Does size really matter??

[baker2acre]

Ok... I've been puzzling over this for a while. With the coming emmision changes in '07 then again in 2010... Ford and Dodge have decided it better to go BIG or go home but I'm not referring just to their power and performance figures. Dodge, after +18yrs has gone from 5.9l up to 6.7l and Ford, after shedding 1.3l to go from 7.3l to an even 6.0l has eaten all the "figgy pudding" and is back up to 6.4l?? Now for power I understand the satement of "there's no replacement for displacement" but I've been confused as to how it aids in lower emissions for one, and the other big one is Dodge claims "better fuel economy." ????? How does this work?? There are plenty of manufactures out there who get GOBBS of go/litre.... BMW for one is cranking 286hp from just 3 litres. That's almost 100hp/litre!! Compare that to our 6.5 & 6.6's and we should easy see the 600's!! (all in theory of course :rolleyes: ) Now there's no way to tell how this BMW would translate it's small stature to better economy and emmisions when strapped to a +10k-lb vehicle... but lets look at it this way. My Dad drives a Semi with an N14 cummins in it. His rig usually tops out around 80,000lbs. His N14 displaces 14 litres... in that ratio he's a weight to displacement of +5,700lb/1 litre!! Now using this number to play with, Ford's new F350 has a GCVW of around 26,000lbs. and if we're moving that with the above ratio Ford should only "require" just over 4.5 litres!!! So, then why do I need to have closer and closer to 7 litres? Or more? Does having "Andre the Giant" up front really make my canoe that much better? I think you see what I'm getting at... how does displacement relate to work being done better?

*Note, I only use the above numbers and calcs. as conversation starters and not as evidence in court. So, before you try to prove me an idiot please know that I can prove me an idiot better than you!!:D Also, this is not a thread of brand loyalty or bashing, but intended to understand and better all diesels!!

Please feel free to offer as simple or as complex an answer as you'd like. Remember this is not just to for me to read today but for myself and others to disect the guts out of to make better diesels!

Thanks, in advance!!

[DmaxMaverick]

The 6.4L Ford and 6.7L Cummins are currently intended for marketing in medium duty trucks. The 6.0L and 5.9L engines will continue in the light truck lines until at least 2010. It's too early to tell what will happen after that.

I don't understand the displacement thing either. Displacement is an enemy of smog requirements. I suspect that to be one reason for the medium duty applications. The smog requirements are not as strict as for LT's. The gas and particulate output restrictions are based on weight ratings.

Looking at the 6.4's performance numbers, I'm not impressed at all. Seems like a lot of hype over no significant gains with a "new and improved" engine design. The HP/torque curves would be more common for a much smaller engine. The displacement may be just a marketing angle. Like the 454 Chevy and 455 Olds. Virtually the same displacement, but if you are looking for cubes, the 455 is more appealing on the sticker, to some. Still, the 6.4 has a lot more moving parts and electronics, and probably a price tag to match. That is enough to scare off a consumer market buyer. Remember the Edsel?

[More Power]

Nox and PM are the biggies for diesel emissions. The higher the combustion temperatures, the higher the level of oxides of nitrogen. Bigger bores allow Ford & Dodge to maintain competitive power while lowering combustion pressure (and hence combustion temperature). This is the primary reason for larger diameter pistons - it's all about psi and surface area. Of course, larger and more effective EGR is also part of the new emissions systems used by all three manufacturers. EGR is used to cool the combustion temperatures. The new 6.7L Cummins utilizes approximately 40% of the engine components used in the outgoing 5.9.

Particulate matter (or soot) probably isn't affected much by a piston diameter increase - in these engines. PM is primarily being controlled by a new exhaust catalyst and DPF (Diesel Particulate Filter). Of course, the common-rail electronic fuel injection really cleans up the soot, as well as the 4-valve per cyl heads and computer controlled variable nozzle turbocharger(s). Reducing smog forming Nox will provide the biggest emissions challenge in the years ahead.

Will be interesting to see what sort of EGT these new engines produce. I'd bet it'll be less than earlier engines.

Jim

[baker2acre]

Hey DmaxMaverick,

Ford's brochure is showing the 6.4l available in '08 down to the F250??
http://www.fordvehicles.com/assets/pdf/2008superduty/fsd08_f250.pdf

I can't find anything definative on Dodge's plans... the 6.7 is available now in the Med-Duty as you said but I can't see them waiting much longer then '08 to release it into the 2500-3500's because they've anounced putting a "new" mystery cummins in the 1500's in '09.

