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Why diesel Wrangler isn't probably better than gas

25K views 79 replies 38 participants last post by  standsbehindthisunit 
#1 ·
With the all the news regarding German diesels, I am having second thoughts about whether buying my first Jeep (NG Base Sport 2-Dr) that is diesel powered is a good idea. After some web research, here are my concerns:

1.) DPF - It eliminates most the of the diesel soot coming out of the exhaust and it's maintenance intensive. Regeneration eliminates the soot but requires higher RPM and longer distance of highway or high speed travel for completion, thus reducing the performance, MPG, & range and increased engine wear, making it very impractical for short and city drives. When the DPF gets, and it will, fully clogged, estimate $8,000 - $10,000 or more for replacement. (May be cheaper if cleaned instead)

2.) Premium cost of diesel - Not only I have to pay the additional $4,000 or more for the engine option (that's a lot of gas money), but also add in the price increases for oil changes and filling the DEF/Urea of every several thousand miles or so.

* $37K starting MSRP for a stock 2 door diesel Rubicon seems a bit too much...

And no, I won't do any emissions delete because California.

FCA should probably & kindly ask Ford to borrow their V6 Ecoboost engines with its 2.7 on Sport & Sahara models and with 3.5 on the Rubicon with its 420 lbs/ft of torque =)
 
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#3 ·
:welcome: to the forum.

Given the choice between Direct Injection gas engine, or Direct Injection diesel, I'll take the diesel every day of the week.
Until 2017 we really won't know what we are getting, so I wouldn't get overly excited about anything... yet. :beerdrinking:

I would really like to see a 4 cylinder diesel to get some room back in the engine compartment, but that's about as likely as Bruce Jenner growing a beard.

Sources at Allpar say Jeep hired a couple of engineers from Morgan, and the 2 door version of the JL will have an air cooled V-twin in front of the grill, that doubles as a factory winch option.
 
#5 ·
:welcome: To the forum.

Given the choice between direct injection gas engine, or direct injection diesel, i'll take the diesel every day of the week.
Until 2017 we really won't know what we are getting, so i wouldn't get overly excited about anything... Yet. :beerdrinking:

I would really like to see a 4 cylinder diesel to get some room back in the engine compartment, but that's about as likely as bruce jenner growing a beard.

sources at allpar say jeep hired a couple of engineers from morgan, and the 2 door version of the jl will have an air cooled v-twin in front of the grill, that doubles as a factory winch option.

hahahah
 
#8 ·
Personally I wouldn't want a diesel either, not only for the reasons initially stated by the OP, but also their relatively greater number of issues with truly cold temperatures without being plugged-in or constantly re-starting which isn't practical for a Wrangler left unattended while you go on a 2-3 day back-country ski trip in the Rockies and then return to your vehicle in -30 temps and try to start it.
My now departed Rubicon with the 3.6L never failed to start in very cold weather, even after being at the Lake Louise parking lot all day in the -38C temp at noon ( was -36 at 6AM and -34C by beer-o'clock at race end) during a race day, a lot of diesels were left overnight and folks got lifts to the inn.

My personal preference would be for FCA to take the 3.2L Pentastar from the Cherokee, and put a Supercharger on it for the Rubicon and Sahara, and leave it NA for the Willys and Sport to offer premium and entry options with off/on-road categories respectively. The torque/power delivery would be improved over the current 3.6L and the fuel efficiency should also improve (over the current 3.6L configuration). I prefer an SC over a Turbo for power delivery, but an eco-boost type scroll-turbo would be 'ok', and both the 3.6L and 3.2L Pentastars were designed from the start to be easily Sc/Turbo bolt-ons.

The Edelbrock SC was a target for my Rubi to survive until the 2017 refresh, but I/she never got the chance. :(

I think the fuel economy people want to get from the diesels is overly optimistic and not worth it, however the desire for the torque from a 3.0L EcoDiesel or something like the Cummins 2.8L they made for Nissan (that Nissan dropped for just using the 5.0L) would be very nice for off-roading and towing. The current 2.8L CRD used in Europe and Australia is just a dog, barely better than the Pentastar for torque delivery, and the 4BT Cummins, is really only worthwhile for people swapping out the old 3.8L petrol engine in earlier JKs.

