3.6L vs 2.0 turbo?? Pros and cons of both??

[Crusifix]

I'm looking at my 5yr 100k warranty paperwork right now. But the dealership threw it in on the deal.

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[SecondTJ]

The 2.0 and 3.6 get the typical 5/60 but 3.0 gets 5/100

 

[rubileon]

"we couldn't guess that the simpler 3.6 would have passenger-side head failure issues, or that the old-school manual transmission would be blowing up clutches."

there were early failures related to the head, but that was fixed something like 6 years ago. The clutch failures track back to LuK making a stupid, bad design of the center plate. It should not be hollow. Hollow plus heat from slippage equals break-up of the plate. Engineers learned decades ago that a plate, such as a brake rotor or clutch plate, should be solid and if you want to save weight or add cooling, you drill holes in it. Despite decades of minimalist engineering, LuK has a strangle hold on OEMs because their lawyers know how to cheaply appear to meet the OEM engineers' specs.

The engineer's rule of thumb is that normally aspirated engines lose 3% power per 1000 ft elevation. Turbo engines lose 0.5% per 1000 ft. Thus the 3.6 and 2.0t are close at sea level, but the 3.6 will lose about 30% at 10,000 ft while the 2.0turbo loses 5%. The numbers may not be exact but should be in the ballpark.

You're mixing up bad engineering with bad quality control.

Elevation, shmelevation... even most aircrafts with piston engine come naturally aspirated... and they have later TBOs than turbo engines. But somehow, for Android auto Wrangler drivers, naturally aspirated is not good enough and turbo means reliability. Please learn something.

 

[BRuby]

Yeah they also put the V6 in the JT for a reason. But insofar as turbos, our 1985 TD Benz 3.0L 5 still runs like it is new. You do have to regularly remove the soot build-up however from the banjo bolt. If not the turbo via the alda does not spool up. Best always is a very hot Italian tune-up and drive like you stole it.

For the 2.0T that is more of a different animal however. If it performs as you like then fine. Be happy and spool up the turbo. Is always so predicable on this forum when the “Which one is better?” question arises. V6 - 2.0T - Diesel. Off-road nobody we know is concerned with that. All us Jeepers are all simply happy as we go on our merry way giving the little wave as we pass one another.

What is more interesting to us is the EPA fuel mileage estimates for the V6 - 2.0T - Diesel vs anecdotal accounts. Same with acceleration times.

 

[Zandcwhite]

You're mixing up bad engineering with bad quality control.

Elevation, shmelevation... even most aircrafts with piston engine come naturally aspirated... and they have later TBOs than turbo engines. But somehow, for Android auto Wrangler drivers, naturally aspirated is not good enough and turbo means reliability. Please learn something.

I don’t think anybody argued turbos guaranteed reliability, but if you don’t think there’s a massive difference in power loss between NA and forced air you’ve clearly never driven both at elevations above 10k feet. Living at nearly sea level and regularly wheeling in the high Sierra Nevada’s in dozens of different rigs for the last 20 years, I can honestly say that the 2.0t wrangler is the only Jeep I’ve driven that still feels like it wants to pull in 2wd, loaded with camping gear, on steep grades. Off road, in low range, any engine is sufficient, even the garbage 2.8L v6 in my old xj. My wagoneer was a dog at altitude (carb mostly to blame there). The v6 xj couldn’t maintain 40mph on a steep grade. The 89 xj with the 4.0 was better, but still struggled to maintain 55 mph pulling a grade. The 09 2 door jk with the 3.8 was a dog even at sea level, often forcing down shifts pushing 6k rpms just to pass someone on the highway. The 3.6 was a massive improvement over that pos, but still feels sluggish on steep grades at altitude. Even the v8 in the 01 grand Cherokee would struggle to maintain 60mph on a steep grade in the mountains. I’ve yet to find a grade at any elevation that the jl won’t accelerate while climbing, let alone maintain speed. Is it the end all be all of engines, of course not. For my use is it superior to the only other option in 2019? By a mile (or more than that depending on elevation). Having driven the ecodiesel in ram trucks, I’d go with that over the 2.0t if I was buying today, but the 3.6L would still be my last choice. Not that it’s a bad choice, or a terrible engine, but I like the way the 2.0 drives. Not worried about reliability so much when I’m buying a brand new rig that is going to be under warranty for years.

 

[rubileon]

I don’t think anybody argued turbos guaranteed reliability, but if you don’t think there’s a massive difference in power loss between NA and forced air you’ve clearly never driven both at elevations above 10k feet. Living at nearly sea level and regularly wheeling in the high Sierra Nevada’s in dozens of different rigs for the last 20 years, I can honestly say that the 2.0t wrangler is the only Jeep I’ve driven that still feels like it wants to pull in 2wd, loaded with camping gear, on steep grades. Off road, in low range, any engine is sufficient, even the garbage 2.8L v6 in my old xj. My wagoneer was a dog at altitude (carb mostly to blame there). The v6 xj couldn’t maintain 40mph on a steep grade. The 89 xj with the 4.0 was better, but still struggled to maintain 55 mph pulling a grade. The 09 2 door jk with the 3.8 was a dog even at sea level, often forcing down shifts pushing 6k rpms just to pass someone on the highway. The 3.6 was a massive improvement over that pos, but still feels sluggish on steep grades at altitude. Even the v8 in the 01 grand Cherokee would struggle to maintain 60mph on a steep grade in the mountains. I’ve yet to find a grade at any elevation that the jl won’t accelerate while climbing, let alone maintain speed. Is it the end all be all of engines, of course not. For my use is it superior to the only other option in 2019? By a mile (or more than that depending on elevation). Having driven the ecodiesel in ram trucks, I’d go with that over the 2.0t if I was buying today, but the 3.6L would still be my last choice. Not that it’s a bad choice, or a terrible engine, but I like the way the 2.0 drives. Not worried about reliability so much when I’m buying a brand new rig that is going to be under warranty for years.

