JyRO

So fellers -

Hypothetical question here. The latest CTD (as I'm aware) is at what 325 h.p. and 610 ft.-lbs.?

Let's look at a trend here. From 12V to 24V now the ISB-E. The power has been going up, up and up. As it should to keep up with competition. But fuel mileage has been going down, down and down. Admittedly not as drastically as the power has gone up.

So here's the question: Would you rather have the next gen ISB keep the same 610 torque and improve the fuel mileage -or- continue the trend and have, say, 625 ft.-lb. sacrificing fuel economy?

Personally, I'd rather have the fuel mileage. I think 610 ft-lb is plenty (stock). And as you can see by my post the other day At seventy foe, ninety fie ole smokey stays home... the way diesel prices are doing, I'll take an upgrade in mileage.

- JyRO

mr T

the mileage has gone down thats so true...and that defeats the purpose of a diesel ...id rather have 500 lbs of torque and then have a dial where i can turn it up or a down a bit as i please...heck if im driving on the highway empty i dont need more than 300 lbs of torque! but dodge wont let the other 2 companies win the power war with the cummins...the 6oh is already backing down...its the new muscle car era horsepower (in this case torque) war...they'll have to stop somewhere or we'll all end up driving 10 000lb trucks with medium duty components to support the power reliably

ds1rider

I wouldnt mind having a cummins that competes with the 5 cyl mercedes. It is 5 cyl right?(in the sprinter)

mr T

u mean like a smaller cummins? the 4 banger cummins is plenty to beat up on the benz

Fronty Owner

Im studying for my upcoming truck and I would like to defuel it to 500 or 555 for the mileage. Its way easier to throw a box on and have the power when you need it. but when you dont need it, 22 mpg would be sweeeeett...

jkitterman

How about a chip off the old, I mean new Hemi, put the MDS on the big C and run 2 or 3 cyl.

Seriously, I would like the economy option I was playing with the Cummins Power Spec and it appears we should aim for 2150 rpm at about 65 for fuel economy and 2250 for power. It also keeps saying the same thing when I changed the vehicle from under 10,000 lbs to up to 50,000 but it is fun to play with... you can download it from their website. What we really would have to look at is the BSFC (brake specific fuel consumption) on the different HP ratings. I also played around on www.detroitdiesel.com and looked over the MBE900 engines. Would you go to the 4cyl for economy? One thing I noticed looking at the automotive applications of the VM Motori brochure was almost all the motors had the same BSFC at peak torque. I think we would just have to take a look at cutting down on rolling resistance, wind resistance and such.

ds1rider

I didnt know there was a 4cyl Cummins.

HOHN

JyRo--

You have to keep in mind that the new ISBe is beig installed into a truck that is MUCH heavier than the old 1stgen mileage champs. Sure, a '91 D250 could clear 25mpg easy. But that's in a truck that weights about 5600# empty.

My second gen weighs in at 6800 lbs-- EMPTY!

A third gen weighs, what- over 7000?

Mileage goes down for the same reason power goes up - not BECAUSE of it. That reason is people want bigger heavier trucks that can pull bigger heavier RVs.

I'd venture to say that if you put a HPCR engine in a first gen truck, with its lighter weight and tiny tires, that it would get as good a mileage, maybe even better-- while making almost twice as much power and way less emissions.

JMHO

JyRO

Hohn, I see your point, but I don't agree entirely. I bet if an ISBe was put in a 1st gen truck, it may do better than when it was in the 3rd gen truck, but I bet it couldn't match the fuel mileage of the original engine that was in the 1st gen truck (assuming both engines performed nominally).
- JyRO

signature600

Don't bet on it HOHN...I think you're finally a "bit off"

Remember, I said "think"

My truck is heavier than my friends 05 by about 800lbs, and he only gets 14 at best, I get 14-16 all the time and that's with a flatbed (not very aerodynamic, as you well know). My Uncles old 2000 weighed 8200lbs (same as mine, but pickup bed) and got no less than 14 loaded at 28K gross, and 17 empty. Also had 4.10 gears.

