Decided to supercharge over a swappina to a Hemi

[Flyin6]

I don't know the answer to any of those questions but generally speaking, pushing a motor harder is always going to have some reaction (every action has an equal and opposite reaction).

My sample size of 1 supercharged motor (which isn't mine) and 1 non-supercharged motor... I've only blown up the non-supercharged 3.6 so I'm biased and salty towards the 3.6. lol

I appreciate your opinion, and it is a commonly held belief.

Let's explore this theory a little further.

Engines are designed with operational specifications and all have limits. But the delta between normal operational range and limits is often pretty wide. Say we operate our motors at 30%-70% of that range. Then isn't pushing it to 85%-90% still well within design limits?

You could operate it at this increased capacity literally for the components' lifespan, with nothing breaking. Now, sure, you may discover the occasional flawed part. A piston with incorrect metallurgy or a connecting rod with an internal casting flaw. Those parts might not survive the added stress, to be sure.

One of the jets I flew had the same GE CF-34 fans as the A-10 has. I had maximum EGT and N1 rpm limits. The A10 operated north of my civil aircraft limits, on the same motor, but with no ill effects.

What is the difference in wear on a 747 engine that flew from New York to Boston vs one that flew from Detroit to Seoul, Korea? Nothing! Yup, no difference. One flight was 40 minutes; the other was 17 hours, but there is no difference or additional wear to the engines, as far as the manufacturer of that motor is concerned.

We seem to believe that if we push something like a motor harder, it will then give us less lifespan. But, really, if that motor is operated within design limits, it doesn't matter how we operate assuming we don't do stupid things like dry start or start a cold motor then do a standing 1/4 mile. That is called abuse. I call it stupidity and ignorance. Nossir, I do not believe operating this motor with a supercharger will negatively affect the engine's life. Now, will it kill a transmission sooner? Well, that is a possibility due to the increased pressures and heat.

You hear one well-respected member here often saying just to rev the motor to get more power; heck, he's said it to me. He is correct, and by doing so, there is no additional stress or reduced lifespan of our little Pentastar motor.

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[Jteakus]

I am looking forward to this build and following your results.

 

[ericw.]

I appreciate your opinion, and it is a commonly held belief.

Let's explore this theory a little further.

Engines are designed with operational specifications and all have limits. But the delta between normal operational range and limits is often pretty wide. Say we operate our motors at 30%-70% of that range. Then isn't pushing it to 85%-90% still well within design limits?

You could operate it at this increased capacity literally for the components' lifespan, with nothing breaking. Now, sure, you may discover the occasional flawed part. A piston with incorrect metallurgy or a connecting rod with an internal casting flaw. Those parts might not survive the added stress, to be sure.

One of the jets I flew had the same GE CF-34 fans as the A-10 has. I had maximum EGT and N1 rpm limits. The A10 operated north of my civil aircraft limits, on the same motor, but with no ill effects.

What is the difference in wear on a 747 engine that flew from New York to Boston vs one that flew from Detroit to Seoul, Korea? Nothing! Yup, no difference. One flight was 40 minutes; the other was 17 hours, but there is no difference or additional wear to the engines, as far as the manufacturer of that motor is concerned.

We seem to believe that if we push something like a motor harder, it will then give us less lifespan. But, really, if that motor is operated within design limits, it doesn't matter how we operate assuming we don't do stupid things like dry start or start a cold motor then do a standing 1/4 mile. That is called abuse. I call it stupidity and ignorance. Nossir, I do not believe operating this motor with a supercharger will negatively affect the engine's life. Now, will it kill a transmission sooner? Well, that is a possibility due to the increased pressures and heat.

You hear one well-respected member here often saying just to rev the motor to get more power; heck, he's said it to me. He is correct, and by doing so, there is no additional stress or reduced lifespan of our little Pentastar motor.

I've done my fair share of tuning, I think the only stock car I ever had was the first car I owned. I still have a tuned and heavily modified twin turbo v8 Audi that's conservatively pushing 600AWHP with the cats back on it. It was pushing a lot more than that, but then I had a baby and life changed a lot.

There's a good chance everything will be fine since it's a Jeep, not the type of vehicle that' you're running hard... but you are adding wear and finding out a lot quicker if you have any weak points in the system. Everything down to the quality and gap of your spark plugs become more important.


That member who tells us that peak power is at 6800 RPM, isn't telling us to run it at 6800 RPM. I realized that in another thread, he's just suggesting that you can use higher RPM to get up to speed. With a 7k red line, I wouldn't want to spend much time at high RPMs.

 

[ShadowsPapa]

Mine spends a lot of time at 4,000 rpm and even above when getting up to speed, or even towing. When I get onto the highway heading north to Altoona, it's at 4,000 for over half a mile.
But I don't advocate holding top rpm for kicks.

 

[NC_Overland]

Mine spends a lot of time at 4,000 rpm and even above when getting up to speed, or even towing. When I get onto the highway heading north to Altoona, it's at 4,000 for over half a mile.
But I don't advocate holding top rpm for kicks.

You’re right. This advice going around here and on Facebook groups about manually shifting when towing is bad advice. I’m not sure what they’re trying to accomplish, but it’s adding stress to the engine.

