3.6 power loss at elevation

[TheRaven]

It's only a straw man when it's an inaccurate representation of what someone said. I asked why you chimed in on the topic if you, in fact, didn't care. Now you're saying you didn't chime in on that subject, but you clearly did:

So you consider that little side note as big enough of a deal to write mini-novels on? You gotta be kiddin me dude. You were going to drag out a horse that's been beaten repeatedly for years with no resolution ONCE AGAIN for another round, just because of two lines out of everything I said?

A simple one line reply would have been more than sufficient to state your disagreement. Now that you've explained your thinking, i've changed my mind - i'd like to apply this meme ALSO to this subject:

That doesn't mean that I don't care about that subject at all, it means that I don't care to get into an argument with Stuart Minkus over it.

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[Zandcwhite]

So you consider that little side note as big enough of a deal to write mini-novels on? You gotta be kiddin me dude. You were going to drag out a horse that's been beaten repeatedly for years with no resolution ONCE AGAIN for another round, just because of two lines out of everything I said?

A simple one line reply would have been more than sufficient to state your disagreement. Now that you've explained your thinking, i've changed my mind - i'd like to apply this meme ALSO to this subject:

No resolution? Physics doesn't lie. All engines lose power with altitude. NA engines lose 3x the power of forced induction engines. These are facts. Is a 15% loss of horsepower significant when you're driving in Denver? Of course it is, but unless you are pushing the Jeep hard, towing, trying to accelerate hard up a steep grade etc, you probably won't notice as the auto will just downshift a bit more and hold gears a bit longer. Now anyone who argues they don't notice the 30% plus power loss when driving above 10k feet is either lying or the most non-observant driver on the planet. That sounds pretty obviously resolved to me? Is the <160 wheel hp at that elevation so little the jeep is useless? Obviously not, 80s Toyota's with half that wheel hp at sea level still wheel all over the mountains. Hell the beloved 4.0L straight six likely only made that to the wheels at sea level brand new. None of that changes the fact that the power loss is substantial and 100% noticeable at high elevations.

 

[TheRaven]

...Physics doesn't lie. All engines lose power with altitude. NA engines lose 3x the power of forced induction engines. These are facts....

...with which I do not disagree.

Is a 15% loss of horsepower significant when you're driving in Denver? Of course it is, but unless you are pushing the Jeep hard, towing, trying to accelerate hard up a steep grade etc, you probably won't notice as the auto will just downshift a bit more and hold gears a bit more.

Yes! There you go. You get it. See? That's it, no whitepapers needed.

This was it, all I was saying - numbers are numbers...but what those numbers actually equate to in real life effect is a completely different thing. We've been making this power loss thing out to be a complete deal-killer while forgetting to note that until 2018, we had nothing but NA motors, with significantly less HP than either mainstream option in the JL. Did no one tow or wheel at high altitudes with those NA Wranglers? OF COURSE THEY DID! They still are! It's just not that big of a deal!

 

[Zandcwhite]

...with which I do not disagree.



Yes! There you go. You get it. See? That's it, no whitepapers needed.

This was it, all I was saying - numbers are numbers...but what those numbers actually equate to in real life effect is a completely different thing. We've been making this power loss thing out to be a complete deal-killer while forgetting to note that until 2018, we had nothing but NA motors, with significantly less HP than either mainstream option in the JL. Did no one tow or wheel at high altitudes with those NA Wranglers? OF COURSE THEY DID! They still are! It's just not that big of a deal!

People wheeled and still do the TJs with the anemic 2.5L, but to me it is a big deal. I would not even try to roadtrip a 4.0L TJ up to telluride to go wheeling let alone a 2.5L. Unless you like climbing grades at half the speed limit with the flashers on? The JL is good enough that it gets the job done, but it's still a big deal to anyone who wants performance.

 

[TheRaven]

People wheeled and still do the TJs with the anemic 2.5L, but to me it is a big deal.

Understood. Then this is what we disagree on. I am not as picky about power. I used to be a high-performance automobile enthusiast but I got frustrated when I would spend $20k on mods only to be embarrassed by the cocky rich kid in town who's dad bought him the new Saleen/Ligenfelter/Hennessey whatever. I just don't care any more - even the base engine in pretty much anything made in the last 20 years is more than sufficient for me. These days things like complexity, refinement, and cost of maintenance and operation matter far more to me. But that's just where i'm at.

 

[Reinen]

I didn't mean to imply you couldn't run low octane fuel in the mountains, more so that of all the places I'm likely to want the best performance possible it's at elevation. From trying to accelerate up a steep grade to wheeling at elevation every bit helps in my opinion.

But that's the thing about octane, it's just a stability rating. Once you're stable there is zero benefit to being stable-er.

On the 2.0T, I find the need for more stable fuel primarily comes with heat. It's inherently a hot engine. Combine that with high ambient air temps and exertion, and that's when you can get pre-detonation requiring the more stable 91 octane.

It ends up being like the opposite of The Price Is Right. You want to come as close to the octane you need without going under. For most people most of the time that's 87/88. But sometimes in more extreme heat environments the 2.0T needs 91. Which is why they recommend 91, it doesn't hurt to have a higher octane rating than you need. But those engineers aren't paying for the premium gas, you are. So only pay for it if you are in a high heat, high stress environment and actually need it.

 

[Remorseless]

So only pay for it if you are in a high heat, high stress environment and actually need it.

Eh, pay for it if you want it and can afford it. Some of the best things in life are things you paid for that you didn't need, but wanted.

