Figured out why I love diesels so much better than gas.....

I had to make a cross country trip this month and we had too much stuff to fit in the Golf Sportwagen TDi. We rented a Dodge Grand Caravan which held everything quite well. It was comfortable to drive and got decent mileage but rolling across missouri and up into the western states the thing was always kicking down a gear or two as we went up hills. It sure gets noisy and kills the mileage. It sure pointed out the big difference between the zero torque gasoline engine vs the much higher torque of the diesel. Even loaded down the TDi doesn't normally drop a gear at highway speeds when going up hills. When it does its because the hill is really steep. The gas engines do it all the time. The Dodge engine puts out twice the horsepower of my TDi at 283HP vs 145HP for the VW. The VW torque peaks at 236 lb/ft at about 1800 rpm where the Dodge peaks at 263 lb/ft at 4400 rpm.



We had a good trip overall and I can see where the dodge would have some followers....especially with the 4 back seats folding flat into the floor. I sure like the high torque diesel pull though.

Frank

I like Diesel torque too.

Sure, most of us regret the reduced torque.

My replacement 1.4 gas Jetta 5M has 52 pound feet less than the JSW TDI 6M.

Somehow it gets 90 per cent of the diesel's fuel economy. So far - 16k - so good.



ez sends

ezshift5 said:

Sure, most of us regret the reduced torque.
My replacement 1.4 gas Jetta 5M has 52 pound feet less than the JSW TDI 6M.
Somehow it gets 90 per cent of the diesel's fuel economy. So far - 16k - so good.
ez sends

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You are correct. A modern smaller gasoline power passenger car, with mostly one passenger driving in it and light on cargo, will do wonders in fuel economy. Ah and let's not forget that these modern small gasoline powered cars do not have yet a GPF or gasoline particle filter.

So for a smaller sedan vehicle (Jetta, Mazda 3, etc.) the complexities/cost of modern light duty diesel might not justify it vs its gasoline counterpart unless you are driving 20K miles or more per year (not a scientific calculation, just my back of the envelope opinion).

amafrank said:

The Dodge engine puts out twice the horsepower of my TDi at 283HP vs 145HP for the VW. The VW torque peaks at 236 lb/ft at about 1800 rpm where the Dodge peaks at 263 lb/ft at 4400 rpm
Frank

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What people do not realize the HP quoted is developed at high or maximum RPM's only.
At lower RPM's you do not get anywhere near that HP!
It's the torque at low RPM' that a Diesel produces which makes the difference.

You can buy the caravan with a diesel but not in the USA.

Jetta_Pilot said:

What people do not realize the HP quoted is developed at high or maximum RPM's only.
At lower RPM's you do not get anywhere near that HP!
It's the torque at low RPM' that a Diesel produces which makes the difference.

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The Pentastar 3.6l V6 actually has a much broader torque curve than a tdi. It makes at least 90% of the peak torque figure from 1600-6400 rpm, and 95% peak torque from 2000-5700 rpm. It has slightly more torque(and power) at 1800 rpm than the tdi.

turbobrick240 said:

The Pentastar 3.6l V6 actually has a much broader torque curve than a tdi. It makes at least 90% of the peak torque figure from 1600-6400 rpm, and 95% peak torque from 2000-5700 rpm. It has slightly more torque(and power) at 1800 rpm than the tdi.

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And my 7.3 navistar makes more hp & torque than the golf, but then again it is 4 times bigger, too.

piotrsko said:

And my 7.3 navistar makes more hp & torque than the golf, but then again it is 4 times bigger, too.

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True, but the pentastar 3.6 makes more power per liter than the tdi- and without a turbo. I'm not saying it's better or more efficient, just that it has a very nice powerband. It's no peaky honda S2000 engine by any means.

turbobrick240 said:

True, but the pentastar 3.6 makes more power per liter than the tdi- and without a turbo. I'm not saying it's better or more efficient, just that it has a very nice powerband. It's no peaky honda S2000 engine by any means.

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They spin bearings. Had to pull one out of a Jeep that spun. Booo

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iamatt said:

They spin bearings. Had to pull one out of a Jeep that spun. Booo

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That's definitely not a pattern failure. Was someone off-roading and got it tilted enough to starve the engine of oil?

Some of the early Pentastars had cylinder head issues. Known issue, fixed under warranty. Sometimes the rollers for the rocker arms fail and thus cause the "Pentastar tick" - that's a known pattern failure, and even then it isn't common. You can swap out the rocker arms if it's caught early. (If someone keeps driving with it like this for months until one actually breaks, of course they're going to do more damage.)

You will of course find multiple examples of those by looking around the internet. Remember, Chrysler has built 5 million and counting of these engines. Even if you find a thousand examples of "Pentastar tick" rocker arm roller failures ... it's still a low failure rate. The "Pentastar tick" will probably eventually happen to all of them but not until high mileage. I don't consider an engine failure with 300,000 miles on it to be a problem.

We see broken Pentastars still almost monthly. They didn't completely fix the problems, they just made them show up later. We almost always have one here at the shop in need of an engine, including now.

