3.6L V6 Pentastar feels REALLY down on power; Am I driving it wrong?

[GraniteWilly]

Hey wranglers, I bought a 2025 Wrangler JL Willys 2-dr 6-speed this year and am worried about lack of engine power. I live in Oregon and recently took the Willys over the Santiam Pass in the Cascades. The Willys had no power on the inclines! I would be in 4th gear with the pedal to the floor and not gaining any speed. Even on flat ground it seemed really hard to pass other cars.

I'm wondering if some of this is driver error. Like I said, it's the 6-speed manual transmission. Maybe I'm lugging it too much? For you folks with manual 3.6's, what RPM do you generally roll in? I figured that this was an engine that liked to stay in the low RPMs. I usually cruise in whatever gear that keeps it around 2000 RPM and I shift at around 3000 RPM I think. It's not a sports car so I wouldn't imagine you want to wring it out. But I wonder if I need to rev it more in general to get enough power out of it.

If it's NOT driver error, and the 3.6 is just a dog, what kinds of mods are people doing to boost the power? From a little bit of research it looks like the only options are cold air intake, upgraded exhaust, and maybe a throttle body spacer (?). Are there any other good options for getting more power out of this thing?

Thanks for any advice!

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[bd100]

Cruising at 1500-2000 RPM is fine. Somewhere over 3000+ the oil pump kicks into high pressure, so don't cruise there. Shifting around 3000-4000 is fine. If you need to move, revving to the redline is also fine! (Once it's broken in.)

Lugging the engine at 1200 and below is bad.

How many miles so far? Per the manual, help the engine break in by doing some full throttle 3000 to 4000 RPM blasts for a moment every now and then, but stay out of the red line until break in. And read what it says about waiting before towing, if relevant.

Also, my truck seemed to suddenly get better around 200-500 miles, and again around 15,000 miles. By better I mean it suddenly had more torque down low, less easy to stall, able to do right turns in 3rd, etc. But that truck has 32" tires and 3.73 gears (JT). 33" tires and 3.45 would be worse. Don't know what the 25 Willy has.

 

[roaniecowpony]

Here's a rear wheel torque and horsepower chart for the JL 3.6.

Keep in mind that torque is a static force like you put on a torque wrench. Horsepower is a measure of work that includes the torque and motion (rpm). So, if you want to move a vehicle up a hill in a certain amount of time, horsepower is the measure you use to compare.

You can see the red line is horsepower. Given that you are shifting at 3000 rpm, the engine is low on the horsepower curve shown. If you are accelerating from 2000 to 3000 rpm, you are about 70 hp and topping around 120 hp per this chart. Bear in mind that these are full throttle numbers. With less than full throttle, you are running less horsepower and torque.

Running your engine to 6500 rpm won't hurt it. Lugging it from 2000 to 3000 rpm will build up carbon in the chambers and plugs. Let the engine breathe by letting it run

 

[Jmos4]

Hi,

Not sure if they offered different gearing in the Willys but use to be anything but a Rubicon was 3.45 gears vs 4.10 standard in a Rubicon and 4.88's optional with a 6 speed manual.

3.45's are not the best with stock tires so may want to start saving.

Regards,
Jim

 

[X35]

OP’s 2025 Willys has 4.10 gears. My ‘25 Willys XR auto with the 3.6 and 4.56 gears does not seem under powered at all.

Try revving it out longer as the torque cure doesn’t really start coming on until above 2,000 RPM. Cold air intakes, exhaust and especially throttle body spacers won’t do anything other than make more noise and separate the money from your wallet.

 

[gek]

The 3.6 in the manual feels like it is detuned under 2k rpm, most likely to prevent slippage. I assume this was part of one of their many software fixes to avoid fixing their terrible clutch design.

I recently switched from a '21 manual to an 3.6 auto and it is like it is a completely different engine. I should have tried a tune with the aftermarket clutch, but honestly, I only miss the manual when I'm offroading, and I don't miss it that much.

 

[jadmt]

3.6's like to rev...don't be afraid to run it higher rpms....

