ECU chip that can increase power?

I practically got 50% off on mine
I did mine because my diff broke and they were much cheaper than Toyota gears and I wanted power back.

 

From studies, the chart is not exact science. It does provide some basic understanding. I believe this chart is based on 65 mph vehicle speed. Its along the similar vein as @speedtre chart above except on his chart he shows 5 speeds transmission. Mine is a 3plus OD for total of 4 speed. I’ll double check my RPM at 65mph but IIRC it is way left of the ‘optimal’ (left of the blue coloring). I feel dirty now.

 

Good points above. I guess I will add that my Tundra was 2wd. If it was 4wd, I might not have re-geared due to cost. And I even did the labor myself.

 

Did you go 4.30 or 4.56?
I think my truck has 4.10 and with the 295s it's not bad but I'm sure it could be better. Especially if I go 35s some day

 

I believe the numbers shown in that power band/RPM band to tire size/gear size chart are in whatever gear is 1:1 @65 mph with the O.D. turned off. I re-geared by going to smaller tires... Example: on my 2007 with a 4:30 and short 31" tires the 5.7 is turning 3150 rpms @ 65 mph in S-4 / 1:1, that's equivalent to a 4:60 gear give or take. If I ever run much taller than stock tires on my 2002, I would want to re-gear to something stronger than the 3:91 it came with.

 

I believe you have 3.92 or 3.91. All v8 tundras from 05-06 regardless of cab have that ratio except for a few oddball 3.62 ratios. I would suggest not even considering 4.30. Go 4.56 and don’t look back

 

Been running 4.56 since 2011. If I went 35s I would go 4.88s but 4.56 would do fine. On paper 4.56 and 35s are as close as you can get to stock hearing but that doesn't work in real life because it doesn't account for added weight.

My RPM don't match that graph, at 65 mph I am around 2300 RPM. Maybe would hit 3k if I turned overdrive off per Rex's note.

 

Great point, I think people tend to follow the graphs as scripture. Like you’ve said before, “on paper” it looks good, but in real world scenarios it’s only adequate or even disappointing. Because of the cost of a regear, it doesn’t make a lot of sense to only go up 2 notches. On the vvti access cabs 295’s don’t even feel too bad but it’d be a heck of a lot more fun with 4.56.

 

As cool as 35’s look on these trucks. It just seems like a never ending battle to fit them. Lift wise you’d need long travel or a combination spindle/suspension lift of 6 inches or more? Regearing would become top priority. Better start stocking up on ramen noodles and hot dogs

 

Confirmed my data today.

1950 RPMs at 65mph (actual using 8% increase due to 285/75/r16)

2250 RPMs at 77mph (actual using 8% increase due to 285/75)

Truck has stock 3.91 gears.

 

So this means at 65mph on the chart (not real life just a gauge) I’m effective 2.94 gearing on ‘33’s’. Yeah baby!

 

That's what I'm thinking

 

https://www.tacomaworld.com/tirecalc?tires=245-70r16-285-75r16

I think the SR5 tundra access cab v8’s were calibrated for 245/70/16 tires. Check out the link above. You might actually be getting a little bit better mpg than you think.

 

Thanks for this. So looks like I under calculated my MPG by 2%.

Now off to the MPG thread to correct everything. Hahahahaa. Just kidding.

 

Forgot to turn off the O.D. today!
Need to re-calculate.

 

With O.D. off

True 65 mph at 2800 rpms puts my 285/75/r16s in the chart sweet spot! Yay!

The truck is theoretically correct and balanced between power and fuel optimization. Its Zen!

 

Cool. So if you were running the standard equipped 245/70/16 tires you’d be right around 58-59mph @ 1950rpm and 70mph @ 2250.

Everybody should check out this very simple Spicer calculator; https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

I tried some of the other ones like grimmejeep or whatever and it was a little over my head.

A340 (4 speed) final drive = .705
A750 (5 speed) final drive = .716

 

Something like that. You’ve reversed the calculation method, but pretty close to your numbers. I was reminded how many RPM’s jump when going out of O.D. when doing so today.

I went through the whole re-gear dilemma last year and concluded not worth it. I do think the 12 holes injectors added some spice and are a way to bump the engine/transmission performance up a hair versus a full double diff re-gear. Value based in thinking here. Larger than my 285’s probs need a re-gear but those won’t ever happen.

 

I’ve always wondered. Do you think toyota actually changes the programming for 245/70/16 vs 265/70/16 equipped models?

 

Keep in mind that quote of mine, that you quoted, was mal-information as I did not have my O.D. off.

Read post #76 where I corrected myself.

 

Hahahahahaa!!!