Pentastar Thoughts - Jeep Garage - Jeep Forum

Go Back   Jeep Garage - Jeep Forum > Jeep Platform Discussion > Grand Cherokee - WK2 -

Reply
 
Thread Tools Display Modes
 
  #1  
Old 06-21-2015, 09:16 AM
padgett's Avatar
Premium Member
 
Join Date: Feb 2012
Location: Orlando
Posts: 1,883
Thanks: 0
Thanked 60 Times in 55 Posts
Rep Power: 82519
padgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond repute
Pentastar Thoughts

Am biased. Having been infected in my yout by Jaguars have always liked DOHC 6s but took many years for me to not need the comfort of an oil pressure guage.

Was reinforced by engineering training and people like Ricardo and Obert plus nothing sounds as good (well maybe a 12) with a tuned exhaust (Jag with bananas or even a Corvair with trombones).

Also think an oversquare engine of 3-3.5 liters with 3.25" stroke is best suited to 87 PON (do not care for long strokes. Jag would go 7,000 rpm. Once).

So my '12 with 3.6 is the best tow car I've ever had. Should the Crossie blow its engine, a Pentastar is in its future.

That was in '12 when I also craved a diesel. In '15 I think the small diesel is ded, killed by expensive fuel coupled with a high initial premium for the complexity & DEF. In Europe, the tax stuctures make it a viable alternative. In the US it is more marketting (ducking).

That said I have seen the replacement though the initial ones are more PBIs and for Those Who Must Have Power.

Have said before that my vision is of direct injection and boost. The rathionale is that the smaller the engine, the lower the IHP (internal horsepower - what it takes to turn the crank). Also lightly loaded engines are not as efficient as those a bit further up the load curve. Finally, while hill climbing is important, for most people is is a very small percentage of the driving experience.

Finally, periodically I tow things ranging from cars to travel trailers. In my retirement, more is planned.

The nice thing about gasoline engines is that not only is 87 PON about the cheapest fuel around, it is part of the infrastructure. Diesel, while part of the commercial industry and except in nitches is not.

So dollar/btu the cheapest easily transportable and refillable fuel around is regular gasoline.

Direct Injection is already common and boosted DI engines are producing 125 hp/l in production cars. This means a 3.2L Pentastar would produce about 400 hp. With a warrenty.

The issue with the most popular DI engine in pickups and SUVs is its sub-3 liter size (there is a 3.5 liter EcoBoost ready for production).

When towing the sub-3 liter engine is going to be into Performance Enrichment any time the load exceeds about 50%. This is why there is not much discussion of towing MPG.

Now the question is whether the current 3.2 has a strong enough bottom end for the increased chamber pressures possible with DI.

Anyone know ?

Reply With Quote
Sponsored Links
Advertisement
 
  #2  
Old 06-21-2015, 09:22 AM
Jim_in_PA's Avatar
Super Moderator

My Jeep: 2012 5.7L WK2
 
Join Date: Jul 2012
Location: SE PA (central Bucks County)
Posts: 4,936
Thanks: 919
Thanked 746 Times in 588 Posts
Rep Power: 112895
Jim_in_PA has a reputation beyond reputeJim_in_PA has a reputation beyond reputeJim_in_PA has a reputation beyond reputeJim_in_PA has a reputation beyond reputeJim_in_PA has a reputation beyond reputeJim_in_PA has a reputation beyond reputeJim_in_PA has a reputation beyond reputeJim_in_PA has a reputation beyond reputeJim_in_PA has a reputation beyond reputeJim_in_PA has a reputation beyond reputeJim_in_PA has a reputation beyond repute
Garage
Re: Pentastar Thoughts

I have no real knowledge at the detail level of these things, but I think that it will be interesting to see what the specifications are when the new engine choice(s) come about in MY16 if they actually appear. The trend very much is for fuel efficient v6 with power boost from DI and turbo. That should benefit towing, although it may not replace the "grunt" you can get from a V8 or the EcoDiesel in that respect, at least at the higher end of the towing range.
__________________
2012 GC Overland Summit - Winter Chill with New Saddle interior. 5.7L HEMI V8 - Pirelli Scorpion Verde Plus "shoes" - LED fogs and DRLs



Day-job...Telecom Technical Sales
Avocations...Woodworking, Equestrian, Food, Photography
Reply With Quote
  #3  
Old 06-21-2015, 09:26 AM
Premium Member
 
