Decided to supercharge over a swappina to a Hemi

[ShadowsPapa]

The 3.6 doesn't cope well with what I put it through.

You meanie!

I have to keep JSCAN up and trigger the fan for long drives with my plow on the front if I don't want to freeze to death in the cabin.
Because the outside temp sensor is up front, and the plow creates a low pressure area just ahead of the grill, hot engine bay air is pulled forward over that temp sensor.
I've seen snow on the ground on 101 degree days! Well, according to my Jeep it was over 100 degrees, in reality it was about 0 degrees.
Most recently I was driving in 15 degrees and that sensor read 84
Now that wouldn't be a big deal except the HVAC uses that temperature reading, so it shuts your heat off and tries to give you fresh air inside. Last time my wife was with me and we had the plow in, she had a blanket over her legs and mittens on.
So I trigger the high speed fan to draw cold air across that sensor so we can have heat in the truck.
Engine temp climbs as well it typically peaks at about 230 or so, so I don't worry about that part.

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[Lunentucker]

The 3.6L Pentastar engine is generally considered a poor choice for supercharging due to its high stock compression ratio, internal components not designed for the added stress, and potential difficulties in reliable engine management tuning.
Key reasons why supercharging the 3.6L Pentastar can be problematic include:

• High Compression Ratio: The engine has a high compression ratio from the factory, which makes it prone to detonation (engine knocking) when boost is added. While lower boost levels (around 5-7 psi) might be manageable with appropriate tuning and high-octane fuel, higher boost significantly increases the risk of engine failure.
• Weak Internal Components: The stock internal components, such as pistons and cylinder liners, are not built to withstand the substantially increased cylinder pressures and temperatures that come with forced induction. Adding significant power can lead to issues like cracked pistons or cylinder liners.
• Rocker Arm and Valvetrain Issues: The engine is already known for common problems with rocker arms and lifters, even in naturally aspirated applications. The added stress from a supercharger can exacerbate these pre-existing weaknesses, leading to premature valvetrain failure.
• Tuning Challenges: Safely and effectively tuning the engine for forced induction is a significant challenge. Erratic fueling and misfires can lead to severe engine damage, including hydro-locking (where a cylinder fills with fuel, causing catastrophic failure). Off-the-shelf tunes are often considered a "dice roll" in terms of long-term reliability.
• Heat Management: The increased power output from a supercharger generates significantly more heat, which puts extra strain on the cooling system components (e.g., water pump, oil cooler housing), which themselves are potential failure points in the stock engine.

For those seeking more power, many experienced owners and mechanics often recommend an engine swap to a V8 (like a HEMI) as a more reliable, albeit more expensive, path to achieving substantial horsepower gains.

 

[caryt]

Waiting for the I told ya so's...

 

[ChrisNLA]

When you start to near 250 degrees (American) coolant temp, it's too hot for my comfort to be downshifting and revving high RPMs. Temps will keep climbing and it will toast that engine if you let it.

My 3.6 4 door wrangler, fully loaded for a multi-week adventure is 6460lbs and towing a trailer that's 2360 lbs. Nearly 9k lbs total weight (8820 lbs) according to the CAT scale printout during my last trip with that vehicle.

For moderate climbs, I'll hold around 4k RPMs but it REALLY helps to get into the 4K RPM range before you start climbing. If not, and you start losing momentum right from the start with all that weight, it's a struggle to regain momentum.

So the best thing I found is to not wait for it to grab a better gear for climbing but manually shift to it, and 90% of the time you can keep your momentum over the whole hill climb unless it's a long climb.

Cruising the flats, 2800 RPM was the sweet spot.

In my JK I saw as high as 265* for short spans climbing highway hills near Moab, and I was in a 2 door and wasn't towing anything. These little fellas can make some HEAT in the right conditions.

 

[ChrisNLA]

The 3.6L Pentastar engine is generally considered a poor choice for supercharging due to its high stock compression ratio, internal components not designed for the added stress, and potential difficulties in reliable engine management tuning.
Key reasons why supercharging the 3.6L Pentastar can be problematic include:

• High Compression Ratio: The engine has a high compression ratio from the factory, which makes it prone to detonation (engine knocking) when boost is added. While lower boost levels (around 5-7 psi) might be manageable with appropriate tuning and high-octane fuel, higher boost significantly increases the risk of engine failure.
• Weak Internal Components: The stock internal components, such as pistons and cylinder liners, are not built to withstand the substantially increased cylinder pressures and temperatures that come with forced induction. Adding significant power can lead to issues like cracked pistons or cylinder liners.
• Rocker Arm and Valvetrain Issues: The engine is already known for common problems with rocker arms and lifters, even in naturally aspirated applications. The added stress from a supercharger can exacerbate these pre-existing weaknesses, leading to premature valvetrain failure.
• Tuning Challenges: Safely and effectively tuning the engine for forced induction is a significant challenge. Erratic fueling and misfires can lead to severe engine damage, including hydro-locking (where a cylinder fills with fuel, causing catastrophic failure). Off-the-shelf tunes are often considered a "dice roll" in terms of long-term reliability.
• Heat Management: The increased power output from a supercharger generates significantly more heat, which puts extra strain on the cooling system components (e.g., water pump, oil cooler housing), which themselves are potential failure points in the stock engine.

For those seeking more power, many experienced owners and mechanics often recommend an engine swap to a V8 (like a HEMI) as a more reliable, albeit more expensive, path to achieving substantial horsepower gains.

I think it's going to come down to 'how good is the tune' and how well the heat can be managed.

