5.29 MPG true expectations?

Hi,

New member here with a 2020 SB. I have a 3" Ironman lift and 34" MT's and a GFC on the back with around 800lbs fully loaded. I currently have the KDMax Pro tune - which I can honestly tell helps a TON. It is what it is, you can't expect too much with 800lbs to the back, but it does well on most occasion. Sometimes going up steep grades I have to put it into manual and stay in 3rd around 4k rpms to get any sort of control on accerlation.

Been searching and it looks like people who have made the swap to 5.29's keep saying, the tune was more "worth it" and I'm not getting any specifics (hard I know) of how much better MPGs would be. I'm sitting at 13MPG tank average usually. I've seen some people say it only helps 1-2mpgs, to all the way up to 5 mpg. The other side of things people have been saying is it's not MPG's but just get that "stock" feeling back/instant throttle (which I have, just not really uphills).

Anyways I know there are threads already, but I wanted to see if anyone could chime in on MPG increases? I'm hoping to go from 13mpg to maybe 16mpg (uphills too). I got a quote for $4k from a reputable shop for the whole package and I think KDMax offers free retunes if you're just going to different settings. I calculated out gas and the way I drive and a 2MPG increase will net me......$1,000 savings in 4 years......lol.

Wonder if it's worth it or not to go with 5.29's or not. Or just trade to a Hybrid Tundra in a few years lol.

 

All the tunes and regearing in the world won't get you to 16+ MPG's. Well, you may get sort of close, but not really... You lifted your truck 3 inches, put on larger and heavier tires and added 800 MORE pounds of weight to the truck. Then, you keep the RPM's at 4k.

Get rid of the lift. Get rid of the heavier tires. Get rid of the 800 extra pounds. Keep the RPM's under 2k. If you do that, you'll EASILY get 18-19MPG without even trying.

Your problem is entirely self inflicted.

 

I think you answered the question yourself. It'll be hard to calculate gas since gas prices keep fluctuating so drastically. Honestly if you are already considering a Tundra in a few years then save yourself the money so you don't have to to pay for parts and installation and wait for a possible EV tax rebate or possibly a Hybrid tax rebate in a few years and get your Tundra. That's what I would do if I was in your shoes. If you plan on keeping the Tacoma until the far foreseeable future like 8+ years then yes, I would consider 5.29's.

 

For some of us (and definitely me) nothing is ever enough. I've done the tunes and 5.29s and now all I want is a supercharger. But who knows if that'll make me happy or not. Either way it's likely I'll find out soon

 

Yeah I dont think you will gain too much more mpgs, maybe 1 or 2. Mainly just the stock feel, and more pep. My truck is almost 6k lbs, and I get 11-13mpg daily driving with 35s/stock gears depending on how much of an asshole I drive like. On long highway trips (Wa to CA, Wa to UT) I can get it up to around 16-18mpg, just since I hold it in the right speed range/rpm range for an extended period of time (usually 65mph gps speed or 75-80mph is the sweet spot).

 

I have a 2020 OR Automatic with similar lift, tires but only about 400 pounds of weight on my truck. I just got a month ago 5.29s ( i have the tune, but forgot which one in particular) and while the driving experience is better, MPGs ( ~12.5 MPG) has stayed the same.

 

And lugging these VVT V6 will make the transmission PCM/ECU unhappy, which is "entirely self inflicted".

Let these VVT V6 engines breathe at higher rpms.

 

Similar tire size and weight as you. Likely more weight as I have full bumpers/armor/tire carrier. I also have the KDMax tune. In my case, I think the 5.29s were better than the tune. I waited to do the tune until after I had the gears. It did make a marginal difference, but nothing like the gears. Not sure where you live, but I am in SOCAL and have a bunch of hills where I live and mountains where I go. I also like to actually wheel and the 5.29 made low range great. Mileage sucks and there is no two ways about it. I have a scanguage and monitor corrected MPH and MPG always. 17 -18, maybe 19 is possible if you are on the highway without major inclines. Hold it around 65 and it will be as good as you can get. Start going over 70MPH and it starts to drop pretty quick. The 5.29s dont help you if you are on flat ground I bet. Otherwise, I could not imagine not having them. 4.88 would probably be fine if it were not the fact I want low range as low as possible without an extra transfer case.