[winemaker]

Don't get me wrong on the points to follow, I love having the power that I have, but historicly I've wondered out loud why we need this power. I love an in-line 4cyl TD, but I own a 6.5!
Your numbers cited illustrate beautifully a major difference from a rig to a pickup. When I see loaded rigs on our infamous Coquihalla highway (very hilly), these guys are creeping up the hills at about 20 kmh and I'm "flying" by doing 70 or 80 kmh, also loaded to my max payload.
If you and I were content to settle in to, say, 50 kmh or less on the hills, we could surely operate a 2.5L mated to the right gearing, but I can't see that happening.
Conversely, what would it take to make an 80K lb rig do 70kmh up an 8% grade?
Good post.

[baker2acre]

Thanks Winemaker...


I too am very disappointed with our lack of choices. We have so many choices in everything except the powerplant in our trucks. Some would say buy a V6 gasser... but then I prick my finger and show them the #2 I bleed.;)

I wander how a truck would behave (performance, economy, emmissions) with a smaller displacing engine, short rpm range, higher torque to hp ratio and more gears. Unfortunately the shame of getting dusted at the 1st hill by a Chevette will not allow it. :rolleyes:

[baker2acre]

I guess I should try and get back on subject.... that being "Is there reason to the ever increasing displacement in diesel engines?" (Trucks Specifically)

Here's an interesting article I read this morning. http://www.dieselforecast.com/ArticleDetails.php?articleID=333

So far it seems to be due to either power demands, emission regulations, fuel economy or just plain marketing.

I think so far Jim's (More Power) explained the issue from the emissions view point very well. More HP = Higher combustion temps. = more NOX emissions so increasing combustion chamber size reduces preasure, reduces temp and reduces emissions while maintaining boost & power. He also noted that the same came be minimized or overcome by the use of and effective EGR to ruduce cumbustion temps. EGR coolers reduce temperatures evan further.

Winemaker has noted the ability to drive a fully laden rig up an 8% grade like it's the family station wagen as a driving force and a larger displacing engine would/should allow for the same performane at lower EGT's and engine temps without loss of durability... or more foot in the pedal. However some simple design principles such as free flowing exhausts, appropriatley sized cooling systems, inter/aftercooling, multi-shot injections and new metalurgy techniques (and common sense :p ) can counter the destructive effects of a HO diesel engine. (Of course there are many more design elements than these..) The above link lists some very compitent smaller displacing engines that I'm sure would shock some of the "big-boys" however I do acknowledge the distance to their limits would be shorter than in with a larger engine.

No one has yet to touch on the aspect of fuel-economy, so I guess I will. I think I should clarify my 1st post on this... I think Cummins claim of fuel economy was not "better" but "to maintain" existing fuel economy. That's great if you're after an "all-out" tow vehicle, which some of us are. But I think this is counter productive in applications such as a 3/4 ton long-bed CC pickup. It's GCVW is much lower and every added weight from the cab and and longer wheel base cut into it's potential that much more rendering a larger engine's improvements useless.

[baker2acre]

I cut myself off...

continued form above:

Cummins has been working witht the EPA for the (reportedly) past 9yrs to improve mpg's and reduce emissions. The report in the link of my last post says they used a smaller v8 and v6 in a Ram and a Durango and were able to achieve 22mpgs. Not bad, but not fantastic either. However, the power ratings were rather good. Still from the 16mpg I'm getting now in my '96 (which would not pass current emission regs. :D ) to the reported 22mpg is an improvement of almost 40%!!! Looking at it from that angle, if I can reduce my fuel cost by 40%... in the words of the late Peter Boyle; "Holy Crap, Marie!"

[morgan]

No doubt, we need a 6 cyl 1/2 ton option. The BIG-trend is getting rediculous. Most loads I see behind them are totally acheivable with much less truck. My coworker pulls his boat behind a Nissan minivan, and parks right next to the guy at the boat landing with the newest, biggest superduty diesel.

If Jeep would offer their diesel in a revived Comanche, that would probably do it for most consumers.

[baker2acre]

Thanks Morgan for your input....


For me, my 190hp is fine. I'd love to have 600lb/ft to back it though. When I was in Drivers Ed. my teacher told me as a rule of thumb to allow "6 seconds" before the next car when merging into traffic. This gives me time to get up to speed and the car coming behind to plan a lane change or reduce speed, etc. My LongBed Crew Cab does this just fine in normal driving and can evan be relied on to get out of the way if I miss judge my 6secs (and kill mosquittos). When I studied for my CDL's, naturally these rules changed, more time had to be allowed, greater distances, etc. For me I don't load up to 16k gross and want to race anybody!! It's just not safe!! Again, my 190hp moves me just fine because I've planned ahead. A lot of people drop there loads in intersections because they've got more foot than brains! :rolleyes:

I see the same stuff too. The biggest truck available with a landscape trailer in tow. (I admit, I'm one. My crew carries just me 90% of the time.) Give me my 4-5 litres, 4-6cyls, 150-200hp and 400-500lb/ft and mid-20's mpg. as standard and make the big-boy an option for those who need it!!

