Re-Gear ? 1fz-fe sweet spot for MPG? (1 Viewer)

[7schulz]

I'm pretty sure I busted my ring gear(found busted tooth in my diff oil) by having the VC in my t-case locked up, well the PO did anyway. So I'm having the front end rebuilt and since I'm needing a new gear, my mechanic said a re-gear would be a smart decision. I will probably go with the FOR 3 inch lift and 33's or maybe 35's. I'm not really a rock crawler, more and expedition rig and mud and snow DD. I have another car for nice weather. What would be the best gear choice.

Also I have a gear calculator if someone can help me with a few variables.

1. Engine governed speed
2. High gear ratio
3. Max mph or hwy cruise speed
4. Desired Engine RPM (sweet spot - lower range)
5. Primary operating MPH
6. Transmission ratio @ primary operating MPH
7. Tire revs/mile

I need governed speed, OD ratio, my highway speed will be 75 tops. And the biggest thing I need is what is the sweet spot for fuel economy for the 1fz-fe. I will play around with the primary operation MPH and if someone has all the gear ratios I need that too. Also the revs/mile of 33's and 35's. I can play around with this calculator with this info.

 

[spdwaver]

315s with 4.88 sounds mighty nice to me. MPG sweet spot: different engine.

 

[mshelby]

I'm running stock with 31" tires, I was thinking of re-gearing for the MPG gain myself which would be 4.88 but I think the price/savings would be minimal under 50k miles.

 

[7schulz]

There is still a fuel curve and somewhere on it is the sweet spot. All engines have it somewhere.
I'm not doing the re-gear for milage per se, more just b.c I need a new gear I might as well get a little more pep b.c the truck is underpowered, and if I can hit a sweet spot in the fuel curve at cruizing speed all the better. If I can get the rpm for the sweet spot it will give me the best gear ratio for that and I can play with it from there.

 

[OGBeno]

There is still a fuel curve and somewhere on it is the sweet spot. All engines have it somewhere.

If you can keep your rig at 55mph, you can get a good 18-20mpg out of a 1FZFE.

 

[mshelby]

I am very easy on the pedal and with stock gears I get almost 14 MPG. Regearing may get me up to 16-17 and while that is nice, the price for the gears is just too much to justify it.

 

[7schulz]

I usually keep her at 60 ish but haven't done mileage check yet. But if I get on the interstate around here the speed limit is 70 and 75 is even getting run off the road at times. My truck shifts at 2K all the way up to OD and the highest revs I see are at cruising @2500 ish.

 

[mshelby]

You really can't go wrong going to 4.88 it will help you out but you may not see the savings any time soon.

 

[7schulz]

I'm re-gearing b.c the gear is shot and I need to buy gears anyway.

 

[mshelby]

If that's the case then yea go 4.88 and never look back

 

[Hilux]

Sweetest spot

If you can keep your rig at 55mph, you can get a good 18-20mpg out of a 1FZFE.

Even more if you drive it in a vacuum, or outer space.

You might have to carry supplemental oxygen for the combustion cycle of the engine though, as the mixture will not ignite w/o it.

If you have a Hydrogen fuel cell you can make oxygen though...


Just my opinion, but if you want to get into that really-really sweet spot, drive it in outer space and install a Hydrogen fuel cell.


here on earth I'd gear it as close to stock, and a little bit more depending on how I felt stock gearing with the tires were.

My friends AWD, 5500lb, SUV, with 212hp, aerodynamic as a barn, 80 (96 Lx) has stock gears and tires. NO POWER, and hideous MPG, but it WILL do 110MPH (or more).

I think it could stand to be geared a little lower

"This calc can be used to find any (one) missing value.
Solve for your MPH.
Solve for your RPM.
Solve for your Differential Ratio.
Solve for your Tire Diameter.
Solve for your Transmission Ratio.
Solve for your Transfer Case Ratio.
Solve for your Crawl Ratio."

http://www.4lo.com/calc/gearratio.htm

http://www.rocky-road.com/calculator.html

http://izook.com/gearcalc.htm

 

[Elijah]

When I was on 315's and stock gears, I'd get 15-16 mpg on the high way at about 65 mph. When I went to the 4.88's it dropped to 14-15 mpg highway. I think the lower the RPM at highway cruise speed, to an extent of course, means the less fuel consumed.