 

[Zandcwhite]

But that's the thing about octane, it's just a stability rating. Once you're stable there is zero benefit to being stable-er.

On the 2.0T, I find the need for more stable fuel primarily comes with heat. It's inherently a hot engine. Combine that with high ambient air temps and exertion, and that's when you can get pre-detonation requiring the more stable 91 octane.

It ends up being like the opposite of The Price Is Right. You want to come as close to the octane you need without going under. For most people most of the time that's 87/88. But sometimes in more extreme heat environments the 2.0T needs 91. Which is why they recommend 91, it doesn't hurt to have a higher octane rating than you need. But those engineers aren't paying for the premium gas, you are. So only pay for it if you are in a high heat, high stress environment and actually need it.

Heat comes with load regardless of ambient temps but is obviously made worse when it's hot outside. I've watched the engine and trans temps climb on a cool day aggressively wheeling and also driving aggressively on a windy road. Of course most Jeep owners don't drive them hard, so for them 87 is fine. I'd hate to be in the mood to run it hard and have the low octane fuel, but I'll be the 1st to admit I push things to the limit at times. For my use the 2.0t was always fed 91 octane but in no way am I arguing that's right for everyone.

 

[TheRaven]

...driving aggressively on a windy road.

I gotta say...this I don't get. Driving a JL "aggressively" on a winding road sounds about as much fun as attempting to fly an airplane with no wings or driving a boat that's not in water. No thanks. Not that I don't find the JL fun to drive, even on pavement...but not at all in that way.

 

[AnnDee4444]

Windy road?

Also a windy road?

Edit: and the hard to find windy windy road:

 

[yokramer]

When does the straw man get introduced? That’s when the thread will get even more off the rails…

About right here

https://www.jlwranglerforums.com/forum/threads/3-6-power-loss-at-elevation.133948/post-2795624

Its blatantly apparent you dont care about how things actually are.

 

[yokramer]

...with which I do not disagree.



Yes! There you go. You get it. See? That's it, no whitepapers needed.

This was it, all I was saying - numbers are numbers...but what those numbers actually equate to in real life effect is a completely different thing. We've been making this power loss thing out to be a complete deal-killer while forgetting to note that until 2018, we had nothing but NA motors, with significantly less HP than either mainstream option in the JL. Did no one tow or wheel at high altitudes with those NA Wranglers? OF COURSE THEY DID! They still are! It's just not that big of a deal!

So this does just confirm you never see more than like 15% throttle and never see off road.

 

[AnnDee4444]

I'm pretty sure DBW throttle mapping is targeting a torque output (via MAP/fuel/ignition/etc.) . This would mean that 50% throttle is always X amount of power. So it's possible that power loss would not be noticable when driving if you aren't requesting the power that's missing.


Somewhat related... with the A/C on in my 2.0 I notice the throttle pedal overcompensates a little too much vs. when the A/C is off. Shift points remain unchanged, so it's interesting to feel more power with the same shift RPMs (at partial throttle). I can replicate this with the A/C off by manually shifting and more throttle.

 

[Zandcwhite]

I gotta say...this I don't get. Driving a JL "aggressively" on a winding road sounds about as much fun as attempting to fly an airplane with no wings or driving a boat that's not in water. No thanks. Not that I don't find the JL fun to drive, even on pavement...but not at all in that way.

I love the looks I get from people who think a lifted Jeep will fall over in a corner. Passed an entire mustang "club" coming down 58 out of tehachapi and some of them looked embarrassed as they slowed way more than necessary for corners that I drove right through...on 39s. Our Jeeps see triple digits in the dirt in the desert so no, I'm not afraid of a turn on the highway.

 

[JeepinJason33]

No resolution? Physics doesn't lie. All engines lose power with altitude. NA engines lose 3x the power of forced induction engines. These are facts. Is a 15% loss of horsepower significant when you're driving in Denver? Of course it is, but unless you are pushing the Jeep hard, towing, trying to accelerate hard up a steep grade etc, you probably won't notice as the auto will just downshift a bit more and hold gears a bit longer. Now anyone who argues they don't notice the 30% plus power loss when driving above 10k feet is either lying or the most non-observant driver on the planet. That sounds pretty obviously resolved to me? Is the <160 wheel hp at that elevation so little the jeep is useless? Obviously not, 80s Toyota's with half that wheel hp at sea level still wheel all over the mountains. Hell the beloved 4.0L straight six likely only made that to the wheels at sea level brand new. None of that changes the fact that the power loss is substantial and 100% noticeable at high elevations.

The folks arguing this the most, rarely drive above sea level so I am not sure why they care. Those of us that live in Denver or above 6,000' don't notice because we are already at a much higher altitude and everything else we drive is as well. Going from 6,000 to 10,000' which is where the bulk of the trails are is a 15% or so further reduction. Once we get up there, we are generally going slow again and do not really notice the change. On the way up, the guys that want to go above 65 mph might feel it more (hard to do most of the time with the amount of cars on the road going over the pass).

Rarely does anyone immediately jump from a car at sea level into the same exact vehicle at 10,000'. You have to drive to the mountains so the reduction is more gradual. I drove the Jeep over Estes (11,500) on a Friday and then hooked it up to my RV and was in Brownsville (sea level) on Monday. Jumped in the Jeep and did a 100 mile drive. Then drove it regularly for the next month at sea level. I noticed the difference, but it was not night and day nor did it matter as everything else on the road was also at sea level and flat so the engine was never pushed. Furthermore, most places outside Utah and Colorado do not see really high elevations on a regular basis so the argument over which engine and how much loss should not matter to anyone else...

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