So far, aside from the advantage of cooler cumbustion temps to lower emissions, I still don't see why getting bigger is getting better. (Unless you plan to power the QE-2! :D )

[morgan]

Hey Baker, I have a CDL too.... nice to have for primary source of employment/income, or as a back up. Mine's a back up for now, but who knows?

A friend at church has a small collection of VW diesels. I like the rabbit truck, but of course it's way too small. There's just no real middle ground available except for an older GM 1500 6.2.

[baker2acre]

Very true.... the vw rabbit pickup, "caddy" in Europe, is very tight. I had an '80 gasser. My father in law has an '81 diesel. I've barrowed it and had it loaded with plywood. Drove just fine for only having 50hp!!! Bed was misserable because of the narrow wheel wells. But it's still fun to drive and at 50mpg's who cares!! I may barrow it again this spring to haul my mowing tractor. I'm short and can't get the mower's lard butt up into my Chev. I could use ramps, novel idea, but the mower's not running... dang!! :rolleyes:

There were other options too, nissan, toyota, mazda and the ford ranger had diesels around the same time frame as the Vdub's... however they are tight as well, although a bit more powerful. Bed size for me's not a big deal from 6'-8' (although I do like the 8') but I have two car-seats and the compacts' ext.cab just won't cut it. I'd love to see a new Colorado Crew Cab with an Isuzu 4 banger. (Please insert a Tim Allen "Tool Time" grunt here.) I heat with wood and would miss my 1-ton in the fall.... but the other 9 months of the year would make up for it!:D

[morgan]

Several months ago, Diesel power magazine rated the 86 Ford Ranger 2wd diesel truck as the most fuel efficient diesel pickup worth looking for. They probably didn't consider the VW due to it's mini el camino image.

[baker2acre]

Morgan, your comment on the diesel ranger sent me digging over at dieselpowers website.... great site. I found an article on a Mercedes V8 smashing out 538lb/ft. from only 4 litres. :eek: I wander if we're not starting to become a belt buckle society? I just want to keep my pants up, ya know? "It's nice that your belt buckle has a cut-out for your naval, and I bet when the wind picks up it does a whole lot better then mine!! But do I need one that big??" :confused:

[Stlheadake]

I personally love my truck. I do use it, but only 40% of the time maybe. The rest of the time I could get by with less HP and I would definitely enjoy better mileage.

My dad has a '93 6.2 that's just getting broken in with 230K on the clock. He routinely gets 24 MPG on the highway. He has the 4spd manual, and I believe the only thing he has done to it is intake and exhaust.

He bought a new Duramax, and loves the new power for towing his 36' travel trailer. He still drives 'Jim' as his daily driver, because of the mileage.

Here's where I'll probably get myself into trouble, I think that while the 'big' (pun intended) three are playing around with these big displacements, Nissan and Toyota could sneak a smaller, MUCH more efficient diesel in and grab the market. They are running them everywhere else with pretty decent success.

This is a very interesting discussion...Thanks for getting it started.

[baker2acre]

I personally love my truck....

Thanks Stlheadake.... I too love my truck. I have a '93 cummins (I do not call it a "dodge" because I feel it an insult the engine that keeps it on the road.;) ) that is displacing 5.9 but like my 6.5 better. It feels like a contradiction but I do!! I like the 6.5 because of it's "manners" not because of it's displacement, however I wish it was a little more frugal. I daily weigh in at below 7k/lbs. (yeah I know, empty!) and I only "pull" when I'm camping which is approx. 4X/year. Not much. I constantly wonder how things would be with a smaller power unit. In your post you make 2 very good points;

1:
Nissan and Toyota could sneak a smaller, MUCH more efficient diesel in and grab the market.
This is both scary and true. The guys who do not own diesels probably don't because they only get better mpg's when fully loaded vs. a gasser (my 6.5=16mpg, '07 Chevy Gasser= +20) and they can't afford the +40K price tag. The later could be rationalized away if the truck were to say... get 30mpg on the highway. "I'm saving X $'s every year in fuel so I'm saving money!" Niave but arguable. The asian auto manufacturers are also notorious for bringing price wars across the pond and would be no different in this market. If they were to offer a full size truck (Titan or Tundra?) with a more fuel efficient engine package and a lower price tag.... triple threat!! There will be guys who are in the business of hauling large... and I mean LARGE, like Mark Rinker. However, I would wager to say that a very substantial portion of the 3/4 - 1 ton market would go for a 1/2 ton with the above features!! (I wonder if this could be why the big 3 haven't brought in a smaller unit. Margins of profits are bound to be higher in a heavy-duty truck?)