 

[nicholas]

Even more if you drive it in a vacuum, or outer space.

You might have to carry supplemental oxygen for the combustion cycle of the engine though, as the mixture will not ignite w/o it.

If you have a Hydrogen fuel cell you can make oxygen though...


Just my opinion, but if you want to get into that really-really sweet spot, drive it in outer space and install a Hydrogen fuel cell.


here on earth I'd gear it as close to stock, and a little bit more depending on how I felt stock gearing with the tires were.

My friends 80 has stock gears and tires. NO POWER, but WILL do 110MPH (or more).

I think it could stand to be a little lower

????WTH????^^^^^

If you can keep your rig at 55mph, you can get a good 18-20mpg out of a 1FZFE.

I agree, the 80 is a huge whale and creates a lot of wind drag at higher speeds. By keeping your rig at 55mph you can decrease wind resistance and keep the RPM's at or around 2K depending on gears/tires.

I notice wind drag tremendously when I am driving into a strong wind and it requires more RPM to keep up to speed compared to windless conditions. I can see the results real time on the scangauge. As soon as the wind picks up the MPG drops.

From my experience 2K is the sweet spot. As I go up to 2.2K+ my mileage drops from 14-15 to 10-12 MPG.

 

[mshelby]

????WTH????^^^^^

He does that

 

[Tools R Us]

When I was on 315's and stock gears, I'd get 15-16 mpg on the high way at about 65 mph. When I went to the 4.88's it dropped to 14-15 mpg highway. I think the lower the RPM at highway cruise speed, to an extent of course, means the less fuel consumed.

Yep, it's called rubber overdrive. For better cruising mileage something like a 3.80ish gear would probably be better, but not available.

Soft, cushy, off road tires don't help, a firm tire designed for highway would improve mileage. Something like this, 33.5", narrow, solid, good rubber overdrive, etc.

tires-easy.com - Details: Goodyear G622 RSD 225/70 R19.5 12PR

 

[Tools R Us]

... 5500lb, SUV, ..., aerodynamic as a barn, ... NO POWER, ..., but it WILL do 110MPH (or more). ...

Right,,,, that math don't add. Maybe if you upgrade it to a 22R it will be better?

 

[Hilux]

Right,,,, that math don't add. Maybe if you upgrade it to a 22R it will be better?

Does to me.

1Fz... Stock 31"(?) tires, 60ish and a long straight, 65S in Franklin.


Either that of his speedo is WAY off...

I think 80's are geared too high, which puts a load on the engine at lower speeds.

It sucks off the line to have such a motor under the hood and stock tires

Imagine that... They need LOWER gears and everybody complaining about a 1Fz's power and MPG are mostly running stock gears and 33's, if not 35's...

a 10th of gear per inch... THAT math doesn't add up.

 

[Ebag333]

When I was on 315's and stock gears, I'd get 15-16 mpg on the high way at about 65 mph. When I went to the 4.88's it dropped to 14-15 mpg highway. I think the lower the RPM at highway cruise speed, to an extent of course, means the less fuel consumed.

Bingo.

The ideal RPM is right around 2k for cruising. Some of the best mileage I've gotten was with 35's and stock gears running premium. Got almost 19 MPG, heavily loaded, with lots of climbs.

Of course then I went taller (33mm spacers) and my MPG dropped from 14-16 regularly to 12-14.

If you want MPG, drop your gearing, drop your lift, drop your weight, drop your speed, and increase the octane of the fuel.

 

[Cattledog]

Between 1900 to 2200 rpm is the sweet spot for fuel economy per toyota's SAE paper on the 1fz. That said I really would not bother looking for mpg, It was a low priority in the design of the engine.

 

[rhyary]

Bingo.

If you want MPG, drop your gearing, drop your lift, drop your weight, drop your speed, and increase the octane of the fuel.

And buy a Prius and go 90MPH.