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2.0 on 37's with 4:10 gears in a JLUR

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So friends and I have been going back and forth on the 3.6 vs the Hurricane from an ordering perspective. I will be running 37x12.5r17s and don't want to regear out of the 4:10's that come in the JLUR.

Question/Discussion: Would the turbo in the Hurricane constantly have to produce boost in order to spin the 4:10 37's? If so, would that cause excess wear and tear on the turbo and/or kill ANY chance of decent MPG. I'm ready to order and really trying to decide if taking the risk of the Hurricane is worth it knowing I will run 37s. I know the 3.6 is a safe choice.

Thoughts?
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So friends and I have been going back and forth on the 3.6 vs the Hurricane from an ordering perspective. I will be running 37x12.5r17s and don't want to regear out of the 4:10's that come in the JLUR.

Question/Discussion: Would the turbo in the Hurricane constantly have to produce boost in order to spin the 4:10 37's? If so, would that cause excess wear and tear on the turbo and/or kill ANY chance of decent MPG. I'm ready to order and really trying to decide if taking the risk of the Hurricane is worth it knowing I will run 37s. I know the 3.6 is a safe choice.

Thoughts?
The engine/transmission, directed by the ECU, will pick the best combination of gearing, valve and spark timing, boost and fuel for a particular engine load. Aside from the physics at takeoff and under hard acceleration, I'm guessing the major difference will be spending more time in lower gears.
 

JLU_rubi18!

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I’m trying to decide if I’m going to run 37s or 40s on this combo and I’m not regearing. You’ll be fine.
 
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That's kind of my question... if the ECM controls the turbo to account for proper boost given particular engine loads, wouldn't 37's put a greater "average" load on the motor causing the need for more frequent (if not constant) boost? If the turbo is constantly working to produce boost to provide specific power levels, would that theoretically cause excess wear...
 

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Rockmaninoff

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The engine/transmission, directed by the ECU, will pick the best combination of gearing, valve and spark timing, boost and fuel for a particular engine load.
Not right to say "gearing" for that because in the world of jeeps, the word always refers to diff ratios.

That's kind of my question... if the ECM controls the turbo to account for proper boost given particular engine loads, wouldn't 37's put a greater "average" load on the motor causing the need for more frequent (if not constant) boost? If the turbo is constantly working to produce boost to provide specific power levels, would that theoretically cause excess wear...
This is a classic engineering problem. The 37s are going to put strain on the engine under acceleration. Once they are rolling, they will actually be difficult to stop. So when cruising, the stress wouldn't be as bad and that should answer your fuel economy question. If you're in a lot of stop and go traffic, the 3.6 would be less stressed and that's always good for longevity.
 

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If you're in a lot of stop and go traffic, the 3.6 would be less stressed and that's always good for longevity.
They'll both be equally stressed but the 2.0 will handle it more gracefully as it can pump out more torque and hp at lower rpm's. The potential downsides with the 2.0 are cost and reliability.
 

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I’m trying to decide if I’m going to run 37s or 40s on this combo and I’m not regearing. You’ll be fine.
Yr joking right?
 

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Since the turbo only works under load, you have a better chance of decent MPGs with the 2.0 because whenever you are cruising slow or coasting or slowing down you'll be using 2 liters instead of 3.6 When you need to accelerate or drive on an incline, the turbo will spool up and do it's job. It is highly likely that the 3.6 makes more torque at very low RPMs (crawling speed), but the 2.0 probably makes a lot more torque much earlier in the mid range than the 3.6 with its more linear N/A torque curve.

If they offered the 2.0 with a manual trans that's what I would get.
 
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Well, on a sour note.. went to go order a 2.0 yesterday and the order banks are down.. you can't order the 2.0 at the moment.
 

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Rockmaninoff

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JLU_rubi18!

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Yr joking right?
Absolutely not. Off road Evo, Rock Krawler, crawler Conceptz a s many others have beat the piss out of their JLUs at EJS on stock axles and gears in 40s and they are fine. The new 8spd does wonders for hwy driveability.

I ran 4.10s with 37s in my JKU 5spd auto and it was fine.
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