4.56 ratios = better economy

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The economy on my 80 is killing me offroad. It's a 96 4.5 auto. I have upgraded the valvebody on the auto (less slippage) and upgraded the ecu. Yeah iut goes heaps better, but still crappy economy. I runs mostly 285 x 75 x 16's. Currently 4.1 ratios. I do heaps of long trips as well and currently at 100kph (by the gps) doing about 2200rpm. I figure i'll end up doing about 2500rpm at 100kph. However am i going to pick up any economy. Has anyone done and give some feedback. I t would be most appreciated. I searched but couldn't find anything on improved economy. I love the auto but if changing the ratios won't help, then I'll have to swao in a manual.

Cheers GReg
 
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I can't think how turning more RPMs for the same speed would help fuel economy?

I drove for many years with stock 4.10 gears in my FJ40 while running 36 - 37" tires. I lugged while accelerating from a stop or when climbing high mountain passes, but could cruise comfortably at 70 mph with my stock 2F. I recently switched to 4.88s and was afraid I would get worse gas milage due to the higher freeway rpms.
I was surprised to find the opposite occured. By switching to gears that were more appropriate to my tires diameter, I put the engine back into its optimum power band and my fuel economy improved significantly.
 
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At a higher more RPM the engine might be more efficient and not lugging around.


Note is say “might”


I.M.H.O



It's a black art.....................?


would more gear make you put your foot in it more?

would me.


haul a small jhon boat around for 2 weeks then take it off, you'd

think you had another 100hp!



simple answer is less drag* on the motor so it use's less fuel*

of coures there is no drag in a vacume or close to it.........

level ground vs. "I live in the mountains"


level ground or down hill you could run a gear ratio of 2:00


wind, hills, towing, elivation, mountains, eliments, driving style, travel conditions, all this must be factored in

in N.A we have highways and better road/street conditions and some enginer's feel we need the gears we got, not always true though.

some countrys can NOT travel the same distence we do as easy.

and "gas" (EFI) motors always run or "sense" the amount of vac. lost or "drag" and compensate it with fuel :) .

to an extent, then it's rpm's (high) that make the ecomony bad..............black art..

I love Diesels! (thats another story)
 
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At a higher more RPM the engine might be more efficient and not lugging around.


Note is say “might”

Yep this was my theory, in worked in a patrol I had went from 3.9 to 4.3 ratios. aAgain this seems to be an unknown test. I suppose i'll try it and see what happens. It will not lug around as much for sure.

Still no-one who has done it has said whether they got better economy or not for this size tyre.

Cheers Greg
 
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Still no-one who has done it has said whether they got better economy or not for this size tyre.

Cheers Greg

some of you economy isn't so much what size tire you have but what type tire. A heavier tire will cost you gas mileage.


Amen on the tire (gas though)



"Still no-one who has done it has said whether they got better
economy or not................................


IF were talkin gas here you aint been reading.....

https://forum.ih8mud.com/showthread.php?t=140203&highlight=4:88's


there is tons more, once again if were talkin gas motor.


Diesel does not apply here.

you must offset the gear : with the torque curve of the Gas motor +/- your preference or needs..


A Diesel has so much low end (and will not rev the top end) you can, and must low gear it and you will get great range with it.


However it felt factory I would go from there......


"Well it was great before I put the big O tires on it" well then add that much back in ratio.


more low end? add tire.

need more top end? add more gear.
 
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If you spend a lot of time in overdrive, try driving it with the overdrive switched off. This will at least give you an idea of what your fuel economy would be like at highway type speeds if you decided to swap in 4.56 or 4.88 gears.

If fuel economy happens to improve with the OD turned off, then you know that adding lower gears will help.

For all of the other Toyota 4x4s, 4.10s is not enough gearing for 31s, much less 33s, so I wouldn't be too surprised if fuel economy was affected running 33s with 4.10s.

I've often wondered how the 1FZ and LC would respond to a 4.88/33 tire set up. That's the most common aftermarket gear/tire ratio on the older Hilux/mini-truck/Surf/4runners.
 
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Amen on the tire (gas though)



"Still no-one who has done it has said whether they got better
economy or not................................


IF were talkin gas here you aint been reading.....

https://forum.ih8mud.com/showthread.php?t=140203&highlight=4:88's


there is tons more, once again if were talkin gas motor.


Diesel does not apply here.

you must offset the gear : with the torque curve of the Gas motor +/- your preference or needs..


