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-   -   2012 Pentastar 4800 RPM for two hours (http://www.wranglerforum.com/f274/2012-pentastar-4800-rpm-for-two-hours-244111.html)

xjrguy 05-21-2013 11:32 AM

2012 Pentastar 4800 RPM for two hours
 
It didn't blow up. :rofl:

Heading back from Overland Expo I hit bad headwinds and was also at elevations between 4000 and 6000ft.

During the trip the engine was singing at 4800rpm for almost 2 hours.

:popcorn:

DJL2 05-21-2013 11:52 AM

Since someone is going to ask, it might as well be me: how was your gas mileage? =)

xjrguy 05-21-2013 11:57 AM

Quote:

Originally Posted by DJL2 (Post 3778260)
Since someone is going to ask, it might as well be me: how was your gas mileage? =)

It sucked. 11.2MPG (I run syn oil in diffs, TC, motor and trans FWIW)

I run a pretty heavy jeep (JKU with bumpers, lift etc) with 37's and the 5 speed auto.

It was also in 3rd gear for those two hours as well.

live_slow 05-21-2013 11:59 AM

Can't do the reverse math, what's your gear ratio?

(I know it's always a trade off when selecting gears, tire sizes, etc., and running heavy, high elevations and other things factor in)

xjrguy 05-21-2013 12:02 PM

4:10

I am usually at sea level so it's a non issue where I usually roam.

Was pretty impressed that I didn't have any temperature swings or burn any oil on the trip especially during the extended high rpm operation.

TOK 05-21-2013 01:08 PM

Wow, doesn't that make you nuts on the highway?

I got spoiled by my V8 pickup turning 1800rpm at 70mph. It seems wrong that my Jeep is at almost 3 grand at that speed. I'd be taking backroads or towing yours all the way home.

I am glad to hear the Pentastar will take a whooping! :thumb::D

xjrguy 05-21-2013 01:18 PM

Nope, no bother where I regularly drive. The Borla exhaust coupled with a CAI was a little loud though for those two hours. :D

4:10's with 37s on the 2012 with the auto work just fine. Without the headwind I think it would have settled into 4th or 5th. The winds were pretty incredible heading back west.

It's always pretty amazing to be a couple thousand feet up in the mountains and feeling the loss of power due to the altitude. Couple in hills and very strong winds and yeah, the Jeep will be in a lower gear and burning the coal to keep speed.

The nice thing is this motor LOVES to rev. I think I redlined the motor every time I got on the freeway on the on ramp after a gas fill up.

Anyone who is afraid of blowing up their Pentastar or concerned about the upper RPM scale, don't be. This motor can take it and so can the powertrain based on my experiences. (this isn't the first time I've had extended high RPM operation, but it's been the longest period of operation in high RPM setting.)

ONETANGO 05-21-2013 05:04 PM

good to know. thanks for the report.

fireguy 05-21-2013 06:25 PM

Same here on a trip to phoenix from Denver to Phoenix we had head and cross winds most of the way. They were steady at 20 and 30 with gusts over 50 to maybe 60 mph. A lot of 4th gear and rpm's 4500 plus sustained. Had the hood lifting (annoying) as well at times. MPG was for the 850 miles about 14 overall and was running in the low 13's at times. Only had 700 miles on it when we left Denver. About the same with wind coming back but had a tail wind for 450 miles MPG 18+ then head winds back to CO. They were worse MPG went down to 13 the hood was lifting at a speed over 60 mph. The engine is running flawlessly and we now have 4400 miles. I think this engine loves to be revved up a bit. Running 3.73' w/auto

Miser 05-21-2013 06:45 PM

Quote:

Originally Posted by xjrguy (Post 3778276)
It sucked. 11.2MPG (I run syn oil in diffs, TC, motor and trans FWIW)

I run a pretty heavy jeep (JKU with bumpers, lift etc) with 37's and the 5 speed auto.

It was also in 3rd gear for those two hours as well.

This say's a lot of positive for the 3.6.
What Brand of synthetic oil are you using in your engine?
Since yours is a 2012, have you had any cylinder heads replaced as of yet?

SilverSport 05-21-2013 07:27 PM

xjrguy - your engine is now broken in. LOL

DJL2 05-21-2013 07:34 PM

I am not sure I could deal with 4.10 gears and 37 inch tires...my 6th gear is already nearly useless during my daily commute on stock rubber. Kudos to you for hanging in there.

MikeK46 05-21-2013 11:08 PM

Quote:

Originally Posted by xjrguy (Post 3778473)
Anyone who is afraid of blowing up their Pentastar or concerned about the upper RPM scale, don't be. This motor can take it and so can the powertrain based on my experiences.

...assuming you don't have a defective head :thumb:

Wingsnut72 05-21-2013 11:12 PM

Quote:

Originally Posted by xjrguy (Post 3778197)
It didn't blow up. :rofl:

Heading back from Overland Expo I hit bad headwinds and was also at elevations between 4000 and 6000ft.

During the trip the engine was singing at 4800rpm for almost 2 hours.

:popcorn:

I had the same thing happen on my vacation to Wyoming last week. I was sitting at 4200rpm heading uphill in a headwind. The jeep was in fourth gear. Use the auto stick to manually move it up to 5th. The RPMs will fall back down. Was pretty happy with it in the mountains. Used the auto stick a lot.

xjrguy 05-22-2013 01:55 AM

Quote:

Originally Posted by Miser (Post 3779407)
This say's a lot of positive for the 3.6.
What Brand of synthetic oil are you using in your engine?
Since yours is a 2012, have you had any cylinder heads replaced as of yet?

Pennzoil Platinum 5w-30

No cylinder head replacement or ticking/codes/problems yet.

Miser 05-22-2013 09:51 AM

Quote:

Originally Posted by xjrguy (Post 3780658)
Pennzoil Platinum 5w-30

No cylinder head replacement or ticking/codes/problems yet.

That's the oil that I have been planning on going to after I get a few more miles on mine.
Great no cylinder head issues!:thumb:


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