Is your 3.6 MT gutless on highway (w 37" tires + gear)

Kreepin1

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I run the highest available octane. In my area that is 93. Out on the trails it is typically 91.

Good call on the air cleaner. I've likely done 1000 miles off road over the last year or so which includes water/mud up north and desert out west.

I'll likely replace - what's the best replacement filter? I'm not looking for a CAI for 'whooshing' noises - I need to keep it protected from the elements.
Well, if the Jeep's always had high octane fuel that's not the culprit.

I've had good luck with K&N air filters for trail rigs that see a lot of dust. There are a lot of people that don't like them though. I think a CAI is a waste in this case. You just pick up a couple of ft-lbs in the upper RPM range and often lose a few down low where we're talking. I would just get a quality replacement filter like AC or Fram or whatever.
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Willing&Able

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Well, if the Jeep's always had high octane fuel that's not the culprit.

I've had good luck with K&N air filters for trail rigs that see a lot of dust. There are a lot of people that don't like them though. I think a CAI is a waste in this case. You just pick up a couple of ft-lbs in the upper RPM range and often lose a few down low where we're talking. I would just get a quality replacement filter like AC or Fram or whatever.
Thanks! I did some keyboard warrior stuff and ordered an AFe dry filter based on lots of favorable feedback and they were on Amazon for $70. Shows up next Monday! At least it removes a variable...
 

omnitonic

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This doesn't add up which is why I was looking for something like retarded timing or a plugged air cleaner...
It's a fair point. On paper, it looks Willing&Able's Jeep shouldn't feel so gutless.

I'm interested in this test case, because I only want to regear once. My current plan would put me at 2093 RPM at 70 mph in 6th with 4.11 gears on 33s, which is somewhere between where you are now and where Willing&Able is.

Is that going to be low enough? Will I regret not going lower? The danger is that if I go too low, now I HAVE to go with bigger tires, and all the new expenses that brings into the game.

Playing with calculators is wonderful fun, but at the end of the day, you have to pick something, go with it, and see whether you made the right choice. I'm not yet ready to commit to anything. Actually, I need to crawl under the Jeep and see what I hit yesterday. I may be making a stronger argument for why I need to suck it up and go with a bigger lift and bigger tires and the whole nine yards, because I need it for the trails around here. I made it just fine, but I heard some bad noises. What did I tear up, and how did I tear it up? Hmmm.

Anyway, blather blather. I'm sorry I talk too much.
 

Kreepin1

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It's a fair point. On paper, it looks Willing&Able's Jeep shouldn't feel so gutless.

I'm interested in this test case, because I only want to regear once. My current plan would put me at 2093 RPM at 70 mph in 6th with 4.11 gears on 33s, which is somewhere between where you are now and where Willing&Able is.

Is that going to be low enough? Will I regret not going lower? The danger is that if I go too low, now I HAVE to go with bigger tires, and all the new expenses that brings into the game.

Playing with calculators is wonderful fun, but at the end of the day, you have to pick something, go with it, and see whether you made the right choice. I'm not yet ready to commit to anything. Actually, I need to crawl under the Jeep and see what I hit yesterday. I may be making a stronger argument for why I need to suck it up and go with a bigger lift and bigger tires and the whole nine yards, because I need it for the trails around here. I made it just fine, but I heard some bad noises. What did I tear up, and how did I tear it up? Hmmm.

Anyway, blather blather. I'm sorry I talk too much.
You won't regret 4.11's but you will regret 4.56's even less, mainly since you don't have the Rubi transfer case. If you do a lot of commuting or hi-way driving I might stick to 4.11's. For cruising and trail, 4.56's and 33's would be pretty optimal.
 
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Willing&Able

Willing&Able

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It's a fair point. On paper, it looks Willing&Able's Jeep shouldn't feel so gutless.

I'm interested in this test case, because I only want to regear once. My current plan would put me at 2093 RPM at 70 mph in 6th with 4.11 gears on 33s, which is somewhere between where you are now and where Willing&Able is.

Is that going to be low enough? Will I regret not going lower? The danger is that if I go too low, now I HAVE to go with bigger tires, and all the new expenses that brings into the game.

Playing with calculators is wonderful fun, but at the end of the day, you have to pick something, go with it, and see whether you made the right choice. I'm not yet ready to commit to anything. Actually, I need to crawl under the Jeep and see what I hit yesterday. I may be making a stronger argument for why I need to suck it up and go with a bigger lift and bigger tires and the whole nine yards, because I need it for the trails around here. I made it just fine, but I heard some bad noises. What did I tear up, and how did I tear it up? Hmmm.

Anyway, blather blather. I'm sorry I talk too much.
You looking for stock JL Rubi 4.11's or something different? I have a front and a rear sitting in my garage with < 10k miles on them...
 

AnnDee4444

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I know there's more to it than just engine RPM, bigger nobbies have more wind and rolling resistance, but GrimmJeeper says at 70 MPH in 6th gear:
1,826 RPM - 32's with 3.45 gears
1,984 RPM - 35's with 4.10 gears (me)
2,234 RPM - 37's with 4.88's (OP)

Looking at the torque curves @AnnDee4444 posted here:
https://www.jlwranglerforums.com/forum/threads/3-6-torque-curves.62669/page-3#post-1545438
We see you are well and truly out of the power band and I'm not much better off. But @Willing&Able is maybe 10% below the torque peak. So why does mine cruise just fine and his fall on it's face? This doesn't add up which is why I was looking for something like retarded timing or a plugged air cleaner...
Keep in mind those are WOT torque curves, and not the full RPM/throttle range.

I haven't driven a manual JL yet (stock or modified). Will they not pull at WOT in 6th with larger tires, or is the difficulty that it requires flooring it all the time to maintain speed?

I think aerodynamic drag is a big variable the above doesn't capture too.
Definitely. I've thought about attempted to graph this out, but the aerodynamics of the JL can change so much depending on model/modifications/etc... it's probably doesn't have any real world value.


Basically, a stock JL is probably somewhere between the Blazer & Hummer:
6f75727365732f70313430312f647261675f706c742e706e67.png


So if the curve above was overlaid with how much force each gear will output (below), then we could see the maximum speed each gear is limited to with wind resistance.
chart.png
 

omnitonic

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You won't regret 4.11's but you will regret 4.56's even less, mainly since you don't have the Rubi transfer case. If you do a lot of commuting or hi-way driving I might stick to 4.11's. For cruising and trail, 4.56's and 33's would be pretty optimal.
That's the compromise in a nutshell. I need to avoid trashing my fuel economy on the highway. As annoying as it is to have a de facto 5-speed, the Jeep still gets better gas mileage than any other vehicle I have to choose from on the commute.
 

omnitonic

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You looking for stock JL Rubi 4.11's or something different? I have a front and a rear sitting in my garage with < 10k miles on them...
I'm definitely interested. I could get beefier axles, the desired ratio, and it's a project I could likely pull off in my driveway. Even if I did change ratios later, I'd be better off working with Dana 44s.
 
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