Join Date: Apr 2014
Posts: 615
Thanks: 177
Thanked 156 Times in 109 Posts
Rep Power: 2499
BubbaATL has a reputation beyond reputeBubbaATL has a reputation beyond reputeBubbaATL has a reputation beyond reputeBubbaATL has a reputation beyond reputeBubbaATL has a reputation beyond reputeBubbaATL has a reputation beyond reputeBubbaATL has a reputation beyond reputeBubbaATL has a reputation beyond reputeBubbaATL has a reputation beyond reputeBubbaATL has a reputation beyond reputeBubbaATL has a reputation beyond repute
Re: Pentastar Thoughts

Speaking of which, I just noticed that the "Future Info" page's mention of the 2016 JGC PUG now includes hp/torque info which is identical to the current spec. (Might have been there for a while, but I just noticed it). We've also been told that the first iteration will be DI but no boost. So, if they've tuned it for the output to be identical to the current model, does that mean we can expect a fairly significant increase in MPG?
Reply With Quote
Sponsored Links
Advertisement
 
  #4  
Old 06-21-2015, 12:40 PM
padgett's Avatar
Premium Member
 
Join Date: Feb 2012
Location: Orlando
Posts: 1,883
Thanks: 0
Thanked 60 Times in 55 Posts
Rep Power: 82519
padgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond repute
Re: Pentastar Thoughts

Depends. The real advantage to DI is that pre-ignition (detonation) is essentially eliminated. In turn this means the compression ratio can be increased (why attention to the bottom end is important).

However without boost, this means the combustion chamber size is also reduced and you have to watch cyl temps to conrol NOx.

With boost you can maintain a larger combustion chamber which means a larger charge for the same charge density.

Part of the reason for a lower compression with boost is to increase the charge size, few notice that. This means you can increase "power" while maintaining a maximum chamber pressure so do not have take extraordinary measures to conrol emissions (like injection of odd liquids).

A side benefit of boost is that you can maintain power levels in Denver and higher (turbosuperchargers were developed for WWII fighters to increase their ceiling - why I originally said I had no use for them under 10,000 feet. DI changes that).

So DI adds some expense but not a lot of benefit without boost. One reason I can see would be to reduce the parts on a production line with both NA and boosted engine for those not wanting to pay about a grand more for about a 30% increase in power. (300 vs 400 hp)

Early DI (GM, VW) had problems with clogging very small nozzles at 30k psi but that has mostly been solved. One issue has been the high sulphur content of US gasoline. That is in the process of being fixed but may cause a rise in the price of 87 PON. EPA has asked for a 2/3 drop in the sulphur content of gasoline by 2017 but the interim may be problematic. (Tier 2 is already in place, this is Tier 3).

So what you can do with direct injection without boost is limited by itself but may be part of a larger picture & tied to the available gasoline.

Anyone know how the Hyundai Veloster Turbo is doing ?

ps original Z-28 was also rated at 290 hp.
Reply With Quote
  #5  
Old 06-21-2015, 04:38 PM
Member
My Jeep: 2015 5.7L WK2
 
Join Date: May 2015
Location: Savage, MN
Posts: 66
Thanks: 0
Thanked 9 Times in 7 Posts
Rep Power: 849
SavageBrewer is on a distinguished road
Re: Pentastar Thoughts

Not sure how the current trend of boosted small engines will fare long term, I have spent a fair amount of time driving a F150 with the ecoboost 3.5. In the end the powerband was narrow and really felt weak below 2000 rpm, also the fuel mileage was not that great. I would take the GM 5.3L L83 or LMG/LC9 engine any day over the 3.5 EcoBoost now after driving and towing with both options.

The Pentastar engine is already tuned to a point where I dont think that a factory level of boost will get it up to the 400hp mark, regardless even in its current form it is a very capable motor. Most boosted factory engines dont run the levels that the aftermarket boys are pushing.
Think about that only 15 years ago the Dodge Ram with 5.9 v8 only had 245 hp and got horrible gas mileage.


I would have built my new jeep with the 3.6 if they would have offered it with the HD suspension and drivetrian that is only available on with the 5.7 or EcoDeisel and tow package.