2:
They are running them everywhere else with pretty decent success.
It's not like these engines would have to be "conceived." And I bet that the challanges of emmisions would be much easier to tackle in an engine bay fitted with a v6 instead of a v8... cooled egr's, larger intercoolers, twin turbos or evan a supercharger/turbo mix like the VW TSI... I think the current re-tooling for a bigger engine and then back tracking to add aftertreatment hardware and gizmos isn't sensible.

Unless I'm missing something, and if I am please chime in. Thanks!:D

[baker2acre]

Yet another question mark in my hat... I just read a press release about GM's new diesel for Cadillac. It's a v6 turbo diesel pumping 250HP and 406lb/ft of torque, and get this... it's from only 2.9L!!! :eek: That's a healthy 86hp per litre and eye candy for me 140lb/ft per litre!! And It's GM!!! Not mercedes or bmw or audi or... This would power a Burb happily (or my crew cab :D ) all day long aannnndd still leave enough room for a monster size radiator and charged air cooler!! :rolleyes:

[Stlheadake]

Yet another question mark in my hat... I just read a press release about GM's new diesel for Cadillac. It's a v6 turbo diesel pumping 250HP and 406lb/ft of torque, and get this... it's from only 2.9L!!! :eek: That's a healthy 86hp per litre and eye candy for me 140lb/ft per litre!! And It's GM!!! Not mercedes or bmw or audi or... This would power a Burb happily (or my crew cab :D ) all day long aannnndd still leave enough room for a monster size radiator and charged air cooler!! :rolleyes:

A 2.9L DIESEL in a CADDY? Those are some seriously optimistic numbers! As soon as I read that, I had a flashback to the 6.2 and all the vehicles they tried it in. Interesting...bring it on!!

I talked to a guy with the Mercedes SUV TDI. I asked him how he was doing on mileage. He sheepishly said he was seeing 19 around town and only 26 on the highway. I thought for that little SUV he would surely be getting MID 30s to MID 40s like the VW.

That "new" GM diesel could give them a run for their money! Pun intended. Regarding your comment about people buying 3/4 ton trucks for the diesel when a 1/2 ton would probably do all the need it to do. I think you've hit the nail on the head!

I tow my fifth wheel about every other weekend during camping season. So I get my use. But truthfully, I have considered picking up an old diesel VW Rabbit PU. I found one locally, but it needs some engine work. I figured that I could still haul a lawn more, yard tools and the lumber I typically use with that, and still get the 30mpg city or even better.

I am still looking for that GM article about their concept car that uses a small diesel 3cyl? to run a generator. A diesel Electric car. Supposedly it has been seen at car shows. I heard about it on one of the other pages I spend too much time reading. But I haven't found any solid info on it.

Oh well, I'll quit ramblin...

[baker2acre]

The vw 1.6l NA diesel are a dime a dozen and it's likely to be only a blown head gasket. My big concern with the rabbit is rust in and around the front suspension. Not sure how your Missouri winters treat your vehicles but the salty sea air here's nasty not to mention DelDOT salts the road for flurries :rolleyes: . Upgrading to a 1.6l td maybe worthwhile while you've go the hood open. HP gets a boost (pun intended as well) to around 60-65 while torque jumps big to close to 100lb/ft? which goes a long way in a light vehilce under load. The best part is the fuel mileage should be low 40's turbo'd and mid 40's and up NA. A 5sp manual can push you into the 50's when gentle. I'd have trouble keeping the right foot of the turbo button!!:D

Are you referring to the Chevy Volt concept?? I think I saw somehthing about it too. It sounds like a really smart idea!!

I don't understand why the Mercedes line of suv's aren't doing better in the mpg bracket either. The Jeep liberty gets between 26-30!! Of course the mercedes do have gobs more go in them but only one diesel engine package for the states!! I think they get a 3L v6 this year. Interseting to see how VW's new tiguan suv based on the Jetta/Golf platform fairs in the mpg's with their new 2.0L TDI. The Toureg's 5.0L though awesome and could pull a Boeing 747 (I have a video link if interested), was overkill and only manages 22mpg. But they offer the 2.5L in line five overseas. Shame :rolleyes: .

[Stlheadake]

I'm looking for a 'project', but that one may have to wait. I have been casually looking for "just the right thing"...

I need more room. I no longer have the facilities, but I am working on that!

Ironically I just RECIEVED an update from GM about the Volt. IT seems that they are committing to having a prototype on the road BY 2010. Fairly lofty. Sounds like they haven't given up on the gas/diesel electric idea either. http://www.gm-volt.com/ with a link to Reuters deeper article.

Speaking of Gas/diesel, GM had a banner on a website that they had an ANY fuel engine that would run on gas, diesel, E85, BioDiesel, and anything else flammable. Unfortunately I haven't fount that banner again.

I'd like to know more 'bout that one!