Tacoma Regear or Supercharge?

mvbeggs

Adventurer
I am a new owner of a 2012 Tacoma. As some of you may know I am building the Tacoma as an overlanding rig. After discussing gearing in some other threads gearing-and-255-85-tire several Tacoma owners have elected to gear 4.56 or 4.88. This gearing gets the 4.0L in the 2500-2700rpm range,at 75mph, where the 4.0L develops about 175-190 ft lbs of torque. This seems to be the sweet spot for the 4.0L.

I like to run 85mph across the flatlands of Kansas and Nebraska which at 4.56, or 4.88 gearig, puts my engine speed above my self imposed limit of 2600rpm.

I found a dyno curve of a TRD supercharged 4.0L. The Dyno curves appear to turn the supercharged 4.0L into a low end torque machine. Essentially a supercharged 4.0L develops 270 ft lbs of torque at 2000 rpm. (see curves below)

My question, what is the opinion regarding supercharging instead of regearing? Could I have the quiet, low reving, economies during flatland highway travel at 85mph while kicking in the supercharger when the torque and power is need to climb grades, at altitude, while towing the Chaser?

I'd also like to hear the experiences of TRD supercharger users regarding maintenance and reliability of the supercharger.

Here are the dyno cuves I found on TacomaWorld.com and CustomTacos.com

Tacoma '07 Dyno Curve.jpg1GR-FE SC with Longtubes copy.jpg

RPM curves of various gearing options:
 

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mvbeggs

Adventurer
More questions

Another great thread on the subject:
http://www.expeditionportal.com/forum/threads/63972-Supercharger-or-regear?

Its obviously aimed at the 1st generation Tacoma's but the logic is the same, my today would be identical to those I posted last summer. Still happy as a clam with my TRD SC and no reason to re-gear.

Thanks for the reply and the link. I read the thread. Many say "re-gear" and don't give much reasoning behind their decision. (Cruiseroutfit excepted.) I was hoping for a little more technically backed debate.

Folks seem to be regearing to 4.88 to put the engine in the torque range of 175-190 ft-lb range (2400-2700rpm) at 70-75mph. If this is true, why is the supercharger being dismissed when it acheives the same torque at 1700-1800rpm? Cost, maintenance issues, need lower gearing on the trail, gears are easier to install, etc.?

My Tacoma is an overland type build and DD. My guess is that 80% of the time will be spent on highways, roads and unmaintained roads. 20% of the time will be spent on trails, with only a small portion of that on truly technical terrain.

WHY isn't a supercharged engine that has the ability to produce tons of low end torque, as needed, desired over regearing?

Loads, speed, and power applied being equal, does a supercharged engine running at 2,200 rpm burn less fuel than a normally aspirated engine running at 2,700 rpm? Or is it simply, that for an engine to move a particular load, X, requires Y amount of fuel to be burned, regardless of engine rpm?

Don't get me wrong, I'm not against regearing. (after all I have hemi in the Jeep and it's geared 5.13) I'm simply in the process of trying to figure out what is best for me, doing my due diligence, looking at all my options, and thinking out the build before I get too far down this path.

Thanks for any light you can shed on the subject.
 
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downhill

Adventurer
Well, for one thing the torque multiplication on a gear swap happens in the rear diff so the transmission and T-case are spared the extra stress. With the SC, the torque boost is coming at the engine, everything behind it is stressed. The engine itself is stressed. I can't say how much of a real world problem that is with the stock drivetrain. I would guess the 6 spd would handle it better. It is certain to need more maintenance and attention. If you are just using it for cruising, with common sense, it may be a nonissue. The problem really is your requirement for 85 mph and 2,600 RPM with a 4 liter engine, on a rig that still has to be trail capable. Too many divergent variables for calculus. You may need to resort to quantum physics (or maybe metaphysics LOL).

There is another possibilty that might be worth checking into, and that is an add on overdrive. I ran one on another rig for many years without issues. The one I had was a Gear Vendor OD. I had 5.36 gears in that rig and could easiy do 70 on the hiway. I have no idea whetter there are any applications for the 05+ taco.
 

NM-Frontier

Explorer
For an overland rig I want to keep the drive train as reliable as possible. Re-gearing the diffs would effect the total stock configuration of the drive train the least so I would go that rout.Seems like adding more stuff means you have added more things that can maybe fail, witch would require you to need to bring more spare parts(more wight).How easy is it to find belts and pulleys for these? Like you asked above I would question how the SC would effect you fuel consumption. After all the idea is to travel long distances to see and explore cool stuff, these trucks don't have the largest range already so taking even more away means bringing more fuel(more weight). If I had to choose between 70mph and the possible loss of reliability and range with the SC to run 85mph, I would just drive slower overall it wont take that much longer to get there.
On the other side the TRD SC is Toyota. And if it were installed on a new truck I would hope that it would carry the same reliability as the rest of the truck. (That is why you got a Toyota right?) I could see that if driven with a soft foot that the extra fuel needed to keep up with the SC could be kept to a minimum.

