Well, only you can decide if it's 'worth' price for the return on the cost. What's the return on your cost? Here's how you calculate it: This is just an example, but your figures plugged in here will work.
20,000 miles driven in a year divided by 20 mpg = 1,000
gallons of diesel fuel used per year.
1,000 X $4.00 (for each gallon of diesel fuel) = $4000 spent on fuel for the year.
Now, we are just guessing that you will get 2 mpg more per gallon, so we just redo the calculations:
20,000 miles per year divided by 22 mpg = 909 gallons of fuel per year.
Multiply that figure, 909, by $4.00 per gallon for an estimate of $3,636 year for fuel.
Now take $4000 (before modifications) and subtract $3,636 (after modifications) to find your yearly fuel savings, $364
Divide the cost of modifications, $1,000, by the savings, $364, to determine how long it will take to recover the expense of updates. In this case the answer is 2.75
(2 years, 8 months) years
, or 20,000 miles x 2.75 = 54,945
miles. Will you keep the truck that much longer?
If you drive fewer
miles each year, and if the per gallon savings are less, it will take more time to recover your expenses. On the other hand, if gas prices keep climbing upwards
, you may see a return in less time.
To get a better picture, just plug in your figures above (miles driven per year, cost of your modification, and price of diesel fuel).
The plus as you say is less wear on the engine, but diesels are designed to keep going and doing and going anyways...
And you will be reducing your 'carbon footprint' as well, which is good for the environment. [APPLAUSE]
I did a search of the forums and the topic of Gear Vendors overdrives has come up before, but it appears nobody has gone that route. I have long wanted to put an overdrive in my 1982 diesel 5 speed longbed. It looks like it was designed for it. Well, I found an older divorced style J type Gear Vendors overdrive in good condition and had it rebuilt by Maximum Overdrive in Aromas, California. It now has all new bearings, seals, gaskets and a new yoke. I have a hot rod fabrication guy ready to install the unit. To engage the overdrive, I intend to install a manual toggle switch in the unused knock out panel next to the steering column. I have heard conflicting advice as to what amperage the circuit should be. I don't expect to increase my mpg substantially, but even a couple of miles per gallon would be nice and having the engine run at a lower rpm while cruising will certainly be nice. I wanted to share this with the P'up community to see if anyone has any advice they would like to share before I jump in.
To see a pic, go to http://farm9.staticflickr.com/8512/8469893404_2bb0397bf0_b.jpg
The unit currently has a flat plate cover on the bottom. I intend on installing a high capacity, finned aluminum sump that will add about a quart extra volume.