate it probably ways close or more than 8Klbs, but I use the momentum to my advantage.... I almost if possible never brake, choose routes that have less stops, or if I have to stop/slow down start doing it early so I can coast through the light or the person in front will have sped up again.

 

You'll get better milage in any vehicle driving that way.





Weight is bad for gas milage... You dont build momentium, with the ability to get it back 100%. You're stuck hauling that extra weight, and allthough u may beable to coast longer, you'll burn up that "saved" gas, and then some, getting back up to speed.


There's a fine balance between a small engine getting better milage because it's more efficiant... And putting too engine of motor into something, where it has to work exceddingly hard to move all the weight.

you haul more stuff, or more people, and your milage goes down all things being equil
~Nate

 

Sounds good. I think I will stick to frame/cage/(drivetrain weight only as much as I need for the engine) I think I only need so much weight if it consist of a good cage or roll bar then I should be safe! I think my rig will weigh about 4900 lbs. And I might run a dana44 with 9" and 351W instead of 360 and dana 60s 7000lbs of iron.

thanks for all help!

 

We could look at this another way. An engine with a heavier crankshaft will launch harder when the clutch is released!

In terms of engine weight itself, less is always more desirable. Essentially you do have a trade-off though. With the heavier engine, you generally have higher strength parts that are better designed for the displacement they're running (better rod ratios, so on).

Where the weight kills you is in-town or city driving. The more weight you have to accelerate, the more gas it's going to use. Period. Be it from your mother-in-law, or your engine. I dont think the effect is nearly what people think it is. Usually the heavier motor is also a larger displacement motor. That's just going to use more gas.

 

And break more stuff when the tires get traction

GREAT fun when it's not your car, but u feel crappy when you buy it after you abused it (my uncles tornado.... )


o well, it can take it at least once, right?
~Nate

 

I'm a traditional archer and momentum is huge for us- but i don't reckon I'll plan on skewering anything with my truck. The only advantage could be downhill- same as when i ride my mountain bike. at 250+ lbs i can outcoast the best racers as long as my 'tuck' is somewhat near form. Been there done that. and who needs a downhill advantage in a truck- usually thats a bad thing.

Weight is bad- like when i ride my bike up a hill- takes a lot of hp.

Good theory though.

also- weight is a very good thing in bad (ice/snow)roads as is longer wheelbase. I had a bronco 2 for a couple of years and semi blowby could result in a 360 real quick. It did get better mileage though.

 

I lighter block is always preferred in any form of racing....
Heres a pic of my new race block for my upcoming 632 BBC buildup.
I didnt spend double to go slower I can assure you.

http://img.photobucket.com/albums/v3...u/DSCN0311.jpg
http://img.photobucket.com/albums/v3...u/DSCN0315.jpg

 

Is that an aluminum block? I still prefer Iron as I am more comfortable with it. I have accepted that weight is not better but I still like the brute force of it. I was looking at some new cars at a ford dealer that had the same GVRW of a Bronco at 5200 lbs not the 6200 for a Big bronco. This station wagon I forgot the model was aluminum no chassis and some plastic. I must say that the EFI on newer cars is nice but that is it. When I get more time on my hands I want to build a 390 all iron I do not know where I will find an iron single plane to fit but when I do I will build port fuel injection for it with a Mustang mass air computer and harness and mount the sensors into the iron which will be hard to drill I expect. I would run 2.08/1.65" valves and a wide 114 lsa with 270 duturation mabe 266 and get a flat torque curve form 2000-5000 rpm I hope for about 400 low torque and mabe 440 peak and 400 hp at 5000 rpm. Oh I just stripped the threads out on the water inlet of my new Edlebrock performer for my 351W an never had the thing torqued, should I have used Iron Bolts? I will use an iron intake next time.

 

This is not a decison over FE vs.Windsor I just have a 351 in my 1982 F-150.