 

[roaniecowpony]

If the engine was majically gone and you put a ratchet on the input shaft of the transmission, in lo gear, and the transfer case in 4 Lo, you could ratchet your way to the top of a hill, over a very long time. That's a lot of torque at the wheels, but little movement.

If you want to go up a hill fast, you need (more) horsepower. It's available to the OP by going to higher rpm.

 

[James Westfall]

Yeah the 3.6's strengths are low end and high end torque...it's mediocre in the middle, and especially with the crappy manual trans you are going to need to use the upper end of the 3.6's power band. It's got sufficient power for a much heavier Unlimited so a 2-door should have no issue at all.

 

[jellis4148]

If you do those three things the Jeep will be way faster because your wallet will be way lighter. CAI, Exhaust, and throttle body spacer are a giant waste of money, and may gain you a 1/2 hp. Don't waste your money.

 

[TrueNorthJL]

Long time listener, first time caller here. We upgraded to 4.56 gearing (from 3.45) when we put on 35's recently and that made a big difference even with the bigger tires. 3rd and 4th gear still feel too tall in the manual transmission, is what it is. 6th is still occasional use and flat highway only. Get used to revving it high...the 3.6 just doesn't seem to have much torque down low.

 

[Blacksport]

Hey wranglers, I bought a 2025 Wrangler JL Willys 2-dr 6-speed this year and am worried about lack of engine power. I live in Oregon and recently took the Willys over the Santiam Pass in the Cascades. The Willys had no power on the inclines! I would be in 4th gear with the pedal to the floor and not gaining any speed. Even on flat ground it seemed really hard to pass other cars.

I'm wondering if some of this is driver error. Like I said, it's the 6-speed manual transmission. Maybe I'm lugging it too much? For you folks with manual 3.6's, what RPM do you generally roll in? I figured that this was an engine that liked to stay in the low RPMs. I usually cruise in whatever gear that keeps it around 2000 RPM and I shift at around 3000 RPM I think. It's not a sports car so I wouldn't imagine you want to wring it out. But I wonder if I need to rev it more in general to get enough power out of it.

If it's NOT driver error, and the 3.6 is just a dog, what kinds of mods are people doing to boost the power? From a little bit of research it looks like the only options are cold air intake, upgraded exhaust, and maybe a throttle body spacer (?). Are there any other good options for getting more power out of this thing?

Thanks for any advice!

I have a '25 2-door, 3.6, 6-speed, Sport S...I gotta say, my 3.6 goes like a bat outa hell, BUT, there's NO hp & torque down low...you gotta use the tranny to keep the revs up. I have an Injen intake & Borla exhaust, but they're adding miniscule power at best. Your Willys has 285/70-17s with a 4.10 gear, my Sport S has 245/75-17s with a 3.45 gear, not sure if that's hurting or helping you. I would NOT trade my tire size & gear because this thing flies down the interstates at 85/90mph, with police permission of course. BTY, someone posted the 6-speed is "crappy", or something similar...I've owned at least 15 manual-tranny cars, and I can say the Japanese 6-speed in the Wrangler is one of the best...so is the clutch...IF you know how to properly use & NOT abuse them!

My advice on your hill climbing; use the tranny to keep the revs in the power band...if 4th has no power, drop to 3rd. (Take my advice with a grain of salt...I live in flat South Florida.)

 

[Cruisin_Nomad]

As soon as I hit 300 miles on my '25 Willys V6 6M I installed a cold-air intake, a Pedal Commander, and an axel back dual exhaust muffler. Huge difference in power and it sounds amazing when under throttle.

