Truck engines

jcsinga

Member
I have an opportunity available to me that I will need to purchase a truck for. Diesel engines are not an option right now. It will involve quite a bit of towing. Smaller engine for more mpg when not loaded but maxed out when loaded. Or larger engine less mpg but not working as hard loaded?
 
A smaller engine might not save as much fuel as you'd think. As an example, a friend of mine used to have a mid-2000 Chevy 1500 with a 4.3L V6. Although he drove conservatively his mileage was only one or two mpg better than other friends who had the same kind of truck but with the 5.3L. Besides that, his overdrive gear was just about useless due to the high (numerically low) axle ratio; the engine just couldn't make enough power at those low speeds to do much with. If your job will involve a lot of towing I'd sure not skimp on power in an effort to save only 10% on the fuel bill.
 
There is a lot more to consider than an engine when towing. How much weight will you be towing. Will it be flat land or mountains? Do you want a straight drive or a slip-o-matic. Differental ratio is a major consideration for power and fuel milage. I have 3 trucks that I tow with. One is an International Diesel 5 Spd -One Ford Gasser with an automatic and One Dodge Cummins 5 Spd with 4:10 Gears. The Dodge will put the other 2 to shame on power and fuel economy, I load heavy and pull in the Mountains. Every case is different.
 
How true! Way more to factor in than engine size when towing loads. When I was dragging tractors and equipment back here from all over the diesel was cheaper to operate than the gasser. Both ton pickups.
 
I upgraded trucks last year to a 95 F250 with a 5.8 and 5 speed. I was hauling hay to an area of Wisconsin with a few more hills than we have locally. in some of the hills I had to down shift to 3rd gear to pull the hill and I didn't have but 180 bales on the trailer. I honestly think the trailer weighed about as much add the hay because it was a heavy trailer that I was using.

Found a 91 f350 that I wouldn't mind upgrading to that has the 7.8 gas engine. That one would for sure pull better, but it would suck a lot more gas too. Plus I don't really NEED it, more of a want.

Donovan from Wisconsin
 
Bear in mind that the smaller engine when overworked will DRINK gas! A larger engine that is properly sized for the job will generally give you the best compromise between performance and economy. A small engine that is always straining will not only be un-economical, but will also be more prone to failure.
 

The size, weight,and configuration of the truck is what determines the miles per gallon. The size of the engine has VERY little to do with it.
 
A 20 year old pickup pulling 9000 pounds of hay and according to you a 9000 pounds of trailer - 18,000 total. The GCWR for that year is about 18,000 pounds putting you about 5000 pounds overweight and about 8,000 pounds over the tow rating. That's when it was new - 20 years of use doesn't help. I'll bet you had to downshift.
 
I use an 81 Chevrolet 1 ton. I've had it for many years and it runs a 454 and 4 speed. At one point I had to borrow a rear from a parts truck and thus swapped the stock 4.10 for a 3.73.

The 3.73 hurts a little on towing with the manual (earlier and more downshifts) but I have gotten as good as 15mpg running empty down the highway. Of course with anything on it or towing it's back to the normal 10. The motor is one I built about 15 years ago and it's in a good state of tune.

My point is not that you should buy a 35 year old pickup but more that engine size is not the sole determinant of fuel mileage. A bigger mill will have more reserve for heavy loads and not have to work as hard when empty. Also a manual will have less parasitic loss compared to the auto.
 
Alright, ya got me. Might have exagerated the weight of the trailer some. But it was still much heavier than I needed for the job. Was a home made trailer by my former boss, and he overbuilt everything. Bales were closer to 40 lbs as they were all grass and made for horsey people. Probably still 13-14,000 lbs. Handled pretty good otherwise.

Worst part about the trailer was the brakes. Had Surge brakes on it which helped, but the one time I had to stop in a hurry the trailer pushed the truck a little bit when I had the fronts locked up (rear ABS on the truck). When I do buy a trailer it's gonna have electric brakes with the controller in the cab. I want that trailer to stop the truck, not push it.

Donovan from Wisconsin
 
How many miles will you drive it per year and what percentage of that will be with a heavy load? The answer will be much different if you drive 30,000 miles per year, but 95% of it empty and only 5% (1500 miles) loaded/towing, or if you drive it only 1500 miles per year, bur all of it is loaded/towing.
 

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