Real world for me: 5 north to work, 19 miles, Avg 17MPG. 73 South home, 19 miles, 12MPG. Hills vs not... Almost every major road trip/adventure/explore: about 13MPG. I usually let it rip on a trip and do 80 on the highway up and down hills.

 

Best and most helpful response yet! Thank you so much I really appreciate it. The issue with me is I have trouble going over 14.5mpg even on flats, at 70mpg, not fully loaded (+500lbs instead of 800lbs). It seems to me like the 5.29's + retune should help me out.

The other comments on +lift/tires, etc....lol. There is a solution to problem, I was asking for real-world usage of if that solution was worth it. Of course the "problem" is self-induced. I don't run these for mall crawling.... I actually do real camping and off-grid stuff with it.

 

If you have an automatic Tacoma, going with 5.29 gears will help MPG, but it's not clear how much. Ordinarily, going to a higher numerical ratio will harm fuel efficiency by making the engine rev higher in any given gear. The 3rd gen Tacoma has the issue where it's last 2 gears are so long that even with 5.29s, it still revs at an acceptable rpm, especially if larger tires are a part of the equation. The 2GR-FKS engine has dual port and direct injection, which further erodes the higher rpm cause for worse fuel economy (meaning dual injected engines don't care as much about being at a lower rpm for economy and are roughly equally efficient at 1200 rpm as they are 2500 rpm) Part of the reason your Tacoma is so terrible on fuel is that the engine has to work so hard in each gear to get going that it can't put the power down without help from the torque converter. The gears are so tall and the torque converter doesn't lock until 4th gear, so you probably don't even see lockup until 50 MPH, maybe 45 but that's probably pushing it. That means at speeds below 50 MPH you're slipping the torque converter a lot more than usual, which means wasted energy as heat in the ATF. Regearing (to higher numerical ratio) shifts all your gears more towards torque and less towards speed, so each gear is accessible at lower speeds and the engine doesn't have to work quite as hard as it would before. That is a double wammy that means your torque converter can lock up sooner and at lower loads than before. The less time you spend with a slipping converter, the less waste heat you generate, which means better MPG. Regearing in this way also puts all your ratios closer together on the speed axis (doesn't effect the RPM axis, so each gear is still the same width apart), which means the transmission is more likely to find the "ideal" ratio for the situation. That also helps. You probably don't use 6th gear at all, and if you do, it probably doesn't stick around long. Regearing will let you use 6th gear much more. There's nothing inherently magical or efficient about 6th gear, it just means that the mechanism that normally makes regearing less efficient doesn't matter as much, while the mechanisms that help you are going to help you a lot.

If you have a manual Tacoma, regearing won't make as much of a difference to MPG.

 

^^- This, for sure.
My '21 TRD OR AC V6 Auto is currently hovering around 19+ mpg (per tank, not instantaneous or per trip) around town.

 

Great info. I too am on similar sized tires and lift, though likely heavier than you both, due to my build.

Speed is your greatest ally. Freeway cruising at 63 mph yields me 16.9 mpg average on my typical out and back 8,000 ft elevation gain freeway trips.

70-75 yields me 11.5 mpg.

80+ is 9.8 mpg.

If you do get gears, 5.29 is a must due to reasons Ruger explained above.

 

4K rpm?

 

Re-gear for the improvement in driveability and maintaining low-range performance, not for fuel economy. You may get some modest MPG improvements but it certainly won't anywhere near 5MPG, and the costs of re-gearing will likely barely be recouped in many years.

 

My truck, relatively light, +300-400lbs over stock. 34's, 5.29's, OTT tune.

70mph avg highway = 18.5mpg
60-65mph avg highway = 20mpg
Round town driving = 15mpg

I was getting roughly the same mileage on stock gears.

Very happy with the truck in this configuration. Peppy around town, drives great, decent enough mileage.