Best JK gearing change with 35" tires: 4.88 or 5.13 or stock
01-17-2011, 06:13 PM
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Just because they 'deal' with JK's all the time doesn't mean that they really have a grasp on the differences in the engine and transmissions. We don't have the old high output inline 6 or a transmission with gearing that is matched to the engine output. Look at the charts in that high altitude threads linked above and see what you come up with.
You are running 40" tires. With this engine/transmission, you need a lot deeper axle gearing than 5.38 - it just isn't available. So, you are running OD Off to keep anything close to freeway speed.
If you choose to drop down to 5.13 or 4.88 to bring your od off rpm's down at freeway speeds, will you have the hp/torque to actually hold those speeds? Or will you be dropping down to second to get your rpm's back up over 3k so you can go 70?
You are running 40" tires. With this engine/transmission, you need a lot deeper axle gearing than 5.38 - it just isn't available. So, you are running OD Off to keep anything close to freeway speed.
If you choose to drop down to 5.13 or 4.88 to bring your od off rpm's down at freeway speeds, will you have the hp/torque to actually hold those speeds? Or will you be dropping down to second to get your rpm's back up over 3k so you can go 70?
01-17-2011, 06:26 PM
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01-17-2011, 06:42 PM
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another thought or question
What if you look at the horse power and torque curves of the engine and the question is what could you do to increase the low end say 1500 rpm to 2000 rpm outputs of the motor? How would having say 50 more hp and 50 more lbs of torgue affect what gearing you have? What can you do to get some serious increase short of an Rip super charger or a engine swap
01-17-2011, 06:54 PM
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What if you look at the horse power and torque curves of the engine and the question is what could you do to increase the low end say 1500 rpm to 2000 rpm outputs of the motor? How would having say 50 more hp and 50 more lbs of torgue affect what gearing you have? What can you do to get some serious increase short of an Rip super charger or a engine swap
01-17-2011, 06:55 PM
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Originally Posted by rj'sjeep
What if you look at the horse power and torque curves of the engine and the question is what could you do to increase the low end say 1500 rpm to 2000 rpm outputs of the motor? How would having say 50 more hp and 50 more lbs of torgue affect what gearing you have? What can you do to get some serious increase short of an Rip super charger or a engine swap
Seriously there is no feasible way to add alot of power down low. I think the best gain might be from a flashpaq which would be modest at best.
Back on topic, great chart, it's very usable for a newb like me for when I order my JKU.
