300 EFI in a 1990 F350: 34.67 MPG

[funkhoss]

I created an account for this site last year when I started working on a project; specifically, I was looking for information about stock camshaft timing on the EFI 4.9, and two threads were particularly helpful (this one and this one).

Now that the project is pretty much finished, I thought that some here might be interested to read about it. I built what I'm calling an "eco-cheapo-franken-350"; it's essentially a 1990 F350 with upgrades for towing and efficiency (including two transmissions, bolted together) that so far has a best tank average of 34.67 MPG (using hypermiling driving techniques). You can read more about it here: https://ecomodder.com/forum/showthread.php/eco-cheapo-franken-f350-41947.html

It was a fun project. I knew little about Ford trucks before I started working on it (most of my experience has been with Chevys), but I sure learned a lot from researching and putting everything together. As I mention in the writeup, one of the main reasons I went with a Ford for this project was because I specifically wanted to use a 300.

I'd be interested to hear your thoughts and questions, if you have some!

 

[Blairsville Ed]

Which transmissions were used?
Which axle ratio?
Final drive ratio?
How many forward gears were used? I ask this because I’ve wondered if a newer 6 speed automatic transmission would be a beneficial project.

 

[funkhoss]

Which transmissions were used?
Which axle ratio?
Final drive ratio?
How many forward gears were used? I ask this because I’ve wondered if a newer 6 speed automatic transmission would be a beneficial project.

All of these questions are answered in the build thread on Ecomodder that I linked (and a whole lot more, too!). But to answer them here briefly:

• A modified T170 (with first and reverse removed) and an NP435. This setup gives nine distinct forward ratios and three reverse ratios.
• 3.07:1 in a full-floating Dana rear.
• During the 389 mile trip on which I achieved 34.7 MPG, 98% of the time I used only three ratios: 3.34, 1.79, and 1 (NP435's 2nd, 3rd, and 4th). There were 16 miles that were on the interstate, and during that time I used the T170's overdrive: .71. Otherwise, I never used the T170's overdrive or split any of the gears. The extra gears are for towing efficiently, not driving empty efficiently.