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I have a 2013 JKU and from time to time I haul a 5x8 enclosed v-nose trailer with my Harley inside & was wondering if theres anything within reason that I can do to help power wise? I've seen some post on superchips & such but really don't know much about them. Would they help with hauling the trailer? What about gas mileage while hauling? Any help & recommendations would be greatly appreciated.

Thanks,
Brian
 

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I have a 2013 JKU and from time to time I haul a 5x8 enclosed v-nose trailer with my Harley inside & was wondering if theres anything within reason that I can do to help power wise? I've seen some post on superchips & such but really don't know much about them. Would they help with hauling the trailer? What about gas mileage while hauling? Any help & recommendations would be greatly appreciated. Thanks, Brian
There's a bolt-on supercharger kit that would help, but at $5k not sure if that falls into your definition of "within reason". I would think most things like superchips, etc would provide marginal improvement at best.
 

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Well, Wrangler's are not the best tow vehicles to begin with, and there isn't much that can be done....but we need to know more about your set up.

You have a Sahara....3.21's or 3.73's?
It looks like you have aftermarket wheels...what size? If larger than stock, did you recalibrate?
Do you have a lift or boost of any kind?
 

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Well, Wrangler's are not the best tow vehicles to begin with, and there isn't much that can be done....but we need to know more about your set up.

You have a Sahara....3.21's or 3.73's?
It looks like you have aftermarket wheels...what size? If larger than stock, did you recalibrate?
Do you have a lift or boost of any kind?
The tires are 285/70/17 with a 2" lift & 3:21 gears, no boost or recalibration.

Thanks,
 

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At the least you should regear. 3.21 is too tall on an Unlimited in general in my opinion, once you start thinking about towing it only gets worse. Chyrsler only rates a 3.21 equipped JKU to tow 2000lbs but rates the 3.73 equipped Jeeps to pull 3500lbs.
 

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The tires are 285/70/17 with a 2" lift & 3:21 gears, no boost or recalibration.

Thanks,
I think the 33"'s on the 3.21's are the biggest issue, espeically without a recalc.

Unless you are ready to drop $1500 on a re-gear....I think you are limited in your options. Maybe a Superchip and a Pro-Calc to recalc you speedo and help with your shift points....but that is about it without spending big bucks.
 

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I agree, that for more power towing, you need to re-gear!

I also have a 2013, but a 2 door, (so mine is about 400 lbs. less weight). Mine has the 4.10 ratio, and I have towed a tandem axle trailer with a UTV, and a ATV on it. I pulled it up into our mountains with plenty of power.
So yes, re-gearing is the answer!
 

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I'm assuming you have an auto tranny.

For right now, get a ProCalc to adjust your speedo (and shift points), and when cruising on the highway, tap down a gear.

Off the top of my head, on 33"'s with a 3.21 axle, you are probably only spinning 1850 RPM at 70mph in 5th gear. Tap down to 4th, that will help.
 

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Tire Size, RPM, Speed, and Differential Ratio Calculator

You will be able to see by using this calculator, how changing your gear ration, will influences your engine RPM, at different speeds, with you 33s...:thumb:

Example of what this will show you:

33s, 60 mph, 3.21 ratio, 1961 RPM
33s, 60 mph, 4.10 ratio, 2505 RPM
33s, 60 mph, 4.56 ratio, 2786 RPM

As you can see, ratio, has a dramatic impact on engine RPM!
 

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Tire Size, RPM, Speed, and Differential Ratio Calculator

You will be able to see by using this calculator, how changing your gear ration, will influences your engine RPM, at different speeds, with you 33s...:thumb:

Example of what this will show you:

33s, 60 mph, 3.21 ratio, 1961 RPM
33s, 60 mph, 4.10 ratio, 2505 RPM
33s, 60 mph, 4.56 ratio, 2786 RPM

As you can see, ratio, has a dramatic impact on engine RPM!
Hmm....I think something is wrong with that particualr calculator. Those RPM's are way too high. It is telling me that I spin 2733 rpms's at 70MPH on stock 32.1 inch tires and a 3.73 axle ratio.

Derf's is telling me it is 2268 RPM's, which is about what I actually turn.