For cars I agree, a small 2.0L to 2.4L I4 with boost is great, but my experience in the larger motors that turbos arent quite as great as some want to hype it up to be.
Reply With Quote
  #6  
Old 06-22-2015, 08:30 AM
Todd3.6's Avatar
Member
My Jeep: 2012 3.6L WK2
 
Join Date: Jul 2012
Location: Twin Cities, MN
Posts: 849
Thanks: 5
Thanked 82 Times in 71 Posts
Rep Power: 350799
Todd3.6 has a reputation beyond reputeTodd3.6 has a reputation beyond reputeTodd3.6 has a reputation beyond reputeTodd3.6 has a reputation beyond reputeTodd3.6 has a reputation beyond reputeTodd3.6 has a reputation beyond reputeTodd3.6 has a reputation beyond reputeTodd3.6 has a reputation beyond reputeTodd3.6 has a reputation beyond reputeTodd3.6 has a reputation beyond reputeTodd3.6 has a reputation beyond repute
Re: Pentastar Thoughts

Quote:
Originally Posted by SavageBrewer View Post
Not sure how the current trend of boosted small engines will fare long term, I have spent a fair amount of time driving a F150 with the ecoboost 3.5. In the end the powerband was narrow and really felt weak below 2000 rpm, also the fuel mileage was not that great. I would take the GM 5.3L L83 or LMG/LC9 engine any day over the 3.5 EcoBoost now after driving and towing with both options.

The Pentastar engine is already tuned to a point where I dont think that a factory level of boost will get it up to the 400hp mark, regardless even in its current form it is a very capable motor. Most boosted factory engines don't run the levels that the aftermarket boys are pushing.
Think about that only 15 years ago the Dodge Ram with 5.9 v8 only had 245 hp and got horrible gas mileage.


I would have built my new jeep with the 3.6 if they would have offered it with the HD suspension and drivetrian that is only available on with the 5.7 or EcoDeisel and tow package.

For cars I agree, a small 2.0L to 2.4L I4 with boost is great, but my experience in the larger motors that turbos arent quite as great as some want to hype it up to be.
I mostly agree with these thoughts.
I would take the 5.0 Coyote over the EcoBoost in a Ford truck any day. And the newer GM V8s along with the redesigned 4.3 liter V6 are 'deep skirt' blocks, which means the crankshaft is seated within the block, effectively making it even stronger than the '4 bolt mains' of the old small block Chevy engines.

As a boater and car nut who likes to see newer/stronger tech in both, I can't wait to see the new 4.3 liter aluminum block V6 GM motor in boats. Stronger engine, better torque and HP.
Reply With Quote
  #7  
Old 06-22-2015, 10:26 AM
padgett's Avatar
Premium Member
 
Join Date: Feb 2012
Location: Orlando
Posts: 1,883
Thanks: 0
Thanked 60 Times in 55 Posts
Rep Power: 82519
padgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond repute
Re: Pentastar Thoughts

Back in the '70s my tow car was a GTO station wagon with a 400-4bbl rated at 200 hp. Cars back then had ded cams to meet emissions and were all done at 4000 rpm.

Pulling a tandem trailer with a race car and A/C on it got 12.5 mpg, 15 mpg without. It had a special order 3.07 posi "economy axle" and was turning 3 grand at 70 through a THM 400.

I like the Ecoboost concept but they do not really have it dialed in for trailer hauling, suspect it is getting into PE too often.
Reply With Quote
  #8  
Old 06-22-2015, 01:52 PM
Premium Member
 
Join Date: Aug 2013
Location: Boston
Posts: 1,930
Thanks: 45
Thanked 237 Times in 186 Posts
Rep Power: 77253
mswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond repute
Re: Pentastar Thoughts

I love the Pentastar V3.6 and I will tow with it, but not often with a heavy load (4500 Lb).


If you are gonna tow a car, I think you'd likely be in the above 5000 Lb range.
4000 Lb car is likely to need 2000 Lb trailer. Probably GVWR 7000 Lb tandem setup.


I'd seriously think about a Diesel or V8.
I agree Diesel is kind of a PITA.


Isn't your '12 now a Pentastar with a 6 Spd Trans?
__________________
07-24-2017 Summit 3.6L Velvet Red W/Black & Brown Int
Tires: OEM 20"/Nokian 18"
Situational awareness: Valentine One with V1Driver on IOS
Reply With Quote
  #9  
Old 06-25-2015, 08:53 AM
padgett's Avatar
Premium Member
 
Join Date: Feb 2012
Location: Orlando
Posts: 1,883
Thanks: 0
Thanked 60 Times in 55 Posts
Rep Power: 82519
padgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond reputepadgett has a reputation beyond repute
Re: Pentastar Thoughts

5 speed Merc. Must admit with a torque band essentially flat from 1600 to 6400, and a 2:1 torque converter & lockup I do not really undestand the driver for lotsa gears.