 

[Lrowe]

Following! I am of the same mind as OP, and I have been considering an AMW swap to a 5.7, but I am interested in the SC option as well. There was a lot of work done by other members trying to get the tune right on superchargers on the 3.6, but not without a lot of nagging little issues that most of us read about. I am going to follow this thread to see if Ripps and the OP can get this running without any negative side effects to drivability.

 

[Flyin6]

Following! I am of the same mind as OP, and I have been considering an AMW swap to a 5.7, but I am interested in the SC option as well. There was a lot of work done by other members trying to get the tune right on superchargers on the 3.6, but not without a lot of nagging little issues that most of us read about. I am going to follow this thread to see if Ripps and the OP can get this running without any negative side effects to drivability.

I will post a note here in this thread when I start, but the actual write-up will happen on my build thread located within this forum.

 

[Lrowe]

I will post a note here in this thread when I start, but the actual write-up will happen on my build thread located within this forum.

Copy, thanks!

 

[Stan H]

I appreciate your opinion, and it is a commonly held belief.

Let's explore this theory a little further.

Engines are designed with operational specifications and all have limits. But the delta between normal operational range and limits is often pretty wide. Say we operate our motors at 30%-70% of that range. Then isn't pushing it to 85%-90% still well within design limits?

You could operate it at this increased capacity literally for the components' lifespan, with nothing breaking. Now, sure, you may discover the occasional flawed part. A piston with incorrect metallurgy or a connecting rod with an internal casting flaw. Those parts might not survive the added stress, to be sure.

One of the jets I flew had the same GE CF-34 fans as the A-10 has. I had maximum EGT and N1 rpm limits. The A10 operated north of my civil aircraft limits, on the same motor, but with no ill effects.

What is the difference in wear on a 747 engine that flew from New York to Boston vs one that flew from Detroit to Seoul, Korea? Nothing! Yup, no difference. One flight was 40 minutes; the other was 17 hours, but there is no difference or additional wear to the engines, as far as the manufacturer of that motor is concerned.

We seem to believe that if we push something like a motor harder, it will then give us less lifespan. But, really, if that motor is operated within design limits, it doesn't matter how we operate assuming we don't do stupid things like dry start or start a cold motor then do a standing 1/4 mile. That is called abuse. I call it stupidity and ignorance. Nossir, I do not believe operating this motor with a supercharger will negatively affect the engine's life. Now, will it kill a transmission sooner? Well, that is a possibility due to the increased pressures and heat.

You hear one well-respected member here often saying just to rev the motor to get more power; heck, he's said it to me. He is correct, and by doing so, there is no additional stress or reduced lifespan of our little Pentastar motor.

Mine likes throttle. 3-4k alot . I'm following this thread also .

 

[AmosMoses]

Seems like stellantis could have saved money by turbocharging the 3.6 rather than developing a completely new platform straight 6 to turbocharge.

 

[ericw.]

You’re right. This advice going around here and on Facebook groups about manually shifting when towing is bad advice. I’m not sure what they’re trying to accomplish, but it’s adding stress to the engine.

My only problem with automatic while towing is that, while going up-hill it would downshift while my temps were getting too hot for comfort. In some situations, that would cause temps to spike rapidly.

I would shift manually because I have the foresight that the ECU doesn't... to see how steep of a hill I'm climbing, how long that climb is, and I could either downshift early to keep momentum before starting the climb or I could decide to hold a cruising RPM and let it slow down if my temps were not happy in the 110+ degree summer heat.

 

[ShadowsPapa]

My only problem with automatic while towing is that, while going up-hill it would downshift while my temps were getting too hot for comfort. In some situations, that would cause temps to spike rapidly.

I would shift manually because I have the foresight that the ECU doesn't... to see how steep of a hill I'm climbing, how long that climb is, and I could either downshift early to keep momentum before starting the climb or I could decide to hold a cruising RPM and let it slow down if my temps were not happy in the 110+ degree summer heat.

How hot is too hot for comfort?
Remember, these are direct drive only in 6th. 7th and 8th are overdrive, so you are still churning things and working the gears in any gear you are in for the most part.
Hunting is an issue, but I've never seen worrisome heat letting it rev - unless like you say it could be up one more gear and still handle the load fine - I might drop it from 4300 rpm down into the 3000s for example

 

[ericw.]

How hot is too hot for comfort?
Remember, these are direct drive only in 6th. 7th and 8th are overdrive, so you are still churning things and working the gears in any gear you are in for the most part.
Hunting is an issue, but I've never seen worrisome heat letting it rev - unless like you say it could be up one more gear and still handle the load fine - I might drop it from 4300 rpm down into the 3000s for example

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.

 

[ShadowsPapa]

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.

OK, just that some folks seem to believe that over 210 is too hot, others over 220 is too hot, and still others believe it should stay under 200 - so thought I'd better ask.
250 - that's a different animal.
That all makes sense.

 

[ericw.]

OK, just that some folks seem to believe that over 210 is too hot, others over 220 is too hot, and still others believe it should stay under 200 - so thought I'd better ask.
250 - that's a different animal.
That all makes sense.

Oh yeah, even in the desert flats between Reno and Salt Lake City, I see 230 hold steady at just normal cruising speeds and low RPMs.

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

I forgot to mention that I would also keep the "trail screen" open on JScan and turn the radiator fan on high when I'd climb hills, with a 5 minute timer to automatically shut off.

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