A Diesel has so much low end (and will not rev the top end) you can, and must ***low*** gear it and you will get great range with it.


However it felt factory I would go from there......


"Well it was great before I put the big O tires on it" well then add that much back in ratio.


more low end? add tire.

need more top end? add more gear.




whoops.......HIGH gear it.....
 

little_joe

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It depends on where the engine is most efficient, and the trade-off you're willing to make regarding efficiency vs performance.

I had a mini with the 3.0L V6, 33's, and 4.88s (and AT). That thing made so much racket over 3000 rpms I consciously tried to keep the rpms low. I came to learn that the engine was most efficient and near the peak of it's powerband around 2800 to 3000 rpms, and revving it had no impact on longevity.

So as Brian said, experiment with the OD and power buttons and find where your truck is most efficient. If you find higher revs is best for what you're trying to achieve, regear accordingly.

The skeptic in me doesn't think you'll see any appreciable gain, the 80 is an aerodynamic barn door over 5000 lbs, not sure you can really wring more mpg out of it.
 

little_joe

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Realy!!!!! :rolleyes: ......................I just looked at the engines power output or

"torquecurve".

:confused:

2800 to 3400rpm is the peak on the 3.0L for hp and torque. Granted the numbers aren't great. As I said keeping it between 2800-3000 rpm, as much as practical, netted the best mpg on my truck while being in its (pathetic) "powerband".
 
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Why is the full throttle torque curve meaningful when we are not traveling at full throttle when concerned about fuel economy?

Wouldn't the part throttle Volumetric Efficiency curves be more relevant? (if they exist?)
 
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Help needed after reading this thread - I am upgrading to a 33" tire, what is the best gearing for my 94 DD.:confused:


You're going up about 6.4% in tire size, so ideally you should regear about 6.4%, which would be 4.37. The closest ratios commonly available for Toyotas are 4.30 or 4.56. I'm not sure if 4.30s are available for the Land Cruiser's rear diff. They are for the mini-trucks. 4.56s would be a good bet.

However, most people seem to live with 4.11s. Regearing is extremely expensive and you're not talking about that much of a gain. It makes a lot more sense to spend the money if you have 35s and then decide to go with 4.88s. The difference there is more significant.
 
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Why is the full throttle torque curve meaningful when we are not traveling at full throttle when concerned about fuel economy?

Wouldn't the part throttle Volumetric Efficiency curves be more relevant? (if they exist?)

We’re conditioned to believe that lower rpms on the highway always equals better mileage, but that couldn’t be further from the truth with a modern engine. Some of us who started out on the mini-Toyotas have found that our engines operate more efficiently at a higher rpm than one might think while on the highway.

A vacuum gauge might offer some explanation as to why this is the case. I know on my mini-truck, which weighs almost as much as stock LC80 with passengers and fuel, the little 22RE is lugging on the highway, when rpms are less than 2500. My foot is further down on the pedal (floor actually) and the vacuum drops to zero or close to it and fuel mileage goes down.

Raise the rpms a bit with a lower gear selection or better diff gear/tire combination and the rpms are higher, such as 2800, but I'm using less pedal and throttle to maintain speed and vacuum reads higher. 2800 rpm just happens to be the peak torque on the 22RE and where the hp/torque cross on a power curve, so there’s been some discussion that’s the sweat spot in rpm range for a engine on the highway.

However, I think it’s more related to vehicle weight and engine output. The most efficient rpm is probably going to be different for different set ups. The Land Cruiser is a very heavy rig, especially when built and even the 1FZ is not particularly powerful. So, considering our experiences with the smaller Toyotas of similar weight/power ratios, I too have wondered if the LC80 would benefit from higher rpms at cruising speed.

What’s always baffled me about the LC80 is that 4.10 gears with 31” tires is already pretty under geared compared to other Toyota 4x4s. Other Toyotas come with 4.56 gears for that tire size. Then add the very high .71, .75 or .76 overdrive ratio and it seems to me that rpms are too low even when stock. In fact some Toyotas with 31s and automatics with similar overdrive ratios have 4.88 gears! But then….add 33s on an LC80, which is extremely common and I just can’t see how even the 1FZ could possible cruise at an efficient rpm on the highway.

Putting in a vacuum gauge and watching its readings at different rpms by, for example, turning off the overdrive on the highway, might prove to be pretty revealing.

Most of us, don’t have stock Land Cruisers, but I would be very interested to see how a bone stock Land Cruiser with 31s performed with 4.30 or 4.56 gears as far as highway mileage.
 

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