 

[GeorgeYJ2JL]

I have had the exact same experience in my '25 Willys 6spd. I have to keep it in 3rd gear with any load, to inclue inclines (as mentioned in previous post). It's related to the 4.10 vs 3.45 gear ratio, as suspected by others. We also get 1-2 mpg less because of this. I also read in the manual that the shift points for the gearing and RPMs is also higher with the 3.6. as per the manual:


Recommended Vehicle Shift Speeds
To utilize your manual transmission efficiently for both
fuel economy and performance, it should be upshifted
as listed in recommended shift speed chart. Shift at
the vehicle speeds listed for acceleration. When heavily
loaded or pulling a trailer, these recommended up-shift
speeds may not apply.
Manual Transmission Shift Speeds in MPH (KM/H)
Speeds Accel. Cruise
3.6L Engine
1 to 2 15 (24) 10 (16)
2 to 3 24 (39) 19 (31)
3 to 4 50 (80) 40 (64)
4 to 5 65 (104) 55 (88)
5 to 6 70 (112) 65 (105)
NOTE:
Vehicle speeds shown in the chart above are for 2H
and 4H only. Vehicle speeds in 4L would be significantly
less.
DOWNSHIFTING
Moving from a high gear down to a lower gear is
recommended to preserve brakes when driving down
steep hills. In addition, downshifting at the right time
provides better acceleration when you desire to resume
speed. Downshift progressively. Do not skip gears to
avoid overspeeding the engine and clutch.
NOTE:
The manual transmission shift system is equipped with
gear blockers, which will prevent downshifts into FIRST
or SECOND gear above certain vehicle speeds.
CAUTION!
● When descending a hill, be very careful to
downshift one gear at a time to prevent
overspeeding the engine which can cause engine
damage, and/or clutch damage, even if the clutch
pedal is pressed. If transfer case is in low range
the vehicle speeds to cause engine and clutch
damage are significantly lower.
● Failure to follow the maximum recommended
downshifting speeds may cause the engine
damage and/or damage the clutch, even if the
clutch pedal is pressed.
● Descending a hill in low range with the clutch
pedal pressed could result in clutch damage.
WARNING!
Maximum Recommended Downshift
Speeds
Do not downshift for additional engine braking on a
slippery surface. The drive wheels could lose their
grip, and the vehicle could skid.
CAUTION!
CAUTION!
Failure to follow the maximum recommended
downshifting speeds may cause the engine to
overspeed and/or damage the clutch disc, even if the
clutch pedal is pressed.
● Skipping gears and downshifting into lower gears
at higher vehicle speeds can damage the engine
and clutch systems. Any attempt to shift into lower
gear with the clutch pedal pressed may result in
damage to the clutch system. Shifting into lower
gear and releasing the clutch may result in engine
damage.
Manual Transmission Downshift Speeds in MPH
(KM/H)
Gear Selection Maximum Speed
6 to 5 80 (129)
5 to 4 70 (113)
4 to 3 50 (81)
3 to 2 30 (48)
2 to 1 15 (24)

 

[mgroeger]

Hey wranglers, I bought a 2025 Wrangler JL Willys 2-dr 6-speed this year and am worried about lack of engine power. I live in Oregon and recently took the Willys over the Santiam Pass in the Cascades. The Willys had no power on the inclines! I would be in 4th gear with the pedal to the floor and not gaining any speed. Even on flat ground it seemed really hard to pass other cars.

I'm wondering if some of this is driver error. Like I said, it's the 6-speed manual transmission. Maybe I'm lugging it too much? For you folks with manual 3.6's, what RPM do you generally roll in? I figured that this was an engine that liked to stay in the low RPMs. I usually cruise in whatever gear that keeps it around 2000 RPM and I shift at around 3000 RPM I think. It's not a sports car so I wouldn't imagine you want to wring it out. But I wonder if I need to rev it more in general to get enough power out of it.

If it's NOT driver error, and the 3.6 is just a dog, what kinds of mods are people doing to boost the power? From a little bit of research it looks like the only options are cold air intake, upgraded exhaust, and maybe a throttle body spacer (?). Are there any other good options for getting more power out of this thing?

Thanks for any advice!

Welcome to the manual with a 3.6L, you are describing one of the things I don't miss about my manual JL. I would be cruising at 80mph on flat highway and then hit the hill and tank right down to 65mph unless I kept the engine screaming at 4-5k rpms. Very annoying, you def need to mod the engine like others have noted to squeak out more horsey.

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