Now mate both the 3.2L C Pentastar and 3.0L EcoDiesel (or a 2.XL revamped diesel with similar power/L number if you need a smaller/lighter footprint) with a 7-speed ZF transmission like the one used in the Panamera which offers both manual and DC-semi-auto on the same platform with 85% similar parts, would make for a great drivetrain option list for domestic and import markets, and for pavement princesses to serious off-roaders. You could split the market
A 7-speed ZF transmission would give the Manual a much needed 'Highway Gear' and the 5-speed Auto a high ratio 'off-road' and similar low ratio 'Highway gear' for trying to improve fuel economy of 'pushing a brick through the wind'.
You're still stuck with a diminishing return due to aero-dynamics, but likely that would better meet the power and MPG needs of the next generation platform than the overly-optimistic opinions of diesel being the panacea everyone seems to think it is, just like people think that direct injection alone would offer much improvement beyond a percentage point or two. the best option is mating that DI with an SC, which might almost offer enough power to satisfy some of those currently asking for a Hemi option as well.

Just my two revs worth. ;-)
 
#10 ·
My personal preference would be for FCA to take the 3.2L Pentastar from the Cherokee, and put a Supercharger on it for the Rubicon and Sahara, and leave it NA for the Willys and Sport to offer premium and entry options with off/on-road categories respectively. The torque/power delivery would be improved over the current 3.6L and the fuel efficiency should also improve (over the current 3.6L configuration). I prefer an SC over a Turbo for power delivery, but an eco-boost type scroll-turbo would be 'ok', and both the 3.6L and 3.2L Pentastars were designed from the start to be easily Sc/Turbo bolt-ons.
I had a similar vision, although if they went this route, a Hemi option would be even more necessary.

What I was thinking was 3 engine options: Turbo 3.2l Pentastar, 5.7l Hemi, and 3.0l EcoDiesel. That way you have an economical gas engine, powerful gas engine, and diesel engine (which is both economical and powerful) as options.

I understand your preference for superchargers, but a low RPM turbo would give similar performance on the low end, but still further increasing MPG over the supercharger since it is not run off of the serpentine belt. This turbo 3.2l would have enough power for the Wrangler not to be considered underpowered for those that cannot afford the Hemi option, but still deliver decent MPG.

Then you have the 5.7l Hemi option, which would probably give similar, if not slightly better, MPG than the current JK with the 3.6l, because there will be other modifications to improve the MPG besides just the engine. If you offered a 5.7l option from the factory with 21+ MPG highway, you will have struck a gold mine.

And then of course the EcoDiesel, which has plenty of power and fuel efficiency to go with it. Of course, this is all me dreaming. Honestly though, if Jeep does a good job with the JL and offers a Hemi, I may end up just trading in my JK for a Hemi JL.
 
#9 ·
After talking to a few techs that work on the VM diesel, the OP nailed it. The engine itself is very good the emissions system is the deal breaker. Altering the emissions system opens up a whole new can of worms, especially for CA residents. Lets not forget warranty issues if the emissions system is tampered with. The up charge is pretty steep too.

I'm no fan of DI gas engines either, it should be very interesting to see what Chrysler powers the Wrangler with going forward.
 
#12 ·
The other thing to consider is exhaust gas recirculation (EGR) in Petrol engines, and is another area where it's beneficial aspects are reduced by adding a Turbo in the equation with additional exhaust back-pressure & flow-through inconsistency (which on their own reduce efficiency too vs an SC).
I don't know the overall impact to EGR and EGR's impact on the current Pentastars, but I do know the Pentastars were designed to take advantage of EGR, though it may not be implemented or implemented well for all I know. It's another reason why more Turbos are on diesel and small petrol engines and Superchargers are on large V8s. IMO the Pentastar likely straddles that region of benefit.

Anywhoo, just another consideration.
 
#13 ·
So this 7 speed you are talking about can be manual or automatic, depending on the configuration? That would be sweet. 1 extra gear for the manual, and 2 for the autos. But it seems like they are going the 8 speed auto route, which is still nice for the auto crowd because you get 3 more gears, but it doesn't affect the manual crowd at all. I have no problem with the current 6 speed though.
 
#14 ·
Yep both the Manual and Dual-Clutch ZF 7-speed share the same base.

Yes, essentially it has a similar base, the 7MT is based on the 7DC. I remember seeing a percentage number in the low to mid 80s mentioned at one point, something like 83% or 85% IIRC.
Here's their link for confirmation of the shared platform;
Cars | 7-Speed Manual Transmission - ZF Friedrichshafen AG

So think of it like this (using parts instead of percentages as to not cross-over percentage meanings).
Lets imagine they both use the same initial 83 parts they share, then the Manual transmission (likely the one needing less to complete) only needs another 17 parts to make an MT version, while let's say the DC needs another 44 different part to make a Semi-Auto DC version. Making it 100 parts for the MT and 127 for the DC but most still shared parts. That allows quicker reaction time to demand changes, and allows production and logistics efficiencies as well as storage/warehousing efficiencies which are all major challenges to Jeep in Toledo. This would also help down-stream for the dealership repairs/servicing and inventory.

