Possible gear change in new to me Ranger

[19bonestock88]

With some aero mods, I think that the 3.27 would be doable on the highway given some consideration to lack of power on steep grades... however I can’t remember the difference in VSS location from the early years to the later ones... some are in the transmission and some are on the differential...

Why not go all the way up to a 3.08 gear and drop tire size to shed some rotational mass at same time? Run like a 195/65 tire?

[hat_man]

I just bought new LRR tires that should last quite a few years even with the mileage I drive. I thought I had read here at EM that the rotational mass didn't make too much difference at speed. It made a bigger difference in stop and go driving. I spend quite a bit more time at highway speeds than not, so I thought the taller gearing advantage was a more useful option.

My idea was to try and mechanically create a secondary overdrive situation. I seem to get better mileage at around 2100-2200 rpm, so if I could find taller rear gears that would put me in that range at 55 mph in 4th gear and the same range st 65-70 mph in 5th gear it would cover about 90% of all my driving. I can now do the math and try and make a better decision.

[hat_man]

@ JRMichler... I'm assuming that I can do the same to figure my rpm's at 55 mph in 4th gear for each rear end then?

(Revs per mile) X (rear gear) X (4th gear) X (scaled speed)

That would give me 723 x (3.27 or 3.45) x 1 x (55/60) = rpm's

If that is correct, then this is what I come up with for 4th gear.....

3.27 rear end = 2151 rpm / 55 mph

3.45 rear end = 2270 rpm / 55 mph

[JRMichler]

Yup, the math works for any gear at any speed.

[hat_man]

Ok. If all the math is correct, here's the recap.....

3.27 = 2151 rpm (55 mph/4th gear)
1700 rpm (55 mph/5th gear)
2016 rpm (65 mph/5th gear)

3.45 = 2270 rpm (55 mph/4th gear)
1793 rpm (55 mph/5th gear)
2127 rpm (65 mph/5th gear)

It looks like it's roughly a 100 rpm difference in all situations. Now I need to figure out how this fits with the information from this thread.

https://ecomodder.com/forum/showthre...ons-36410.html

Things like pumping losses, high/low load driving, and peak efficiency. An uneducated guess tells me the 3.45 may actually be more efficient than the 3.27. But the technical stuff is a bit above my head. Still trying to learn from all the "teachers" here.

[elhigh]

I'm looking for a BSFC chart for the Duratec 2.3 and coming up with nothing. Even on the Focus and Mazda forums.

Scratch that, I'm finding some charts but they're dyno charts generated by rodders and don't look at BSFC. Some of those guys are wringing 250+hp out of these things but that's not going to help you.

[hat_man]

Thank you elhigh.

I've been looking in between working 58 hours a week and trying to sleep. LoL. The BSFC seems to be that last elusive piece of my puzzle.

[hat_man]

Hello again everyone.

There's seems to be some question, at another Ford Ranger site, that the 2.3 doesn't produce enough torque to be able to hold speed with the 3.27's. They even think the 3.45's are too tall, but I'm pretty sure that Ford put those in the earlier Rangers that had the 2.3 Lima. I don't think Ford would have done that if it wouldn't work.

The new Duratech has 35 more HP and a bit more torque so the 3.45 should be fine. The 3.27 is what I'd rather have, but it becomes an expensive experiment to find it too tall. Not being extremely mechanically inclined and not having the time or equipment to do the swap myself, I'll have to hire it out.

So, what to do.....what to do?

Just swap in the 3.45 and take the gains and wonder if I've left anything on the table. Or jump in with both feet, and swap in the 3.27 and hope the water isn't too deep?

[Ecky]

Food for thought, BSFC contours are usually wider than they are tall. Or, in other words, even if peak BSFC happens at a higher RPM, the increase in load from a higher gear is almost always better than lower load and higher RPM. See here for an example:




As for maintaining speed, my Insight is geared such that I can basically only maintain speed in 5th gear on level ground or slight inclines. Any appreciable grade and I have to downshift, sometimes even two (or three) gears. I get my best fuel economy in whatever gear is the highest that I can barely maintain speed in.

[hat_man]

I think I see what you are saying Ecky.

So, I'm now thinking that even though the 3.27 would probably be the choice for the highest MPG it would be a lot of shifting to maintain that MPG number, as my drive can range from very hilly as it is now, to gentle rolling hills. At some point it may become second nature to do all that shifting, but not mentally relaxing. My drive to and from work is my time to talk to God or unwind from a bad day.

The 3.27 may be able to maintain speed, but only just. The 3.45 may be more of a set it and forget it situation. I'm used to downshifting on steeper inclines, but having to shift on almost every incline isn't what I was hoping for.

The 3.45 should still give some MPG improvement without changing my driving style too much.

I'm still open for opinions though.