My first real tow car was a '72 that had a THM-400 & turned 3k at 70. One I bought in '98 had a 4 speed with lockup (2k at70) & factory towing package, now I have a 5 speed with lockup (1900 at 70) & factory towing package. Have never felt the need for another gear.

Now have a tow dolly and haven't towed a car this year, mostly a 3500-4000 lb (depending on load and how full the water tanks are) folding camping trailer. Also live in flat state. Pentastar suits me very well
Reply With Quote
  #10  
Old 06-25-2015, 11:05 PM
Premium Member
 
Join Date: Aug 2013
Location: Boston
Posts: 1,930
Thanks: 45
Thanked 237 Times in 186 Posts
Rep Power: 77253
mswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond reputemswlogo has a reputation beyond repute
Re: Pentastar Thoughts

More gears is for better MPG and power when not on the Highway Cruising.

I love the 8 Speed. Best Transmission I've ever had. And I've had plenty.

Flat with 4000 lbs Pentastar/8 Speed will be fine. Unless you towed a LOT.

I get low 20's in the City (very light foot) and high 20's on the highway (not too fast 65-ish). When not towing of course. My "City" is the burbs. Not inner city.
__________________
07-24-2017 Summit 3.6L Velvet Red W/Black & Brown Int
Tires: OEM 20"/Nokian 18"
Situational awareness: Valentine One with V1Driver on IOS
Reply With Quote
  #11  
Old 06-26-2015, 06:20 AM
overlanding's Avatar
Senior Member
 
Join Date: May 2012
Posts: 1,878
Thanks: 1,148
Thanked 360 Times in 302 Posts
Rep Power: 9157
overlanding has a reputation beyond reputeoverlanding has a reputation beyond reputeoverlanding has a reputation beyond reputeoverlanding has a reputation beyond reputeoverlanding has a reputation beyond reputeoverlanding has a reputation beyond reputeoverlanding has a reputation beyond reputeoverlanding has a reputation beyond reputeoverlanding has a reputation beyond reputeoverlanding has a reputation beyond reputeoverlanding has a reputation beyond repute
Re: Pentastar Thoughts

Quote:
Originally Posted by padgett View Post
5 speed Merc. Must admit with a torque band essentially flat from 1600 to 6400, and a 2:1 torque converter & lockup I do not really undestand the driver for lotsa gears.

My first real tow car was a '72 that had a THM-400 & turned 3k at 70. One I bought in '98 had a 4 speed with lockup (2k at70) & factory towing package, now I have a 5 speed with lockup (1900 at 70) & factory towing package. Have never felt the need for another gear.

Now have a tow dolly and haven't towed a car this year, mostly a 3500-4000 lb (depending on load and how full the water tanks are) folding camping trailer. Also live in flat state. Pentastar suits me very well

This most be the only vehicle you have ever driven. The 3.6/5speed is a complete dog. The 3.6/8speed is now as fast, if not faster than the 5.7/6speed.
Reply With Quote
  #12  
Old 06-26-2015, 07:38 AM
Premium Member
My Jeep: 2015 6.4L SRT WK2
 
Join Date: Sep 2010
Posts: 560
Thanks: 38
Thanked 91 Times in 59 Posts
Rep Power: 3066
GlowingGhoul has a reputation beyond reputeGlowingGhoul has a reputation beyond repute
Re: Pentastar Thoughts

Quote:
Originally Posted by overlanding View Post
This most be the only vehicle you have ever driven. The 3.6/5speed is a complete dog. The 3.6/8speed is now as fast, if not faster than the 5.7/6speed.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pentastar Cold Air Intake Kits? Lazzman Engine Performance/Intakes/Exhausts 25 11-29-2011 04:31 PM
E85 capable questions. Pentastar 3.6L abby Engine Performance/Intakes/Exhausts 45 05-08-2011 09:55 AM
Initial Thoughts: 2007 WK Hemi to WK2 Pentastar BEERnALE Grand Cherokee - WK2 - 21 10-23-2010 09:56 AM
Liberty with Pentastar V6, when? i0r15 Liberty-KJ and KK 7 08-26-2010 10:55 PM
Pentastar V6 JEEPWK2 Grand Cherokee - WK2 - 23 06-23-2010 01:46 PM

» Premium Vendor Showcase
Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 12:11 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community

JeepGarage.org is in no way associated with or endorsed by FCA US LLC. Chrysler, Dodge, Jeep, Ram, Mopar and SRT are registered trademarks of FCA US LLC.