In addition to the cylinder head problem and the rocker arms, they have burnt valve problems, the oil cooler under the intake which is part of the oil filter assembly can blow in cold weather, suddenly, with no warning, and empty the contents of the engine in about 60 seconds, the variable displacement oil pump control valves go bad a lot, which is a pain on some models to access, the catalysts do not last as long as they should, and are an even bigger pain on some models because of the dumb, dumb design they use to attach them to the head, they have cam phaser control problems that are difficult to isolate and often become a major engine tear down problem because of the actual actuators in the cam gears get stuck, and most of the transverse applications get bolted to a miserable POS turd of a transmission.

They do perform well, I will give them that. Lots of power. Until they don't.

These are off a 2015 Wrangler:



Shoot, were not even on there long enough to get dirty (this pic was taken right after they were removed, notice how clean they are inside and out?)

And these crapbox transmission are croaking so much that along with the days long process to get the Transits apart for almost anything, including but not limited to, their craptastic transmissions, we are putting another truck rack in the shop!



In fact, we have a Transit on the rack right now!



You need to remove the subframe to do almost anything to one of these things. In the case pictured, a DPF replacement. Problem is, Ford use low quality fasteners and threadlocker to hold all this to the unibody... so stuff breaks... and you have to usually cut off the control arms, drill-cut-weld holes in the sides of the unibody to cut out the captive threaded inserts and the broken bolts, then weld a plate back over it all. And we are not really in the rust belt, even though we do get some winter weather, we are not like Chicago.

This is another Transit:



These things suck. Bad. Awful, awful bad. You cannot even remove the transmission PAN without dropping the subframe.

GoFaster said:

That's definitely not a pattern failure. Was someone off-roading and got it tilted enough to starve the engine of oil?



Some of the early Pentastars had cylinder head issues. Known issue, fixed under warranty. Sometimes the rollers for the rocker arms fail and thus cause the "Pentastar tick" - that's a known pattern failure, and even then it isn't common. You can swap out the rocker arms if it's caught early. (If someone keeps driving with it like this for months until one actually breaks, of course they're going to do more damage.)



You will of course find multiple examples of those by looking around the internet. Remember, Chrysler has built 5 million and counting of these engines. Even if you find a thousand examples of "Pentastar tick" rocker arm roller failures ... it's still a low failure rate. The "Pentastar tick" will probably eventually happen to all of them but not until high mileage. I don't consider an engine failure with 300,000 miles on it to be a problem.

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I had like 3K warranty left when it started clacking. Spun on a blue oil filter and drove that junk to dealership. Had to wait months. Service writer was like we got another one!

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So gross.

Either someone is flipping the bill happily or you're just that nice of a guy to cut a labor deal...





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From what I have seen over the years, gassers can get decent mileage these days under fairly light loads, but fall flat on their face when used hard. Diesels on the other hand can be worked fairly hard without the same kind of loss of efficiency.

Took a new Toyota Corolla on the same trip we often take with MkIV Jetta and Q7. The Corolla can't come anywhere near the Jetta's consumption and is barely 10/15% better than the Q7 at same speed. While I doubt I will play with this on the Q7, many of my other diesels have been run on all kinds of alternate fuels. Try that in a new Corolla (or Cadillace, etc.).

Then, of course, check back with me in a few hundred thousand miles and let's see where the gas vs. diesel statistics stack up. Last year I had to rebuild my DDECII Detroit after a mere 1.05 or so million miles (1.7MM kms) - first time the major components of the drivetrain were ever touched. Haven't got much over 600,000 kms out of our VW Jetta TDs, but they died from body rot, not engine wear.

Now, I understand that many people don't put big miles on their vehicles, don't keep them very long and all that, so it matters not to them. BUT: anyone I know who is dedicated to getting real efficiency from any vehicle puts compression ignition far ahead of spark. Just waiting for that same level of availability to solve the same problems in general aviation (it's coming). Just hope I can get what I want while I can still hold a license (no spring chicken here).

So I'm wrong. Chrysler has built 10 million Pentastars (and counting).

Wow.

https://www.allpar.com/news/2019/02/10-million-pentastars-43805

To the top.

I too rented a Grand Caravan recently. I was impressed with the power. I had it loaded down with 1000 lbs of people, a motorized scooter and plenty of other gear. after 400 miles of mostly freeway driving i calc'd 25 mpg. Not bad for gas anyway.

oilhammer said:

We see broken Pentastars still almost monthly. They didn't completely fix the problems, they just made them show up later. We almost always have one here at the shop in need of an engine, including now.

In addition to the cylinder head problem and the rocker arms, they have burnt valve problems, the oil cooler under the intake which is part of the oil filter assembly can blow in cold weather, suddenly, with no warning, and empty the contents of the engine in about 60 seconds, the variable displacement oil pump control valves go bad a lot, which is a pain on some models to access, the catalysts do not last as long as they should, and are an even bigger pain on some models because of the dumb, dumb design they use to attach them to the head, they have cam phaser control problems that are difficult to isolate and often become a major engine tear down problem because of the actual actuators in the cam gears get stuck, and most of the transverse applications get bolted to a miserable POS turd of a transmission.

They do perform well, I will give them that. Lots of power. Until they don't.

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I'll stick with the 4.0/AW4 combo in my XJ, thanks.