The engine is built similar to an LS V8, which can take boost - though with a lower compression ratio (10.4:1 on a 6.2L L99 vs 11.3:1 on a 3.6 PUG). Cast pistons are the biggest thing to watch out for. Otherwise it's got forged steel rods and a cast iron crank. Keep boost conservative and don't get weird with the ignition timing and it shouldn't knock a hole in a piston immediately, lol.

 

[ShadowsPapa]

The 3.6L Pentastar engine is generally considered a poor choice for supercharging due to its high stock compression ratio, internal components not designed for the added stress, and potential difficulties in reliable engine management tuning.
Key reasons why supercharging the 3.6L Pentastar can be problematic include:

• High Compression Ratio: The engine has a high compression ratio from the factory, which makes it prone to detonation (engine knocking) when boost is added. While lower boost levels (around 5-7 psi) might be manageable with appropriate tuning and high-octane fuel, higher boost significantly increases the risk of engine failure.
• Weak Internal Components: The stock internal components, such as pistons and cylinder liners, are not built to withstand the substantially increased cylinder pressures and temperatures that come with forced induction. Adding significant power can lead to issues like cracked pistons or cylinder liners.
• Rocker Arm and Valvetrain Issues: The engine is already known for common problems with rocker arms and lifters, even in naturally aspirated applications. The added stress from a supercharger can exacerbate these pre-existing weaknesses, leading to premature valvetrain failure.
• Tuning Challenges: Safely and effectively tuning the engine for forced induction is a significant challenge. Erratic fueling and misfires can lead to severe engine damage, including hydro-locking (where a cylinder fills with fuel, causing catastrophic failure). Off-the-shelf tunes are often considered a "dice roll" in terms of long-term reliability.
• Heat Management: The increased power output from a supercharger generates significantly more heat, which puts extra strain on the cooling system components (e.g., water pump, oil cooler housing), which themselves are potential failure points in the stock engine.

For those seeking more power, many experienced owners and mechanics often recommend an engine swap to a V8 (like a HEMI) as a more reliable, albeit more expensive, path to achieving substantial horsepower gains.

AI

 

[LouisvEarlleJT]

For moderate climbs, I'll hold around 4k RPMs but it REALLY helps to get into the 4K RPM range before you start climbing. If not, and you start losing momentum right from the start with all that weight, it's a struggle to regain momentum.

Unrelated but forever ago when I was taught to drive I was always taught to anticipate hills (when you can see them) and speed up a bit prior to hitting the climb to avoid momentum loss. Seems like you're in the same camp. Decades later and I'm still doing this, but I've noticed lots of other drivers just step on it a bit more and send their RPM's to the roof.

Just cool to hear it from someone else, anywho, carry on!

 

[ShadowsPapa]

Waiting for the I told ya so's...

Yeah, guess you might not realize that was AI and it takes sources from forums, and maybe you don't know about dynamic compression vs. theoretical compression. Few engines run 100% pumping efficiency, and the actual combustion pressures can be controlled by valve timing and lift. In low lift mode, I bet these are a whopping 70-80% efficient

 

[LouisvEarlleJT]

AI

Saw that too

 

[ShadowsPapa]

In my JK I saw as high as 265* for short spans climbing highway hills near Moab, and I was in a 2 door and wasn't towing anything. These little fellas can make some HEAT in the right conditions.

Yeah, so much for the hand-wringers when these hit 220 and they are freaking out

 

[Sandman 4x4]

Thanks, I’ll have to practice on my next trip. I’m only towing 1000 lb trailer but I weighed it and I’m 7600 lb combined. I was running 5-6 gear in auto with 35’s and 4.10’s. Might have been a headwind. I’d love 37’s but don’t want to make things worse. 35’s have been enough for me so far.

Wow but your truck is running heavy if you’re 7,600cgvw, while your trailer is only 1,000? At 6,600 you are either over or dam close to the GVWR.

 

[Sandman 4x4]

Why such low RPM?
Are you striving to hit 25 mpg in a gasser?
It's more likely to detect needed torque and open up the high lift valve system. Hell, I don't even let my 4.0 run that darned slow. Not good for it.

But I now have a lifetime average of 20.5 mpg, get 24 on highway trips and 20 city if there’s not too many lights a bumper to bumper. I do not ever use the start stop system. Never use any oil between 4,000-5,000 oil changes at the dealer.

 

[ShadowsPapa]

But I now have a lifetime average of 20.5 mpg, get 24 on highway trips and 20 city if there’s not too many lights a bumper to bumper. I do not ever use the start stop system. Never use any oil between 4,000-5,000 oil changes at the dealer.

Gee, no Jeep I've ever owned needed any oil between changes, and I sometimes take that out to 7,000 miles.

 

[Sandman 4x4]

Gee, no Jeep I've ever owned needed any oil between changes, and I sometimes take that out to 7,000 miles.

I had a 2015 Cherokee TrailHawk 3.2 4x4, that on my first oil change at 4,000 miles needed a pint, so instead I changed it. But it was like that till I traded it in. A pint of full synthetic every 4,000 miles.

 

[ShadowsPapa]

I had a 2015 Cherokee TrailHawk 3.2 4x4, that on my first oil change at 4,000 miles needed a pint, so instead I changed it. But it was like that till I traded it in. A pint of full synthetic every 4,000 miles.

Mine is still very close to the full mark between changes. I've never needed to add anything. I'd say they've never even been a pint low.

A pint is nothing - why bother with that?
I'm not sure why you would bother changing until a change was needed or it was a quart low.

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