While most of these discussions boil down to two camps arguing against the other, we currently have both with 2 models of experience with '10 SportX and '15 Sport S with the NSG370 6MT and also a now being replaced 2012 Rubi with the original Euro-made WA580 with it's better shift patterns, and currently a rental Sahara (while I decide on the replacement for the Rubi) with the N.Am. made version of the W5A580/NAG1 which is slower but does do a better job with the auto-stick/tiptronic function except when trying to 'bump' a gear in drive it actually flips you into that gear vs the WA580 just up-shifting and keeping you in Drive (which is annoying if all you want to do is force a shift to lower RPM vs actually picking that gear). Plus my experiences with previous generation wrangler transmissions (both MT and AT). I'm not trying to say either is better than the other, they both have their good & bad and preferred applications. The thing is I want to see them BOTH get needed updates, especially the rather old 6-speed which is from 2005.

The NSG370 isn't a terrible transmission, but it is jiggly-poppy, and could use a refresh in my experienced opinion, especially when you try as many other manual transmissions as some of us have since it came out (even comparing recent generations of Mustang MTs back to back). Most Wrangler drivers don't really like the NSG370 so much as like the fact that they have a manual transmission option. The problem with this 'good enough' thinking is that it is far more likely that Jeep would drop the manual transmission far sooner if it doesn't get an update because the required tweaks would simply negate some of it's benefits to the people who currently like the option. The biggest issue, is that if Jeep doesn't update the MT with another gear, then they are going to have to muck heavily with its ratios, or more likely lower the axle ratio which is the compromise of capability for efficiency that most of us are afraid they will make in a JL refresh. And the argument that 'anyone can add after-market ratios' should've quieted all the whiners who whine about the 3.73 in a Sport or Willys if true, and doesn't address the fact that a great low end gear and great highway gear mated with your preferred up-ratio axle gear is still a win-win, without over-reving at highway speeds, thus not a compromise on either end.
Why not get all the benefits of a consolidated platform and at the same time give the Manual folks a Highway gear to help them with the highway trips to the trailhead, or occasional road-trip, and also quietly help with CAFE/EPA/Euro6 numbers, all the while creating a nice platform that could be applied in other areas (the Viper sorely needs another gear as shown in almost all shootouts where it is great off the line and dies a painfully slow death in 6th) where you could maximize efficiencies and options.

Also the base 7- speed does give you slightly better torque numbers than the 8-speed 845RE found in the Pentastar Ram 1500 (525NM vs 500NM) , and the uprated ZF-7 version offers the same 700NM capability of the the 8HP70 found in the EcoDiesel GC & Ram and non-hellcat versions of the Charger and Challenger. So supporting engine options or mods is not an issue (although technically the current NAG1 supports more power (580NM [hence the 580 in the name]) than either of the base ZFs.

Now I'd usually be concerned and say that it's not possible to see this in the 2017/2018MY JL because they haven't announced a re-tooling of a plant to prepare for producing the transmission, however they did the same thing with the Wrangler, as I mentioned above the first WA580s were European derived, and then the next year they started putting in the US made W5A580/NAG1s into the Wrangler, allowing for a two stage implementation while the plant was being re-tooled.

Again though, this requires that the folks at FCA do something other than applying existing solutions to the situation rather than finding the 'ideal' solution which could last the entire lifespan of the JL and other generations of vehicles.

Again, just my view from the cheap-seats. :wavey:
 
#15 ·
That's some good info. The reason I like the current 6-speed is because I used to have a 5-speed TJ. The 6-speed is a little more tolerable of higher axle gears, and the close ratios make it easier to stay in the optimal RPM range. That said, I would have no problem with a 7-speed.

I see what you are saying. If you have the 7-speed, then you could gear the axles so that the 7th gear has optimal highway RPMs for MPG while not sacrificing the power of 1st gear. You could then reduce the number of options for axle ratios to just 3.73 for non-Rubis and 4.10 for Rubis, or the equivalent to whatever this transmission would require. But that would further reduce production costs.
 