I'm arguing for physics and not against physics so I never said a turbo isn't beneficial in creating power over N/A when the air density is low But the point about a turbo creating higher cylinder pressures and not easily letting the engine operate in a reliable steady state because of boost coming in and going out every time the accelerator is used, still is true whether you're at high altitudes or not.

Now if you somehow can control the boost so that turbo is used when air density falls below sea level, it won't be creating higher pressures than what naturally aspirated is about at sea level. Still, because of the nonlinearity of the boost curve, you don't get the benefits of steady state operation even if you're driving around in a completely flat town in the mountains. To put it differently, if there are no other issues, a naturally aspirated engine will probably last even longer at altitude (vs. sea level) but the turbo might actually fail sooner because now there's a greater difference between boost and no boost states.

Pleasant dreams boosters *evil laugh*

 

[Zandcwhite]

I'm arguing for physics and not against physics so I never said a turbo isn't beneficial in creating power over N/A when the air density is low But the point about a turbo creating higher cylinder pressures and not easily letting the engine operate in a reliable steady state because of boost coming in and going out every time the accelerator is used, still is true whether you're at high altitudes or not.

Now if you somehow can control the boost so that turbo is used when air density falls below sea level, it won't be creating higher pressures than what naturally aspirated is about at sea level. Still, because of the nonlinearity of the boost curve, you don't get the benefits of steady state operation even if you're driving around in a completely flat town in the mountains. To put it differently, if there are no other issues, a naturally aspirated engine will probably last even longer at altitude (vs. sea level) but the turbo might actually fail sooner because now there's a greater difference between boost and no boost states.

Pleasant dreams boosters *evil laugh*

Your theory my have merit if internal combustion engines operated at a steady state, but they don't. The na engine screaming at 6k rpms when the transmission kicks down in an effort to maintain speed at altitude is likely more detrimental to longevity than boost. Under your theory those low compression motors of the late 70's should have run forever, but they didn't. Diesels are known for longevity, they must be the exception to your boost theory? Good thing I didn't buy my jeep to be a high mileage commuter car, I might have to worry about the boost making it only last 150k miles. At less than 15k per year, I'm sure I'll want to replace it before those 10+ years are up.

 

[whiteglad]

Most OEM turbochargers have a wastegated exhaust (turbine) housing to limit maximum boost while allowing quick spool-up. In the old days when some diesel smoke was allowed, they just used the scroll size of the housing to determine rate of building boost and maximum boost. There are several common modes of turbo failure, besides old age: 1. working them hard for high boost in thin air (high altitude) 2. taking your foot out of it abruptly so the boosted air tries to back up and drive the compressor wheel backwards, 3. old, contaminated oil, and 4. shutting off the engine while the turbo and exhaust are very hot.

 

[rubileon]

Your theory my have merit if internal combustion engines operated at a steady state, but they don't. The na engine screaming at 6k rpms when the transmission kicks down in an effort to maintain speed at altitude is likely more detrimental to longevity than boost. Under your theory those low compression motors of the late 70's should have run forever, but they didn't. Diesels are known for longevity, they must be the exception to your boost theory? Good thing I didn't buy my jeep to be a high mileage commuter car, I might have to worry about the boost making it only last 150k miles. At less than 15k per year, I'm sure I'll want to replace it before those 10+ years are up.

Is high altitude the only excuse people are left with for the turbo? Still, turbos put more cylinder pressure even at high altitudes. Piston turbo aircraft engines need to be overhauled earlier than non-turbo piston ones of a comparable design.

6K rpm: Coming back down to earth from your high altitude location, do you ever find youself where "na engine screaming at 6k rpms when the transmission kicks down in an effort to maintain speed"? For how long does it stay at 6k, I'd like to know.

Steady state: This is relative. You're thinking of a perfect equilibrium which is not the concept here.

Mileage: Not a good indicator of work done.

Low compression N/A motors of the 70s not running anymore: They probably ran longer than they would have had they got turbos.

 

[Headbarcode]

Please moderators, lock this thread! A lot of brilliant minds on this board, and none are willing to waste their time posting in it any further.

Sometimes the horse isn't worth being led to the water.

 

[whiteglad]

My experience with turbo engines is primarily diesels. The Cummins B engine used in Rams has given or been wastegated to 18-35 psi over ambient for decades. It is a medium duty engine and specs 350,000 miles between freshening up. If designed well, turbo engines can last.

 

[rubileon]

My experience with turbo engines is primarily diesels. The Cummins B engine used in Rams has given or been wastegated to 18-35 psi over ambient for decades. It is a medium duty engine and specs 350,000 miles between freshening up. If designed well, turbo engines can last.

Cummins B

vs.

Jeep 2.0 T a. k. a. Global Modular Engine, sometimes made in China, and has a brother named "Giorgio"

Worlds apart... in more ways than one.

 

[AnnDee4444]

Worlds apart... in more ways than one.

It's about as close as an airplane engine.

 

[rubileon]

It's about as close as an airplane engine.

lol to be fair, I did compare turbo piston aircraft engines vs. naturally aspirated piston aircraft engines

 

[whiteglad]

Uhhh, the Cummins is also a piston engine. Also, the one you showed is a B variation not used in Rams.

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