Why no fuel effecient Jeep?

Lon, you replied to the wrong part of the thread..

go hug a tree....

jeeps are TRUCKS not SUV's. They were around a lot longer then the SUV moniker. And they got bad mileage before that too...lol

All that extra powerttrain equipment: Front differential, etc, , transfer case takes POWER to run, even when its disengaged (viscous shear of the lubricants on the gearing). The high drag due to the large frontal profile, the lack of an aerodynamic shape, the 'skin' friction due to all that equipment hanging below, the high road clearance, the large (relative) low pressure tires, extra weight due to high strength (plus equipment) - all take power.

So if you want a Jeep thats fuel efficient, its gotta be sleek, flat bottomed, light weight, low clearance, no 4WD, etc. ..... and much smaler. Actually a (real) Jeep isnt all that bad > snipped-for-privacy@privacy.net ( snipped-for-privacy@privacy.net) wrote on Saturday 30 October 2004 03:20 pm:

Agreed. I show a remarkable improvement in gas mileage when I keep my

Mark '98 TJ '98 XJ

i own an '04 dodge/cummins 4x4 and an '01 dodge/cummins 4x4. either truck weighs twice what a jeep does yet with only 5.9 liters have no trouble at all hauling 2 (and even nearly 3) times their own weight (in addition to their own weight) all over these amazing rocky mountains. im not sure about anything existing now but feel almost certain that if set up properly a 2.5 diesel would have no shortage of power pulling around a jeep.

The newer euro style diesels have the high efficiency allowed by their higher compression, have moved upwards in horsepower to acceptable levels for sustained power, and have torque curves with enough low end grunt to make a street racer weep. In some vehicles [e.g. the VW SUV] the diesel *is* the hot street setup with mileage better than the gas variants. However, even the euro diesels still have a dirty little secret you tend to see only in places like Scientific American and the more engineering oriented auto magazines--they are still dirtier than a gas engine and worse, their pollution is both harder to remove and more of a contribution to greenhouse effect and human health problems. It isn't an unsolvable problem, just that currently no roadgoing diesel has solved it. The pollution is the aerosol output of the diesels, not the particulate--that could be solved easier.

Dave Milne proclaimed:

not convinced Nate. I've driven properly set up 2.5 diesels vehicles with the same weight as a Jeep, and its ok sort of. Just not great imo.

i dont think i expressed what i meant clearly. im not referencing one thats running properly, im referencing one thats designed to produce adequate torque in stock form. my '04 produces 600 ft. lbs. of torque stock which is just over

I understood you; we are just debating how much is enough :-)

The torque aspect is what I love about diesels, and why I think, to the annoyance of some, that they make great offroad engines ( apart from the running when wet aspect ). However a 2.5 is probably only going to put out around 140hp. The Jeep 2.8 common rail puts out 150 hp and 266 lb/ft torque. It wouldn't take much more to produce something spectacular instead of just about adequate ; based on those figures a 4.0 would put out 214 hp and a whopping 380 lb/ft. That would really make a Wrangler shift.

Dave Milne, Scotland '91 Grand Wagoneer, '99 TJ

Lon,

wasn't aware of the aerosol problem. Have you got any links on it so I can do some more reading ? The particulate problem can be solved by traps (I think this is part of the Euro 2006 legislation or something).

Dave

Google gives a pretty good set of cited and referenced links with just [diesel aerosol emissions], a goodly number of which also appear here:

Unfortunately, attempting to follow up on what particular combinations of these all tend to be most bothersome tends to have a goodly portion of kook sites.

Dave Milne proclaimed:

They could probably deal with failure to change the filter with the engine management system...after so many thousand miles/km of warnings, you get a limp mode and a service visit.

I've seen other references to thermal reactors somewhat similar to the old Mazda rotary srubbers for reduction of the aerosols that also tend to help with the carbon particulates.

Haven't honestly seen any reviews of the engines on a nice winter day in Rogers Pass Montana and whether they become just part of the snowbank until spring.

L.W.(ßill) Hughes III proclaimed:

cheers. Dave

Ya know, all the unburned hydrocarbons spewing from the tailpipe of a Nuttered 258 with no catcon doesn't smell all that great either ... I think I prefer the smell of diesel exhaust to be honest.

/Peter

HA!

I got the paperwork to show my 'Nuttered' 258 blows 15 ppm HC and 0.16% CO into the air.

Why don't you cough up your fancy 'injected and computerized all to crap' numbers eh?

Mike

Peter P>

Sorry Mike, my comment may have been more pointed than I meant it to be. It's not just your rig either, most of the older carbureted Jeeps I wheel with have a very strong raw gas smell coming from the tailpipe. To be honest, being pretty light-informed as far as science is concerned, I've no idea whether this odour is a "bad" emission or not, pollution-wise. It may well be innocuous, and diesel exhaust may be far more objectionable in every way. In fact, even some of the newer gas rigs with more in the way of emission controls smell pretty bad to me in the same way when they are starting up cold - my wife's ZJ for example has an awful raw gas smell. It goes away once warmed up though.

It's just that my personal opinion is that following some gas rigs on the trail is an unpleasantly oderiferous experience, so rejecting diesels as "stinky" seems a bit contrived to me.

I can't share any numbers on my TJ because it's too new to have been tested, although that particular grace period is about to expire. The aforementioned ZJ (with a 360) was tested at 2 ppm HC (1 ppm at idle) and 0.00 CO%.

Don't you tune your carb specifically for the emissions tests, then change it for your "25% seat-of-the-pants" boost after then tests are done? If so, that may be why my ol' honker seems to think > 15 ppm.

Anyway, you've got me pretty convinced that diesels are a bad thing, at least for around here. I just wanted to point out that gas engines can be pretty "stinky" too ... at least to some of us.

/Peter

----- Original Message ----- From: "Mike Romain" Newsgroups: rec.autos.makers.jeep+willys Sent: Monday, November 01, 2004 10:06 AM Subject: Re: Why no fuel effecient Jeep?

I find most of the 'carb' Jeeps are very seldom tuned up at all and smell bad like you mention.

They don't 'have' to and they shouldn't!

Rather than properly clean the carbs with a kit every main tune-up like the maintenance schedule calls for, 'mechanics' like some of the ones on this group cut the poor carbs open to get at the factory settings to try and make up for dirt (or their fear of opening a carb). This tosses the computer out of balance and the damn things stink to high heaven like you have noticed.

They make them pass, then set it to run after or worse have no emissions so they just set them rich and go. They will run rich, it covers a lot of defects up.

Then the average owner starts playing with the settings because the 'mechanic' cut it open to make them accessible and the thing will never run clean.

One friend went in to get his emissions and the garage bay had 17 ppm HC in it's air so the machine wouldn't initialize for the test. Those mechanics were breathing worse than comes out my tailpipe.

I tuned my idle jets 1/4 turn leaner than my ear called for for 'beat lean' for that emissions and got the low readings. I probably could have left them because I am allowed 350 ppm HC!

So you gotta figure the 15 ppm or even the allowed 350 isn't what you are smelling on the trail. Those rigs are way out of whack.

But man oh man have you ever followed one of those black smoke belching rattling leaky diesels on the trail? I have LOL!

Maybe in a few years after they clean out some of the sulfur (we have some of the highest sulfur in the world in our fuels) and force a diesel to pass a real emissions test, my opinion could change, but not for now.

Mike

Peter P>