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Old 05-12-2009, 10:24 PM   #1
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Red face Gear Ratio / HP and Torque Range

I have done a lot of reading on the subject of what would be the preferred gear ratio in relation the the tire size but I have not come across anything that talks about the RPM range.
The 3.8 liter V6 that is in the my jeep has 205 hp @ 5200 rpm and 240 ft/lbs torque @ 4000 rpm.
These high rpm ranges just throw my mind in to a whirl trying to calculate what would be the appropriate gears for my 08 Sahara 4 door unlimited with 33" tires.
I do plan to tow with this rig and I'm flopping back and forth between the 4:56 and the 4:88.

Any insight to my setup would be appreciated.

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Old 05-13-2009, 08:00 AM   #2
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I run 33's with 3.73's in a 2-door 6-speed, and even with the Superchips Flashpaq (actually added decent power/torque), it's about as slow as I'd want to go.
You forgot to mention if you're 6-speed or auto. Silly rabbit...
For your setup, I'd run at least 4.10's if you want to tow, and 4.56 would be my max- 4.88's would likely be too short for a 6-speed. For the auto, 4.56 or 4.88 should be fine- the auto needs a bit more poke due to wider gear spacing- Mark W.

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Old 05-13-2009, 09:09 AM   #3
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Which tires and size? Auto or stick?
I'd go 4.56 with a stick and 4.88 with auto if they're real 33's.
I find myself wishing for 4.88's every time I tow...

Everything is fine on the trails; it's the winding podunk 2-lane backroads that get annoying in a Jeep when you have large tires. Add a trailer and it's near impossible to maintain speed without some gearing help.

And since it's an unlimited and breakover angle will eventually become an issue if you wheel with 2-doors, are you ever thinking of going to 35's maybe?
That's something to think about too.
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Old 05-13-2009, 02:32 PM   #4
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I guess trany is important factor as well. I have the auto.
The tires I have on there are Toyo M/T Open Country 295/70/17. They actually measure 32.50"
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Old 05-14-2009, 07:31 AM   #5
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Gotcha- sounds like 4.56's are in your future, amigo Mark W.
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