But, another thing to remember is what the competition had then too...the 6.2L GM/Detroit would get 20+ mileage all day long, don't know about the 6.9L Navistar. The Cummins had to be the same.

The 6.5L and the 7.3L (Powerstroke or not) would get about the same as the the later 12v and 24v.

Today, the 6.OHL gets about the same as the Cummins, and the Duramax will get what the 24v's did empty...but don't load 'em too heavy

Oh yeah, if the weight of the 3rd Gen is what did the fuel economy in, why did the Pre-600's get the same mileage as the old 24v???

Just my thoughts on what really doesn't matter to me...I drive my truck for a purpose, to do a job, and worry about cost later. As long as diesel isn't 1.5x higher than gas, I'm still coming out ahead at 12-18mpg rather than 6-10 with a Big Block.

Yeah, I know it's irresponsible to be using more fuel than I need, but it took this country WAAAY to long to figure out and implement solutions, and I'd be glad to start burning biodiesel at a higher cost if they'd offer it in my area

That's the way I see it,IMHO,
Chris

Haulin_in_Dixie

Its EPA guys.... my engine is 660 torque stock and gets good mileage. I would bet that you could advance the cam timing on the 325 and make it good on ecomony and more power yet.

JyRO

Haulin-in-Dixie - I'm inclined to agree with you, that meeting EPA reg's has contributed to lower mpg. These days I do prefer to keep this world as green as we can. But from the power we have now, I'd prefer that Cummins works to improve the mpg and maintaing the EPA standards, than push for more power while maintaining the EPA standards and continuing to sacrifice the mpg.

Sure, going against the standards may give you more of both mpg and power, but Cummins & DC don't have that option.

Looks to me that out of the 3 (EPA standards, mpg, and power) that engine manufacturers can make decent gains at generally only 2 of the 3 at one time. And 1 of the 3 is forced (EPA). My vote is to go for mpg next time, I think the power is sufficient ... I don't need to be able to pull the earth out of orbit.

- JyRO

kingofdodge7131

one thing to think about with the 600+ and the lower, the 04.5s and up have a 3rd injections even at town like speeds and idle. For epa reasons, and the general public wants there cummins to sound like a duramax. but at highway speeds it goes to a 2 injection event. One thing i would likek to kknow is what the diffrent fuel values are. Per power stroke on the engine

Next to remember. the engine is most fuel efficent at full load. What i mean by that is you get the most power or most work out of the engine for the buck, Yeah at 1600 rpm you might get 20 mpg as apposed to pullin your 5ver and getting 16, but none the less its more effecient, otherwise you waste energy in the forms of heat and so on,


If i can keep my foot out of it i can get 20 on my 04.5, Yeah i can get 22 or so with the 99.and i might drive at 60. but im fine with that. the 04 has 8k on it the 99 has 160kk when the 04 gets to 160 then ill worry

One thing that ive never figured up and i think DC may have done it. That 99 use to get 27 at 55. no kiddin. took her in one day and she dropped like nuttin. I would imagine that there was some kind of burp at the factory and they reflashed the ecu or somthing. OR i may be smokin some good stuff i dunno.


and you cant blame the "high power" being the 2nd gens were makin more than this and same mileage. Its all epa bullhookie. Gotta get hotter burns so ya use more fuel,

HOHN

Well, I overstated my point. True, an HPCR in a 1st gen probably won't equal the MPG, but I was simply pointing out that it's an apples-to-oranges comparison.

Each truck is its own beast. It makes sense that a 320hp should get less mileage than a 160 hp one does.

Yes, emissions are the single biggest reason that the MPG has crapped out. But if you think about it, it's pretty remarkable that mpg is as good as it is, given the heavier trucks, larger tires, and bigger HP of the newer trucks.

jlh

mr T

umm what about people treating their diesels nowadays like hotrods and flooring it in town...diesel trucks are in fashion and people like to drive with a heavy foot more and more too handling is so much better on the new trucks ud think ur drivign a lightning or something...back when the first gens came out i just cant picture people flooring it more likely they were taking it really easy with those trucks till u needed it to do some work....driving habits with these good looking modern trucks also doesnt help MPG's (along with everything else that was said)