cwg

i have not looked at this site in a while and i've searched and i can't find where it states what the real differences are in the 305/ 555 and the 325/ 600. i've got a 04 HO and would lke to know how upset i should be. is it the same motor?

doug

there are comments all over the board, but basically:

1. the big engineering ahievement is the 2004 NOx without EGR, but with software changes to the injection event

2. There is a CAT

5. There is an 8% increase in torque


Should you be upset? well, maybe if you intend to stay bone stock and you play numbers games (if its important to you that you have numbers larger than Ford and Chevy). Thats about it, really. 8 percent is probably "just" noticable. I once went through a calculation and showed that the new motor could sustain the same speed on a grade that was about 5 feet per mile steeper, or something silly like that.

me, I'd rather not be subject to the new emissions regs, and my 04 will be easier on my concience to put on exhaust . Only time will tell if the new injection controls are better or worse for the fueling boxes.

cwg

I knew about all of that, was just making sure that it was the same motor without any internally or mechanical changes.

doug

oh, well, there are some minor mechanical differences in the engine itself, including

1. different turbo w/ electronically controlled wastegate
2. different cylinder head
3. different exhaust manifold

other than that, its the same motor as the 03.

spots

Was there any mention of the pistons changing at all??

cwg

but that's not cool. i can't believe they changed the motor after 2 years.

doug

the only "non air" things they changed was the head. something about improved swirl due to a different piston bowl. remember that all these changes are motivated by emissions regs, so its all about NOx ,not reliability or HP. The exhaust manifold, turbo, exhaust system and the intake systems (which I didn't mention) are all about reducing EGTs apparently. Remember too that all these changes are there to support the completely different injection event design of a late fuel charge, which was there in the first place to reduce NOx. Note that these may sound like a lot of changes (esp to the air system) and all they got out of it was 8% more torque. thats a lot of hocus pocus to go through for 8% increased torque -- my point is that all those things may not necessarily benefit you as the owner, they are there to benefit DCs ability to sell engines!

now, at the same time that doesn't mean emissions motivated changes don't benefit you, make more reliable engines, etc. I'm only saying not to jump to the conclusion that the 04.5 engine will perform better or more reliably in a way that directly benefits you, except for the NOx reduction and the 8% increase in torque.

no piston changes; the engine internals are all the same, mechanically. I think there are only a half dozen or so new parts on the whole engine.

Crabjoe

I wonder what the 555 Cummins upgraded to the redesigned turbo and a 4" exhust would do? You think it might put out the addition 45 ft/lbs of torque?

spots

Thanks I guess I was mixing up newer pistons with a redesigned bowl. I knew I heard something about pistons...

Vaughn MacKenzie

Spots, the piston bowls are revised so the pistons have been changed a little and are a different part number.

The bowl is a physical part of the piston, the top of the piston, so a revised bowl = revised or new piston.

Vaughn

doug

not without additional fuel, no. The way I see it, those additions are there to cope with the consequences of the new heavily retarded fuel charge, combined with the additional fuel requried to produce the additional torque. Its a pretty big price to pay for the 8% increase and DC wouldnt' have done it unless they were required to meet emissions or deal with a seconary consequence of those changes that directly impacted emissions. It requires more air to meet the new regs. I still think it will be more difficult and/or expensive to legally bomb.

you can bet your life that some very careful tuning went into dialing in the engine/exhaust/CAT/turbo parameters on the 04.5s, and that all those new parts are all carefully designed with one primary goal in mind: NOx reduction. So I wouldn't get too worried or upset that the 04.5s have a different air system. The beauty of the 04s is that they can be modified in will still meet federal EPA emissions standards. So add air to an 04 and you'll be adding a lot better system than the stock 04.5s . I'm not yet convinced that the new 04.5 head design benefits overall fuel efficiency either. It may or it may not, I don't know. what I do know is that it benefits NOx emissions!

I admit its tempting to think of the 04.5 changes as a better platform upon which to bomb, or for a more reliable stock truck. I just dont' see it that way -- I'm more likely to see them as a necesary consequence of the new emissions targets, not something that benefits me directly. I'm no engine designer, but I'm tempted to think that the 03-04 platform itself will be the "one to bomb" looking forward. It was designed as a platform upon which to build the emissions-freindly end product and has the greatest flexibilty. from 04.5 onward, I'd suggest that bombs will be more difficult and/or more expensive as they deviate from the basic 03 platform engine to meet ever increasing emissions standards pressure.

doug

thanks vaughn for clarifying what the piston bowl is. So that makes better sense, in that they changed the head and the piston bowls together to optimize the design for the target goal.

spots

Thank you for clearing that up for me.

cwg

thanks

Vaughn MacKenzie

You're welcome y'all

While on this subject I was thinking of something today. . . since Cummins puts together such successful engine packages they have the ability to tweak, revise and make refinements and meet emissions challenges, while Ford/Navistar has to exhaust so much resources just trying to make a diesel that runs.

The fact Cummins pulled off the emissions thing *without* EGR is no small feat. The DuraMax and 6-liter PSD are far newer engine designs yet they have EGR and catalytic converters for 2004.5. The basic Cummins B-series which has been around almost 20 years marches on with refinements and leads the way technologically.

Vaughn