#16 ·
I see what you are saying. If you have the 7-speed, then you could gear the axles so that the 7th gear has optimal highway RPMs for MPG while not sacrificing the power of 1st gear. You could then reduce the number of options for axle ratios to just 3.73 for non-Rubis and 4.10 for Rubis, or the equivalent to whatever this transmission would require. But that would further reduce production costs.
Yep.. although.. let's be realistic, FCA would likely still keep the 3:21 ratio in the options book just so they could still lay claim to an optional mileage of standard+X more for marketing purposes of that number people would quote like it's the mileage of a 4.10 geared Rubi with MTs.

In reality though you're still pushing a brick through the wind and gear ratios only get you so far and the 3:21 might start seeing diminishing returns as the power to overcome wind resistance requires ever increasing power (somewhat geometric progression), so indeed they might drop the 3.21 ratio and move to consolidating on the other two. Of course they could consolidate on the other two and drop the 4.10 by adding a shorter first gear, but... while that would match the high reving Pentastar which wouldn't force you to shift too soon, it would be problematic for the lower reving diesel possibilities, so I think you're correct in that they would do best to move to principally 3.73/4.10 as a good all around fit and delete an SKU/inventory item.
 
#18 ·
I have a '14 GC with the 3.0L Ecodiesel, when I went looking for a GC I didn't even consider the puny 3.6L gas. We test drove it about 10 miles, then brought it home. I've had Hemi's and a 6.0 LS motor, the Hemi is ok, but no LS. I WISH we would see the 3.0L diesel in the Wrangler but it won't happen. FCA will never give us anything close to 400 foot pounds of torque in the little Wrangler. An engine swap of the Ecodiesel and the 8sp paddle shit would be freaking great, but it is too long, don't see how a 7sp is going to be much shorter. We can conjecture till cows give chocolate milk but FCA will give us what they have, what is cheap, and you can bet your ass it won't be enough motor for most of us.
 
#19 ·
Technically I am not a fan of burning diesel. In spite of all the advances in engine technology it's still a "clunky" and dirty engine and I would prefer a V8 gas engine BUT unquestionably the gobs of low end torque make it a very attractive choice for crawling off road and improving fuel economy (although the cost per mile doesn't hold the same advantage over gas).


Jeep needs to to introduce the diesel engine in the US and to have brisk sales of diesel JLs if for no other reason, to lessen the burden of CAFE requirements. That is a benefit to all of Jeep owners. So if someone wants a diesel JL don't try to talk them out of it. It's just great to have a choice. :thumb:
 
#20 ·
Many people here already know that VM has been the supplier for most diesel engines in Jeeps for years. Well, it just so happens that GM is part owner and the new "baby Duramax" 2.8L diesel that is in the Colorado and goes on sale next month is pretty much the exact engine that Jeep is looking at putting in the JL.

So...we'll be able to gauge dependability and issues by watching the Colorado pickups for a year or two before we see this engine show up in the Wrangler. That's a good thing.

It's already been said that the engine is designed so that it meets U.S. standards with no cheating or other tricks needed.

My experience with diesel is that I owned two 2005 Jeep KJs with the 4-cylinder diesels and I loved them. Once you deal with the emmissions junk on them and tune the ECU, they become rock solid engines. The KJ was 4,300 lbs. or so and had a lot of heavy duty hardware from the factory, and that little diesel would move it around fine. 370 lb/ft at 1,600 RPM(!) It made so much torque that the converter would slip while trying to lock up and created a "shudder" that was eventually fixed under TSB by upgrading the springs in the converter. Lol. Those little diesels are awesome. AND...I averaged 26 MPGs on my daily routine and 14 MPGs while towing 7,000 lbs. down the interstate with a lift and larger AT tires on the Jeep.

Once you drive a diesel in a Jeep...you'll never want to go back. Having all that power at such low RPM spoils a guy.
 
#27 ·
There are some who think you will get your wish since the 3.0 is already certified and is on sale already in the U.S. It would be easy for Jeep to drop it into the JL and sell it. Easier than the 2.8L
 
#22 ·
No thanks & the people that have to deal with state emissions testing will have to keep it factory & If you don't think the EPA is going to put the screws down even harder now because of the VW mess, you're crazy.... I had a Diesel and really wouldn't want one post 2007.5 ....
 
#24 ·
- Towing is dependent on chassis

Short Wheelbase (Current JK) has less towing capacity than Long (JKU)

- Fuel economy is much improved than gas at the expense of NOX emissions and diesel maintenance. FCA says est. 30 MPG Highway with 8 Speed Automatic.