Oh...and 33"s on 3.21's comes up at 1899 RPM's at 70mph.



Here is derf's.... Gear Ratio Calculator
 

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Tire Size, RPM, Speed, and Differential Ratio Calculator

You will be able to see by using this calculator, how changing your gear ration, will influences your engine RPM, at different speeds, with you 33s...:thumb:

Example of what this will show you:

33s, 60 mph, 3.21 ratio, 1961 RPM
33s, 60 mph, 4.10 ratio, 2505 RPM
33s, 60 mph, 4.56 ratio, 2786 RPM

As you can see, ratio, has a dramatic impact on engine RPM!
Hmm....I think something is wrong with that particualr calculator. Those RPM's are way too high. It is telling me that I spin 2733 rpms's at 70MPH on stock 32.1 inch tires and a 3.73 axle ratio.

Derf's is telling me it is 2268 RPM's, which is about what I actually turn.


Oh...and 33"s on 3.21's comes up at 1899 RPM's at 70mph.



Here is derf's.... Gear Ratio Calculator
Yep, agree. The Calculator that I am using, is only going to show you a apples to apples comparison, at a given transmission ratio output, (same verses same output revolution)!
It merrily indicates how Differential ratio impacts engine RPM, with a constant given input.
The part of the equation that it is missing, is different transmission output speeds. And to do that accurately, it would have to have all of the different output speeds, inputting the Differential........:thumb:

It was merrily meant to show a RPM comparison, at a constant given input, of which it does.
 

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It's time to up-gear..

Expecting horsepower to compensate for torque where gearing solutions are readily available is foolish, and usually much more expensive...
This, a supercharger is an exaggerated solution and a fuel tune will do nothing... Probably a ratio of 4.56 will suit better as they are usually cheaper than 4.10.
 

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As others have said you need to re-gear. It's the only thing that'll give you the results you're looking for. Even throwing 5k at a centrifical supercharger would be a disappointment IMO as they need rpm to build boost. With your gearing it wouldn't be a good choice. For reference my stock auto Rubi with 4:10s and 32" tires turns about 2650 rpm give or take at 70 mph. For me it seems to be an ideal setup. I really don't want any more gear because the fuel burn would take too big a hit. As is it's a 17 mpg jeep at 70 on the highway. I occasionally pull a 5x10 utility trailer with a Road Glide Ultra and it does just fine. Can't say it ever feels underpowered. Your Jeep isn't undeowered it's just under geared.
 

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Discussion Starter #16
As others have said you need to re-gear. It's the only thing that'll give you the results you're looking for. Even throwing 5k at a centrifical supercharger would be a disappointment IMO as they need rpm to build boost. With your gearing it wouldn't be a good choice. For reference my stock auto Rubi with 4:10s and 32" tires turns about 2650 rpm give or take at 70 mph. For me it seems to be an ideal setup. I really don't want any more gear because the fuel burn would take too big a hit. As is it's a 17 mpg jeep at 70 on the highway. I occasionally pull a 5x10 utility trailer with a Road Glide Ultra and it does just fine. Can't say it ever feels underpowered. Your Jeep isn't undeowered it's just under geared.
I curently have 3:21 gears, what would be the optimal setup to go with? Will changing the gears void my warranty?

Thanks,
Brian
 

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I curently have 3:21 gears, what would be the optimal setup to go with? Will changing the gears void my warranty?

Thanks,
Brian
Since you have a JKU, (which is heavier), your running 285s, (33s), plus you tow at times, I would go with either a 4.56, or 4.88........:thumb:
 

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I curently have 3:21 gears, what would be the optimal setup to go with? Will changing the gears void my warranty?

Thanks,
Brian
I'd say something in the 4.10 range. BUT...the way gears work, it would probably be more cost effective to go with 4.56's, however, I don't know if that is too much gear for you when you are not towing. You will be turning 2698 rpms at 70mph on 33"s with 4.56's. That is fine for some, but it might seem fast for you if you are used to 3.21's.
 

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Thanks, any idea about the warranty?
The only thing impacted will be whatever can be traced to a re-gear. Some dealers are fine with it, some dealers are jerks.
 
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