Need some HP

I've begun making some changes on my 2002 Dbl cab w/ 3.4 & auto trans
3 " lift
front diff dropped 1"
KN cold air intake
285/75/16 TKO2
Off road things are ok. On road need more HP to push the big tires. They sucked the life out of the stock engine and trans. Any kind of grade now and I loose the overdrive and the engine is screaming at me to keep up speed.
I was planning on adding front bumper, rock sliders, rack etc. I'm concerned about the added weight when I've lost this much power due to the big tires.
Changing tire size is not an option at this time
Not too interested in adding a turbo
Is it possible to remap the engine and/or trans?
Any ideas?
Thanks

 

Supercharger.

Or regear.

 

Regear the rear diff or the transmission?
What's the difference between a turbocharger and supercharger?

 

If you increase tire size you effectively raise your gear ratio. The engine has to work harder than it did with stock tires where it was designed to work. It will also throw off your speedo. To correct you need lower gears in your diffs. I'd go 1 step past the ratio required to take you back to stock as you will also be losing some power to their additional weight. You can't really regear your transmission, you can regear some transfer cases. I'm not sure if yours is one of them. With the expectation of more weight to come gears would be the only thing I would consider as a fix. You can add forced induction later.

A turbocharger is driven by exhaust gasses, a supercharger is driven directly from the crank shaft generally by a belt. Forced induction will make up for the HP lost, but generally it will be higher in the rpm range before it really starts to work, regearing will fix things from a dead stop up through the rpm range.

Messing with fuel mapping etc won't get you back to stock performance, that's what you end up doing to maximize the gains provided by your hard parts.

A cold air intake, most 'bolt on and gain up to 15hp" items for that matter, aren't worth what it costs to package them.

 

By going to larger tires, you reduced your gearing by about 10%, meaning you lost approx 10% of your torque multiplication. Add that with the significant rotating weight increase (your tires weigh 59lbs, the stockers were likely in the mid 30s) and the fact that the auto only has 4 gears and is not geared well for the highway to begin with (but geared great for offroad) and you have the scenario you are in now where the engine is strained on mild grades and shifts to 3rd and screams to try and keep up but cant upshift to 4th and maintain speed.

What you need is a regear to regain the lost torque multiplication, by going up to the next gear size in your front and rear diff (if 4x4). If you have 4.10 now, you should run 4.56 to return it to near stock gearing (though you still have the added weight). This is the correct and most effective solution to your problem. I'm not sure if 4.88 is ever recommended for that tire size in the 1st gen Tacoma, but the Jeep guys sometimes overgear for more power and better crawl control at the cost of fuel economy.

Other things you can do:
-Supercharge as mentioned above. This doesn't resolve the issue of lost torque multiplication, but instead throws more torque at it to overcome it. Superchargers are run off a pulley from your engine, turbos run off the exhaust gases. This is the most expensive solution.
-Lighter wheel/tire combo. On my 2003 DC 3.4 auto, I swapped out the 16" wheels with 15" wheels from a 2000 Tacoma, I could then run floatation tire sizes which are much lighter. Rather than running a 59lb tire, you could run a 33x12.5R15 Ko2 that weights 54lbs, or the same size Duratrac that weighs 49lbs. Significant weight savings for rotational weight.
-Hit the auto trans power button, which holds the RPMs higher and drink more fuel. Unfortunately doesn't help for 4th gear.

A remap of the ecu will not give you significant torque gains needed to compensate for your gearing loss and rotational weight gain.

 

What shop can do the reg earing of the F&R diff? is this something that 4Wheel can do?

 

I believe 4wheel parts will do it. No experience with them personally. The expert shop that all 4x4s go to in my area is Randy's Ring and Pinion. You don't have your profile filled out, so I'm not sure where you are located, but Randy's has a few shops in different regions. I highly recommend them.

Regearing is an excellent time to consider adding traction devices if you can swing the extra cost, since you only need to pay for the part as install is covered by the regear. If you have an open rear end (again don't know by your profile), I would recommend a detroit trutrac. It is an torsion LSD (not clutch based), not as extreme as a locker, but more usable in a daily driver and excellent off road with exceptional reliabilty.

 

My choice was to regear with 4.88s, not 4.56s. 4.56s are ok with a manual trans but the 4.88s are perfect with 33's and the auto.

If you have to ask about the difference between supercharging and turbocharging, best to forget the turbo option. Of the 3, its the most expensive solution anyway.

What part of the country you in?

 

I'm in Southern California. It's cheaper just to buy smaller tires but I think that I'll regear the differentials. Thanks for the input on this. I read that Toyota will stop selling the supercharger for the 3.4 soon. What do you think about adding the TDR supercharger? What about the reliability and maintenance?
Also I have 254k on the motor. Never been opened.
Thanks again.

 

Thanks again for the input.

 

Yotamaster are super expensive... No thank you

 

If you want one you should pick it up ASAP. However, with 1/4 million miles on the motor, you probably want to consider a rebuild before boosting. I'd give the engine a good once over with compression and leak down tests first. But regearing is really the better way to go in your scenario.

Correct, gearing is not something that you look for the cheapest shop to do. You look for the most experienced, they are unlikely to be the cheapest. Gearing is almost an art form, any mechanic can slap gears in there but if not adjusted exactly correct they will not last.

 

Contacted Yotamaster in Corona and 4 Wheel to change out both diff gear
Both recommended the same gear ratio based on the tire size to return to factory as close as possible. Yotamaster came in around $2200. Eric was very informative. 4 Wheel came in around $2800. Both need three days. 4 Wheel is much closer to my home however. When I figure out how to get my truck to Corona I'll probably go to Yotamaster. I'm in Ventura county and aside from 4 Wheel I'm having a tough time locating any place to do the work. Well at least a place that specializes in or is at least familiar with gear changing diff work.