Thoughts on power upgrades for 2006 TJ 2.4?

[pbeach]

Regearing to a more appropriate axle ratio will give an immediate and dramatic boost in performance. I even started getting roughly 25% better fuel mpg after my last regear since the engine rpms were too low before regearing causing the engine to be on the edge of lugging on the highway.

!

 

[Fishtaco]

Go back down to 31,s which will be around 30" perfect for 3.73 gears

 

[Jerry Bransford]

Go back down to 31,s perfect for 3.73 gears

View attachment 260400

Charts like that don't show the rpms we'd actually see except with a transmission without an Overdrive, like the 32RH. With the exception of the 32RH, none of those rpms are what you'd actually see on the highway, all of those are higher than what you'd see except with the 32RH. Unless you shifted out of Overdrive... like turning the Overdrive off on the 42RLE, shifting to 4th with a 5-speed, or into 5th gear with the 6-speed.

Only by using the gear calculator at http://www.grimmjeeper.com/gears.html will be correct once you tell it which transmission you're using.

 

[Fishtaco]

Charts like that don't show the rpms we'd actually see except with a transmission without an Overdrive, like the 32RH. With the exception of the 32RH, none of those rpms are what you'd actually see on the highway, all of those are higher than what you'd see except with the 32RH. Unless you shifted out of Overdrive... like turning the Overdrive off on the 42RLE, shifting to 4th with a 5-speed, or into 5th gear with the 6-speed.

Still a good first guide dont you think? OP,s tires are clearly too big for his 4clyd even though his 3,73,s are in the range, Nothing is perfect

edit : this chart relates to TJ,s.

 

[Jerry Bransford]

Still a good first guide dont you think? OP,s tires are clearly too big for his 4clyd even though his 3,73,s are in the range, Nothing is perfect

Not really. Its rpms are not accurate and will mislead probably >90% of anyone looking at it. Those who are unclear on how rpms are derived and how the transmission model affects them.

 

[Fishtaco]

Not really. Its rpms are not accurate and will mislead probably >90% of anyone looking at it, those who are unclear on how rpms are derived and how the transmission affects them.

So you are saying OP,s tires are not too big on his 4 cylinder for the type of use which is highway, cross country highway and some hills?
I am asking as I don't know?

 

[Jerry Bransford]

So you are saying OP,s tires are not too big on his 4 cylinder for the type of use which is highway, cross country highway and some hills?
I am asking as I don't know?

I'm not sure what you're looking for but his 2.4L engine is fine for 33's when his axles are geared appropriately.

 

[Gunnersmate]

LS
Hemi
Cummins
in no particular order

 

[Gunnersmate]

Or Gears and lockers

 

[pbeach]

You've confirmed my thoughts, Jerry - Ideal suggestion, man. Thx.

BTW, Jerry - sincerest thanks are in order: 4.56s were just what the doctor ordered. Money's tight (when is it not) - a good deal on Yukon's helped the choice over 4.88s. Substantial difference. Fun has returned to driving the TJ. Essentially I'm one gear higher than before, throughout the range - highway: used to be at 2400+- RPMs in 5th @, say, 55-60mph. I'm now comfortably cruising in 6th, 2400+- RPMs @ 65mph. Before, I'd rarely be in 6th on the highway because I never had the power to maintain, especially into the wind or uphill. Haven't measured the gas mileage just yet — as you noted you experienced — I suspect it's improved.