All in all the added power is great if you can still keep the reliability and range. But if you compromise those on a overland rig then no amount of added power is worth it.
 

cruiseroutfit

Supporting Sponsor: Cruiser Outfitters
...On the other side the TRD SC is Toyota. And if it were installed on a new truck I would hope that it would carry the same reliability as the rest of the...

That is kinda where my thoughts lie on the system, I've seen far more issues with aftermarket r&P setups (most often install error) than I have with TRD SC's, in fact I can't really think of an instance where the modern TRD SC's have left anyone stranded. The belts are available at any Toyota dealer and I suppose you could match it up easy enough aftermarket, I carry a spare behind my seat along with the other belts. Other than that there are no real maintenance issues to speak of. Re-do the oil ~120k, beyond that?

Likewise a good gear install can be equally as trouble & maintenance free.

I think it really comes down to a budget and the intended returns. The SC isn't going to give you the low speed crawl abilities off-road particularly in 4-low, and the gears are not going to get you the top end up a canyon :D
 

mvbeggs

Adventurer
More-

Downhill, glad to see you got in on this!

Lots of good points here. As many of you have pointed out, mechanical reliability is #1.

Like cruiseroutfit mentioned, I also assumed the TRD SC is a Toyota factory engineered and integrated product for the Tacoma. Toyota's extension of the factory warranty for a "dealer" installed SC tended to reinforce that assumption.

Replacement belts really don't concern me as I carry spares anyway. I could lump a pulley into the spare parts bin as well.

Driving slower on the highway isn't a problem when it's just me and the wife. The problem arises when I'm traveling with others that can run 85 down the highway. I don't like to be the slow wagon in the wagon train. :eek:

The near vertical torque curve on the TRD SC dyno chart really caught my attention. (i.e. 85% of the total torque made before 2000 rpm) :drool: I started thinking the SC might be an answer to my 15-16mpg, 2600rpm/85mph highway cruise speed, trail capable, vehicle. (withouth having to resort to downhill's suggested quantum physics solution. :) ) If the drivetrain is up to the task, it sure would be nice to be able to fly down the highway < 2600 rpm.

I'm not worried about not having the low speed crawl, in 4LO, afforded by lowering the gearing. I don't think this rig will see that much technical terrain. That's what the Jeep is for. The Tacoma will be used more for hunting type trips. I do need the Tacoma to be able to run high altitude passes pulling the Chaser.

Cruiseoutfit, what is your setup? (i.e. vehicle, tires, armor, gearing, etc.) What kind of gas mileage are you getting?

Thanks for everyon's input.
 
In an Apples to Oranges example, I have a local Jeep Rubicon that I look after from time to time, they installed a SC without regearing, then went about adding bumpers, taller tires, winches and every other gizmo they could find. Then they wondered why it was sluggish on the highway, got lousy gas mileage and kept throwing computer codes even with a programmer.

Your SC would be better tuned to your Tacoma so maintenance and compatibility would not be a problem, but unless you know and weight everything you will possibly add to the truck in the future (plus the additional wind drag), your projections of RPM and speeds and fuel mileage are going to be shortsighted. As mentioned the stress on the rest of your drivetrain is going to become compounded with the growing need for RPMs of the SC, you will begin to have to really weight any additions to the truck versus your goals.

The gears would put less stress on fewer drivetrain parts, and if you go to an even lower ratio like the 4.88s then you could always add a taller tire or (kind of more weight) to bring you down to the numbers you are trying to hit, so almost an excuse to add more stuff:)
 

Utah KJ

Free State of Florida
I think you'd have to burn high-octane fuel with the SC. I'm a fan of re-gearing. My previous rig was a turbo diesel and I always locked in the speed limit, wagon train be damned.
 

trump

Adventurist
Or is it simply, that for an engine to move a particular load, X, requires Y amount of fuel to be burned, regardless of engine rpm?

This is what I would consider the more accurate statement... There's no such thing as free power. You might be turning more rpm's with lower gearing, but you're not going to need as much pedal. That said, the supercharger does add good low-end torque. Sorry for not helping.:p
 

NothingClever

Explorer
I went with the re-gear for a few reasons:

1) In my research for the Toyota SC I saw a ton of tweaking notes in the TTORA forum which led me to believe that if I didn't add $1,500 more in aftermarket components (7th injector / URD) that I would be one of the lucky few if my SC worked properly. This turned me off from going that route.

