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Gear Ratio Calculator

On my previous rig (2nd gen tacoma). I was locked front and rear on 35's and i had 4.56 gears. It was just about right. I think if you are going bigger (37s) you might want to look at 4.88s

Magnuson gives no guidance whatsoever on any subject. I've called them before to ask if the supercharger was compatible with the safari snorkel - no help whatsoever - seemed like i was bothering them.

The gearing has to do with wheel size, weight and intended use - nothing to do with the supercharger. Having more horsepower helps by making it easier to drive.

If your T4R is an overland vehicle and not a dedicated rock crawler and have 33" ~ 34" tires then 4.56 is the tallest gearing that you would want to go.

Like the guys at Marlin Crawler told me when they re-geared my T4R and i asked about putting 4.88 gearing: "are you gonna trailer your 4runner?"
no
"then 4.56 is the tallest that you want to go so you can still drive it on the freeway"

This has proven to be very true.
I can only go about 80 ~ 85 mph on the freeway before it feels like it is going too fast for the vehicle.

What would be very useful is a fuel consumption map for the dual vvti 1GR. I don't know that I've ever seen one. I also think 4.88 would be too low for comfortable or efficient highway travel with 34" tires. The 1GR is rough at higher RPMS. My bet is that fuel consumption map shows a significant increase in consumption around 2500rpms and up. At 85 you're going to be over 3k rpms. Without a BSFC map for this engine I have no idea what that means for fuel efficiency. If the engine were similar to something like the GM ecotec 4.3 - you'd expect about a 15% drop in fuel efficiency purely as a result of lower thermal efficiency - making the same power, it uses quite a bit more fuel. The problem is that I don't know what that map looks like for this engine. It could be a 30% hit, could be zero. Just don't know. My gut tells me that the efficiency drops fairly rapidly around 2500 rpms and up. It is not a free revving motor like the 2GR. I think the 3rd gen Tacoma for example would be much more friendly to low gearing.

They're inexpensive because the carrier is different offset to the mounting flange so you can't re-gear them with any of the common gear sets. I want to say the OEM 4.56 gear set might fit the rear, but I cant remember for sure. What matters is that they're not a desirable used part. I'd guess you could buy both front and rear diffs for $500 or so. I don't think you'll find a rear e-locker version in north america. So the e-locker axle the 3rd member housing will not be interchangeable, nor will the carrier fit the e-locker housing (the driver's side bearings are different size). But if you had an SR5 or Limited you could probably swap them in for not a lot of money.

Edit: Also I mis typed. It's a 3.91 ratio (43/11).

The front 8" clamshell has essentially a full range of options. Including 4.10 - which would be a good option IMO. It's the rear 8.2 that is lacking many ratios. I believe Circle K is the only non-OEM gear manufacturer for the 8.2 - so all gear brands are really the same rear diff gears. I don't know what the minimum order would be for a run of 4.10 rear gears.

I had 315/70/17s with 4.88 gears and its honestly overkill. I would go with 4.56s but wouldnt bother with 4.10s

I'm not sure, but I'd definitely be in if someone set it up. I don't plan on going any larger than 285/70, and I think it would be perfect with 4.10 gears. Mine will see plenty of highway road trips, so 4.56 is a bit much.

Just to follow up quickly. I switched to 4.56 recently. I'm probably going back to 3.73. Why? Because my MPG really tanked with the 4.56 when towing my camper. This past weekend I went to Moab and averaged only about 11.7mpg on the highway - going slow. 60-65mph. With a 2500lb camp trailer. I was in 4th gear most of the way and 4th gear with 4.56 is worse for mpg than 4th with 3.73. So in my experience over this trip, I'd rather have 3.73 and run in 4th gear. Off road the 4.56 was really nice. The initial launch feels a lot better on the street. And the engine feels less stressed towing. But it's sucking down fuel. With 373 gears I would normally get about 14mpg, but going a faster. At 65mph I'd usually get more like 15. If I'm going to get 10-12mpg towing and 15 empty - I'm going to trade for a LC200.

I'm still convinced that 4.10 is the best gear ratio for me. And the only way to get there is to swap axles or have a custom LC9.5 rear end build by Diamond axles, build my own hybrid, or see if Circle K would make a production run and how many I'd have to order to get them produced. (I think I've read somewhere it's something like 100 sets). None of which are really good options.

I have some ARB issues to sort out as well. I think I actually ended up somehow with bad spider gears. This gear swap has been a comedy of errors. I'm getting grinding noise while at highway speeds - unless I shift into 4hi - then it all goes away. The ADD actuator was not changed and the nose is gone when in 4hi. Indicator light suggests shifting of the ADD is working as normal. So that points to spider gears making the noise. So my front diff has to come out again. Lots of frustration. Fortunately I have spare front and rear original diffs that I can just swap back. It's just a lot of work to keep doing this. I'll be chatting with ARB once I pull it out to see what's wrong. The only other thing I can think of is that it's not fully disengaging. Either way - it has to come out to diagnose and/or fix.

After being stock for 18 months, I moved to 33's on stock gears. Wasn't too bad. Then for 5 years I had 34's on 4.56 and loved it. Then came 35's for 4 yrs on 4.56 and disliked it. Then went to 37's for 18 months with the 4.56's and hated it. Now moving to 40's with 5:39's woohoo.

Caveat - I usually carry a lot of weight in/on my truck including front bullbar and steel cable winch, Full length roof rack, Full steel skids, four bags of tools, and when away camping LOTS of camping gear.

What tire size are you running? I'm still on the stock the 265s & 3.73, and got 10.5mpg towing my similarly weighted R-Pod camper from SLC to Reno and back. Same case with running almost entirely in 4th, and sometimes 3rd, at 60-70mph.

IMO, running 5.29's and 40's in something this heavy is looking for pinion issues...........

It depends on the trip. I normally have 275/65/20's (they're just a bit taller than a 285/70/17). That trip was with the more dirt friendly set of 285/75/17's (34").

I just did two more trip in the past three weeks. The first was through Jackson/Yellowstone/Montana and then I went last weekend to Great Basin NP in Nevada. From Utah to Montana going north I averaged about 14mpg on the dash. On the way south it was 30mph sustained winds and the mpg went to shit - 10.7. Out to Great Basin and back is very mountainous and the average was 12.5 out and back with the camper. Both trips with the smaller 33" tall tires. And I did swap back to 3.73 diffs - so those were both with 3.73. Better mpg towing and I'm back to getting around 19mpg highway empty. For most of my towing I do just put in 4th gear and leave it there.

I'm wondering if adding a Mag Supercharger along with 4.56 gearing would help at all to keep my 4runner in 5th gear while towing around 2k lb camper trailer, or do y'all think it would still just require 4th gear normally? Do you think having both would be a huge hit to MPG?

I haven't pulled anything yet, just trying to plan ahead before I get the camper.

Regardless of pulling a trailer or not, I really need either the gear change or a SC. Still have 3.73 stock gears.

My rig:
2016 T4R Trail Premium with KDSS
3" lift Bilsteins - sliders - and UpTop rack
33" Falken LT285/70R17