- Expect diesel options from $4,000 (Ram Pentastar to Ecodiesel) to $8,000 (Ram Cummins) extra.
 
#26 ·
I'm guessing this is the same EPA that released lots of toxic crap in that CO river? Yea I trust them a bunch, and completely believe everything the government tells me.
Now for a paragraph that isn't filled with sarcasm the last long trip we took in the Ecodiesel GC we managed 30.2 mpg as figured by mileage. That V6 gas won't get that and the Hemi won't come close.
 
#33 ·
Diesel fuel is less than gasoline here.

And ditto what was posted above ^^ it looks like the "upgraded" Gen 2 automatic is likely to be the only option with the diesel. There are lots of reasons for this...strong government oversight (especially now that VW screwed everybody over), meeting torque output demands, sales expectations, etc.
 
#35 ·
I was never much of a diesel fan until I picked one up myself. I commute in my VW Golf TDI ('03) the 60+ miles to and from work per day. It currently has 276k miles and runs like a champ! I run Rotella T6 5W40 diesel oil which I can pick up for around $40-50/gallon. The engine and OEM filter easily gets 10,000 miles out of a change. For those worried you can use Blackstone Labs for testing their oil samples to verify.

My '15 JKU rocks, but having a diesel option in a Wrangler with potential for 30+ MPG is precisely what I am looking for. I'd love to take more road trips in the JKU and a diesel would help that very much. If FCA verifies a JLU will be available with an auto trans and diesel I'm selling the JKU and picking up a JLU as soon as possible. I'm keeping my fingers crossed!

-Rick
 
#41 ·
If the JL only has a diesel w/auto only FCA is being exceptionally lazy IMHO.

They don't even have to source another tranny, just cut some new gears matching the final drive with the 8 speed auto. The G56 that is in the current RAM CTD 2500/3500 would be able to handle all the torque that is produced with the engine. Not sure if the 6.7 is de-tuned for the G56, but the 6.7 currently produces 800lbs of torque. My G56 has been flawless for the last 10 years. How have the 8 speed slushies in the last couple of years fared?


From the RAM website:

6-Speed Manual G56 Transmission The six-speed manual transmission lets you choose the gear you're in for better performance and control.
 
#45 ·
Not sure if the 6.7 is de-tuned for the G56, but the 6.7 currently produces 800lbs of torque. My G56 has been flawless for the last 10 years. How have the 8 speed slushies in the last couple of years fared?
Yeah the 6.7 is significantly de-tuned, especially in the 2007 version, the 2011 update got a torque boost. But it's still in the 600s not 800s, although that would still be within the target engines' envelope.
One issue may also be weight as it's a dozen or two pounds heavier than the 8-speed and that's not good for a manual vs auto.

The 8-speeds have been pretty good sofar, but they are still 'new' age wise, but there are a bunch out there with workhorse hours on them.

The 6-speed is suitable of course, it's just kinda big IMO compared to the slightly more svelte newer options out there, that's why I'd rather see them go a route similar to the ZF 7-speed, although as we've mentioned that was unlikely even before the recent announcement.
 
#46 ·
Anybody seen info. on if the 2018 will still have the Manual Transmission. I keep seeing the 8 speed auto is coming to the V6 and Diesel, which is fine, but if the Manual Transmission goes away that's bad news for me, I can't imagine having an auto Wrangler..
 
#48 ·
I've owned and deleted/tuned a couple of diesels. Ford Excursion with the 7.3L - probably the best SUV Detroit has ever built. And most recently a Ram 3500 Dually to pull a 40' 5th wheel. Both were great vehicles.

The Ram had a Smarty Jr programmer. A few weeks after I did the delete, the government essentially shut down the Italian company that makes the product. Getting new/updated tunes required going thru one of the forum members. Nevada also has a visual inspection requirement for diesels....so California isn't the only state cracking down. I also had issues with a cold soaked engine and trying to get it started during a Colorado ski trip. Another consideration is when it is time to sell the vehicle - you have voided the warranty and most potential buyers probably don't know what the delete/tune is and what the benefits are to having it. It's great that the cost of diesel is now lower than gasoline, but it seems like that has not been the case for most of the last 15 years.

I'll definitely buy another diesel truck if we decide to go the RV route again, but short of that....it seems like way too much of a hassle to own diesels these days. Don't get me wrong - the capability of these new trucks is awesome, but the cost/benefit is debatable for a vehicle that does not truly require it. I'd much rather see a factory Hemi as an option.
 
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