2) The re-gear was much cheaper.

3) The re-gear kept the engine completely stock and the drivetrain only slightly modified.

Now, that much said, if I had bumped into Kurt before I re-geared my truck I might have a SC under the hood. His advice has always risen to the top here in the forums so if he says, "It's good." I'm inclined to chase that solution.

For your stated needs (85mph), I think you SHOULD go with a SC. Re-gearing will definitely take away from your top end when you're chasing your friends.

As for me, I'm happy with the Toyota's 4.88s. I had mine installed by a reputable shop so I'm not worried about failure. 70mph top speed (well, top comfortable speed) can get old on the interstate but we don't try to do more than 300 miles in a day so it's not that big of a deal. Maybe if I change tires I'll bump up in my 'top speed' but the decreased gas mileage will probably make it a diminishing return.

Best of luck....let us know how you make out with the decision and install.
 

downhill

Adventurer
Well, after some thought I would have to say that the problem needs to be reframed. SC or final gearing is not the right the choice given the requirements. I don't think that the regear should even be considered. Instead I would recommend the most radical solution yet: leave it stock. I spent some time on the Grimm Jeeper calculator and guess what? There are gear options to keep you in the power band of the stock engine at both 65 and 85 with either the auto or the 6spd (assuming 255/85-16 tires). The only hole occurs with the auto when the speed drops to 55. The drop to 3rd gear is too drastic to use at all, and staying in 4th leaves you at 2000rpm which is flat.

Before I swapped gears I pulled my trailer from MN to OR. It weighed around 2200 at that time, and I did 80 all the way across North Dakota and into Montana with no trouble at all. That was with 32" tires though, not 33.

The only problems with staying stock are that acceleration with the trailer in tow will be poor, and if you have the auto that 55mph hole will be a major PITA. That is perhaps where the question of the SC legitimately comes in. If you have the 6spd, you won't have the 55mph hole because you have 4th, 5th and 6th as usable gears.

So here is what I would do. Forget the diff gears. Try the truck stock and see if the performance works for you. If you have the auto, you will be screwed though because you really need the option of 55 on hills, and in some areas like CA, you can't exceed 55 anyway. The SC would solve that, and the acceleration as well if you see the need. The only remaining question then is the trail performance of the stock gears. That can be more than fixed by adding a crawl box. Actually, a twin stick with a crawl box would be the ultimate.

Remember this. Once you hit the steep mountain grades you MUST slow down. If you get the SC and stand on it up a steep grade with the trailer in tow you will weld that rear diff. This is no BS. The one positive aspect here is that the 3.73 gears should run cooler than a lower gear set. They are the best choice with the SC, but you need to keep an eye on that till you understand how it works. You can use a simple infrared thermometer, but you need to get the number quickly because the temp drops fast once you stop.

Ultimate rocket taco = stock gears + SC + crawl box + twin stick. Just use the SC sanely to keep it all in one piece. Gas mileage will be what you make it. That SC doesn't run on air alone. You push 30% more air down that intake and you will need 30% more gas to make it go boom.

One last comment. I don't buy the idea that complexity reduces reliability. A stock truck relies on thousands of parts to keep running, and somehow they do. Adding 1/10% more parts isn't going to suddenly make you anymore fragile. The things that fail are the little things that people neglect. Fan belts, hoses, U-joints,valve cores, etc. Hell look at TACODOC. A great reliable truck and he's dealing with a frigging glovebox failure! Buy good parts, install them with diligence, and travel with confidence.
 

TangoBlue

American Adventurist
...look at TACODOC. A great reliable truck and he's dealing with a frigging glovebox failure!

Yeah - I can't wait to see the thread on that. :rolleyes:

All for lack of performing periodic glovebox door latch maintenance... tsk, tsk.

Oh - and all that other stuff before you mentioned - well said/good gouge!
 

Stick Figure

Observer
Couple comments....

Never confuse TRD "engineering" with Toyota engineering. TRD parts are very often rebranded products from another company. I'm not sure who actually designed and manufactured the supercharger kit in question, but I highly doubt it has the same level of engineering that the original truck did. That's not to say it is bad or that you will have problems, just don't have that same blind faith that you can have in most Toyota products.

The other thing to remember is that the supercharger uses a good amount of power to make HP. The added stress on the internals of the engine is greater than just the gain you see at the back of the crank.

As far as the original question, its a tough call and I don't have any first hand experience with that engine or vehicle to give any solid been there done that type advice.
 

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